title: Why does handwriting change?

text:
# Question
Title: Why does handwriting change?
In New York magazine it is stated:

> \[I\]t’s strange that your handwriting changes over time; scientifically speaking, there’s no reason it should. At a certain point, you’ve learned all there is to learn about it: You’ve mastered the fine motor skills, you know the right way to grip a pen, you’ve written enough that you no longer need to think about the physical act of forming letters with your hand.

But they continue:

> But still, odds are decent that your handwriting right now looks a little bit different than it did five years ago, and will look different again in five more.

Now **I am wondering if handwriting can also change on a smaller time scale, and specifically with regard to emotional states**. If yes, I would be interested in **what part of the brain controls it**.

# Answer
The brain is an **interconnected whole**, when we have high activity in one area of the brain other connected parts are affected.

The writting is mostly controlled by the part of the brain that controls movement (lateral and medial precentral, motor cingulate and primary motor cortices, and postcentral gyrus). Research revealed that there is a direct path between amygdala and the parts of the brain that controls movement. Subsequntly writting will be affected when the amygdala is highly active.

> Using diffusion-weighted magnetic resonance imaging and probabilistic tractography on a cohort of 40 participants, we provide evidence of a structural connection between the amygdala and motor-related areas (lateral and medial precentral, motor cingulate and primary motor cortices, and postcentral gyrus) in humans. ... a direct amygdala-motor pathway might provide a mechanism by which the amygdala can influence more complex motor behaviors.

Reference

Grèzes J., Valabrègue R., Gholipour B., Chevallier C., A direct amygdala-motor pathway for emotional displays to influence action: A diffusion tensor imaging study.
> 3 votes

# Answer
I can say if you look into the way hand-writing is analyzed you can find that emotions is your answer. This is old, but a few years ago people were televised for being able to read your hand-writing and psychically read your emotions.

To answer one of your questions, i think a less emotional review in business could get you a more consistent handwriting. Maybe a business memo, but you should take notice to the changes. I always do. When i'm sad I see the letters of my writing go downward below the line. When i'm ecstatic i see the writing go upward
> 0 votes

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Tags: cognitive-psychology, neuroscience, emotion, writing
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# Question
Title: What is the optimal way to run the Piaget Conservation of Number Task?
I am hoping to run a standard Piaget conservation task to test the conservation of number. The task is as follows:

> Coins such as pennies are placed on a table. A certain number of coins are placed in a row, and a matching series of coins is placed directly below the first one. So there are two equal rows of coins on the table. Now the experimenter spreads out one of the rows so the coins are farther apart. The child is asked whether the two rows of coins still have the same number of coins in them. A small child who does not yet know how to count will typically claim that the spread-out row has more coins in it.

Previous studies are quite varied in several ways. First, in the number of coins that are presented (typically it looks like it is 5-8). Second, how many trials are performed. Third, how many trials must a child pass/fail to conclude that he or she does or does not conserve number.

Therefore, I am asking for advice on the ideal protocol for running this task (i.e. trial types, number of trials, pass/fail requirement).

# Answer
Particular attention should be given to the theoretical framework (Piaget's Theory and constructivist perspective), hypotheses to contrast (levels), information gathering and common difficulties.

"Levels" in quantity conservation test:

**Level of absence of term-to-term correspondence:** 4-5 years. Simple intuition. Consider the global and static configuration of the rows (not quantity of chips or accounts). They are limited by the configurations of the tabs.

**Level of correspondence term to term without conservation:** 5-6 years They establish correspondence 1 to 1 in both rows, before the transformation of them, they break the equivalence. They focus on aspects such as density or length.

**Level of non-durable conservation:** Around 7 years. They are conservative in some situations, depending on the context.

**Level of conservation required:** 7 years. They are persevering and gives evidence of compensatory behaviors (length / density) or reversibility (join / separate).

