# Question
Title: What is the data structure used by the brain to store data?
As a computer science undergraduate I was wondering if there are any special data structures used by the brain to save data?

I am especially interested in the hash tables data structure. If data are saved in this type of data structure then you could search, insert and delete them in a short time no matter the size of the data (or technically speaking in O(1)).

I was wondering if the brain works in the same way or not? And if it does, how does it?

# Answer
Memory in the brain isn't super-well understood, so going to the level of "data-structures" isn't really possible with purely biological models. Not that a purely biolgocial description would be very useful anyways. When people ask how the brain works, they typically don't want to be told "molecule A interacts with molecule B, which triggers molecule C".

Since you're coming from computer science, I am going to assume that you're probably more interested in models or the "data-structures" (how to structure data, like a list or a tree) we assign to a brain. One way to build biologically plausible brain models is with the Neurological Engineering Framework (NEF) and there's been a couple data structures based on this that have been used. You can see more detail on this in my other answer "How is memory accounted for in the NEF?"

However, it's important to note that the NEF is a framework, thus much work is being done on implementing more complex data structures than the ones mentioned in that question. In particular, Aaron Voekler has implemented a dynamic hetero-associative memory using the framework, which functions somewhat in the same manner as a hash table.

I hope this answer gives you a good starting point for further investigation.
> 4 votes

# Answer
The brain structure for memory, association, learning and thinking works more like a network of weighted, linked nodes.

> in machine learning and related fields, artificial neural networks (ANNs) are computational models inspired by an animal's central nervous systems (in particular the brain) \[...\] Artificial neural networks are generally presented as systems of interconnected "neurons" which can compute values from inputs, and are capable of machine learning as well as pattern recognition thanks to their adaptive nature. \[...\] For example, a neural network for handwriting recognition is defined by a set of input neurons which may be activated by the pixels of an input image. After being weighted and transformed by a function (determined by the network's designer), the activations of these neurons are then passed on to other neurons. This process is repeated until finally, an output neuron is activated. This determines which character was read. http://en.wikipedia.org/wiki/Artificial\_neural\_network
> 3 votes

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Tags: memory, long-term-memory, short-term-memory
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title: How to compare brain waves?

text:
# Question
Title: How to compare brain waves?
I'm a Java developer completely naive of brain waves and such. Could anyone tell me how to compare them?

For instance, how can I compare:

and this:

What fields of study should I focus on? I understand there are some Pattern Recognition involved. Other than that, what else? Related Questions:

# Answer
> 8 votes
The field of study you should focus on is the one for which you have already identified in your paragraph above which is EEG based "brain-computer interface".

EEG signals are compared by their "features". Each of the signal you have provided above have different features. These features can be mean, variance, frequency, kurtosis, skewness of each of the signals (statistical parameters which also includes fractal dimension, Hjorth parameters, common spatial pattern, fano factor... ...) or power as computed through frequency space algorithms such as fast fourier transform.

More sophisticated techniques such as blind source separation, empirical mode decomposition and wavelet coherence (a phase domain approach) should yield additional insights but these are more reserved for research purposes.

The most common algorithm for post processing is the wavelet transform which plots the energy as a function of both time and frequency.

During a seizure, the wavelet transform will display a clear high energy periodic signal at the lower frequency. While highly efficient in pin pointing exactly where and how the seizure is happening, the wavelet transform is highly advanced (challenging to implement) and runs at O(n^2) for a naive implementation and O(nlogn) for a fast implementation. It is quite computationally expensive.

What you need to implement is a real time seizure detection based on EEG features.

(offline) This is done first by grabbing the EEG signal when he has a seizure using EEG headsets or through research, estimate what the characteristics of this type of seizures are. (this can be done even with a single electrode).

(real time) Once this done, hook the patient with the EEG headset and compute the features of the seizure signal at every other other second worth of samples as they stream into a computing platform. The features are constantly compared to the threshold features. When all these features are have their respective threshold (A and B and C and D all meets threshold). Send alert that a seizure is happening.

The threshold approach is a basic one, but because our brain continuously changing and EEG depends on many many external variables, what is commonly used in practice are the detection of seizure through artificial neural networks (ANN) - it will not only tell you when a seizure is happening but could in fact PREDICT when a seizure will occur! (\*)

One challenge I can see with what you are attempting to do is that the patient will be constantly hooked up with a headset in order to perform real time seizure prediction. The distance between your USB and the headset will be a hard constraint. The headsets needs to be recharged frequently. Emotiv EPOC (one popular headset) contains 16 electrodes which can be quite burdensome when worn. Wet electrodes provides better data but requires delicate preparation which can take a long time. If worn constantly, I would pick a headset containing a few electrodes at key places like the frontal-polar lobe (since seizure is more easily picked up than other EEG patterns, we don't need many electrodes) and would choose one that is aesthetically pleasing (one from Neurosky or one of the recent headset from Emotiv i.e. insight) and has a long battery life time

Good luck

(\*) *Prediction of seizure onset in an in-vitro hippocampal slice model of epilepsy using Gaussian-based and wavelet-based artificial neural networks. - A. Chiu*

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Tags: computational-modeling, eeg, signal-detection
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title: What does fMRI measure exactly

text:
# Question
Title: What does fMRI measure exactly
It is true that blood flows to wherever the brain is most activated and does fMRI measure the blood flow inside of the brain through oxygen content?

# Answer
> 12 votes
As a slight modification of your statement: blood flow *increases* wherever activity in the brain *increases*.

The type of fMRI that uses this principle is blood-oxygenation-level-dependent fMRI or BOLD fMRI. MRI in general detects signals by picking up proton signals from water molecules. This proton signal is basically caused by magnetizing the protons causing their spin to change. A subsequent powerful radiowave disrupts this spin and the following relaxation phase of the protons to the original state can be detected by MRI. Water, and hence protons are everywhere in the body, including the brain and the blood. Deoxygenated hemoglobin (hemoglobin without oxygen) in blood changes the proton signal in its immediate surroundings due to the magnetic properties of deoxyhemoglobin. This is caused by the fact that deoxygenated hemoglobin is paramagnetic and decreases the signal that protons release. In fact, it has been regarded as noise in structural MRI scans. Oxygenated hemoglobin does not have this property. Radiopaedia has a nice explanation as to exactly how the BOLD signal is used in BOLD fMRI, and I quote:

> When a specific region of the cortex increases its activity in response to a task, the extraction fraction of oxygen from the local capillaries leads to an initial drop in oxygenated haemoglobin \[...\]. Following a lag of 2-6 seconds, cerebral blood flow (CBF) increases, delivering a surplus of oxygenated haemoglobin, washing away deoxyhemoglobin. It is this large rebound in local tissue oxygenation which is imaged.

So to sum up: brain activity increases the BOLD signal by picking up oxygen-changes after an increased blood flow to that specific part of the brain. So your statement that fMRI measures blood flow is technically incorrect. Doppler techniques can be used to measure the actual flow of blood.

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Tags: measurement, neuroimaging, fmri
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# Question
Title: Do animals have some kind of rudimentary personality types or preferences?
I'm looking at the Myers Briggs type indicator and am trying to understand if type/personality preferences are a human only construct. I'm talking about Introversion-Extraversion, Sensing or iNtuition, Thinking-Feeling, Judging-Perceiving.

Reading books on personality, human children are frequently described as already having some type preference (for example the intuitive child versus sensing child) which gets developed as the child matures. This makes me question as to where this original preference comes from. If it comes from some brain structure, I'm interested if lower animals also have these structures.

I know that animals have alpha/beta males which determines social dominance, but **are there other personality traits that have been identified in animals?**

For example, a common proverb is "curiosity killed the cat" - are some cats more curious than others? Are some specimens of the same species more sociable (extraverted) than others?

Another example would be experiments in primates, where monkeys were able to deceive their peers.

# Answer
"**are there other personality traits that have been identified in animals?**"

There are quite a bit of hits on Google about this.

Here's a foundation dedicated to research on animal personalities:

> The Animal Personality Institute (API), founded in 2004, is an interdisciplinary group of researcher dedicated to advancing the scientific understanding of personality and temperament in non-human animals. http://animalpersonalityinstitute.net/

Here's a summary of a study on some personality traits among ducks:

> Weissing and his colleagues ran various model simulations of scenarios that included a resource as well as responsive and unresponsive animals. He said the new model shows, for example, when it's optimal for animals to react to a change in food and when it's not. It turns out that competing personalities help to keep a healthy balance in a group.

Research on personality among fish:

> Working with Dr Bart Adriaenssens at the University of New South Wales, Dr Biro observed the behavior of adult male mosquitofish over 132 days. They found that the behavior of some individuals was consistently more predictable in a given context than others. Mosquitofish were used for the study because they are widespread and easily sampled from ponds in and around cities. "We observed that individuals differed in their average levels of activity, but also differed in variability about their average activity," Dr Biro explained. "Some individuals chose to be active, others chose to be sedentary, some were consistent in their chosen level of activity, others not. But, we found no association between activity levels and predictability. "What this tells us is that the fish differed in how unpredictable they were, and that this unpredictability is a consistent attribute over time. http://www.sciencedaily.com/releases/2013/10/131031092311.htm

Here's a research document on animal personalities:

> The past decade has seen a very rapid growth in research on animal personality. The growth is taking place across a wide variety of fields ranging from **applied ethology, beha vioral ecology, and zoo management to biology, primatology, and comparative psychology**. Having established that **personality exists in animals and can be measured**, researchers have begun to exploit numerous benefits of animal research, such as the high degree of experimental control, the ability to measure a range of physiological parameters, the opportunities for naturalistic observation, and animals’ accelerated life span. http://homepage.psy.utexas.edu/HomePage/Group/AnimPersInst/Animal%20Personality%20PDFs/G/Gosling%202008.pdf

Wikipedia also has an article on the topic:

> Personality is the consistent patterns in cognitive and behavioral traits, such as affect, cognition, and behavior.\[1\] These traits are measurable, are found in a broad array of species, and are commonly transferable among species (Gosling, 2008). http://en.wikipedia.org/wiki/Personality\_in\_animals
> 4 votes

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Tags: personality, animal-cognition
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# Question
Title: Why is it more acceptable to get rich doing sports than business?
I live in Finland where it is not acceptable to emphasize of being rich, eg. buying expensive sportcars/houses/apartments and introduce them on "yellow press".

