# Question
Title: How to analyze auditory steady state responses?
How does one usually go about analyzing the auditory steady state response (ASSR)? I have data where speech was amplitude modulated to a 40 Hz sine tone. There's 3.5 minutes of data; should I just take the FFT or do some averaging first? What is the usual process? The data has been already preprocessed.

# Answer
> 1 votes
ASSR analysis is based on the fact that the electrophysiological responses are time locked with the stimulus repetition rate.

There is not one possible method of analysis. Generally spoken, ASSR analysis occurs in the spectral domain, and specifically the frequency of the stimulus repetition rate is analyzed, as well as its harmonics. For example, if the stimulus repetition rate is 100 Hz, the ASSR will occur at 100 Hz, 200 Hz, 300 Hz *etc* (Fig. 1). The base frequency (in this case, 100 Hz) will have the largest amplitude, and the harmonics decrease in amplitude. Detecting the presence of ASSR in the spectral domain means relying on amplitude and/or phase values (sometimes combined into a vector).

Fig. 1. ASSR base frequency and harmonics. Stimulus rate was 90 Hz. source: The Hearing Review

**Sources**
**-** The Hearing Review, November 2007
**-** Audiology Book (in Dutch)

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Tags: eeg, hearing, electrophysiology, signal-processing
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# Question
Title: What is the closest scientific branch to cognitive science?
I was thinking about studying this awesome science but, unfortunately, it's not being taught anywhere in my country (Czechia). What is the closest scientific branch to cognitive sciences?

# Answer
As @Lucianopaz said in his answer, this question is very broad and depends on what area of Cognitive Science you are interested in.

Cognitive Science is an "umbrella term" or a "collective term" for many different sciences.

As the link I provided says, there are 6 main sciences within the collection;

* Philosophy
* Linguistics
* Anthropology
* Neuroscience
* AI (Artificial Intelligence)
* Psychology

but within those sciences there are branches.

Take Psychology for example, and you could specialise in Social Psychology, Behavioural Psychology, Criminal Psychology... the list goes on.

You need to work out what interests you within this collection of sciences to work out what you want to study in college and university.
> 1 votes

# Answer
I think it depends on what you find particularly interesting in cognitive sciences.

I think that if you are drawn to learn about human behaviour, emotion, learning, and other aspects of human cognition on an abstract level, then Psychology may be the best branch for you.

If you are interested in the neural-side of the matter, i.e. how a bunch of cells can organize and give rise to function, then you have a broad set of branches to look at. Biology is the most thematically related, and it studies the brain at several scales, from molecular biology that aims to understand gene-expression/regulation, the involvement of different proteins, neurotransmitors or other compounds in brain function, to ethology that studies how living organisms behave.

There are also other scientific branches that are becoming more involved in neuroscience such as computer-science, mathematics and physics, however the core of these branches is farther away from cognitive science than Biology and Psychology. Again, your question is mainly opinion based and it strongly depends on your particular inclinations.
> 0 votes

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Tags: study-cognitive-sciences
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# Question
Title: Can we truly random choose which finger to raise by counting to 10 in your mind?
If a test person is asked to raise one of his 10 fingers at a given signal, is the choice truly random if he counts in his mind from 1 to 10 and associates with each number one of his fingers? The 1 he associates with the left pink, the 2 with his left ring finger, 3 with his left middle finger, etc. So the test person starts to count, the experimenter gives him a signal, after which the test person raises the finger associated with the number he arrived at while counting. Let's suppose the signal is given at a random moment. Is the choice "in sync" with the random signal given?

In other words, if the experimenter records which finger is raised after each of a 1000 signals are given to a single person, will the experimenter see that each finger is raised the same number of times (more or less, because the number of signals given is finite; the more signals, the better you're getting at the real distribution)? So in the case of 1000 signals given to a test person will the experimenter record that each finger is raised about 100 times?

Or does the test person not make a choice at all?

# Answer
> 3 votes
I think your question ultimately is about whether people can or are able to behave like a uniform random number generator drawing numbers from 1 to 10. I don't think the fact that the participant needs to raise a finger changes things much.

Note that there is a distinction between what people do, and what people are capable of. A lot of research suggests that people are not very good at simulating randomness. That said, one can think of strategies that would allow a person to simulate randomness more effectively (e.g., drawing on sources of random information in the environment, or even applying a formula similar to that used to sequentially generate numbers using random number generators).

The broad question has already been posed on the site: How well can a human-generated "random number" be predicted?

I also note that a participant could just report sequentially 1,2,3..., 10, 1, ... This data would show 100 of each number for 1000 signals. Of course, this would exhibit structure that would not be present were each trial independent.

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Tags: decision-making
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# Question
Title: How can I create computer based psychology experiments using OS X?
I've used E-prime to create computer based psychology experiments (you know, the kind where you for example show a number of pictures to the participant and record their responses to them, for example keypresses) for Windows. However, I'd now like to create similar experiments in OS X.

If I search Google for this, I find a couple of different hits but it's hard to evaluate the quality of these programs. What's a good program to use for this purpose?

# Answer
My research group has gone pure python for coding experiments; we've been burned too many times by glitches and implicit behaviour in boxed experiment-building software to bother trusting it. Moving from a point-and-click experiment design interface to pure code does have a large learning curve, and you want to be careful to model your own code on well validated code from others (esp. for ensuring that you're implementing timing properly, which can be nuanced).

It may be tempting to hire CS students to code your experiments, but the danger there is they don't come to the table with the same experimental design background as you do and we've encountered some implementation errors as a consequence (ex. failing to check for input during dead time between stimulus presentation, etc).

While I recognize and indeed support the push to specialization in cognitive science, I do think that in the same way that we require all researchers to have a bit of background in statistics, we should also require all researchers to have a bit of background in coding, not least because it helps engender a mindset amenable to considering formal models of mind.
> 22 votes

# Answer
I would recommend Matlab and the Psychophysics Toolbox. It lets you display all sorts of stimuli in full-screen mode, and it lets you capture key strokes and mouse clicks.
> 13 votes

# Answer
*OpenSesame* is a recent entry that is cross-platform and seems to promote GUI-based design while allowing customization via Python scripting.

It can be found at their website (link above). A recent article has references and summarizes 16 other tools as well (including some reported in the other stackexchange responses). I found great video tutorials and the interface to be friendly and easy to use.

It seems to not yet provide included ways of networking experiments (e.g. for yoked experiments or multi-subject games), but I suspect you could add this in with the custom Python scripting. For simple stimulus presentation and response tracking, I found it worked great and allowed rapid development. I wrote the experiment on my Linux machine and deployed for subject testing on Windows machines with no problems.
> 8 votes

# Answer
I use Adobe Flash. My colleague Yana Weinstein has written a book on Flash Programming for the Social & Behavioral Sciences that should be out next month. I'm a contributor and helped write some of it! Check it out by clicking here.
> 6 votes

# Answer
Another option is to program in C/C++ using the Tscope library. If you're not experienced with programming, it's a bit tricky at first, but I'd say it pays off in the end.

> Tscope is a C/C++ experiment programming library for cognitive scientists. It is distributed under the Gnu Public License, and is intended to run on Windows 2000 and XP platforms. It provides functions for graphics, sound, timing, randomization and response registration. Restricted Linux and Mac OS X versions are also available.

The introduction page gives a broader overview of features.
> 6 votes

# Answer
Great question. There are two software packages that might be interesting to you:

1. I have tried to run EPrime in a virtual machine on my Mac and it was a catastrophe. As I found out it used to work, but some of the later updates made it impossible. In the process of figuring this out, I came across PsyScope X. It is an actively developed open source alternative for EPrime on the Mac and, apparently, even the collected data is somewhat compatible to EPrime. If you are interested in the importing of PsyScope-data into Eprime see the EPrime-FAQ.
2. However, agreeing with Mike, I felt like I needed more flexibility and control for my recent experiment and turned to LiveCode, as it was recommended to my by a neighboring department. It is a high-level programming language similar to VisualBasic but the language is very English-like and the software suite is quite cheap. What I particularly like about LiveCode is that you can program on your Mac and create Executables for Mac, Windows, Linux, and even iOS and Android if necessary. I collected all my data on Windows machines and there were only very minor compatibility issues (such as native fonts etc.). I would recommend LiveCode as the learning curve is not as steep as that of other languages and there is a great documentation with (video) tutorials and a responsive community happy to help.

Also, for a further overview of behavioral experiment software refer to the Wikipedia comparison page.
> 6 votes

# Answer
You should consider SuperLab. It runs on Mac and Windows.

It uses a point-and-click user interface that makes it really easy to setup experiments. Even "programming" contingencies are done via point-and-click.

Disclaimer: I wrote the original version of SuperLab and I work at Cedrus, its developer.
> 5 votes

# Answer
It has been a while since I asked this question, but I've tried out PsychoPy as some people suggested in the comments, and so far I'm really digging it. If you want you can use only the GUI to create your experiment, but if you're doing more advanced stuff you can export the code and start digging around in it.

As a bonus, it's also compatible with all major operating system, that is: Windows, OS X, and Linux.
> 3 votes

# Answer
It has been a while since the question was asked, but I am going to give my answer anyway. PsychoPy is really good and easy to use and is what I typically recommend people to use.

However, I recently found the Python library Expyriment and it seems promising. Although you will have to write your own code there are available methods for creating the window, presenting a fixation cross, and so on. A plus with this library is that you can also code experiments for Android devices (and, of course, Windows, Linux, and OS-X).
> 3 votes

# Answer
As of version 4 Inquisit has Mac support. See this announcement. You can run experiments locally or over the web. It is a commercial product.