The count for Piaget is a social skill with no logical mathematical content (concept of number). It would be necessary to differentiate between logical structures or schemas (classification, seriation and number) and infralogic structures (substance, weight, volume, space). Often smaller children count simply by saying the words: One, two, three, etc. as if it were a song but they do not follow any order or logic. Other times, although the child already has numerical structures developed, errors occur. The final step is when the reversibility of the transformations (deformations, displacements or fractions) is established. **THEORETICAL FRAMEWORK SHOULD BE VERY WELL ESTABLISHED**.

**ALWAYS MUST ASK FOR REAFFIRMATION AND ASK WHY THE ANSWER HAS BEEN GIVEN** (but not so that the child thinks that perhaps he is giving an erroneous answer). **YOU MUST PRACTICE SERIOUSLY BEFORE THE TEST**.

Leaving aside the presentation of the test that you could present as a game (and try to make it really fun) try to follow the words or terms that the child expresses, once the child responds do not add other terms, sometimes there is distraction for some concepts said by the experimenter.

Keep in mind **common difficulties** in test with children: Lack of attention or motivation and distractions (many children can pay close attention to their mom or dad or they can go to the test with their favorite toy).
> 5 votes

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Tags: developmental-psychology, cognitive-development, numerical-cognition
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# Question
Title: Cockroach olfactory bulb response to novel stimuli
I've heard anecdotally, that the cockroach olfactory bulb responds differently to novel stimuli vs. known stimuli. Specifically, it sends an oscillatory firing pattern for known stimuli and a constant firing pattern for novel stimuli. However, I'm having a hard time finding a reference for this? Does the olfactory bulb in insects (not just cockroaches) actually respond with different firing patterns?

# Answer
> 3 votes
According to Kay and Stopfer (2006) in their paper, Information processing in the olfactory systems of insects and vertebrates, it looks as though oscillatory firing patterns in insects fire as a mechanism for categorizing *all smells, novel and familiar:*

> Several imaging techniques that assess afferent or principal neuron responses all indicate that odor stimulation evokes maps of activity that vary with the odorant; not all odorants activate all glomeruli and principal neurons.

More specifically:

> In both insects and vertebrates, odor stimulation elicits the oscillatory synchronization of responsive principal neurons.

Note that no distinction is being made here between *novel and familiar* olfactory stimuli. It seems that much of the research on novel olfactory stimuli as related to olfactory bulb firing patterns has been done on vertebrates, as discussed here.

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Tags: cognitive-neuroscience, reference-request
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# Question
Title: Are emotions a function of muscle contractions? If so, how does the map look like?
I hope this is the right (or rightest) place to ask this question, I wasn't sure whether this question is more appropriate for cogsci or biology. After all, it does concern the biology of emotions.

To my knowledge, it is established research that the brain 'knows' what emotions you are having by examining their manifestations in the body. This absurd rube-goldbergian wiring can for instance be used to force oneself to become happier (at least temporarily) by smiling for a few minutes.

*This brings up the question, whether emotions have any identity separate from a cluster of bodily sensations (or even more specifically, muscle contractions) at all.*

It is certainly true (by introspection for e.g.) that 'negative' emotions are accompanied by muscle contradictions. On the other hand, there are several different 'negative' emotions that can be easily distinguished by the person having the emotion (e.g. shame and fear). Unfortunately I am not able to simply recall the sensations I had when I was ashamed or fearful from memory and compare them, but I would assume you could even tell from the outside, simply by looking at the person afflicted, which of the two emotions they are going through.

*So, what does the research say? Are emotions uniquely recognizable by facial expression/muscle contractions? Or do emotions have some kind of 'hidden variables' in the brain?*

# Answer
> 4 votes
Your brain mentally represents afferent bodily input as **affect**, or feelings of pleasantness/unpleasantness and arousal (Craig, 2002). In certain theories (e.g., Barrett, 2017), your **emotions** are cognitive interpretations (conceptualizations) of your affect in a context.