But there is one exception. If you have earned your money doing sports (eg. playing ice hockey, driving Formula One) it seems to be totally acceptable.

What is the psychology behind this?

# Answer
It's all about what people think are your motives for what you do, how hard people think you work for your money, and how nice people think you are.

If people think you earn money just because you love money, you can easily come off as cold and less pro-social. That makes people skeptical of you.

A bias makes people tend to think that whatever work they don't see you do, you never did (personal experience). This makes people value you less and admire you less if they can't actually see your contributions to society. Most office-work is prone to this bias.

People tend to see social people as more nice than less social people, and like them more. This is likely due to the advantage our race gains from social cooperation, which we would not have survived without. We prefer people who we think we can cooperate with and get well along with.

Talking about getting well along, we also prefer people with whom we share any interest, hobby, attitude, history etc because it increases the chance we get well along with them. Birds of a feather flock together. This means that 1) We prefer people we know are social and 2) we prefer people who share some of our interests.

Business people will go well along with their kind. They might not be very fond of athletes. Athletes go well along with their kind. They might not be very fond of business people.

Fact is, that which of these "professions" is more popular depends entirely on who you ask and the circumstances. So I take it you wonder why the *general* attitude is that business people are less popular than athletes. Well, that's because most people feel they have more in common with athletes (who share their passion for sports) than business people.
> 1 votes

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Tags: cognitive-psychology, social-psychology
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# Question
Title: Does the brain get rusty if out of practice?
A couple of years back I was in the midst of a lot of competitive exams (for my career, degree etc.). I needed to put my mind to a lot of work. Maths problems, physics problems, logic and GMAT-type questions; you name it.
I haven't been doing these rigorous mental exercises recently. Now, I find that in class I struggle to grasp even the simplest of new concepts.
So, my question: Does the brain lose its edge if out of practice?
(Please state your reasoning. Any references would be appreciated too.)

# Answer
It doesn't lose its edge; it loses the strength of related associations.

Cognition and skills is very much about memory, and it's all about the neural networks that make up our mental associations. It might feel like you haven't forgotten anything from the past, but in reality you have forgotten more than you know.

You are not aware that you have forgotten something until something reminds you of something you can't quite remember exactly. Then you might think "I know I used to know this, I know it's somewhere in my head", or you're more like "How did I use to do that?"

Our neural networks (that is, our associations, our memory) will weaken over time if not used. Whenever we think of something, that association will strengthen. The more we think about something, the stronger the association will get, and that is why we can remember by repeating something again and again.

So when you used to study, your associations got strong because you thought about things often. Then you stopped thinking about most of it, and the association(the memory) weakened a lot.

Now you have to train your memory back to where it used to be.
> 5 votes

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Tags: cognitive-psychology
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# Question
Title: What causes introverts to lose "energy" in social settings and require recovery afterwards?
Over the years I've seen numerous articles about introverts that mention that they dislike large social interactions (meetings, parties, etc) because they drain their energy. These articles mention that it can take days or weeks to recharge this energy.

This is anecdotal evidence, but I've personally felt it twice in the last week, which peaked my interest. A good way to describe this phenomena is - after a couple hours of large corporate meeting, the energy is gone, and I feel demotivated and just want to go home. "Feeling drained" is another good way to put it.

**Are there scientific theories about what is causing introverts to lose energy in social settings?** Is it related to mirror neurons? Is it related to a particular neurotransmitter system in the brain? Maybe it is related to a specific neurotransmitter receptor mutations?

Edit:

I found this relevant question that asks for the name of the "introverts losing energy" phenomenon. It mentions the following terms:

* Social overload
* Social exhaustion
* Decision fatigue
* Over stimulated

# Answer
> 3 votes
My sister and I are both introverts, and have been talking about this before. We have agreed about the following:

* When being social, we feel like we are obliged\expected to do\say certain things and avoid doing\saying others. We are supposed to ...
    + go where the others go.
    + be nice and agree rather than say what we think
    + do the same activity as everyone else
    + do it at the same time as everyone else
    + listen to the same music
    + eat the same or at the same place
    + etc etc etc...
* Our will to do\say what *we* like\want is challenged whenever we are social. We feel restrained, and We feel that we are unable to relax because we are restrained from doing what we feel like doing. Sometimes being social feels like being at work with colleagues all day - it feels like it's more obligations than our will.
* We happen to love some activities that happens to not be a good party activity. Like reading, programming, painting, etc. We need to choose either these activities or being social, and *we prefer to have some of both*, but we are forced to choose.
* When I was a kid I had this dilemma that I wanted to play computer games, but my friends didn't want to. So at my computer I missed my friends, and with my friends I missed my computer. See the problem?
* Introverts are just not that interested in talking just for the sake of talking. In my case, I go into different modes: In social mode I will chitchat and spend all my attention to people. In private mode(most of the time) I really don't care to talk unless there's something specific I **need** to talk about, and then I just space out of every discussion around me. I've never used to be interested in talk that has no clear purpose. It's like why talk if you don't have a point?
* When we don't feel like being social this is often partly because our thoughts are focused on completely different things - not on the people around us. My experience (from me, my sister and friends) is that introverts are more interested in inanimate stuff and topics than extroverts are. This might be false, and it might not.
* While being social I am mostly unable to really think through anything. When I don't filter out what people are saying, all my thoughts are interrupted and I have a hard time thinking anything logic. I'm not comfortable with this, it makes me feel unsure of my decisions, and I hardly trust my own decisions in this situation. When I later get back to my private sphere I will spend time thinking through everything again. Make up my mind again for anything I've been talking about, figure out my decisions again for anything I had to decide, and so on.

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Tags: social-psychology, empathy, introversion, mirror-neurons, social-neuroscience
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# Question
Title: How to best prepare the mind for a problem identification brainstorm?
I am a manager of a team of software engineers. We often use brainstorming sessions to generate solutions to problems. We use typical cognitive games, e.g. word association, to "warm-up" and facilitate the ideations sessions. These sessions are fruitful.

Tomorrow we are having a brainstorming session to identify problems, not solutions. It would seem that we should prepare our minds with a different technique. Personally, I find that I am best at noticing problems when I am in a negative mindset. Does that hold true against existing research? If so, what would be a good way of getting in to that type of mindset? I would assume causing some kind of mental anguish would facilitate negative thinking. However I don't want to upset my team or do any lasting damage.

Some random ideas that have come to mind include: \- Taking a minute to talk about historical atrocities \- Having food at the session, but not letting anyone eat

If I go down this road, what would be a good decompression method to get people back in to a positive mindset at the end?

# Answer
I'm wondering if your approach to "identify\[ing\] problems, not solutions," will include so-called *reverse* or *negative* brainstorming, in which participants are directed to consider "what can be done to break something instead of focusing solely on narrow-minded fixes,"1 to be "highly critical, rather than highly creative."2 If this is the case, the group could "warm up" by applying this technique to some other area: their own lives, their favourite sports teams, public policy issues, etc.

1 Stephen C. Harper. How to Solve Problems with Reverse Brainstorming, posted on his TalentSpace Blog, December 14, 2011.

2 Harper. Extraordinary Entrepreneurship: The Professional's Guide to Starting an Exceptional Enterprise (Google eBook), 2005, p.78.
> 1 votes

# Answer
I'd like to share an observation from a personal experiment, loosely based on creative thinking exercises I've read about "somewhere".

Over a course of 21 days, I was looking for innovative products in the world around me. I took pictures of them using my iPhone, and then did a short writeup about what problem this innovation is trying to solve and why I think it is awesome. **In short, the exercise is two fold: first see solutions applied to problems (like below), then see problems that don't have solutions yet.**

For example - looking at cars in a parking lot, I noticed something like this - a roof rack with a little cloth piece in front of it which reduces drag caused by the roof rack. These things did not exist in the 90s:

Another example would be a promotional flag like the one below. The curved top shape means that the flag is always stiff. It's rotating flag base prevents the flag from tangling around the pole:

Yet another example would be stackable office chairs like the ones below. Not only does their architecture save storage space, but it allows a single person to move multiple chairs at once:
> 0 votes

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Tags: problem-solving, brain-training, ideation
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# Question
Title: Is there a term to define the influence and sharing of common expressions among people?
I'm wondering how to call the phenomenon that happens when people spend a lot of time together and end up sharing similar vocabulary or reusing the other's expressions? Is there a term for this?

# Answer
You might be referring to *mimicry* or *linguistic mimicry*. Mimicry is more broad than just vocabulary and expressions, but the general principle of imitating what others in a social group are doing applies.
> 2 votes

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Tags: terminology
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# Question
Title: If I have ADHD, how can I focus on programming task for hours?
Already in 9 years, I was identified as ADHD child. I was quite obviously weird.

I can observe many known symptoms of ADHD even now.