To quote the website:

> Inquisit is used by behavioral scientists throughout the world for creating and administering numerous cognitive, social, and neuropsychological measures. Now in use in over 1077 research institutions throughout the world.

The Mac support was only introduced in early 2012 so I imagine there will be a polishing process. I've used it many times. I wrote up a few introductory notes about Inquisit.
> 2 votes

# Answer
As a further plug for PsychoPy (I'm the author so I'm a fraction biased) see also the independent data collected by Vic Ferreira and Brendan Tomoschuk (at UCSD, neither of whom I've met): http://lpl.ucsd.edu/software-survey-results summarised neatly by kindredChords

https://cogsci.stackexchange.com/a/16662/9955
> 2 votes

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Tags: methodology, experimental-psychology, software
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# Question
Title: How does the brain use old information to make new connections?
I assume that if my brain forms a new connection (registers a new information), it can't really know "where does the new element stand in the system of things". Nonetheless, it is being said that information is useful even if you forget it.

Let's say I would learn how photosynthesis works (not the words itself) when I'm 5 years old and forgot it (at least the conversation about it) since. Is it possible that the brain somehow brings the knowledge up when I'll hear about it in school ten years later?

I think I need to learn about the basic "remembering algorithm" brain generally used. It seems weird to me that the brain would automatically find the exact same neurons where the information had been stored before.

In other words: How does the basic architecture of the brain work so that the "consciously forgotten" information (in the sense that we cannot consciously recall the information) still be useful?

# Answer
> if my brain forms a new connection (register a new information) it can't really know "where does the new element stand in the system of things"

There is a lot of contention on the specifics, what we have are theories of Memory and Information processing in the brain, and as such nothing I am going to mention is settled.

In a nutshell, there are 2 main overarching themes into how the brain processes environmental information: ***Maps and Hierarchies***, perhaps the most researched map is that for vision or what is know as a Retinotopic map this is a simplification,there is a lot of processing and multiple overlapping maps ( movement,orientations,color),***1*** the Hierarchy part comes into play as the outputs of these primary maps combine to make more novel maps like edges and shapes, other parts of the brain in turn connect these primary and secondary maps into higher meaningful percepts, perhaps the most striking feature, is that you recreate the original pattern as you remember, that is the neurons (or a subset) that fired when you first experienced something, fire again when you remember it for a second time***2***.

This scheme more or less repeats through the brain with a number of specializations***3***, we devote a lot of real state to vision,social behavior ( maps and hierarchies of how to behave in public and what other people are thinking), language ( maps and hierarchies of words and meaning or a mental lexicon), as well as personal history (all the people that have wronged me, my favorite food), and finally, we have areas devoted solely to the association of other areas, a map of maps and a hierarchy of hierarchies with temporal buffers.

This was a whirlwind overview of how we believe information is organized, but it does not answer your question since I have mostly neglected mentioning how the information is stored and retrieved, that is mostly the domain of memory.

Memory is not a unitary concept and by that I mean that there are a lot of behaviors that are bunched all together into the word memory ( there are around 11 different types for instance)***4***, I am skipping much of the details that are not relevant, but we believe that the following mechanism is at play for the type of memory you are describing:

When you experience something, besides direct access to your primary processing maps and hierarchies, an extra or a number of extra copies are generated and routed through a switchboard, ( the Hippocampus and related structures), it is in this switchboard that the interconnections necessary for associations are first generated, and later through a process of selective repetition, the relevant ones are preserved and eventually consolidated closer to your primary maps and hierarchies.***5***

> Is it possible that the brain somehow brings the knowledge up when I'll hear about it in school ten years later?

Yes, the specific phenomenon is called priming, granted, in light of the previously discussed models, It will depend on some variables, was the information stored originally in long term memory, has there been interference from other more recent memories, how much time has it been.

> It seems weird to me that the brain would automatically find the exact same neurons where the information had been stored before.

Yes, it is amazing, the information finding happens due to the organizational scheme previously described and another phenomenon called plasticity or synaptic plasticity, this last part utilizes the connective weights in between neurons to both preserve ( connections with higher weights get preserved) and then finding related connections ( through a path of least resistance in between neurons with high weights). Additionally, long term memories utilize other strategies and optimizations and there could be further temporal and functional aspects to encoding,storing and retrieving. ***6***

> In other words: Can the totally forgotten information still be useful?

Yes,provided the information was encoded and stored originally,even after years of non use, there is evidence that a priming effect might still be available.

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*Notes, reference & sources:*

**1.** For an early look at Hierarchies and maps I think Vision (Marr) is a good introduction, Vision science (Palmer) has the full overview.

**2.** This one fact deserves more attention, a good overview is found in Cognitive Science (Gazzaniga)

**3.** Neuroscience (Purves) & Cognitive Science (Gazzaniga) both deal with how the neocortex subdivides and specializes.

**4.** Cognitive Science (Gazzaniga) has a great overview of Memory and The Oxford Handbook of Memory (Tulving,Craik) is a comprehensive bible of sorts if slightly outdated.

**5.** Gateway to memory (Gluck, Myers) has a very readable and detailed overview of the hippocampus, Rythms of the Brain(Buzsaki) expands it.

**6.** In search of Memory (Kandel) deals with plasticity at length.
> 3 votes

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Tags: learning, memory, semantic-memory
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# Question
Title: Can an external stimulus change the way your dream ends?
I sometimes have the experience that because of a thunder or some other kind of loud sound my dream ends in a way that seems to match with the loud sound. For example, the loud sound of a nearby thunder translates to something making a loud noise in your dream, after which you wake up.

# Answer
> 5 votes
I don't know any scientific evidence of it, but I personally have experienced it many times. I have come to think that it is due to the decreasing depth of sleep. You may know that sleep progresses through different phases. I've read that you only dream during the light sleep phases , or at least you remember to be dreaming during theese phases. Hearing sound doesn't affect the end of your dream , your brain reacts to the sound with including it in it's own way to your dream at anytime , you just think it's the end of the dream because in that case it wakes you up but your brain does this all night long !

I've already head my alarm ringing in my dreams and it took me several minutes to find out it was realy time to awke up , and not just a background music !

Sorry if it's not scientific enough for you but it seems pretty "normal" to me ^^

**EDIT :** It seems like people are still trying to prove it but they're convinced it's true : Check this studies results

During the study they observed an impact but due to their lack of technical language the subjects couldn't describe with enough details the impact of internal stimuli on their dream , but new tests will be done with subjects trained with technical language.

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Tags: dreams
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# Question
Title: Do neurons fire at a faster rate during dreaming?
When I dream it seems that the (subjective) time is slower than the objectively passed time as seen on my clock radio. Is this because neurones fire collectively at a faster rate, so you can "put an hour of dream time in a minute of objective time"? If they fire at a faster rate, then this does not mean that you perceive the events in your dream as going faster, as you adapt to your experience of time in the real world.

# Answer
In REM sleep, the EEG is remarkably similar to that of the awake state (Purves *et al*., 2001). Although the EEG represents the *synchronized activity* of many neurons in the cortex, it does give us a clue whether they are firing faster or not.

Wakefulness is mainly dominated by beta and gamma waves (source: Scholarpedia), i.e. 12 - 100 Hz. REM sleep is characterized by low-amplitude mixed-frequency brain waves, quite similar to those experienced during the waking state - theta waves, alpha waves and even the high frequency beta waves more typical of high-level active concentration and thinking, i.e. 4-30 Hz (table 1) (source: Sleep).

Table 1. EEG bands. source: Neurosky

So if anything, I would say REM sleep, being largely devoid of the gamma band, is associated with slightly lower-frequency oscillations and hence lower neural activity overall.

**References**
**-** Purves *et al*. (eds). *Neuroscience*. 2nd ed. Sunderland (MA): Sinauer Associates (2001)
> 5 votes

# Answer
> Is this because neurons fire collectively at a faster rate, so you can "put an hour of dream time in a minute of objective time"?

I believe it has more to do with what information becomes available to the association cortex and ncc (or consciousness) in the waking/sleep brain.

In the waking brain the neocortex is connected to the environment, so things tend to progress smoothly and for the most part we have contextual references to measure the passing of time,in sleep there is a varying degree of a disconnect both internal and external culminating in REM sleep, where thalamocortical connections (a switchboard/router for the senses) are at it's lowest, so cut off from the environment an cues, the thalamus- neocortex interplay stimulates only neocortical areas ( presumably those recently active through interplay with the hippocampus ) which in turn activate related areas through plasticity. So you could be in one scene where the only measurement of time is internal followed by another one without, the passage of time thus becomes hard to gauge. ***1***

The firing rate specifically as it pertains to cycles I believe is a wrong measure to focus on, for one, even in the waking gamma ( 30 \>htz ) we top at something like 24 fps comprehending a scene and it takes about 200ms to bind information***2***,there is little to no information ( although if I am wrong please point it out), that we increase our comprehension and perception rates as information presents itself faster, rather we drop frames, and so even at a faster rate the information available to consciousness in the sleeping or waking brain seems to be capped.

*Notes, reference & sources:*

**1.** An excellent and readable overview of dream and it's data components is : The Secret World of Sleep (Lewis).

**2.** Rhythms of the brain (buzsaki) deals in depth with EEG measurements as they relate to information exchange in the brain. In search of consciousness (Koch)looks at the binding problem and ncc in detail.
> 2 votes

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Tags: sleep, dreams, neurophysiology
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# Question
Title: What is the term for two mutually exclusive, contrasting emotions
I am a psychology student and I vaguely recall a term being used to describe two emotions that cannot be expressed simultaneously. The example was fear and relaxation in terms of Systematic Desensitization. Can anyone help me out with this? Many thanks in advance.