In general, there is very weak evidence that discrete emotions correspond to specific and reliable bodily responses (for the most up-to-date meta-analysis, see Siegel et al., in press).

There is also indeterminate evidence for specific and reliable correspondences with facial movements. This has not been studied well enough to be known, although there is compelling evidence to suggest that there are no specific/reliable links on average (see Hillel Aviezer's work).

In general, emotion research is converging on the view that emotional events are highly variable, both within and across emotion categories, as well as within and across individuals and cultures. We see this variability in neural activity, physiology, behavior, hormones, vocalizations, facial movements, and so on. From this perspective, there are no unique emotion signatures.

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Tags: emotion
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# Question
Title: In the digit span test, why do some strategies work and others don't?
I got a free copy of PEBL, psych experiment software, which includes a couple of standard working memory tests.

When I perform the digit span working memory test, I can repeat the numbers as they appear, and do some basic chunking. For example, I can repeat *'3-1-8-4'* as *"thirty one" "eighty four"*. But when I try any other chunking or rehearsal technique I find it impossible to do the task. I think my working memory just empties. My question is why that happens? More specifically -

**What cognitive functions do more complex rehearsal and chunking techniques tap into? Is there a means to improve / train those specific cognitive functions?**

# Answer
> 6 votes
Chunking leverages long-term memory for the chunks, i.e. we recognize and remember much easier the familiar chunks, sometimes algorithmically. This is much easier explained in the domain of letters/words, e.g. we'd recognize USA as substring among random letters. Similarly most would recognize the pattern 1945 (WWII end) by paired association, or 12321 algorithmically.

In the classic case of SF he used sequences familiar to him (running times) to greatly improve his performance. More unusual (cf. *Memory Search By A Memorist*) is Rajan's ability to recognize 13- to 17-digit chunks visually/syntactically, without assigning them meaning. Ishihara, who could memorize overall longer sequences than Rajan \[under controlled settings\], but was much slower, used a method to convert them into syllables; he was naturally very gifted at remembering nonsense syllables though (cf. *Superior Memory*).

A few other association methods exist, including with places ("loci"), which relies on visual memory etc. It's possible to train the average person using these and attain significant improvements; the graph below (3rd one bein relevant, but I've included all for the caption) is from a recent PhD thesis. It takes a significant amount of practice/time to become proficient/fast in the encoding/decoding techniques.

Some clarification in regards to these graphs:

* The other two tests are self-paced (just with overall time limit) memorization tests, i.e. how many words/digits in a sequence can be retained in a 5-minute interval with no time pressure for learning each word/digit.
* The digit span was tested with 2 second intervals, which probably helped with learning a bit. Other authors have used 1 second, which makes it harder to apply encoding/decoding techniques.
* The training protocol (for the blue lines) was fairly involved using the Memocamp software which can display the memorization aids (loci or images), and can also display a configurable metronome.
* "SEM" stands for "Standard Error of the Means (the error bars).

The handful of people (not in this thesis/experiment) who have practiced for years (one of SF's colleagues and two in a replication experiment) have reached 80-100 digits in the digit span test. For that level of performance, not only did they use an associative system, but also a hierarchical chunking method. The chunk size was almost universally 4 for these performers (thus the need for hierarchy). On average it took about 500 hours of practice to decrease decoding/encoding time from an initial 5 seconds to the 1 second required by the digit span test (all this cf. The *Neuroscience of Expertise*, pp. 110-112).

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Tags: experimental-psychology, working-memory, brain-training, psychophysics, executive-function
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# Question
Title: Can information be lost while traveling through neurotransmitters?
Can information be lost while traveling through neurotransmitters, if so then why? If information can be lost while traveling then is it possible to retransmit them and put back in order? For example data can be lost while traveling through network therefore we need to use **TCP** (transmission control protocol).

If information can be lost while traveling through neurotransmitter. Then is it possible that, not being able to remember something you want or remembering something that are not in their orders?