* I'm unable to focus on stereotypic tasks which results in many failures in work, where I'm usually supposed to assemble electrical devices.
* I often just stop listening what somebody is talking directly to me. This happens so often that I stopped pretending anything what's so ever. I just say "Sorry, I wasn't listening. Could you repeat it?". Friends just repeat it, other people are usually so shocked that they repeat it too.
* In school, I always used to draw stuff al over my notebooks instead of paying attention. But I think even totally normal people do this. Maybe just not as much.

Now while this all happens, when I have an interesting programming project I can focus on it for hours. Yes, it's true that I often distract myself with various details instead of doing the main task, but generally I'm still concentrated on some intellectual task without losing train of thoughts.

So where does my problem disappear?

# Answer
> 3 votes
If you don't focus, then your efficiency easily drops to 50% of other people. But if the task is truly engaging you, you work 200% compared to other people and you forget everything else.

This has a name: Hyperfocus!

> Like distractibility, hyperfocus is thought to result from abnormally low levels of dopamine, a neurotransmitter that is particularly active in the brain's frontal lobes. This dopamine deficiency makes it hard to "shift gears" to take up boring-but-necessary tasks.
>
> "Children and adults with ADD have difficulty shifting attention from one thing to another," says Russell Barkley, Ph.D., a research professor of psychiatry at SUNY Upstate Medical University in Syracuse, New York. "If they're doing something they enjoy or find psychologically rewarding, they'll tend to persist in this behavior after others would normally move on to other things. The brains of people with ADD are drawn to activities that give instant feedback." http://www.additudemag.com/adhd/article/612.html
>
> Hyperfocus is an intense form of mental concentration or visualization that focuses consciousness on a subject, topic, or task. In some individuals, some subjects or topics may also tend toward including daydreams, concepts, fiction, the imagination, and other objects of the mind. Hyperfocus on a certain subject can cause side-tracking away from assigned or important tasks.
>
> Hyperfocus may bear a relationship to the concept of flow.\[1\] In some circumstances both flow and hyperfocus can be an aid to achievement, but in other circumstance or situations, the same focus and behavior could be a liability, distracting from the task at hand. However, unlike hyperfocus, "flow" is often described in more glowing terms, suggesting they are not two sides of the same condition under contrasting circumstance or intellect. http://en.wikipedia.org/wiki/Hyperfocus

On a more personal note:

I've been doing programming since I was about 16 y.o, I was diagnosed with ADHD at about 24, and I have now been working as an in-house hired developer for a year.

I personally experience that when I work on a topic that honestly interests me and engages me, I will be more focused and have more energy than everyone around me. I've been told by friends etc several times "God, how do you have time for all that? How are you able to do all that?" At the same time I can be incredibly inefficient with my time on less interesting tasks. Often I don't even understand what I've spent all my time on, because I haven't really done anything.

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Tags: adhd
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# Question
Title: Computational Model Linking Neural Activity to Behavior
A big question in neuroscience is how neural activity represents knowledge. We can use modelling to explore how different levels of neural activity- subthreshold currents, action potentials, local field potentials, etc.- relate to one another and, finally, to behavior.

Some models simulate behavior, for example which color flowers a bee prefers or how a mouse will navigate the Morris water maze. (Think Ch. 9 in Dayan & Abbot (2001).)

Other models simulate the behavior of groups of neurons. Some of those even address what knowledge that activity could be representing. (Think Ch 10 in Dayan & Abbot (2001).)

What are examples of linking the two? (I'm aware of computational limitations, aside from computing power such as the foolishness of simulating stiff equations for long periods of time. )

EDIT: One example is exploring how local field potentials (LFPs) could arise from networks of integrate-and-fire neurons. Earlier models of LFPs were phenomonological. They were simply coupled oscillators with different time constants and so didn't allow one to see how more detailed levels of description could create LFPs.

# Answer
There are several such models in the field of auditory perception. For example Patterson 1996 \[1\] suggests a model that starts with a simulation of the cochlea and the neural activity and reaches up to perception; Winkler 2006 \[2\] reviews the process of auditory perception, again from the cochlea up to perception.

Somewhat old and does not mention a specific model, but still a very relevant review of the neural activity - behaviour interaction debate is provided in Barlow 1972 \[3\].

---

\[1\] Patterson R.D., Holdsworth J., A functional model of neural activity patterns and auditory images. *Advances in Speech, Hearing and Language Processing*, 1996. link.

\[2\] Winkler I., Denham S.L., Nelken I., Modeling the auditory scene: predictive regularity representations and perceptual objects. *Trends in cognitive sciences*, 2009. doi: 10.1016/j.tics.2009.09.003

\[3\] Barlow B.H., Single units and sensation: A neuron doctrine for perceptual psychology? *Perception*, 1972. link
> 7 votes

# Answer
The only modelling method that I know of for creating large-scale biologically based models is the Neural Engineering Framework (NEF).

The NEF is basically a framework for associating functional computations and dynamic systems to biologically plausible populations of neurons. Given this foundation, advanced applications linking behaviour to neural function become much easier.

An example of this is Dan Rassmussen's work on hierarchical reinforcement learning, which relates behaviourist reinforcement learning to neural activities and brain regions as observed in neural data.

Spaun, which is an amalgamation of many isolated models (basal ganglia, visual cortex) created using the NEF, has also replicated various human behaviour (same rate of forgetting, recognition and recall) in simple tasks such as list memorization.
> 2 votes

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Tags: neuroscience, cognitive-modeling, computational-modeling, theoretical-neuroscience
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title: How do the blind dream?

text:
# Question
Title: How do the blind dream?
Lately, a friend of mine has been telling me that he's been having recurring dreams involving a certain rabbi, who died around a hundred years ago.
Since there's been some controversy surrounding the truth of several famous pictures of him (some say that the most famous images of him really show someone else), I wanted to ask my friend which picture he looked like.
Luckily, I stopped myself before I did -- this friend of mine is blind.

Therefore, I'd like to know what the blind experience when they dream -- do their dreams contain whatever types of experience they have in real life (ie, purely based on touch, hearing, smell, etc), or might they dream with vision? If they dream with vision, do they see color?
Is this impacted by whether the particular person in question had ever had sight (or partial sight) at any point in their life?

# Answer
You may want to read Meaidi et al (2014). They obtained dream reports from congenitally blind, late blind, and matched sighted controls. To quote the abstract, they found:

> All blind participants had fewer visual dream impressions compared to sighted control participants. In late blind participants, duration of blindness was negatively correlated with duration, clarity, and color content of visual dream impressions. Congenitally blind participants reported more auditory, tactile, gustatory, and olfactory dream components compared to sighted control participants. In contrast, late blind participants only reported more tactile dream impressions. Blind and sighted control participants did not differ with respect to emotional and thematic dream content. However, congenitally blind participants reported more aggressive interactions and more nightmares compared to the other two groups.
>
> Our data show that blindness considerably alters the sensory composition of dreams and that onset and duration of blindness plays an important role. The increased occurrence of nightmares in congenitally blind participants may be related to a higher number of threatening experiences in daily life in this group.

In summarising previous research they note that:

> previous studies seem to suggest that individuals who become blind after the age of 7 years retain visual imagery in their dreams, though congenitally blind or early blind (onset of blindness before the ages of 5–7 years) individuals do not.

They cite a number of previous studies that have looked at dreams of blind people that you may want to check out:

```
[5] Kerr NH. Dreaming, imagery and perception. In: Kryger MH, Roth T, Dement WC, editors. Principles and practice of sleep medicine. Philadelphia, PA: W.B. Saunders Company; 2000. p. 482–90.
[6] Amadeo J, Gomez E. Eye movements, attention, and dreaming in subjects with life-long blindness. Can Psychiatry Assoc J 1966;11:501–7.
[7] Berger R, Olley P, Oswald I. The EEG, eye movements, and dreams of the blind. Quart J Exp Psychol 1962;14:183–6.
[8] Kerr NH, Foulkes D, Schmidt M. The structure of laboratory dream reports in blind and sighted subjects. J Nerv Ment Dis 1982;170:286–94.
[9] Hurovitz CS, Dunn S, Domhoff GW, Fiss H. The dreams of blind men and women: a replication and extension of previous findings. Dreaming 1999;9:183–93.
[10] Kirtley D. The psychology of blindness. Chicago, IL: Nelson-Hall; 1975.
[11] von Schumann H. Träume der blinden. Basel: S. Karger Co.; 1959.
[12] Sabo KT, Kirtley DD. Emotions in the dreams of the blind. Int J Rehabil Res    1980;3:382–5.
[13] Cason H. The nightmare dream. Psychol Monogr 1935;46:1–51.
[14] Kirtley D, Cannistraci K. Dreams of the visually handicapped: toward a   normative approach. Am Found Blind Res Bull 1973;27:111–33.
[15] Spielberger CD, Gorsuch RL, Lushene PR, Vagg PR, Jacobs AG. Manual for the state-trait anxiety inventory (Form-Y). 2nd ed. Palo Alto, CA: Consulting    Psychologists Press, Inc.; 1983.

```

### References

Meaidi, A., Jennum, P., Ptito, M., & Kupers, R. (2014). The sensory construction of dreams and nightmare frequency in congenitally blind and late blind individuals. Sleep medicine, 15(5), 586-595. http://dx.doi.org/10.1016/j.sleep.2013.12.008
> 14 votes

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Tags: vision, dreams, color
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# Question
Title: Is there a name for reading things how you meant to write them?
I'm sure many of us have this experience: When I'm proofreading my own writing I will pass over it multiple times, but miss mistakes since I read what I intended to write (what's "in my head") and not what is actually on the page.

Is there a name for this? I tried searching google, but had no luck.