# Answer
In terms of systematic desensitization, you're thinking of **reciprocal inhibition** (see, e.g., Wolpe, 1954).

For what it's worth, beyond this literature, there's a general debate about whether positive and negative affect can be experienced simultaneously. (Indeed, *Emotion Review* just published a series of articles about this.) It's fair to say that the debate has not been resolved.
> 1 votes

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Tags: cognitive-psychology, emotion, terminology
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# Question
Title: After how much time should we review a particular study material after once studying it thoroughly so as to retain it longer?
I am having some doubts regarding my study regime; I am wondering if psychology could help?

So,I studied this one chapter thoroughly and due to shortage of time, I didn't review it for another 2-3 weeks. When I sat down to solve the related problems after 2-3 weeks, I didn't have that confidence anymore and I faced difficulty in attempting the problems that I was very comfortable with 2-3 weeks ago.This happened many times and it is spoiling all my hard work and is affecting my grades.

Is there a specific time interval after which you must review things after first learning them so that you can retain them longer?

How many times should I review it before I could remember it for an extended period of times(at least 5-6 months) ?

What percentage of a particular study material could I forget after not reviewing it for 2-3 weeks?

How much time does our brain take to forget things?

I know that it is always easier to learn a material second time than it is to learn for the very first time. It is because every bit of that information is somewhere stored in our subconscious memory. But, still how much time it should take for me to gain the same amount of confidence about that chapter as I had a couple of weeks ago?

# Answer
Memory is a complex phenomenon with a number of variables for which we don't have yet the whole picture, let alone specific recommendations, a lot of research is also disputed since we tend to be different from human to human, perhaps that is why it hasn't been used in academia,i.e. we don't teach how to learn. Having said that here's a brief overview of your situation.

The first step is information encoding, a number of variables are at play here, but in short: "*The retention of briefly presented information depends on past experience,context, and it's perceived importance*"***1***, very little information is new ( you are not re-learning the periodic table every time you are presented with a new molecule), rather you are learning a new association and your physical situation (like where you are, distractions, motivation,emotional state, stress levels) influence the process.

The second step is information consolidation, that is transferring your newly formed associations from a short term memory to a longer term storage, a continual process. Any new conflicting information will negatively impact this first short( day to day) to medium (weeks) bridge.Sleep: (non REM,slow wave or even naps) after information encoding seem to be both critical and helpful at this stage, diet,stress levels and lack of sleep work against this process.***2***

> Is there a specific time interval after which you must review things after first learning them so that you can retain them longer?

**Caveat emptor**: A quirk of human memory, specially during early consolidation, is that retrieval ( or rehearsal ) alters the state of previously stored information, so an incorrect rehearsal session has the probability of affecting you previously well formed memories.***3***

Beyond that and previously mentioned variables, the consensus seems to be:

* Rehearsals are only effective if they involve successful retrieval, in other words, if you can't remember the lesson, you are mostly at square one***4*** and need to relearn.
* Number of successful repetitions (rehearsals) increases chance of recall.
* The optimal spacing strategy is as far apart as possible.
* Each successful retrieval/rehearsal gives you a cumulative bonus.

> How many times should I review it before I could remember it for an extended period of times(at least 5-6 months) ?

Memory in general stabilizes 3 to 5 years after the acquisition period***3.2*** ( so as many times as possible during that time based on the above recommendations seems reasonable) with the emphasis that (another memory quirk) in a process similar to how it is originally stored and rehearsed for consolidation, it becomes easier to recall something as you try to retrieve it.***5***

> What percentage of a particular study material could I forget after not reviewing it for 2-3 weeks?

Depends on the aforementioned initial encoding and subsequent stabilization plus the particular study material, ( is it a list of elements, a concept, a multi step process).In general memory tasks with unique multivariate associations (mnemonic devices for instance) fare better than less complex or even similar/competing memories. So each particular study material is expected to have a different forgetting curve in specific circumstances. Ebbinghaus forgetting curve which skirts these issues and a lot of newer research non the less can still be considered a good general estimate and starting point for how memory fades:

The plot is exponential, which means that the initial conditions greatly influence future retention rates, ( *I've used a mix of subjects/conditions for an average*), **But** as mentioned your starting point and specific situation can greatly influence memory strength (your exponent over time ), so under bad learning conditions, no interest on the subject and a very hard to discern subject matter, your curve would look like this:

I am leaving aside flashbulb memories (aliens landed during your study session !, good luck thinking about anything but aliens for the next 3 weeks!), which are a separate topic and do not seem to obey normal memory consolidation rules.

> How much time does our brain take to forget things?

As mentioned the initial conditions are critical and influence the process, there is a period of consolidation (more variables) which further influences consolidation and then one of relative stability, this period in a general simplified way looks this:

So you get a nice long sub exponential tail thanks to long term consolidation.

Just a quick note before wrapping up, in general people are overconfident, specially at the high end when it comes to memory retrieval ***3.3***.

> how much time it should take for me to gain the same amount of confidence about that chapter as I had a couple of weeks ago?

Due to all the above variables, it is hard to give you a definitive answer, beyond the obvious one that 2-3 weeks under your initial learning conditions are inadequate and you will have to relearn (albeit you will be doing it a slightly faster rate), there are a number of strategies for sequential learning that pair our basic understanding of memory into a studying regime, here is one such strategy:

This is an oversimplification, in order for you to answer your own question, you need to standardize your learning environment and subject matter in as much as possible (don't forget to adjust for overconfidence), come up with your own decay rate and then plan your studying regime based on your learning curves which would need to be updated as you relearn and specialize, sounds like a lot, but it's basically jotting down a couple of numbers and perhaps the hardest part making sure you have the correct learning environment.

Finally, I haven't talked about learning aids, the effect of mnemonics as well as other strategies is well researched and I believe can be beneficial to anybody,specifically students, but I believe it should be used as a sort of extra boost rather than a foundation for learning. (i.e. An understanding of the material should come first) Use at your own risk.***6***

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*Notes, reference & sources:*

The overarching note is that memory research stands in stark contrast to most academic programs and learning environments, practices and popular myths.

**1.** Neuroscience (Purves)

**2.** The Secret World of Sleep (Lewis).

**3.** The Oxford Handbook of Memory(Tulving,Craik) **3.2** Strictly speaking there are a number of other variables that influence memory stability, a high emotional context for instance seems to solidify them earlier. **3.3** Not trivial either and something like 20% of errors can be observed in high confidence reporting.

**4.** You still have the benefit of the priming effect and other temporal benefits, so it's not all wasted, you can catch up faster.

**5.** What is sometimes called Spontaneous recovery.

**6.** Your Memory: How it works and how to improve it (Higbee) has a lot of useful advice aimed mostly at students.
> 3 votes

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Tags: brain-training
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# Question
Title: Awareness of unconditional positive regard
When Unconditional Positive Regard is in use through several therapy sessions and a client asks about this technique. What explanation should be given?

# Answer
Unconditional Positive Regard is one of the core conditions in Person Centered Counselling and so is congruence.

In order for you to provide Unconditional Positive Regard (UPR), you need to be congruent and in order for you to be congruent you need to be genuine in your responses. Therefore, you should only provide the truth to any question asked.

You need to tell them what UPR is and that in order for UPR to exist you will be non-judgemental and you would provide a safe and warm environment for them to explore what is troubling them in the here and now.
> 2 votes

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Tags: cognitive-psychology, clinical-psychology, positive-psychology, person-centered-therapy
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# Question
Title: How do we explain that some humans require far more evidence for some claims than others?
Tell people that God says something and they believe.

Tell people that the paint is wet and they have to touch to believe.

If I ask people if God really made http://thegoodlordabove.com/god-talks-several-trump-supporters-need-safe-space/ people would laugh at me.

If I ask people if God really made the bible or send prophets, many will stone me for even asking their sacred beliefs.

Why?

Is fear of authority or instincts to obey the authority, or lack of personal cost of being false makes people easily believe things?

The bible and quran, for example, carries tons of authority and tend to support status quo. People would at least have incentive to pretend they believe. A wet paint doesn't. Or what?

What are the explanations?

# Answer
There are at least two important factors or phenomena at play here. The first is whether the subject of the belief has real-world **consequences to the believer**. The second is whether the belief relates to **groups to which the believer associates** or belongs.

When a person's belief on a particular matter makes no functional difference to that person, he or she is free to believe whichever or whatever way without gain or loss. In this sense, it is easy for a person to criticise others for doing something a certain way when the person doing the criticism is not in the business of trying to accomplish the same goal. A person might complain, for example, that company X would be more successful if they focused on product Y instead of product Z. Having this belief is inconsequential to the believer since he or she has nothing to gain or lose from being right or wrong. A similar occurrence is when a person believes something to be dangerous without real evidence, as for example the consumption of GMO foods. Whether GMOs actually hurt you is irrelevant to a person who eats strictly non-GMO organic foods. Granted the person has no shortage of money, the accuracy of this belief makes no functional difference, so there is little if any incentive to be honest about the actual safety record. For a person having barely enough money to buy food, on the other hand, the actual safety record of low-cost foods is much more pertinent and important since the decision makes a substantial difference in financial burden. It is easy for a person having ample money to make the claim that expensive items are substantially safer and more effective. For a person with limited funds, the truth of the matter is far more important.

In the case of **wet paint**, if there is a risk to the person of getting the paint on his or her clothes, then the person is likely to see real consequences in the reality of the matter. Hence, there is little room for carelessly choosing a belief -- **the truth has real consequences** to this person.