# Answer
# Synapse Information Processing

In the Neural Engineering Framework (NEF), synapses are:

1. Leveraged to provide filtering of spikes at different time scales. This allows for managing heterogeneity in neurons, as well as allowing to trade-off speed of response for information integration over time.
2. Used to create dynamical systems using these filtered spikes including oscillators, integrators and temporal memory networks.

In all of these cases, information can be lost. However, this is always framed as a trade-off between informational integrity (which can be measured various ways, such as how well a signal is classified, how well a dynamical system is approximated, how much information is compressed over time) and resource use.

# Retransmission as Information Recovery

In the context of the brain, TCP doesn't really make sense. TCP assumes there is a copy of the information that is desired to be transmitted somewhere, but that's usually not the case in the brain. That being said, there is something called the phonological loop which appears to be a short term store of what was heard. Consequently, you could interpret this replay as a retransmission and consider it to be information recovery.
> 5 votes

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Tags: theoretical-neuroscience
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# Question
Title: Is reading from the screen more difficult than reading from paper and how can screen reading be made easier?
I've noticed that as a student when reading material, there is a choice between reading from the screen or reading from paper. When reading from paper I find that I concentrate more and that comprehension is much better. I can partially memorize the material rather than reading from screen. In addition, I find reading from screen is more tiring. When I feel tired reading from the screen I often print to paper, and it provides relief.

### Questions

* Does research support this observation that reading from paper results in less strain and greater comprehension?
* Are there any techniques to improve reading from screen?

# Answer
Research would suggest that reading from (well printed) paper is easier; due to ease of making annotations, navigation and the lower risk of eye strain that can be caused from VDUs.

There are ways to minimise potential eye strain on VDUs, due to lighting and positioning.

Friendly User Interfaces would ease navigation, and the development of new technologies for monitors, would assist in visual acuity and reduction in potential eye strain and problems associated with glare.

> We report on a laboratory study that compares reading from paper to reading on-line. Critical differences have to do with the major advantages paper offers in supporting annotation while reading, quick navigation, and flexibility of spatial layout. These, in turn, allow readers to deepen their understanding of the text, extract a sense of its structure, create a plan for writing, cross-refer to other documents, and interleave reading and writing. We discuss the design implications of these findings for the development of better reading technologies.

**A Comparison of Reading Paper and On-Line Documents
Kenton O'Hara & Abigail Sellen**
**Rank Xerox Research Centre (EuroPARC)
61 Regent St.
Cambridge, CB2 1AB, U.K.**

> The advent of widespread computer use in general and increasing developments in the domain of hypertext in particular have increased awareness of the issue of reading electronic text. To date the literature has been dominated by reference to work on overcoming speed deficits resulting from poor image quality but an emerging literature reveals a more complex set of variables at work. The present review considers the differences between the media in terms of outcomes and processes of reading and concludes that single variable explanations are insufficient to capture the range of issues involved in reading from screens.

**Reading from paper versus screens: a critical review of the empirical literature
Ergonomics
Volume 35, Issue 10, 1992**

**Proof-reading: VDU and paper text compared for speed, accuracy and fatigue Behaviour & Information Technology
Volume 6, Issue 2, 1987**

**Visual strain during VDU work: the effect of viewing distance and dark focus
Ergonomics
Volume 31, Issue 10, 1988**
> 7 votes

# Answer
> Question: Are there any techniques to improve reading from screen?

Yes! I employ many different "techniques" myself:

1. Temporary on-the-fly changes to websites which I do not frequent.
2. Cut-N-Paste content to a text editor.
3. Temporary changes for my viewing needs.
4. Permanent changes for my viewing needs to sites I frequent.

You bring an important point regarding readability. It is such a problem for those of us who work at a computer most of the day, that many programmers have come up with some tools to help with the readability of websites which we frequent.