# Answer
Unofficially, it has been called "illusion of expectation" by Christopher Chabris and Daniel Simons, the guys famous for the Invisible Gorilla experiment.

Technically it falls under inattentional blindness (or perceptual blindness):

> ... the event in which an individual fails to recognize an unexpected stimulus that is in plain sight.
> 10 votes

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Tags: bias, reading
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# Question
Title: Is cognitive science a concentration of psychology?
Is cognitive science apart of psychology? If I major in psychology, will it be easy for me to be a cognitive scientist?

# Answer
It's the other way around: Psychology is a discipline within Cognitive Science, which includes Artificial Intelligence, Neuroscience, and possibly Philosophy of Mind. Research work in Psychology presumably makes you a Cognitive Scientist.
> 8 votes

# Answer
Arnon's answer is right, but I thought it might help to explain why.

Cognitive Science is the study of minds. This can include human minds, other animal minds, and artificial minds. The method could be to study how agents with minds behave in experiments (psychology), to study the physiological properties of biological minds (neuroscience), to create and model synthetic minds (artificial intelligence), to theorize about properties of minds (philosophy), to study the cultures and history of agents with minds (anthropology), and/or to study particular, especially complicated, aspects of minds (linguistics).

Psychology is just one way of approaching the problem (which can tell us quite a bit about minds), but a broader perspective would be needed to get a complete picture of what minds are and how they work.
> 5 votes

# Answer
I agree with Arnon that cognitive science is, by most people's definition, multi-disciplinary. And one of those disciplines included is psychology.

However, if you were to attend a cognitive science conference or read a cognitive science journal, you would see that it mostly includes areas of psychology that broadly relate to cognition.

There are many sub-disciplines of psychology that would not readily identify with cognitive science. For example, clinical psychology, I/O psychology, most of social psychology, most of personality psychology, and so on.

Thus, you might want to think of cognitive science and psychology in terms of partially overlapping Venn Diagrams.

As a final note, we use the term "cognitive sciences" on this site in a very inclusive sense. It is unfortunate that there is no single word that easily captures all that psychology and cognitive science encompasses.
> 3 votes

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Tags: terminology
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# Question
Title: "Do it yourself" Cognitive-Behavioral-Therapy-style intervention methods
In Cognitive Behavioral Therapy, what should happen between the occurrence of a *negative automatic thought* and, finally, its *neutralization* is *logical thinking*: looking at the **evidence for** the automatic thought, and the **evidence against** the automatic thought, and coming to the conclusion that the automatic thought is not worth thinking about. Or that it wasn't valid at all.

In an *emergency situation* coupled with *very high anxiety*, an ***intervention*** is needed. The therapist uses the CBT model to show the patient that the negative automatic thought is not valid. This is especially important for patients with anxiety disorders. **This is CBT performed in a timely, efficient and immediate manner (perhaps on the phone), when waiting for the next therapy session to come by is not an option.**

Is there a way patients can *perform a CBT intervention without the aid of a therapist* in a high intensity, emergency situation, with high propensity for negative thinking, and high anxiety, *just in case the therapist isn't reachable/available at that moment*?

# Answer
Actually, reconceptualization is only one tool of CBT.

The basis is still what you might call "conditioning" or "skills training" (depending on the disorder). The depressed person does not "think away" (or "feel away") his depression, but learns and practices new behaviors until they become habitual. And it is this behavior change that leads to different experiences, new insights, and to a different "feeling" and "thinking".

For example, a person with Social Anxiety will simply learn social skills and practice them until they become second nature. This person *experiences* that they are not repulsive (as they had thought), when their new skills (e.g. smiling when approaching a stranger) lead to positive outcomes (e.g. the stranger smiling back). Discussing the mental concepts ("Believing that you are repulsive has the function to help you avoid situations that cause you fear.") and changing them ("I behave in a way that repulses people, and I can change that behavior.") helps motivate the patient to commit to the therapy and supports the practical exercises.

Reconceptualization accompanies behavioral methods and complements them. That is why it is not called Cognitive Therapy, but Cognitive *Behavioral* Therapy.

Basically, what CBT does is "faking it": you act as if you weren't afraid of spiders, until you have lost your fear; you act as if you weren't depressed, until you no longer are. The C-part helps you understand what you are doing and process your experiences.

What you also need to keep in mind is that behavior change might entail removing the patient from a pathogenic environment. For example, an alcoholic might profit from not going to bars to meet his dinking buddies. A depressive might profit from divorcing an abusive spouse or finding a job more in tune with his values and interests.

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Reading through the old edits of your question, I realize that I have probably misunderstood your intent. Please comment, if you are looking for something else.
> 3 votes

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Tags: abnormal-psychology, clinical-psychology
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# Question
Title: Which is the shortest duration for a pitch difference in audio signals to be perceived by the human auditory system?
If I have two short audio signals, for example pure tone C4 and C#4, so half-tone difference, how short can they be that the human can hear the difference in pitch? Was there any blind-experiment/research with a good set of subjects done about this?

I was causally testing with a short script and it seems I am able to distinguish down to 30 ms long samples if I play one sample, then one second of pause, and another half tone higher sample.

I can also do it for shorter, but I am not sure anymore if I really hear it, or if I just imagine hearing the difference.

Bonus question: how short can it be if the signal consists of two tones. So of both C4 and C#4 at the same time. Can one hear that there are both C4 and C#4 in the signal if it is only 30 ms long?

# Answer
> 5 votes
It really depends on what you mean by difference in pitch. Subjects can discriminate differences in frequency for very short tones, but it does not mean they are being perceived as pitch differences. The classic paper in this area is Moore (1973):

As the duration is reduced from 200 ms to 6.25 ms, performance falls off, especially for low frequency tones. It is worth noting that creating extermely short sounds with narrow bandwidths is difficult. With a 12.5 ms duration, subjects can still discriminate between tones with frequencies of 250 Hz and 255.7 Hz (a Delta f of 5.7 Hz and a (Delta f)/f of 0.023).

C4 has a frequency of 261.63 Hz and C4# has a frequency of 277.18 Hz for a Delta f of 15.55 Hz and a (Delta f)/f of about 0.06. One would expect that you could discriminate C4 from C4# with durations substantially shorter than 12.5 ms

In regards to your "bonus question", when the stimulus consists of two tones, things get very complicated. Judgements like can you hear both tones are very different from can you hear the difference between a single tone and the pair of tones.

# Answer
> 2 votes
I used 5 ms long tone bursts in an experiment where people had to discriminate between a 1000 Hz and a 1200 Hz pure tone (or rather, click). They could generally do this very well, if I remember correctly accuracy was above 90%.

I then had a different paradigm which was a bit more difficult in terms of the task, and I had to increase the tones to 20 ms for similar accuracy. So I would guess that 30 ms should be plenty, if your sound equipment is reasonably good.

My study participants were healthy young people (otherwise known as students) of normal hearing.

# Answer
> 0 votes
The absolute minimum duration of tone bursts is limited by mathematical (physical) limitations and more importantly, your hardware.

Mathematically, the minimum duration will depend on the frequency, as one period is the minimum time necessary to mathematically define a particular frequency. For example, to complete one period of a 100 Hz tone, at least 10 ms is needed. For a 10 kHz tone 0.1 ms is enough.

Regarding the hardware limitations - presenting a short tone burst may result in frequency splatter. This phenomenon is hardware-dependent and even the most expensive speaker systems are subject to this effect. Basically it's the result of the generation of unwanted frequencies due to the onset and offset of the tone burst. The splatter can be reduced by using onset and offset ramps. Onset and offset ramps are used in order to gradually increase and decrease the power of the signal at the start and end of the tone burst, respectively. Exactly how long these ramps have to be depends on the hardware used. As a rule of thumb, onset and offset ramp times of 2 periods can be used with a plateau phase of at least 2 periods in-between. This adds up to a total of 6 periods. A 500 Hz tone burst, then, would need at least 6\*2 ms = 12 ms.

At relatively high frequencies (say 1 kHz and above) this rule of thumb may not apply as periods become very short. At higher frequencies, therefore, the answer by @Strongbad will give a good indication of the lower duration limit. However, keep in mind that introducing onset and offset ramps is always a good idea, even at long stimuli (say 100 ms) since frequency splatter always contaminates the signal.

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Tags: experimental-psychology, hearing, psychoacoustics
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# Question
Title: Is all learning a subconscious activity?
As a non-native English speaker I recently tried to understand difference in phrases "to study" and "to learn". I found some explanations here on *English language and usage SE*, stating that learning is a subconscious activity. Then in some articles I've found, authors stated that language learning is subconscious and that acquiring knowledge and skill isn't the same \[ also that learning language is actually learning a skill, while learning history is acquiring knowledge.\] .

So I got confused : **is all learning subconscious or not?**

**Is there a difference in learning language and learning anatomy, laws of physics or programming?**

Additionally some articles got me confused, especially those that want to sell you hypnosis DVDs and instruction manuals to "boost" your subconscious mind. Aren't we already equipped with proper subconscious mind?

# Answer
We should not confuse the psychological terminology of consciousness, the subconscious and the unconscious with the lay meaning of activities being performed consciously or subconsciously.

The distinction between "conscious" learning and "subconscious" acquisition of linguistic knowledge goes back to the Monitor Model that linguist Stephen Krashen developed in the 1970s and 1980s. According to this theory, human beings develop linguistic skills in two ways: either we

* "subconsciously" **acquire** knowledge, without realizing that we do so (e.g. by growing up in a certain linguistic environment), or we
* "consciously" **learn** (e.g. by memorizing lists of words in a foreign language).

Krashen's theory has been both praised and criticized, but this is not the place to go into that debate. It should be enough to note that the hypothesis has as yet not been empirically proven.