A person's affiliations and group identity may be given high priority, especially when a person stands to gain from that association. **Any attack or perceived attack on the group or its collective beliefs may be taken as an attack on the individual. The group may be seen and felt as an extended self**. A person having no such association or feeling toward a group or its beliefs is not likely to be much offended or protective of those beliefs. Hence, he or she is free to consider their truth or falsehood. Someone whose life and well-being depend on that group or set of beliefs, on the other hand, is not going to take skepticism lightly since it poses a very real threat. In this sense, the situation is similar to that mentioned above about consequences. If a person depends on a group or belief-system for material or emotional well-being, then any attacks on that group's reputation or status may harm the person indirectly.

Naturally there is a third factor where certain religions impose or threaten **penalties for those who do not defend the religion** and its beliefs. In this case, a true believer may protect the group and its beliefs purely out of fear for said consequences.

To answer your main question more directly, those for whom knowing the truth is more consequential will require greater evidence than those for whom knowing the truth is irrelevant or even harmful (whether materially or emotionally). A person dependent on a group for material or emotional support is more likely to believe in that group and its teachings, regardless of the truth.

On a side note, even science can be seen as a group identity these days, from which we can expect that some individuals would derive emotional or material well-being. Having an emotional stake in science would make a person require more evidence to the contrary before considering a religious perspective. Unfortunately, this type of group identity can blind individuals on both sides of the science/religion debate, among other debates (politics, GMOs, et cetera). Ego and emotion, when left unchecked, can be very harmful.
> 2 votes

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Tags: religion
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# Question
Title: How does timing of pleasure / dopamine / reward influence the formation of positive association?
Suppose the following idealized experiment:

**Setup:**

1. A pill/medication which simply induces pleasure. Perhaps something like a perfect dopamine antagonist with no side-effects. Call it *P*
2. A task which is to be trained. Call it *T*. (Assume that *T* is not intrinsically pleasurable or unpleasant, and has no unpleasant associations for the subject)

**Goal:** The subject of the experiment is to be introduced to *T* in such a way that reinforces the "enjoyment" of *T* and the desire to again do task *T*.

Variables: *P* can be administered any time -- before during or after -- task *T*.

**Question:**

* a. Is there an optimal time to introduce *P* to facilitate the development of the desire/interest/motivation to do task *T*?
* b. Is this even possible if the subject knows that *P* induces the pleasure?
* c. Even if pleasure and *T* are then linked, is it only under the assumption that *T* leads to pleasure, and thus if *P* is no longer present, the interest in *T* will wane?

# Answer
> 0 votes
i will offer an answer to this, because i don't believe this is homework. see next comment below:

> Perhaps something like a perfect dopamine antagonist with no side-effects. Call it P

no, let's call it an antipsychotic. perhaps P stands for prochlorperazine. i think you mean dopamine *agonist*. dopamine antagonists invoke what could best be described as a chemical lobotomy, and are antithetical to any notions of motivation, salience, achievement, or reward.

> a. Is there an optimal time to introduce P to facilitate the development of the desire/interest/motivation to do task T?

yes -- immediately once the desired behaviour has been undertaken successfully. with some interesting exceptions e.g. food poisoning, the shorter the latency between any behaviour and its consequences, the stronger the association between the two will become apparent to the individual. think of it as a "theory of causality" -- the shorter the latency, the more confident we become that the behaviour caused the outcome.

this is why the route of administration of a drug has a strong influence upon an individual's susceptibility to addiction, or to put it another way, motivation to consume the drug again. smoked or IV versus oral administration. conversely, it's much harder to engage in behaviours that might be beneficial to us years down the track because we have less confidence that engaging in that behaviour will result in the desired outcome.

> b. Is this even possible if the subject knows that P induces the pleasure?

yes. however, if there is no intrinsic motivation to do the task, it will be much harder to facilitate the desired behaviour in the absence of the reinforcer. if you only did something because of the outcome, and not because you found some inherent enjoyment from it, after a while you might start thinking about other behaviours you could engage in to attain the same outcome.

in the case of our fictional substance P: sure, i could keep doing what you want me to in order to obtain it. but in engaging in your task as simply a means to an end, i might start to consider more direct routes to that same end. for example, i could steal the keys to your medicine cabinet. or place a blood-filled syringe to your neck and tell you to hand it over.

> c. Even if pleasure and T are then linked, is it only under the assumption that T leads to pleasure, and thus if P is no longer present, the interest in T will wane?

yes. here, new learning takes place: the individual has now constructed a new theory of causality. whereas once upon the individual learned that engaging in T offered access to P, it now no longer does.

i would go so far as to argue that if one was not aware of the presence of P, one's interest in the task would persistent for far longer a period, and perhaps indefinitely. "perhaps i'm not doing the task correctly... i know, it's because i've had a lousy week... " etc, etc. one might even start engaging in superstitious behaviours in the belief that it is this superstitious ritual that influences the likelihood of the reward.

in order to "slow down" this new learning (extinction), it would be important to ensure that the reinforcement of T with P is not 1:1. the more tightly a behaviour is linked to an outcome, good or bad, the more one expects the outcome to occur when they engage in that behaviour. when the outcome is now absent, the more apparent it is that *something* about the behaviour -\> outcome relationship has changed.

to understand how this works, read into the relationship between different reinforcement schedules and rate of extinction. also read into the phenomenon of spontaneous recovery.

now, you will need to excuse: my motivation to continue typing has now waned, and in it's place, a desire to go get high.

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Tags: experimental-psychology, motivation, habituation, dopamine, reward
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# Question
Title: Can experience alter one's preferences for beauty?
My friend (a woman) is convinced that **all men who find those posters of "women scantily clad in their bathing suits or thongs and big breasts (often fake)" *attractive*** are simply brainwashed by society.

I told her I disagreed. I told her that her experiences with a previous boyfriend (who was ugly, chubby, but she loved him dearly) had radically changed *her views*, such that *she* was the outlier, not "everyone else". What the average male thinks of those posters is the *default* genetic predisposition that males have towards women -- we tend to look for big breasts for breastfeeding our children, good WHR, typically healthy-weight (toned,not excessively fat but not crazy skinny either) as an indicator of overall health, etc.

Is there any literature on:

* Whether experience can alter one's perception of attractiveness (i.e. over time x women you find hot will no longer be attractive to you). Note, I certainly think this is true, but I never learned about it specifically in psychology so if anyone know's more that'd be awesome
    + If experience can alter this perception, to what extent?
* Whether the average person is "brainwashed" into thinking that the not-entirely-natural (makeup, breast implants, etc) women on TV are attractive.

# Answer
There are many reasons why men may find 'not-entirely-natural' women more attractive.

One reason, perhaps obvious, is simply based on evolutionary preferences. A rosy complexion may indicate good health, whereas larger breasts may signify fertility. Whether fake or not, women use makeup and surgery to accentuate features that men already find attractive. Though it is true that some women may accentuate features to the point of unrealism, it is worth noting that aesthetic reactions are established prior to one's cognitive appraisal for attractiveness \[citation needed\]. The mechanism in our brain that judges instantaneous beauty is likely not privy to information such as 'that woman in front of me has fake breasts'.

That being said, I think a better answer to your question relies on the notion of fluency--the metacognitive experience of difficulty associated with any cognitive act. Familiarity fosters high fluency, because our mind processes familiar things more quickly or easily than novel things. Several studies have shown that familiarity or fluency leads to an increased rating on any number of positively valence dimensions, including likability and attractiveness. \[1\]\[2\] (As a side note, it's also interesting that the reverse is also true-- attractive faces are judged a more familiar \[3\]).

The media certainly plays a large part in increasing this familiarity through what we see on TV and in magazines. Different cultures develop different cultural norms for attractiveness as a result of their exposure. The same effect is frequently observed in people who are attracted to others of the same race. This preference is shown even in young infants, as a result of increased exposure to faces of their own race. \[4\]

Lastly, the 'message' conveyed by media likely influences our perception of beauty as well. Ads tell us that we have to constantly use the right shampoo, or diet supplement, or facial cleanser-- pressuring us to believe we won't be beautiful if we don't use these products. The message is not cryptic-- products often reference the 'healthy' or 'attractive' effects of their use. Perhaps someone better versed in the literature on belief formation or persuasion could add some useful citation here as well, this it not my area of expertise. (I often refer people to Cialdini's *Influence: Science and Practice* for an overview of the literature related to persuasion, which may be worth checking out if no one can provide more targeted references).

> \[1\] Peskin, M. & Newell, F. N. (2004). Familiarity breeds attraction: Effects of exposure on the attractiveness of typical and distinctive faces. Perception, 33, 147-157.
>
> \[2\] Reber, R., Schwarz, N., & Winkielman, P. (2004). Processing fluency and aesthetic pleasure: Is beauty in the perceiver's processing experience? Personality and Social Psychology, 8, 364-382.
>
> \[3\] Monin, B. (2003). The warm glow heuristic: When liking leads to familiarity. Journal of Personality and Social Psychology, 85, 1035-1048.
>
> \[4\] Kelly, D.J. et al. (2005). Three-month-old, but not newborns, prefer own-race faces. Dev Sci, 8, F31-F36.
> 8 votes

# Answer
At one time Mauritanians considered fat women more attractive than thin. Unless Mauritanian men were born different to other men, surely we have to suppose that Mauritanian men were trained that way.

Sources:
> 6 votes

# Answer
We should differentiate between the behavior aspects of attraction and the physical aspects. Behavior involves what bathing suit someone chooses to wear, what makeup they wear, how they carry their body, etc.

Regarding the behavior aspect of attraction: Judith Butler argues that it is a culturally-constructed performance. Behavior varies by culture.