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(1) While most web browsers support increasing/decreasing font size (Ctrl+ / Ctrl-), they do not allow easily changing actual font or colors on websites. Ignorance of html/css programming by non-programmer "web designers" have recently lead to many websites inadvertently not even allowing the above-mentioned font-size changes!

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(2) If I'm on a website which does not allow quickly changing text size, I simply cut-n-paste the text into a text-editor. I can then easily change font-size there. That also allows me to save the URL of the site where the information was found. I suppose this dates, me but this is a twist on technique of using index cards for term paper research. It saves you from trying to figure out where material originated from. If you are like me and prefer hard-copy, placing file-path & file-name on the bottom of your page, can help you find your saved copy (as often websites disappear or change content).

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(3) I use a debugging add-on tool within firefox (called "Firebug") to make temporary changes to a page I am viewing. If I frequent that page, I can make those changes more permanent by putting those changes in item 4 below:

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(4) Changing the way text is displayed helps so much with readability, that there is an add-on for Firefox which allows just that: "Stylish". It is extremely useful for people who have problems due to color-deficiency(color-blindness).

This particular forum (and other stackexchange forums), does allow the Ctrl+/Ctrl- font-size changing! Adjusting font-size helps; however it is not always enough. Personally, I find that adjusting the font, color, and background increase readability dramatically. Since I spend so much time on-line for work, I use Firefox web browser, along with and add-on called "Stylish" which allows me to customize frequently-used websites to make them more readable to me!

For websites/forums which I frequent, then creating a special "Stylish" modification for that site makes sense to me. I can modify the actual font, as well as the font-color and background on which the font is displayed for websites which I visit frequently. Knowing html/css allows me to customize a websites readability to my preferences!

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I actually used Firefox with "Stylish" add-on modifications for a client who had an older employee with vision problems. The web-based hotel reservation software had poor readability on a couple of screens for which I had no direct control of. The software has since been modified, allowing each individual user to select background color in those text areas.

---

There is now an updated version of Stylish For Firefox. Also, there is now a version of stylish for Chrome as well...

Also, you no longer need to have extensive css/html background to use Stylish. Along with the new Stylish version, there are numerous pre-made Stylish Alternative Themes/Skins for many popular websites.

## Many of the alternate "themes" are specifically geared towards helping with eye-strain -- look for the word "dark" in their name.

https://userstyles.org If you use openid, you can use your stackexchange openid You can use your openid login by choosing "login" then "openid", then https://openid.stackexchange.com An example of an alternate "theme" which will help with eye strain is here: Youtube - Lights Out - A Dark Youtube Theme This dark grey background with light text is much easier on the eyes.

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> 2 votes

# Answer
In response to the *First Question Only*:

> Does research support this observation that reading from paper results in less \[eye\]strain ...?

This study which seemed to be focusing on finding an objective measurement of eye strain does seem to show that reading from paper does result in less eye strain than reading from a VDT.

**Objective evaluation of eye strain using measurements of accommodative oscillation** **Ergonomics** Vol. 30 , Iss. 3,1987

> Accommodative oscillations occurring during eye strain induced by two different types of experimental visual search task—visual display terminal (VDT) work and conventional hard-copy (paper) work— were objectively measured using infrared optometry.

...

> The low-frequency component (0 to 1-5 Hz) of the accommodative oscillation was found to be significantly increased after the VDT work, but not after the paper work.

...

> In a questionnaire survey the subjects using the VDT complained more than the subjects given paper work of ocular symptoms such as eye strain and blurred vision.

Related to *both questions,* this more-recent study shows that "book-like positioning" of the VDT makes a difference in eye strain:

**Reading from computer screen versus reading from paper: does it still make a difference?** **Ergonomics** Volume 59, 2016 - Issue 5

> Four experiments were conducted to test whether recent developments in display technology would suffice to eliminate the well-known disadvantages in reading from screen as compared with paper.

...