From a psychological point of view, learning – of which acquisition is a part, namely that a response to a stimulus has been established – is *always* not conscious. A conscious activity is one that we are aware of (like intentionally putting a book on a shelf), but learning, that is: the storing of information in the brain, takes place through processes of which we are unaware and in parts of our anatomy over which we have no control.

For example, when you try to memorize a foreign word and its meaning, you cannot consciously put that knowledge in your memory like you can place a book on a shelf. What you must do, for example, is repeat the information until you no longer forget it. But you have no awareness of wether or not the storage was successful. You can only deduce that success from your ability to retrieve the information (i.e. correctly remember). A conscious storage would give you a direct (sensory) feedback of the storage process, similar to how your eyes show you wether or not the book is now on the shelf. If the placing of a book on a shelf worked subconsciously like storing knowledge in your brain, you'd have to retrieve the book from the shelf again to know that it had been put there. Until you took it off the shelf, you couldn't know if it was actually there.

So to answer your question:

# For a psychologist, all learning is "subconscious" (but he would not use that word).
> 2 votes

# Answer
What you describe here is two types of memory the **declarative memory** and the **implicit memory**.

Declarative memory is consciously retrieved and stored. It is this kind of memory that is used to store historical facts. See below extract from wiki :

> Declarative memory (sometimes referred to as explicit memory) is one of two types of long-term human memory. Declarative memory refers to memories that can be consciously recalled such as facts and knowledge

Implicit memory is created with practice, by doing things. This is the type of knowledge that is mostly used in language learning (We also learn some declarative knowledge at the beginning e.g. grammar rules. But after we apply these rules many times, implicit memory is created and usually the declarative rules fade away). See below extract from wiki :

> Implicit memory is a type of memory in which previous experiences aid the performance of a task without conscious awareness of these previous experiences. ... In daily life, people rely on implicit memory every day in the form of procedural memory, the type of memory that allows people to remember how to tie their shoes or ride a bicycle without consciously thinking about these activities.
> 1 votes

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Tags: learning, consciousness
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# Question
Title: List of experiments contradicting the expected utility model
I proposed this question as an example question for the Area51 proposal "Mathematical modeling". User Artem Kaznatcheev suggested that it be asked here too, which I thought was a good idea.

So I am looking for a list of experiments which cannot be accounted for by the expected utility model. By the expected utility model, I mean the model of individual preferences over vectors of uncertain events (e.g. $\Big(P(rain) = 0.4, P(sunshine) = 0.6\Big)$ and $\Big(P(rain) = 0.6, P(sunshine) = 0.4\Big)$) which satisfies a list of axioms proposed by Von Neuman and Morgernstern, namely

* Completeness
* Transitivity
* Continuity
* Independence

A rigorous formulation of these axioms can be found on page 8 of Axiomatic Foundations of Expected Utility and Subjective Probability, by Edi Karni, from the Handbook of Economics of risk and uncertainty.. **The violations of these axioms I am most interested in are the ones related to the Independence axiom** (violations of completeness, transitivity and continuity would deserve a separate question. See this question for an example of intransitivity.).

Alternatively, by Von-Neuman and Morgenstern's representation theorem (page 9 of the same reference), these axioms are know to be equivalent to the fact that the preferences of the agent can be represented by a utility function of the form (in the discrete case):

$U(L) = \sum\_{all~possible~events "e"} P(e)u(e)$

where $P(e)$ is again the probability that $e$ occurs and $u(e)$ is the utility of getting event $e$ for sure.

I am looking for situations which cannot be accounted for by the expected utility model. Some well-known examples are the the Allais and Ellsberg paradoxes (although there is still a debate regarding Ellsberg paradox). On the other hand, I do not see the Saint-Peterborough paradox as contradicting expected utility theory, because it can be accounted for by the theory if one assumes an appropriate degree of risk aversion.

I hope this question can serve as a repository of famous experiments contradicting expected utility theory, so feel free to add many.

# Answer
I asked the same question in the private beta of the newly open Economics.SE and got some interesting answers. You can check them out at https://economics.stackexchange.com/questions/95/experiments-contradicting-the-expected-utility-model
> 1 votes

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Tags: decision-making, economics, behavioral-economics
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# Question
Title: Is there a report of a successfully EEG-Based Brain-Computer Interface (BCI) using image training?
Currently I am involved in constructing an EEG-Based BCI.

The goal of the BCI is to control which light in a series of lightbulbs lights up. The plan is to use different images (i.e. a flower versus a tiger) to elicit different neuron response that will show up on the EEG. The light bulb will light up in any order these images are given (tiger -\> flower -\> mountain -\> sky -\> white noise -\> bright red...etc.)

Does anyone know if there has ever been a successful realization of such system? Please provide me with a link to it.

# Answer
> 4 votes
This article by Bobrov et. al seems to be similar to what you are looking for. They were able to classify (at above chance performance) whether subjects were imagining houses or faces. The training protocol is particularly interesting: they started by showing subjects pictures, but then used a feedback process of showing the subjects the output of the classifier while they were imagining the images to try and improve the subjects' 'imagination' of the images.

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Tags: neuroscience, reference-request, methodology, eeg
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# Question
Title: What is the meaning of "little efferent input" to retina?
Gollisch & Meister (2010) state that "the retina receives little efferent input from the brain" (p. 157). Could anyone describe what exactly this "little efferent input" (where it originates, whether it is present in primates, its function ...) is or point me to the relevant literature?

Here is the paper in question:

Gollisch, T., & Meister, M. (2010). Eye smarter than scientists believed: neural computations in circuits of the retina. Neuron, 65, 150–64.

# Answer
> 5 votes
Interesting question!

The paper you read should have inserted an appropriate citation. Moreover, "little input" is a subjective statement and doesn't make much sense in the context, as it can mean that there are few efferent axons (which may still have large effects on retinal functioning), or that the efferent input is relatively unimportant when compared to the afferent visual projections (which may indeed be so). In fact, I think what the authors actually try to say is that there is not much data available on efferent retinal input.

To answer your question: The efferent projections from the brain back to the retina, referred to as **centrifugal projections**, are indeed not extensively studied. The studies done were mainly performed in avian species. However, centrifugal projections have been shown to exist in **monkeys and humans**. In the macaque, they originate in the brain in the **hypothalamus**, and constitute **histaminergic** neurons which are thought to be involved in **regulating blood flow** in the inner plexiform layer of the retina. They may also be involved in **regulating retinal dopaminergic amacrine cells**, at least in mice and other species. Specifically, dopaminergic amacrine cells in the retina may be receiving centrifugal input from the **suprachiasmatic nucleus** (SCN, situated in the hypothalamus) where **circadian rythms** are initiated from melanopsin containing ganglion cells. The dopaminergic amacrine cells in the retina target photoreceptors, horizontal cells and amacrine cells and thereby regulate the retina depending on the state of the **circadian clock**. Most studies are histological in nature and functional data remains scant.

**Reference**:
Webvision - Feedback Loops (by Helga Kolb)

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Tags: vision, neuroanatomy, neurophysiology
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title: How does masking work?

text:
# Question
Title: How does masking work?
Masking occurs when the delay between the target and the mask is less than a threshhold (say 50 milliseconds). If sensory data passes from lower to higher visual cortices/processing regions as in a linear one way street, how can the mask (which comes later) influence the perception of the target (which moved ahead of the mask)?

So does this mean masking works because the neuro-network consists of nested connections folding back and forth on itself? If so, at what scales do they operate? Do they occur both within higher regions and between higher and lower regions? Do we understand how they work in detail in the case of masking?

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I learned that masking is often used as a research tool for subconsciousness/unconsciousness. But maybe neuro-feedback disruted using masking is just one of the many ways subconscious perception can occur? If so, shouldn't we reserve some qualms about general conclusions about subconsciousness/unconsciousness drawn using the masking method?

# Answer
> 10 votes
Apparently your question is on **backward masking**, which means that the masker follows the stimulus (probe) in time. **Backward masking generally occurs at higher levels, typically the cortex**. In case of visual stimuli this can be the primary visual cortex, or V1 (Mace et al. 2005). Ongoing processing of the probe is then thought to be interfered with by the subsequent presentation of the masker, as long as the masker-probe interval is not too long. The PNAS article by Covaks et al., 1995 shows this nicely at the cortical level: neurons working on the stimulus change their response patterns when a masker is presented afterwards. So although there may be **connections folding back and forth onto themselves**, a serial 'one-way' route where the processing of a stimulus changes upon arrival of the masker is the most parsimonious, and experimentally supported explanation. Cortical processes are often affected by **consciousness** (alertness/vigilance) so the presence of backward masking effects can be interpreted as a marker of **cortical higher-level processing**.

**Forward masking**, and **simultaneous masking**, on the other hand, work at the neural level through adaptation processes. Although the effects of forward masking can be observed at the cortical level as shown by Brosch & Screiner 1997, forward masking is caused by processes occurring in the periphery (e.g., the cochlea or auditory nerve in hearing) and are unaffected by mental state. Hence, the presence of forward masking indicates that the neural process under investigation reflects a peripheral process that can also occur subconsciously, whereas the presence of backward masking generally point towards a higher-level neural process that is typically affected by mental state. Hope this helps.

# Answer
> 4 votes
There are different types of masking that may have different mechanisms. Even backward masking may mean:

* noise masking - such as when white noise is presented
* pattern masking - when target-resembling pattern of lines is shown
* metacontrast masking - when an object adjacent to target (but not occluding it) and highly different in contrast is used
* object substitution masking - when target itself is not occluded by mask (e.g., four dots are present near the corners of a target), but nevertheless is not perceived

Thus, different explanations exists for different types of masks and different conclusions can be made both about consciousness and about brain mechanisms. What I mean is that no clear answer on your question is possible without specifying further what kind of masking we are talking about.