For example, the European conception of masculinity is often thought to be different from the American conception of masculinity. (more "metrosexual")

Another example: Lesbians are more attracted to women who look like a typical butch lesbian. Why is this? Is there an evo-psych aspect to being attracted to short spiky or asymmetrical hair, thumb rings, and other things that make someone show up on other people's lezdar? Possibly, but more likely it's a cultural signifier, a shibboleth, so that members of the same group can identify each other.
> 1 votes

# Answer
Heterosexual Romantic Couples Mate Assortatively for Facial Symmetry, But Not Masculinity (Burriss et al, 2011) "the authors found assortment for facial symmetry but not for sex typicality or independently rated attractiveness." As the study concludes, "humans may mate assortatively on facial symmetry, but this remains just one of the many physical and nonphysical traits to which people likely attend when forming romantic partnerships. "
> 0 votes

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Tags: reference-request, evolution, physical-attraction, cross-cultural-psychology
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# Question
Title: What experiment in a simple decision task should we run to obtain one million trials?
**Context**: Models of cognitive processes require very large datasets to be fitted. Sadly, it is difficult for a single laboratory to achieve this alone. I propose that we work collectively and collaboratively in realizing a 1 million RT experiment. This initiative is described on my ResearchGate page, www.researchgate.net/profile/Denis\_Cousineau.

Beyond model fitting, such a dataset will be beneficial for other purposes. Examples: Are parameters describing performances normally distributed across subjects? Does training effect --resulting in faster RT-- imply that the parameters are all evolving in one direction? Does Bayesian estimation more apt than Maximum Likelihood at characterizing the parameters? How can we estimate non-decision times? What is the shape of the RT distributions and how training effect alter its shape? In Bayes again, after how many trials does priors have no longer an impact on the estimates? etc.

**Task Requirements:** The task must be behavioral only (response times and response choices) as it is not possible to move EEG or fMRI material all around the world. The precise task used is not a critical constraint because the current models of cognition (sampling models such as LBA or Diffusion) are very flexible; they aim at predicting performance in a wide variety of situations.

The tasks proposed will be evaluated based on the following criteria criteria:

* small number of response alternatives
* few conditions
* low error rates
* stimuli that can be characterized for modeling purposes
* possibility of extended training on that task.

Possible candidate tasks could include: A redundant target detection task (Miller, 1982) or a same-different task (e.g., Bamber, 1969). These tasks are simple and accuracy is typically high (above 90% correct); they are possibly performed using some form of parallel processing; response times are generally well below 700 ms.

So in summary:

**What task and experimental design would be most suitable given the above constraints?**

*Please let's see what are the possible tasks, comment on others' proposals, and if you find the perfect task, upvote it. Have your colleagues make comments or propose new tasks.*

# Answer
> 4 votes
I don't like the idea that the task should be low error, errors are needed for modeling choice. I don't like random dot motion because there are big individual difference making it hard to find a common calibration point over people. I prefer instead a numerosity judgement, e.g., are more of less than 50% of a square array of pixels (usually a large number) blue or orange? You can make the array big enough to get fine grained control of difficulty, and randomly choose which pixels to have in each color (or brightness) on each frame if you want to make particular strategies hard to use.

# Answer
> 4 votes
I like this idea! I think the task should be one where the data could be used by many analytic tools. Hence, the data would not only be beneficial for one particular question, for example parameter estimations, but also for other tools such as Systems Factorial Technology (see Townsend & Nozawa, 1995), which provides a deeper understanding of the underlying cognitive sub-processes architecture, and other interesting information such as the process' capacity.

I suggest that the task at least respect a double factorial paradigm. This design is very simple: you have four conditions in a 2 x 2 design, where you vary two variables. It could be any variable, the only restriction is that you have to vary them independently one from another. In other words, each variable should reflect a cognitive sub-process. In one condition, both variables are in scenario where the sub-process should work very effectively (or optimally). In an other condition, both variables are in a scenario where the sub-process should work less effectively (or sub-optimally). And in the two remaining conditions, one variable works optimally and the other sub-optimally, and vice-versa.

As for the very details of the task, such as the stimuli that will be used and the specific variables, I do not have preferences. Letters are very manipulable, but they do carry semantic (more or less). Abstract stimuli could work. We could play with color, shapes, complexity, etc. At Psychonomics this year, they were many experiments which have use this design.

Reference for citation: Townsend, J. T. & Nozawa, G. (1995). Spatio-temporal properties of elementation perception an investigation of parallel, serial, and coactive theories. Journal of Mathematical Psychology, 39(4), 321–359. doi: 10.1006/jmps.1995.1033

# Answer
> 4 votes
I agree with Marc-André, the selected stimuli should have no semantic association (or as little as possible) which is why I would encourage the use of geometric shapes that vary in colour. Additionally, I believe that the task should be as simple as possible in order to encourage the overall cleanliness of the data.

As you suggested, one such task is the redundant attribute target detection task (Miller, 1982). In this task, participants are asked to keep in mind target dimensions (e.g. blue and square) and as soon as one of the dimensions is presented on screen, the participants respond as quickly and as accurately as possible. Results are typically fast, accurate, and slightly skewed – appropriate for this initiative! We could select a few colours and shapes (if we do go forward with this task) as well as what colour harmony should be selected.

Additionally, having colours that vary in “obviousness” can potentially give us a clearer understanding of the parameters within certain models. For example, an obvious blue should have quicker RT than a muted blue and the rate parameter of each individual channel should reflect that (assuming, of course, that the rate parameter is associated with "obviousness" at all). I am particularly interested in this aspect.

While a go/no would be great for this task, I also strongly believe that a 2AFC task would yield much more interesting results and the 1million RT initiative could help us really understand the “race” in “race models”. This could be as simple as modifying the task as one with “target present” or “target absent” decisions. With clearer trends in RT we could hopefully gather information on the independence of dimensions and whether there is crosstalk between detectors.

Additionally, having such data would not only benefit model fitting but also more solid architecture analyses. This would, in turn, help us get a more concrete understanding of coactive architectures (the architecture that Miller, 1982 suggested was at play in this type of task) which haven’t been as rigorously defined like other architectures (as noted by Houpt & Townsend, 2011).

EDIT:

Houpt, J.W., & Townsend, J.T. (2011). An extension of SIC predictions to the Wiener coactive model. Journal of Mathematical Psychology, 55, 267-270

Miller J. (1982). Divided attention: Evidence for coactivation with redundant signals. Cognitive Psychology, 14,247–279

# Answer
> 4 votes
Just a few comments...

Since one of the advantages of a large data set is high statistical power, it might be a good idea to use a task where the key effect has *not* been found in previous studies. That would produce a guaranteed result: i.e., a high-power test of an important null result.

A pop-out condition in visual search would be one example (i.e., no effect of display size), but this is not ideal because it would limit the modelling end of the project. That is, it wouldn't be too helpful to model multiple conditions with identical performance (or nearly so).

A better example would be an additive-factor experiment (somewhat as suggested by Marc-André Goulet). I would suggest a simple 2x2 design for which previous studies had reported theoretically important factor additivity (i.e., non-significant interaction). A big study would provide a high-power test of the null interaction. And, as long as both main effects were present, there would be four distinct conditions to model. This design is also interesting because a lot is known about conditions that should be satisfied by the RT distributions under certain models (for examples, see the references below).

A final point: After selecting a task, it might be very useful to test out the planned analyses on simulated data, which are considerably easier to get than real data. This would help make the project's precise goals more explicit and also make sure the goals would be achievable using the proposed data set. It might also help to reveal what aspects of the planned task/conditions were necessary for getting informative results (e.g., minimum effect sizes).

References

Cortese, J. M. & Dzhafarov, E. N. Empirical recovery of response time decomposition rules II. Discriminability of serial and parallel architectures. Journal of Mathematical Psychology, 1996 , 40 , 203-218

Dzhafarov, E. N. & Cortese, J. M. Empirical recovery of response time decomposition rules I. Sample-level decomposition tests. Journal of Mathematical Psychology, 1996 , 40 , 185-202

Dzhafarov, E. N. & Schweickert, R. Decompositions of response times: An almost general theory. Journal of Mathematical Psychology, 1995 , 39 , 285-314

Roberts, S. & Sternberg, S. The meaning of additive reaction-time effects: Tests of three alternatives. In Meyer, D. E. & Kornblum, S. (Eds.) Attention and performance XIV. Synergies in experimental psychology, artificial intelligence, and cognitive neuroscience., MIT Press, 1992 , 611-653

# Answer
> 3 votes
I myself am interested in obtaining such a dataset on the Same-Different task (Bamber, 1969). The answer is binary (same or different), accuracy is very high and there is a learning effect (short term, at least). Concerning the number of conditions, we could simplify the original task to go from 14 conditions to 8 by either:

* limiting the number of letters to 4 (instead of 1, 2, 3 and 4)
* using 1, 2 or 4 letters stimuli, and having 1 or 2 mismatches for the 2 letters stimuli, and 2 or 4 mismatches for the 4 letters stimuli

The second option is closest to the original. The first, however, would be very informative on the 4 letters condition, as there is little data on them due to the experiment's design.

# Answer
> 2 votes
Given many individuals (mostly men) have anomalies of colour perception, you might avoid colour; you also want a simple task with 'easy' stimuli, to enable short trial durations. Visual search paradigms are good for this. I echo the call for a project in which the experimental design would address something of particular interest, and ideally that would be difficult to address with a 'standard' design (e.g., with 10,000 data points, rather than 1,000,000). Estimating the distribution of processing times for a process inferred from indirect measures may be an interesting problem domain.

PJ

# Answer
> 2 votes
I vote for a simple random dot motion task. This has the advantages that: 1. It's easy to program. It can be delivered over the web via javascript, which makes the "many labs" aspect easy. 2. It's very well studied and well understood. 3. It is easy to set 5-ish coherence levels that will sweep out almost the full range of accuracy, from chance level to 100%. This is important for distinguishing between the models.