> Given the developments in screen technology, a re-assessment of the differences in proofreading speed and performance, well-being, and preference between computer screen and paper was conducted. State-of-the-art TFT-LCDs enable unimpaired reading, but a book-like positioning of screens seems necessary to minimize eyestrain symptoms.
> 2 votes

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Tags: cognitive-psychology, reading, human-factors
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# Question
Title: A formal term for overcoming something, or getting over something
I am trying to find a correct psychological term for a specific type of behavior.

When a person is trying to distance themselves from past suffering by projecting an idea of "I'm over it" to others. Trying to convince others and maybe even themselves that they've overcome something.

For example, a person who has suffered depression is trying to project an idea of "I'm over it and never going back" to another person suffering from depression.

A similar example would be about two people dealing with divorce or breakup and one person tries to project that they are over it not wanting to feel the pain or suffering that the other person is experiencing.

Is it distancing? Is it disengagement? Since there are different types of distancing, some positive some negative, what type is this? Is it overcompensating? Or something else completely?

# Answer
The term you are looking for is probably **dissociation**.

There is a range or continuum of experiences that can be subsumed under "dissociation", going from mild to pathological. On the pathological end of the continuum, for example, there is dissociative identity disorder.

Dissociation is technically a kind of defence mechanism. See for example the article Dissociation Isn't a Life Skill on Psychology Today. The International Society for the Study of Trauma and Dissociation has a long list of Dissociation FAQs.
> 3 votes

# Answer
My first thought was **closure**.

Closure can be defined as (source: Psychology Today):

> \[F\]inality; a letting go of what once was. Finding closure implies a complete acceptance of what has happened and an honoring of the transition away from what's finished to something new. In other words, closure describes the ability to go beyond imposed limitations in order to find different possibilities.

Often this term is related to broken relationships, but it can also be applied to grievance. Generally, closure means the closing of a 'chapter', *e.g.* a closure of the hurt after the ending of a relationship, or after loosing ones job (Bell & Taylor, 2011).

The issue of closure can be debated, however, and especially in the case of exceptionally painful life events, such as the death of a loved one where grief can be persistent for a life time, or in the case of progressive dementia, because the lost person is here, but not here, and the grief is 'frozen' (Boss, 2010).

<sub>**References**
**-** Bell & Taylor, *Scand J Management* (2011); **27**(1): 1-10
**-** Boss, *Pastoral Psychology* (2010); **59**(2): 137–45</sub>
> 3 votes

# Answer
The above answers are both quite good. Could this also be just "in denial"?

Medical Definition of denial. : a psychological defense mechanism in which confrontation with a personal problem or with reality is avoided by denying the existence of the problem or reality.
> 3 votes

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Tags: cognitive-psychology, personality, terminology, bias
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title: Why do people bully other people?

text:
# Question
Title: Why do people bully other people?
What is the psychology behind bullying from the bullier's perspective?

What kind of people become bullies? Do bullies generally have anything common in their childhood histories?

N.B. This question excludes Cyberbullying.

# Answer
> 3 votes
Long story short, aspiration for leadership / dominance.

By having bullied someone (and not having been told where to get off), the bully effectively establishes dominance over the victim, which indulges their ego and makes them feel strong and lifeworthy.

Anybody with power or strong character can become a bully towards less strong/powerful ones, unless educated or motivated not to.

That said, bullies do not necessarily have anything common in their childhood histories that caused them to become bullies, however, having been bullied in the past or having seen bullying increases the likelihood of one becoming a bully. Vivid examples of this are dedovshchina and ragging — where people justify their bully behaviour by "I was bullied by older mates before, now it is my turn to take it out on the newcomers", or simply seeing that as a de-facto tradition.

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Tags: human-factors
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# Question
Title: Are there any long term cognitive impairments from prolonged period reduced sleep?
What are the consequences of chronic lack of sleep? For example, insomniacs are known to sleep less than normal sleeping individuals.

I am wondering if there are any long term cognitive impairments from reducing sleep time to, say 4h instead of the normally recommended 8 hours in the long run, say for a year or so?