See, for example, these papers:

Delord, S. (1998). Which Mask is the Most Efficient: A Pattern or a Noise? It Depends on the Task. Visual Cognition, 5, 313–338.

Enns, J. T., & Lollo, V. Di. (1997). OBJECT SUBSTITUTION:. A New Form of Masking in Unattended Visual Locations. Psychological Science, 8, 135–139.

Goodhew, S. C., Pratt, J., Dux, P. E., & Ferber, S. (2013). Substituting objects from consciousness: A review of object substitution masking. Psychonomic Bulletin & Review. doi:10.3758/s13423-013-0400-9

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Tags: cognitive-neuroscience, theoretical-neuroscience, consciousness, neurophysiology
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# Question
Title: What is the biological reason behind disorganized thinking and disorganized behavior in thought disorders?
Having disorganized thinking is different for everyone. But, it is sometimes described as not being able to connect thoughts together. *I am asking about disorganized thinking other than communication problems.* **To be more specific, disorganized thinking, relating to the thoughts one forms, that causes disorganized behavior.**

Is there a biological reason behind this, something relating to dopamine activity in the brain?

# Answer
> 2 votes
There is some evidence that thought disorder (also called loose association) arises, at least partially, from **increased spreading activation**; schizophrenics, for example, often show a greater increase in activation to indirectly related words compared to unrelated words, than do non-thought disordered controls. This is primarily a cognitive mechanism, not a biological one, of course, and I have found very little biologically-based explanation of spreading activation itself; it comes from the computational cognitive science end of things, and is often discussed as part of a neural network model of cognition.

To address Alex Stone's comment above, I believe what he is talking about is either Broca's area (the language-dominant hemisphere's inferior frontal gyrus), generally understood to be important for producing language as well as comprehending complex sentences, or Wernicke's area (the language-dominant hemisphere's posterior superior temporal gyrus), which is generally thought to be important for processing the dominant meaning of words as well as understanding nonliteral language such as jokes, sarcasm, etc. There is some evidence for a **correlation** **between volume reduction in both Broca's and Wernicke's areas, and thought disorder symptoms**. Again, however, no mechanism has been suggested; and as with much imaging research, it is at this stage impossible to tell whether the neural abnormalities are the cause of the symptom or themselves a symptom of another cause.

Schizophr Res. 2013 May;146(1-3):308-13. doi: 10.1016/j.schres.2013.02.032.
Schizophr Bull (2008) 34 (3): 473-482. doi: 10.1093/schbul/sbm108
Neural Basis of Semantic Memory, ed. Kraut & Hart (2007). Cambridge University Press.

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Tags: cognitive-psychology, neuroscience, terminology, schizophrenia, unconscious
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# Question
Title: Freudian repressed unconscious as the biological reason behind self-destructive behavior?
Self-destructive habits include:
\- smoking whilst being aware of the effects
\- not exercising whilst knowing that it is healthier to do so
\- taking one more hit of a drug "for the last time, really"

Is there any truth to the following statement?:

Freudian repressed unconscious is what allows us to be in conflict with our emotions. If System 1 were consciously aware of these hidden things, self-destructive behavior wouldn't exist.

**This question is inspired by the following book:<br>O'Connor, Richard - Rewire: Change Your Brain to Break Bad Habits, Overcome Addictions, Conquer Self-Destructive Behavior - Penguin Group US.**

# Answer
> 1 votes
It has been a while, but I've always understood the theory to say that the superego, the internalization of values and rules, can cause us to repress ideas that aren't inline with our values. Basically, as we continue to do things that we 'know' are 'wrong' there is a resultant feeling of anxiety, which we often seek to avoid.

There are better ways to explain this type of phenomenon though; I would suggest some basic cognitive behaviourism. For instance, if we suggest that a person's thoughts of guilt, let's say around exercise, create a punishing effect, then we can in turn come to associate exercise with the negative feeling of guilt. If we expand out and include the further associations of obesity/guilt and their close association with exercise, we can start to build a theoretical model of why neurotic behaviors develop around exercise.

-edit-

I'll do a quick edit to respond to the a comment about sources. I was doing some research after I posted this, I managed to find an article discussing how attitudes relate to the avoidance of exercise:

http://onlinelibrary.wiley.com/doi/10.1038/oby.2010.234/full

I'm having a harder time finding anything specifically talking about exercise and the types of avoidance/escape you see in high anxiety behaviour. Here's an article talking about how avoidance and escape can serve as reinforcing mechanism for phobias:

http://www.gracepointwellness.org/1-anxiety-disorders/article/38494-operant-conditioning-and-avoidance-learning

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Tags: cognitive-psychology, abnormal-psychology, terminology, unconscious, behavior
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# Question
Title: How would losing episodic memory affect a person's functioning?
Episodic memory is defined as the difference between remembering and knowing. Roughly speaking, the criteria for episodic memory is a memory which you remember from a first person vantage point, contains visuals, and is remembered as a specific singular instance.

What would likely effects be of someone losing the ability to access this type of memory, or to process events into memories in this way?

# Answer
The best evidence for what you are asking comes from amnesic patients. The most famous and most close to the condition you describe was patient H.M.

See below some extracts from wikipedia :

> Molaison's general condition has been described as heavy anterograde amnesia, as well as temporally graded retrograde amnesia (Smith & Kosslyn, 2007).Since HM did not show any memory impairment before the surgery, the removal of the medial temporal lobes can be held responsible for his memory disorder. Consequently, the medial temporal lobes can be assumed to be a major component involved in the formation of semantic and episodic long-term memories

...

> Despite his amnesic symptoms, Molaison performed quite normally in tests of intellectual ability, indicating that some memory functions (e.g., short-term stores, stores for words, phonemes, etc.) were not impaired by the surgery (Smith & Kosslyn, 2007; Corkin, 2002). However, for sentence-level language comprehension and production, Molaison exhibited the same deficits and sparing as in memory (MacKay, James, Taylor & Marian, 2007).

...

> In addition to his intact working memory and intellectual abilities, studies of Molaison's ability to acquire new motor skills demonstrated preserved motor learning (Corkin, 2002). In a study conducted by Milner in the early 1960s, Molaison acquired the new skill of drawing a figure by looking at its reflection in a mirror (Corkin, 2002).

...

> Experiments involving repetition priming underscored Molaison's ability to acquire implicit (non-conscious) memories, in contrast to his inability to acquire new explicit semantic and episodic memories (Corkin, 2002).
> 2 votes

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Tags: memory
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# Question
Title: What is the psychological cause and meaning of "common sense"?
To what extent is common sense innate versus influenced by interactions with others? If someone has grown up with minimal interaction with other people, would their common sense be different?

# Answer
It is difficult to say that "common sense" is rigidly defined enough to be studied in the way stated above. There are interesting topics concerning common sense in Psychology, but most don't come from the angle you are suggesting. For instance, here is a really decent article discussing cognitive bias and common sense:

http://www.elkinsappsych.com/uploads/8/4/3/5/8435157/cognition-\_cognitive\_biases\_make\_common\_sense\_neither.pdf

You also have to consider that common sense doesn't tend to employ rigid enough requirements for theories; we also allow for conflicting theories to serve as 'valid' explanations. Take for instance:

Birds of a feather flock together vs. opposites attract.
> 3 votes

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Tags: cognitive-psychology, social-psychology, decision-making
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# Question
Title: What are the key features of dreams that trigger dream recall in the waking state?
There are various ways of writing down dreams upon awakening in one's dream journal. I've seen long, detailed descriptions that read like novels and take a page or two. Then there are terse notes of place, action and characters.

In both cases, it is possible that the dream is forgotten, and upon reading the description, no recall happens, instead the mind starts to visualize the writing anew.

This makes me ask - **Is there a key feature of a dream that prompts recall upon reading/thinking it?** Is it a place, a feeling or something else? Is it recalling a known dream, then reading the description?

For example, in my current dream journal, i note the following:

* Record the location, note indoors/outdoors
* Record the main action, focusing on feelings
* Record light level (ex: dark/light)
* Mention dream characters
* Record the topic of conversation
* Record any remembered phrases or response

But the above list is still not guaranteed to trigger recall

# Answer
No recall happens when reading the description is probably because one is focusing on reading and visualizing it but not recalling. I think there are different key features to prompt recall for different dreams, since dreams are a mixture of several features, and their proportion or intensities varies in different dreams (Foulkes and Vogel, 1965). E.g., in a dream with intense emotion, emotion/feeling contributes more to the recalling while people, place account more for the recalling in a dream consists of events.

Foulkes, D., & Vogel, G. (1965). Mental activity at sleep onset. Journal of Abnormal Psychology, 70(4), 231.
> 3 votes

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Tags: cognitive-psychology, experimental-psychology, dreams
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# Question
Title: Effective sampling rate in human visual system
The \[stroboscopic effect\]\[1\] is often explained as one of the problems of sampling. If sample rate is too low, you might have the impression of the signal frequency being low or even reverse. There are many animations on the internet describing the process but I find static sinus function graph more comprehensible:

You definitely know this effect from car wheels or plane propeller in movies. That's because the movie captures certain amount of frames. If the event is significantly shorter than capture rate, the output doesn't make any sense anymore.

My question is, how can I observe the stroboscopic effect in full light with my very own eyes? I thought there's no fixed frame-rate for human vision. I thought it's an analogous process (continuous stream), rather than digital (timed sampling).