# Answer
> 1 votes
May I ask, have you thought about using existing large datasets, such as those provided by Project Implicit? Dataset.

(sadly, it seems Project Implicit has not stored individual data points but rather a computed 'effect' per participant).

# Answer
> 1 votes
May I suggest collecting data online?

With the latest browser technologies, RTs are extremely accurate, in the order of 5 microseconds (discussion). Even with slightly older browser tech, collected RTs can be accurate (ref).

There are several sites where people freely volunteer to do research (discussion).

Collecting data over multiple sites is most certainly easier when there is setup time per location.

# Answer
> -1 votes
Please allow me to question your setup:

Your assertion that you need a million data points to distinguish between models raises the question whether your're still doing valid science, I think. Are you sure that the differences between the models are scientifically sufficiently interesting to warrant a monster project to try and distinguish between them? Especially, if this is all based on a single task. I am sure, your quest will result in a "winning model". But I am not sure that it will result a generalizable scientific insight.

# Answer
> -1 votes
A million trials isn't really that many. There are lots of tasks where you can collect 1000 trials an hour. With a ten person subject panel where each person works 2 hours a day (10 hours a week) you could collect a million trials in 10 weeks. Assuming you are paying 15 USD an hour you can collect all the data for 15,000 USD which is a small grant. To run a ten person panel you would ideally want 3 testing stations and an RA to run things.

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Tags: cognitive-modeling, decision-making, reaction-time
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# Question
Title: What color is this dress? -- And why do some see it as white and gold and others see it as black and blue?
Here's the dress (and keep reading, this is actually a serious question):

This question about this image has apparently become quite a rapidly spreading meme on the internet. And after conducting my own little home experiment I can see why! My brother an law looked at this image on the same screen as I did and said matter-of-factly that the dress is black and blue. I, on the other hand can't see this as anything but gold and white. I tried this question with a few others with similar results.

So the question is... what is going on here? What is causing this to either appear strongly as black and blue or gold and white?

# Answer
> 15 votes
My hypothesis: The world accidentally stumbled upon the first (to my knowledge) bi-stable color illusion

Here is an example of bistable illusion:

This bistable illusion involves the perception of motion. Is the dancer spinning clockwise or counterclockwise? The deal is that the image is actually ambiguous. But you can't possible perceive both clockwise or counterclockwise motion at once, so you are automatically drawn to one and it's hard to switch off to the other.

And here is an example of a color illusion:

Amazingly the "blue" in the left cube and the "yellow" squares in the right cube are both the same color - grey! (Go ahead and take out your RGB color meter and see for yourself.) And the effect here is caused by the "context" of the color placed over the images of the cubes.

I'm thinking that somehow an ambiguous background to that dress image and the possibility for a fabric that has a sheen, is leading us quickly come to the subconscious conclusion that this is either a black/blue dress under bright yellow-tinted light or a gold/white dress that is in a bluish shadow. And whatever conclusion we start with is so strong that we can't break from it or see it any other way.

# Answer
> 5 votes
There is an interesting demonstration in this YouTube video (4:10 minutes) by Jean-Francoir Gariépy which shows a difference in the color perception depending on whether the dress is scanned from the top to the bottom of the image or vice versa.

A conclusion from this could be that people scan pictures of dresses in different ways, although an individually calibrated color perception might of course still play a subordinate role.

# Answer
> 1 votes
Have people actually been shown a **real** photograph of this dress, i.e. an image that's **not** shown at the screen?

Look at your screen from beneath. Or if you have a laptop, turn the screen as far as possible away from you so that the angle between a line from your eye and the picture becomes very small. You can try it with this page. The blue on the top changes to a greenish color, and also other colors change. Anyhow, when you do this you'll see the color of the dress change from black and blue to white and gold. So the problem is related to looking at a (LED) screen from different angles. Black turns to white (grey, actually) and blue to gold.

For example, look at this photograph:

Now, look at it from beneath. What do you see?

Or look at an arbitrary picture somewhere on the web. You'll see the same effect.

I think that if the real picture of the dress (so *not* the picture on a screen) is shown to a number of people, *all* will perceive the dress as black and blue.

So: print the picture, show it to whoever you want, and see how they perceive the colors of the picture. It's my guess that the described phenomenon won't be there. **All** people will see the colors of the dress (in the same conditions or context) in the same way!

It was just a fake internet hype!

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Tags: perception, color, optical-illusion
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# Question
Title: Why do western people's orientation/navigation differ from non-western cultures?
We show western orientated people the picture above: A line which represents a trip from A to B.

Then we ask them to turn 90 degrees to the right and look at the image below:

Most people who think in the western way (whatever that may be, but I think you know what I mean) answer to the question which of the two trips from A to B corresponds to the trip above that it's the upper line from A to B. In other words, they see as if the map has turned 90 degrees as well.

The same question was asked to people from non-western cultures (Hopi-people, Aboriginal people, Native Americans, you name it). They (almost) all said that the lower picture was correct. Instead of the entire map that turned, they perceived as if only they (or the letters) turned by 90 degrees.

Like Dennis Cousineau commented below, western people use maps and the north is always on top of our maps. Non-western cultures who don't use maps (like the Native Americans or the Hopi) arrive at the right answer maybe because they don't associate, while looking at maps, the north with the upper part of the picture. They directly put the second line piece in the second picture on the line piece of the first picture.

What could explain this difference in orientation?

# Answer
This is a classic example of the analytic vs holistic perceptual systems, one of the cornerstone theories on cross-cultural cognition. For a good overview of this see *Perceiving an Object and Its Context in Different Cultures* by Kitayama et al. (2003) or you can start with the seminal piece *Culture and the self* by Markus & Kitayama (1991).

Essentially, due to differing cultural norms certain groups of people tend to favour a more holistic or analytic attentional style. The former puts equal or greater emphasis on contextual features/factors, while the latter emphasises specific or unique characteristics.

I.t.o. the current question, a holistic perceptual style is better able to take into account the contextual factor (rotation) when making decisions, while a analytic style does not and so can cause errors in judgement.
> 3 votes

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Tags: perception, cross-cultural-psychology, spatial-cognition
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# Question
Title: Is there evidence for cross-cultural differences in problem solving skills?
Does the thought process in our mind for solving a problem or bringing out a solution to a problem depend on culture or language?

If so, how can these skills be represented and addressed?

# Answer
> 2 votes
A bit of a broad question as a full answer will really depend on the specifics of the problem being addressed.

In short though, yes, cultural factors, and probably to some extent linguistic factors as well, do impact on problem solving processes.

One of the main cross-cultural factors that can alter problem solving is the whole individualism/collectivism distinctions between broader cultural systems and they promote the use of analytic vs holistic perceptual styles. The answer in this post perhaps answers the question in a slightly more applied manner. Another thing to consider can be how certain cultural norms can promote logical vs intuitive reasoning processes as well (see Buchtel & Norenzayan, 2005).

As for language, the general consensus is that it is not the language in and of itself that shapes cognition, but rather the cultural norms or ways of being associated with any given language as a means of cultural communication (See Earle, 1969 for an example).

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Tags: problem-solving, linguistics, cross-cultural-psychology
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# Question
Title: How to fit averaged data to obtain a single psychometric function?
I have psycho-physical data from a motion discrimination task in order to obtain PSE (point of subjective equality). I am using *psignifit* and have constructed individual psychometric logistic functions. How can I construct a distribution with averaged data?

# Answer
> 3 votes
**Short answer**
Averaging psychometric curves may not be the preferred way to pool psychophysical data.

**background**
Typically, extracted gold-standard outcome measures from the psychometric curves will be pooled and averaged to perform statistical analyses and so on.

For example, in the visual sciences a much-used outcome measure is the visual acuity where, for example, gratings in four orientations are shown using standard psychophysical tests. Since it's a 4AFC task, the 62.5% correct score will be taken as a measure of the threshold, where the gratings will be varied in their width, measures in cycles per degree (*cpd*) or related measure of visual angle.

To pool and average individual subject scores the acuity scores will be averaged, measured in cpd, and *not* the psychometric curves. For examples see Nau *et al*. (2013) and Bach et al. (1996).

If you would really insist, you could pool every measurement in case the method of constant stimuli or related paradigm was used. Then one single psychometric fit could be performed on the congregate data. Problem with this approach, as opposed to the preferred method described above, is that the fit will yield awesome outcomes in terms of superbly small variances in the fitted outcome parameters, as well as favorable descriptive statistical parameters, such as the correlation coefficient, simply because there are so many data points and hence many degrees of freedom. Further, random errors occurring in one, or a few subjects will now affect the overall fit and 'weird' data points will tend to be obscured by the multitude of data points per x value.

A better approach in terms of statistical descriptive outcomes would be to first average every data point and then do the fit. However, also here outliers will be obscured because of the averaging procedure. The power of psychometric fits is that individual subjects can be analyzed.

In case an adaptive method is used above procedure won't hold as each subject will have different x values. Adaptive procedures in general do not lend themselves very well for curve fitting as the data points around threshold are dense, but the trials targeting chance level or 100% correct are sparse or nonexistent altogether. Hence the asymptotes are ill-defined. You could average these data, if you insist, by averaging each of the fitted parameters and generate a 'master' fit out of those. Beware of logarithmic values, though, as averaging those is not arbitrary. Again, descriptive statistical parameters become obscure in such a master fit, and statistical analyses become difficult.

In all, my advice is to stick with pooling the single outcome measures obtained from the psychometric curve, *i.e*, stick to pooling your PSE outcomes.