# Answer
> 1 votes
Wikipedia has some good information on this issue. Search for:

Effects of sleep deprivation on cognitive performance

In summary, 'yes', sleep deprivation can have a multitude of negative consequences on your cognitive abilities, like weakening your ability to handle complex cognitive tasks.

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Tags: sleep, brain-development, brain
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title: Learning In Retina

text:
# Question
Title: Learning In Retina
Most of the sources studying retina seem to suggest that retinal connectome is hardwired and species dependent (like specialized vertical movement detector in small rodents). I couldn't find a single publication exploring possibility of learning within retina. My understanding of learning is somehow rewiring ganglion-amacrine neural circuits based on which visual features are useful for a particular individual.

Modern artificial neural networks use backpropagation to learn feature detectors but there seems to be no information flowing from brain back to retina. I guess that would mean that backpropagation isn't possible in biological visual system. That in itself doesn't rule out other mechanisms of learning.

Are there grounds to believe that retinal wiring is immutable or it is just lack of research on the topic?

# Answer
It is not immutable. There are many studies on retinal plasticity, for example using laser coagulation and showing that after selective lesions new connections can be formed even in the adult retina, restoring the responses of retinal ganglion cells in the lesioned area (e.g. see this paper).

There is also evidence that visual experience is required for the development of the retinal circuitry after birth (see this other paper), so it doesn't seems to be entirely hardwired.
> 4 votes

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Tags: learning, theoretical-neuroscience, vision
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# Question
Title: Can you catch up on sleep over the weekend?
The lack of sleep has many negative effects associated with it. Maintained sleep deprivation results in a degraded performance over time (in this case reaction time).

Assuming one needs 8 hours of sleep each night, but during the weekdays he only sleeps 6, is it possible to catch up on those lost hours of sleep during the weekend?

There is evidence that 'recovery sleep' is different from ordinary sleep. Carskadon and Dement (2005) measured a sleep pattern that favors Slow Wave Sleep (SWS) after 38 hours without sleep. Personally I also experience it takes me longer to wake up after being sleep deprived, which makes me believe at least your body is trying to make up for something.

A study by Gumenyuk et. al (2011) concludes:

> Reduced time in bed is associated with deficiency of the neuronal process associated with change detection, which **may recover after one week of sleep extension**, whereas attention-dependent neural processes do not normalize after this period of time in habitually short sleeping individuals and may require longer recovery periods.

It gives an indication recovery of some symptoms is possible, but recovery time is not equal for all symptoms. However, the participants in this study seem to be habitual short sleepers.

A more recent study (2015) by Brice Faraut concludes *"\[...\] data suggests a 30-minute nap can reverse the hormonal impact of a night of poor sleep, \[...\]"*.

I am wondering whether it is possible to recover from the lost hours over the week during the weekend **entirely**. E.g. if you lost 8 hours, by sleeping 8 hours more during the weekend. The notion of sleep dept still seems to be up for debate, but perhaps there is more certainty on short term (1 week) effects?

<sub> Carskadon, M. A. and Dement, W. C. (2005). Normal human sleep: an overview, chapter 2, pages 13–23, pp. 13-23 In Principles and Practice of Sleep Medicine Elsevier Saunders, Philadelphia (Free PDF)
Gumenyuk V, Roth T, Korzyukov O, Jefferson C, Bowyer S, Drake CL. (2011) Habitual short sleep impacts frontal switch mechanism in attention to novelty. Sleep. 2011 Dec 1;34(12):1659-70. Napping Reverses the Salivary Interleukin-6 and Urinary Norepinephrine Changes Induced by Sleep Restriction </sub>

# Answer
Well, to be able to answer your question affirmatively, we'd have to know all the effects of sleep deprivation, including the long term ones, and those are still are not fully accounted for.