* **Q:** How can be human vision in non-flashing (such as sun) light be subject to stroboscopic effect? Where does the damage happen?

# Answer
> 3 votes
Yes, you can experience the stroboscopic effect under continuous illumination. This wikipedia article does a nice job of summarizing relevant findings.

As mentioned in the article, there are two competing theories for how the stroboscopic effect happens under continuous illumination in the human visual system. The first theory is that human visual processing is like a movie camera and it operates on roughly discrete frames. The second theory is that **neural adaptation** is responsible: the brain adapts to the very regular patterns of motion, which can cause visual after-effects where the opposite pattern is perceived. Overlaying the actual motion with the visual after-effect will 'cancel out' the perceived motion.

Kline and Eaglemen (2008) present evidence against the discrete sampling hypothesis and supporting the adaptation hypothesis. Macdonald et al. (2014) present evidence for the discrete sampling account.

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Tags: perception, cognitive-neuroscience, vision
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# Question
Title: Have there been any scientific experiments attempting to communicate with one's unconscious mind?
For the purposes of this question, I will define unconscious/subconscious as the parts of the human mind that are not normally available for introspection or control, but which are still involved in cognition. These parts of the mind might be involved in memory recall or assimilation of information. While I would define communication as receiving a recognizable response to input.

**Have there been experiments attempting to establish communication with the researchers own unconscious mind?** If so, what were their results? I'm not looking for "new age" kind of articles, but genuine scientific research findings.

The most **direct** way of communication that comes to mind would be talking to dream characters in a lucid dream and evaluating their responses upon awakening. Such characters are capable of semi-intelligent speech, and their responses at least casually appear to be related to the question at hand. A consistent pattern of responses over several dreams might be considered a form of communication.

Another experiment I can think of, which uses **non-verbal** communication would be using some daily activity to consistently triggers a recurring dream setting at night. For example, intense study causing dreams of classrooms or exams. In this case, the setting can be considered a response of unconscious system.

Another example I can think of is exposing a person to a stimuli which consistently causes some song to surface and "get stuck in one's head" - earworms during waking cognition. Alternatively, some saying or **thought** might arise unbidden in response to the stimuli. In this case, this can be considered another form of response.

Have there been scientific experiments along the lines described above? What would be the term I would use to search for "communicating with unconscious" in a scientific setting?

# Answer
In order to find such studies, it's a good idea to start off with mapping out what kind of situations would be relevant - that is, in what cases would it even be possible to communicate with someone's unconsciousnes? Then you need to define what kind of communication you are interested in. Here are some ways to find some kind of unconscious communication: Sleepwalkers, hypnosis(highly controversial), vegetative states and the like, subliminal messages, facial expressions, etc. As such, the short answer to your question is "yes". The long answer is that your question is too wide.

Here's an article on using unconscious communication as a way of identifying narcissism:

> In this paper I suggest that analytical material implicitly carries in it a message proceeding from the unconscious and which is transmitted through representations. The message is expressed only when the object is recognized as such by the subject. In the narcissistic situation the unconscious message is not emitted. http://europepmc.org/abstract/MED/3667086

An article on communicating with patients suffering from trauma:

> The interface among trauma, dissociation, and regression is discussed in the context of unconscious communication as a transferential enactment of unsymbolized experience.The view is offered that for certain patients in particular, past experience is not so much unconscious as “frozen in time” and that a key element of the psychoanalytic relationship is bridging dissociated aspects of self through the creation of a dyadic experiential field that is both “inside” and “outside.” http://www.tandfonline.com/doi/abs/10.1080/10481889109538911?journalCode=hpsd20#.VIAkl8mZGkU

Research on facial expressions:

> Studies reveal that when people are exposed to emotional facial expressions, they spontaneously react with distinct facial electromyographic (EMG) reactions in emotion-relevant facial muscles. These reactions reflect, in part, a tendency to mimic the facial stimuli. We investigated whether corresponding facial reactions can be elicited when people are unconsciously exposed to happy and angry facial expressions. Through use of the backward-masking technique, the subjects were prevented from consciously perceiving 30-ms exposures of happy, neutral, and angry target faces, which immediately were followed and masked by neutral faces. Despite the fact that exposure to happy and angry faces was unconscious, the subjects reacted with distinct facial muscle reactions that corresponded to the happy and angry stimulus faces. Our results show that both positive and negative emotional reactions can be unconsciously evoked, and particularly that important aspects of emotional face-to-face communication can occur on an unconscious level. http://pss.sagepub.com/content/11/1/86.short
> 3 votes

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Tags: experimental-psychology, dreams, unconscious
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# Question
Title: What is the difference between feeling sad and feeling unhappy?
The first two questions on the Burns Depression Checklist ask about (1) Feeling Sad and (2) Feeling Unhappy. Specifically, they ask how much you have experienced:

1. Feeling sad or down in the dumps
2. Feeling unhappy or blue

What is the difference between these two questions?

### References

* The BDC is from the book Feeling Good, by David Burns.

# Answer
It is common for psychological tests to include multiple items with similar meaning. These items are then combined to form an overall scale score (e.g., depression or depressed thoughts). Multiple items with a similar meaning are used to increase the reliability of measurement, which is also important for validity.

I don't think there is a huge difference in meaning between the two items, and presumably they are highly correlated. However, they may provide slightly different connotations to different people. Thus, by having multiple items, the scale may have improved reliability.
> 3 votes

# Answer
I think that there is some difference, at least to me.

All emotions are results of thoughts.

Sadness is most likely a result of negative thoughts about past or future (and, therefore, disconnecting from present moment).

"Feeling unhappy" is often misunderstood, because people often mistake true happiness for external stimulation/excitement. So I think what people are experiencing, when they say they're feeling blue, is simple lack of excitement. It doesn't have much in common with happiness (which is almost the opposite - it comes from the inside and is permanent).
> 0 votes

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Tags: depression
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# Question
Title: Why does strobe lighting trigger seizures in photosensitive epilepsy?
> Photosensitive epilepsy (PSE) is a form of epilepsy in which seizures are triggered by visual stimuli that form patterns in time or space, such as flashing lights, bold, regular patterns, or regular moving patterns.

Why does strobe lighting trigger seizures in photosensitive epilepsy?

# Answer
Seizures induced by stroboscopic lights are an example of reflex seizures. This type of epilepsy includes seizures evoked by touch and movements as well. The mechanism behind generalized reflex seizures (generalized epilepsy, as opposed to partial epilepsies, is accompanied by a loss of consciousness) was abstracted nicely by Ferlazzo *et al.*, 2005:

> Patients with \[\] generalized reflex seizures appear to have regions of cortical hyperexcitability overlapping or coinciding with areas physiologically activated during specific sensory stimulations and cognitive or motor activities. When these areas receive appropriate afferent volleys and a critical mass of cortex is activated, an epileptic activity is produced that ultimately involves cortico-reticular or cortico-cortical pathways resulting in a generalized or bilateral epileptic event.

In other words, stimuli such as stroboscopic light evoke activity in sensory cortex. If the area of excitation is large enough and occurs in a region of the brain that has an epileptic focus (hyperexcitable cortex) than it may trigger a seizure characterized by an uncontrolled wave of activity spreading across the cortex.

Specifically for flashing-light induced seizures it is thought that seizures start in the visual cortex in the occipital lobe due to impaired cortical mechanisms of contrast gain control for certain visual patterns, producing an abnormal excitatory response to patterns of relatively low temporal frequency and high luminance contrast. Specifically, the seizures may be caused by a loss of control over high-frequency oscillatory processes that normally operate transiently to connect the involved neural assemblies. Generalized seizures can occur if normal excitation of visual cortex involves a ‘critical mass’ of synchronized activity in a cortical area with synchronization and subsequent spreading of excitation from the occipital lobe trigger zone (Parra *et al*., 2005).

<sup>**References**
**-** Ferlazzo *et al*., *Brain* (2005); **128**: 700–10
**-** Parra *et al*., *Curr Opin Neurol* (2005); **18**(2):155-9</sup>
> 7 votes

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Tags: neuroscience, abnormal-psychology, epilepsy
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# Question
Title: What is the name of the concept in psychology that makes requirements hard to articulate?
One of my teachers in Computer Science explained this idea about requirements:

> Product owners don't know what they want, they need a feedback loop of requirements gathering to push them to say precisely what the requirements should be.

I know there are plenty of exceptions to this, but in my experience this has been generally true.

He explained that it was related to an idea in psychology.

My question is: **What is the name of the concept in psychology that makes requirements hard to articulate?**

# Answer
I think the concept you are looking for is Tacit Knowledge (aslo known as implicit knowledge).

The main reason that users cannot articulate what they want, is that they do not have any conscious access to the knowledge they have acquired over the many years of practice. That’s why an iterative process is needed to bring the tacit knowledge on users awareness, so that they can articulate it.

Definition from wikipedia :

> Tacit knowledge (as opposed to formal, codified or explicit knowledge) is the kind of knowledge that is difficult to transfer to another person by means of writing it down or verbalizing it. For example, stating to someone that London is in the United Kingdom is a piece of explicit knowledge that can be written down, transmitted, and understood by a recipient. However, the ability to speak a language, knead dough, use algebra, or design and use complex equipment requires all sorts of knowledge that is not always known explicitly, even by expert practitioners, and which is difficult or impossible to explicitly transfer to other users.
> 8 votes

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Tags: cognitive-psychology
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# Question
Title: Are the two halves of the brain mirror images of each other?
Can this question be answered in terms of the relationship between handedness and hemispheric asymmetry. so the left hand controlled by the right hemisphere, and right hand controlled by left hemisphere.