<sub>**References**
**-** Nau *et al*., *Transl Vis Sci Technol* (2013); **2**(3): 1
**-** Bach *et al*., *optom Vis Sci* (1996); **73**(1): 49-53</sub>

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Tags: methodology, data, psychophysics, task-analysis
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title: Getting started with EEG data

text:
# Question
Title: Getting started with EEG data
I want to get started with getting signals from EEG and learning on how I can read data. I have some programming skills, so designing a database and manipulating data with ruby (python seems also cool, but never worked with) wouldn't be a problem, but I don't know where to start.

I'm interested in Neuromarketing because I'm working in advertising, but health is in my heart.

So can anyone please send me some books on what data I can get from EEG (theory) and what hardware should be good to use? Also books on how I can easily develop and calculate the data (emotiv sounds nice but not much electrodes and may not be working well, however for that money maybe good to begin with).

So something like getting started with EEG... Like with programming my first "Hello world" :)

UPDATE: Bought EPOC EEG Research edition :) And there I can even choose, I think I will go with ruby then :) But still need some very basic book on how to get long with all that data, I had suggestion on Introduction to Event Related Potential Technique and is there some easier to learn video tutorial or book... real basics :)

# Answer
> 10 votes
Steven J. Luck's "An Introduction to the Event-Related Potential Technique" is a great beginner's book on EEG. It's basic but not too simple, and it goes into the structure of the signals as well as into issues on experimental design.

# Answer
> 7 votes
Do you mean evoked potentials, or event-related potentials, or just straight-up EEG? The general way to distinguish between the two is that EEG will tell you about state (aroused, asleep, etc) where evoked or event-related potentials will tell you about operations (processing sound/language/etc); evoked or event-related potentials also generally require more, and more discrete, trials than EEG.

I'd recommend running some simple experiments yourself (on whoever is hanging about) and then analysing them. Do an auditory oddball experiment (Wikipedia's article is a pretty good intro) and analyse it; do a block experiment with basic state changes and analyse it.

I wouldn't start out trying to learn EEG AND program your own analysis suite at the same time; there are packages for EEG/ERP analysis in R (a free, open-source analysis language/platform) that will get you started much faster. But in general, people learn this stuff in labs, and learn it by helping on more experienced people's projects, so there's very little formal introductory material.

Good luck!

# Answer
> 5 votes
I will second the above comment that equipment like EPOC is unlikely to be of much use. EEG research generally requires relatively large numbers of trials per subject even when conducted under the best of circumstances (low impedance electrodes, a shielded chamber, etc.).

As for data analysis, the gold standard for open-source EEG analysis is EEGLAB, which is written in MATLAB. If you don't have access to MATLAB, I believe that Windows binaries are available.

# Answer
> 5 votes
If you are considering an alternative to matlab that is free I would recommend octave. If you are on linux you might consider the whole neurodebian. In terms of book I did not find Steve Luck's book very helpful, but Todd Handy's one was more suited for me. Also a very good book is van Drongelen's Signal Processing for Neuroscientists (cannot put the link sorry, not enough reputation), which includes matlab code with it. It is however tailored to a more technical audience. In terms of video I liked these youtube video. They are on brain computer interfaces, but the introduction also explains a bit about EEG. It is also a bit for the technically oriented.

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Tags: neuroscience, measurement, eeg
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# Question
Title: Do hormonal factors cause a trend of lower IQ in women?
This is a hard question to ask without coming off as a sexist, merely via the title, so I'd like to make one thing clear right away: I understand that men and women have an identical capability of developing intelligence on perfectly equal levels. I'm not expressing that I think any one woman is any less capable of equal or greater intelligence compared to any man.

With that said, I understand that the human mind is a very dynamic tool that can be excersised and developed. Just like after never lifting a weight in my life, I wouldn't be capable of walking in and bench press 350, I can't expect to have an IQ of 130 all in a sudden after never once putting my mind to solving a tough problem.

In my life experience, I've met highly intelligent people, both men and women. However I've noticed a strong trend of women having far less interest in the very problem solving that defines one's IQ. I have put some thought into this, and after learning that men and women have identical brains for the most part, I assumed the trend must be due to hormonal differences, causing women to spend far more time on emotional thought processes rather than on problem solving.

Am I completely wrong? Partially wrong? I'm not an expert in cognitive sciences, so I ask this question with an open mind. Thanks!

Edit: This question hasn't been received well. See my comment on an answer below for a brief explanation of my thinking. Basically I'm either asking the wrong things, or in the wrong place. I'm not trying to be sexist though. I genuinely want to study the topic in order to understand, in the best interest of women, whom I find aren't engaging as much as men are in intellectual topics.

# Answer
I don't think anybody wants to limit particular topics on here, but the point of the site is to discuss science. Science starts with empirical observation, rather than just anecdote. So the first flaw in your view seems to be that you are taking your anecdotal experience as evidence for "a trend of lower IQ in women". Many people have looked SCIENTIFICALLY at sex differences in cognitive abilities, but these tend to be small and not to include a general difference in IQ.

Later on in your question/comments, it sounds like you are more interested in "a strong trend of women having far less interest in the very problem solving that defines one's IQ". This seems to be about interest rather than ability, and note that there is a big debate about IQ tests and the things they measure (and interest in problem solving is not one). So again, there is, as far as I know, no scientific evidence of differences in this and certainly not enough to qualify as a "strong trend". For more about sex differences in cognition, see http://www.apa.org/action/resources/research-in-action/share.aspx and the references mentioned there.

Your comment that "I came here to figure out why all women that I meet seem to be less interested in topics of intelligence (science, engineering, philosophy) compared to men Ive met. " is again anecdotal and you seem to be presuming that those subjects are "topics of intelligence" more so than, say, linguistics or art. There is evidence of course for sex/gender differences in take-up of STEM careers, and if you look into this you will see that you are completely off by saying that "women aren't getting more involved in science after the Womens Rights Movement". There is a big drive to celebrate women in STEM, partly because early encouragement is thought to be a factor in what boys and girls end up studying.

Since your initial trend is not supported, it seems pointless to look for a "hormonal factor". If that is your interest you might be better off looking at differences in cognition between/within individuals with different amounts of hormones (e.g., related to the menstrual cycle). Sex hormones such as testosterone might be of interest to you (see this answer).
> 4 votes

# Answer
According to the following study, the level of sex hormones do affect spatial performance: http://www.sciencedirect.com/science/article/pii/030645309400076X

Now if we subscribe to the premise of general intelligence (g factor, IQ) of how all the different cognitive abilities are positively and significantly correlated, then the above means that lower androgen levels cause a trend of lower IQ, in both sexes.

Since I find Assortative Mating to be valid, and the positive IQ correlalation between spouses seem to be even more important than that of some physical traits, I find the above study interesting. How can the two sexes handle a natural "by default" mismatch, if they strive to find mates with intelligence levels as similar to their own as possible?

I think your question is valid and I'm highly interested in this topic as well.
> 3 votes

# Answer
What you've ask is totally valid. what you assumed to be the cause is horribly invalid.

However I'm glad you asked, because I have a good answer for you.

First of all, women have more harmonized brain than men.neural connections are disturbed all over both hemispheres.men have single hemisphere concentrated neurons. so it is safe to say women brain is at least in a physiological way, better.

Second of all, they are really better. women can read social conditions more precise than any man and they emotionally understand better and can detect hidden deceptions in a better way and at the same time, they are as much competent in intellectual efforts as men.

Third of all, the only reason some women are less into computational or scientific problem is sexist people in society.and these sexist people are both male and female parent. according to Freud's theory of psycho-sexual development, the stage that kid plays with certain parts of their body is essential in developing a sense of curiosity. I don't know about the place you live, but in my culture boys play with their genitalia freely and no one cares, but if a girl do that, they will bring the hell down on earth. so it is product of this manner, leads to suppression of sense of curiosity in a baby girl and later in adulthood as a woman.
> -3 votes

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Tags: intelligence
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# Question
Title: Does the International Affective Picture System (IAPS) contain weapon stimuli?
I'm looking to use the IAPS for my research, but I specifically need to use images of/or containing weapons. Does anyone know if IAPS has any such stimuli, and, if so, roughly how many?

# Answer
Use the MAPS https://www.ncbi.nlm.nih.gov/pubmed/26255051

You can request from Auburn Univeristy
> 3 votes

# Answer
I happen to have access to the IAPS and had a quick look. There are about 20 pictures that include guns, most of them are held in the hand by someone, sometimes pointed at someone. Only two are photos of just the guns. Then there are about 8 pictures involving knives, and a couple of other pictures of weapons (a rocket, a tank, two jet fighters). Finally, there are a number of mundane objects that could be used as weapons (e.g., hammers).
> 2 votes

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Tags: emotion, methodology, stimulation
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# Question
Title: Does having wrong answers available while studying distract the mind from the correct answer?
I am studying for a big exam which will include 100 out of the 300 questions I was given as material for the exam. **They are the exact questions that will be used on the exam, including answer choices.** While I am reviewing, should I make the incorrect answers available to myself, so that when I am taking the test I see the questions and answers I have been reviewing, or should I make no answers available to myself except the correct answer on the other side of a flash card?

Which is the best way to learn the correct answer?

# Answer
> Which is the best way to learn the correct answer?

There is no correct or best way to learn if phrased that way, let me elaborate:

In the first case you are really learning 2 things:

* A series of statements : a),b),c), d).
* 4 relationships : a)= false, b) = false, c) = true , d) = false.

In the second case you are only learning a single relationship:

* statement X ( c in the previous case) = true

This might sound counter intuitive, but the first case will prepare you better (even though it takes longer to practice), Why ? Because it simply matches better the recall task,which can be read as: out of this 4 cases which 3 are false and which one is true. ( a discriminating strategy can even be formulated by grouping the wrong ones via some similarity)

The opposite learning strategy is expected to fare poorly since instead of being helpful, the additional wrong choices work as recall distracters, they will each elicit the same response ( technically the correct one will also have an extra priming effect, but in order to outweigh the distracters, it would need to be consolidated over time), that is you would be expected to write it down word by word.

So your choice comes down to either learn to discriminate or learn to recall perfectly, in general we fare poorly on the second task for short to medium term memories and only after repeated (or emotional) and complementary exposure can we master perfect recall ( mnemonic devices can also be used).

Sources:

* The Oxford Handbook of Memory(Tulving,Craik) (expertise, familiarity, distracters,etc,etc)
* Cognitive Science (Gazzaniga) General discrimination in memory.
> 0 votes

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Tags: learning, methodology
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# Question
Title: Do workers retain information from audio lectures when working in a physically demanding job?
If I were to start listening to lectures instead of music will I retain the information?

I've attempted to do this myself once with Assembly Language but I worked in a loud environment (sand blasting and concrete mixing) so couldn't really hear the audio most of the time and programming makes for a bad audio book. At my current job it's also loud but the management doesn't care if we use ear plug headphones just don't want to pay the money for them if I wont retain much information.

Anyone have any experience with this or links to studies done?

If it matters I plan to listen to lectures on computer science, quantum physics, psychology, neurology, and medical basics (anatomy, physiology, etc) and maybe various other sciences.

# Answer
> 2 votes
First off, if you want to retain information, you have to actively listen to it. Simply putting it on like you would background music is not going to help that much. However, if you do want to learn by listening to a lecture, there are several strategies you can use. Here are some listening strategies you can try to employ. They are mostly targeted at being in lecture, but listening is listening either way.

Another useful fact is that the speed that the average brain thinks at is 400 words per minute. Find the speed of speaking at which your brain doesn't tune out at, but still has time to process everything coming its way. If you have a friend, have them speak at different speeds and observe the effect on your attention span. Then when you turn on your audio lecture, see what speed the lecturer speaks at and adjust the speed in an audio editing program to match your brain's attention span. Also, if you can't change the speed of the audio but it's slower than you want, then ask yourself small questions in between sentences so that you don't lose attention.

Obviously if you are trying to "multitask" you have to make the audio slow enough to where you can hear every word and work on your job, if that's what you wanted, but multitasking has been proven to be impossible.

There was a study done on audio-tutorials versus in-person lab-lecture and the people who used audio had better scores/retention.

A few questions you might want to ask about yourself are:

What sound intensity of music helps block out ambient noise but still allows me to hear myself think? Where are the best places for me to listen to audio? Which subject am I going to be listening to? (You answered this in your question but some of those subjects can't be simply listened to once through for retention. I would say Computer Science and Quantum Physics need a very quiet environment if you are going to be listening to them. Hopefully you have a pause button. Meanwhile, the others you mentioned might be possible if you are able to memorize quickly.)

Finally, if you have a car, I would highly recommend listening to your lecture in the car, and then when you are sitting down elsewhere, re-listen to that same lecture. Repetition really helps with retention! (You can find lots of articles on that online.)

Hope this helps! Let me know if you need clarification, etc...

# Answer
> 2 votes
Straight answer: No. There is no such thing as free lunch when it comes to learning material. Your question is based on the studies of hypno-learning (learning by listening to tapes while sleeping) which has never received empirical support.

To memorize in long-term memory you need: Deep encoding. Deep encoding requires transforming the material to things you already know. For example, rehearsing the material using synonyms, analogies, or examples taken from your own life. For that to happen, it requires attention and concentration. More on this next.

If you can't transform the material so that it becomes deeply encoded, it needs singularity. It has to be something that hit you by its novelty. Again, to notice singularity, it takes attention on the material.

Attention is quite central to learning. It is the gate by which all material reaches your working memory and from which it can reach long-term memory. Yet, you only have a limited pool of attention. If you try to stretch it over multiple tasks, it creates fatigues, stress, or diffuse anxiety. All these factors are known to reduce your ability to learn. Worse, under stress or anxiety, you will revert to stereotype techniques (here, to learn, you will revert to rote repetition of the material). Stereotype technique require less attention, but are notoriously known to result in the poorest form of learning (no duration and no understanding).

If you want to assimilate material, only one option: concentrate on it (avoid multitasking at all cost), rephrase materials and make connections to what you already know. Otherwise, try to see in what ways it is completely novel (singular).

Some references:

* Daniel Kahneman, Thinking, Fast and Slow, 2011.
* Schmidt SR (1991) Can we have a distinctive theory of memory? Mem Cognit. 1991, Nov;19(6):523-42.
* Craik et Tulving (1975) Depth of processing and the retention of words in episodic memory. Journal of Experimental Psychology: General, 104, 268-294.

# Answer
> 0 votes
I do not know about specific evidence on dual-task settings with 'lectures listening' as one of the tasks, but there is plenty of references in multitasking studies. Then you could consider all the evidence on the detrimental effects of dual task on human performance. It practically boils down on how much the lectures will entertain you.

I have experience with both listening to podcasts and to audio streams extracted from video lectures on coursera.

My experience is that lectures are much more interesting than music and therefore have a much higher divided attention cost. For example, I do listen to every nature podcast while riding my bike to work. I must admit I am glad I am not driving a car because it happened that I surprised my self in a kind of trance status while listening to the podcast. And that is not helpful when I should be paying attention to what happens on the street.

Lastly we could consider all the literature on mental work-load. I remember there is quite a bit of literature on traffic psychology manipulating cognitive load and the ability to drive a car and ride a bike. But in terms of physically demanding job the cognitive load might not be as apparent/influential. I think it might also depend on the type of physical work. Maybe if you are at the gym and listen to the lecture the two things could not interfere with one another. I remember listening to Bill Bryson's A short history of nearly everything while painting my house and enjoying it quite a bit. With A brief history of time by Steven Hawkins sometimes I had to listen to a paragraph twice before proceeding with the book.

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Tags: learning, music, perceptual-learning, auditory-discrimination
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# Question
Title: What are the methods to reject ocular artifacts in the EEG?
Is there any way to remove ocular artifacts from an EEG signal, other than applying independent component analysis, or manual rejection?

# Answer
According to a review by Croft & Barry (2000), a number of possible methods exist to prevent, or reject ocular artifacts in the EEG;

**Prevention/reduction of artifact instances**

* Recording with eyes closed -
A very effective method, but eye closure alters the EEG, *e.g.*, it increases alpha band activity;
* Let subjects fixate on a target -
Method reduces blinks, but does not eliminate them.

**Rejection**

* Exclude trials with amplitudes larger than, *e.g.*, 50 microV -
Method works only with a trial-based approach; artifacts below criterion level will remain.

**Reduction**

* Subtract a certain standard voltage when an artifact occurs -
A crude method;
* Online attenuation of the EEG signal when an artifact is detected -
Works better as the former technique, but is still crude;
* Regression techniques where different electrodes are used to estimate the artifact component in other electrodes -
A more sophisticated method with apparently good results.

For details I refer to Croft & Barry (2000) and the primary literature cited therein.

<sub>**Reference**
**-** Croft & Barry *Neurophysiol Clin* (2000); **30**: 5-19</sub>
> 2 votes

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Tags: eeg, signal-processing
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# Question
Title: Do direct cortical pathways exist in the visual system, or do they all go via the thalamus?
Do visual cortical signals always go back and forth between the thalamus, or other subcortical structures, or can they travel directly from one region in the cortex to another?

# Answer
**Short answer**
Intracortical projections can be routed directly to other cortical areas (cortico-cortical projections), or via the thalamus (cortico-thalamo-cortical projections).

**Background**
Intracortical projections do not have to cross the thalamus or other subcortical structures. Take for example the visual system - it features many cortical projections and these connections do not always enter the thalamus or other subcortical structures (Fig. 1). These connections are called cortico-cortical projections (*e.g.*, Guandalani, 1998). Connections going via the thalamus, however, also exist in the visual cortex (*e.g.*, Kato, 1990) and are referred generally to as cortico-thalamo-cortical projections.

Fig. 1. Visual system. source: McGill

The projections from the LGN to primary cortex (V1 in Fig. 1) and via V2, V3, V4 up to V5 all may occur without visual information entering the thalamus or other subcortical structures.

Also note that on the cellular scale direct cortico-cortical connections in the cortex are abundant (Fig. 2).

Fig. 2. Local cellular connections in the visual cortex. source: Kang *et al*. (2014)

**Reference**
**-** Guandalani, *Brain Res Bull*; **47**(4): 377–85
**-** Kang *et al*., *Front Syst Neurosci* (2014); **8**: 172
**-** Kato, *Brain Res*; **509**(1): 150–2
> 5 votes

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Tags: neuroscience, vision, neural-network, neurophysiology, brain
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# Question
Title: What is the voltage that an intracortical electrode is expected to receive?
When a neuron fires, an action potential of about 100 mV is generated. An electrode measuring brain activity will record several hundreds neurons at a time. How much voltage an electrode directly in contact with brain tissue is expected to receive?

# Answer
The Utah array is a multi-electrode array for intracortical recordings. In one of many publications on this device, the authors show some sample traces that reveal amplitudes generally **between 5 and 40 microVolts**. However, measured voltage will depend on the vigilance state of the brain, recording area, time on the millisecond scale, time on the macro scale (gliosis) and insertion depth and so forth.

Note that extracellular electrodes will never measure the high potentials that occur at the membrane surface as recorded through *intracellular* electrodes. Because of the distance of extracellular electrodes to the neuronal cell membranes, the signals are much smaller.

<sub>**Reference**
**-** Craig *et al*., *Electroencephal clin Neurophysiol* (1997); **102**: 228-239</sub>
> 2 votes

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Tags: measurement, electrophysiology
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