# Answer
> 2 votes
"Are the two halves of the brain mirror images of each other"

I'm not sure if this will answer your question but here goes.

If we look at the two hemispheres say from a axial view (looking down from the top), we'd find there's some asymmetry there. In terms of internal brain structures and "regions" yes, what's in the left hemisphere is also in the right hemisphere.

If we then look at function or "activity" related to certain actions and or cognitive processes in a "neural typical"(brain of a "normal" person) you'd again see some asymmetries. For example, spoken and written language is USUALLY , primarily "processed" by the left hemisphere.

There's a contralateral nature in terms of wiring for the left and right portions of our brains and body & this may just be a consequence of wiring. However, if say you take a patient who's missing some portion of their brain, in the left hemisphere, where there is an association of some function to activity in that brain area and if this is the condition from a very early age, what you find is the right hemisphere for that area will take over that function.

If they have the same structures, same sulci and gyri, and can take over the function of the other half(to an extent) when the other half is damaged does this mean they are mirror images? I don't know.

In short, it's difficult to give a definitive answer for this (at least with my limited knowledge).

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Tags: brain-development
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# Question
Title: Does dream recall alter the dreaming process?
I've encountered the following phenomenon : within a single night of starting a dream journal again, my dreams became more numerous, recall improved and I'm waking up after each sleep cycle except the 1st one with more recall.

In particular, I scribble down my dreams on paper immediately upon awakening from a dream. This happens 5-6 times a night.

This makes me ask- does activating dream recall mechanism in the middle of the night alter brain chemistry or dream process, facilitating more recall?

# Answer
> 7 votes
Your experience with more dream following dream recall can be explained in this paper, Effect of encouragement on dream recall (Halliday, 1992). People experience lighter sleep when they recall dream upon awakening (Shapiro, Goodenough, & Gryler, 1963), Armitage (1992) reported that males had more dream recall in low stress days while females showed the opposite.

Armitage, R. (1992). Gender differences and the effect of stress on dream recall: A 30-day diary report. Dreaming, 2(3), 137. http://dx.doi.org/10.1037/h0094354

Halliday, G. (1992). Effect of encouragement on dream recall. Dreaming, 2(1), 39.http://dx.doi.org/10.1037/h0094346

Shapiro, A., Goodenough, D. R., & Gryler, R. B. (1963). Dream recall as a function of method of awakening. Psychosomatic medicine, 25(2), 174-180.

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Tags: memory, dreams, short-term-memory
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# Question
Title: Why is it easier to learn something when you have a teacher explain it?
I find that things you learn in school are much easier to learn than before you take the course. For example, there is a mathematical theorem that seems unnerving when I self studied calculus, but the same theorem appeared to be so much easier when I actually learned it in school.

Why is it easier to learn something when you have a teacher explain it?

# Answer
> -1 votes
I'm not sure what you mean by harder, because I find things about the same, if not easier(thanks internet), after leaving school and understanding how our memory works.

I think you're noticing the difference between a teacher and a book. A teacher will draw pictures, use gestures, tone of voice, and answer any questions. A book will just tell you things, and assume you understand, and leave you to set the tone of voice.

If you want to learn maths, give the site Khan Academy a go. Also if you really want to learn, use a flashcard program like Anki. I use Anki for learning ***everything***. Once you learn something, you easily forget it. I use Anki to keep reminding me of whatever I'm learning, so I never forget it. You do have to use it every day, but it's a good habit to get into, whilst having breakfast.

EDIT: added this: You'll also notice on Khan Academy, Sal Khan uses just a blackboard and his voice, because the tone of voice really helps get the point across, also he draws and moves things around, so you can see and hear how it all goes together.

# Answer
> 0 votes
A bad teacher would explain things in a manner that's harder to digest, when compared to a good teacher. However, in general, for any teacher, even a tutor, it is easier to concentrate because the prefrontal cortex is reminded continuously of the goal (of learning). This is called goal-directed behavior. Learning alone, however, makes it harder to concentrate at the same level. I may have misunderstood what you you were looking for in the answer.

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Tags: educational-psychology
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# Question
Title: What is the correlation between the development of the sense of self and the senses?
Children develop different senses of self at a couple of different ages. Normally developing children pass the 'Sally-Anne' test at about 4 years of age and the 'Mirror test' at around 18 months. My question refers to these cognitive tests and the relation any loss of sense has on these developmental stages. I'm aware of the case studies of down-syndrome, and autism however i'm currently interested in the effect of blindness, loss of hearing, smell and if the effects of reduced sensory perception causes a delay in when these tests are passed.

# Answer
This question is quite broad, firstly, because these tests measure different (though interrelated) cognitive faculties and at different developmental stages and secondly because there is a lot to say for each sensory impairment. However, it touches on quite interesting topics for which there have been many studies and I think a summary of the findings can be made without being too big. For this purpose, it will be more useful to talk about the capacities that are associated with the tests rather than just studies with these tests, in order to get the bigger picture. Also , I would like to point that my answer is almost entirely about visual and auditory impairment because that is what I could find. If anyone knows of anything else, feel free to edit my post.

* The Sally-Anne test is used by developmental psychologists to test the ability to attribute false belief which is a measure of one's theory of mind. Theory of mind is the "*ability to attribute mental states — beliefs, intents, desires, pretending, knowledge, etc. — to oneself and others and to understand that others have beliefs, desires, and intentions that are different from one's own*". As you described, this skill is almost fully developed at around 5 years of age.
* The Mirror test or Rouge test (specifically for human infants) is used by develompental psychologists to test self recognition/self awareness which can be defined as "*the ability to become aware of one’s own mental and bodily states (e.g. perceptions, attitudes, opinions, intentions to act) as one’s own mental and bodily states*" (Vogeley & Fink, 2003). As you described infants pass this test around 18 months of age, however it has been suggested that self-awareness should not be viewed as a unitary achievement but rather as a process that has successive stages being fully developed at around 5 years of age (Rochat, 2003).

Both these tests have to do with the sense of self as distinct from other beings which according to the proposed developmental pattern that it follows is also not to be treated in a unitary fashion (for a review see Baumeister, 2010 and Geangu, 2008). Theory of mind is more associated with the aspect of self which is called interpersonal self while self recognition as measured by the mirror test is associated with what has been called as bodily self or body image (Geangu, 2008).

So referring to your question about the effect of sensory impairment to these abilities:

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* Regarding the theory of mind, there have been studies on blind and deaf children.Yagmurlu et al (2005) summarized such studies in their article.

> Research with deaf children has emphasized the role of environment, particularly exposure to conversation, in theory of mind development (Peterson & Siegal, 2000). In their review, Peterson and Siegal (2000) have shown that children’s access to conversation is correlated with theory of mind development. They found that profoundly deaf children with hearing parents who generally have almost no access to any communication means until they start school are more severely impaired in theory of mind development than orally trained deaf children who use hearing aids or deaf children with deaf parents who use sign language from an early age (Peterson & Siegal, 1998, 1999; Woolfe, Want, & Siegal, 2002) Further, Peterson and Siegal (2000) argue that early conversations, especially those about imaginary or abstract ideas, or about beliefs appear to be necessary cognitive input in theory of mind development.
>
> Research on children with visual impairment also shows that these children are delayed in theory of mind development (Green, Pring, & Swettenham, 2004; McAlpine & Moore, 1995; Minter, Hobson, & Bishop, 1998; Peterson, Peterson, & Webb, 2000). Visual impairment may limit communication with parents due to lack of shared visual experience (Minter et al, 1998), and may also impair understanding what is in others’ minds because access to visual cues is cut (Peterson et al., 2000). Despite this disadvantage, language skills of visually impaired children continue to improve, and their social experiences with peers and teachers become richer, which contribute to a gradual acquisition of theory of mind skills (Green et al., 2004)

Reviewing the findings of some of the above studies Malle (2002) suggested that anything that prevents the development of language and communication in general, is likely to cause a delay in the development of theory mind.

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* Regarding the mirror test, as it is dependent on visual cues alone, I don't think blind people would be able to pass it, while there is no reason to expect that people with hearing or olfactory impairment wouldn't pass it. Of course an inability to pass this test does not lead to the conclusion that blind people and especially congenitally blind people lack a sense of self and specifically a body image. This is likely achieved through different sensory inputs. Geangu (2008) noted that while a perceptual sense of self requires the integration of sensory information such as visual, auditory, tactile and kinesthetic, it is the proprioception and visual processing of the body that have higher relevance for the construction of a personal representation of one’s body in space. Bermudez (1998) had a slightly different opinion.

> The developing child may first acquire a sense of self when it becomes able selectively to attend , in however ill differentiated a fashion , to its individual body parts in the somatosensory modality . It would then become acquainted with the internal causal consistency of their positions and displacements relative to its own volitions . The assumption that the visual channel soon reveals to the infant which body parts are its own (Neisser 1978) may be mistaken . Logically , the visual channel should soon betray which (body) parts are always present and one ' s own and which (external ) objects are present only sometimes (Neisser 1978) . But the mechanisms for accomplishing this during development (Gibson 1969, Bower 1974) may follow rather than precede somatosensory attending . Poeck and Orgass (1964a, 1964b) found that blind children developed knowledge of their body at about the same age as sighted children

Also, maybe blind people can rely on auditory input from early age to form a sense of self and this view is supported by a recent imaging study (Ma & Han, 2011).

So, to conclude this section, while I didn't find enough empirical data on blindness or anything on deafness to support a typical development of self awareness in these people, I don't think there are enough reasons to think that such a developmental delay occurs when these sensory systems are impaired.
> 3 votes

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Tags: abnormal-psychology, developmental-psychology, theory-of-mind, cognitive-development, self
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