However I did find some more recent research that addresses the question of weekend sleep recover on some parameters. Pejovic et al. found (quoting from the abstract):

> Serial 24-h IL-6 plasma levels increased significantly during sleep restriction and returned to baseline after recovery sleep. Serial 24-h cortisol levels during restriction did not change compared with baseline, but after recovery they were significantly lower. Subjective and objective sleepiness increased significantly after restriction and returned to baseline after recovery. In contrast, performance deteriorated significantly after restriction and did not improve after recovery. Extended recovery sleep over the weekend reverses the impact of one work week of mild sleep restriction on daytime sleepiness, fatigue, and IL-6 levels, reduces cortisol levels, but does not correct performance deficits. The long-term effects of a repeated sleep restriction/sleep recovery weekly cycle in humans remain unknown.

The good news is that on most measures there was recovery after the weekend, and this is consistent with other studies e.g. with that by Faraut on hormonal measures. I still find their performance finding rather shocking, so it's perhaps worth taking note at exactly what performance they looked at; it was basically just the PVT:

It's indeed a good question how many more nights of leisurely sleep would cause PVT to recover. I strongly doubt the impairment is permanent. Alas the study by Pejovic et al. didn't have any follow-up after the weekend.

A similar study was conducted prior by Banks et al., and they made a prediction on PVT recovery, but it still hasn't been confirmed

> Neurobehavioral deficits induced by 5 nights of sleep restricted to 4 h improved monotonically as acute recovery sleep dose increased, but some deficits remained after 10 h TIB \[time in bed -- my note\] for recovery. Complete recovery from such sleep restriction may require a longer sleep period during 1 night, and/or multiple nights of recovery sleep. \[...\]
>
> PVT fastest reaction times were projected to require a sleep dose of more than 13 h TIB (11 h TST \[total sleep time -- my note\]) to intersect the control condition. However, the confidence intervals for intersection with control group levels were large for all outcomes presented

I found one more recent *animal* study on the matter, by Deurveilher et al., which used a rat version of PVT, with rather different results

> A 28-h period of the 3/1 chronic sleep restriction (CSR) protocol \[sleep reduced to ~60% of normal as result of this protocol -- my note\] disrupted performance on a sustained attention task in rats, as sleep deprivation does in humans. Performance improved after longer \[one week -- my note\] periods of CSR, suggesting allostatic adaptation, contrary to some reports of progressive deterioration in psychomotor vigilance task performance during CSR in humans. However, as observed in humans, there were individual differences among rats in the vulnerability of their attention performance to CSR.

Below are the graphs from the paper on the week-long CSR, which shows the remarkable allostatic adaptation on PVT, but not on weight loss.

So I'm guessing the jury is still out how quickly humans recover or if they may even adapt to sleep deprivation on PVT. I'm guessing that given the other effects of sleep deprivation, controlled longer-term studies in humans are probably going to be difficult to come by...

I've also consulted the 6th edition (2017) of *Principles and Practice of Sleep Medicine*; its chapter on sleep deprivation (and recovery) has among its authors two of the co-authors (the lead and the PI--Dinges) of the Banks study I already mentioned. So its conclusion are somewhat similar.

> Few studies have examined recovery sleep after periods of sleep restriction. \[...\] Although participants felt that their functioning was restored, with subjective reports of sleepiness and performance recovering to baseline, subjective measures do not appear to accurately parallel objective measures of neurobehavioral recovery. These findings suggest that more than 2 or 3 nights of extended sleep may be needed to return neurobehavioral functions to baseline levels. \[...\] Overall, work to date suggests that complete recovery from a period of sleep restriction may necessitate a sleep opportunity of more than 10 hours or more than 3 days if sleep is restricted to 8 hours a night. In addition, different aspects of performance and neurobehavioral function appear to recover at different rates, with different trajectories.

That combination finding is additional based one other study they highlight, by Rupp et al., which did look at longer recovery periods; the summary from the book

> Rupp et al extended the recovery period to five 8-hour sleep opportunities, following a week of sleep restricted to 3 hours of time in bed each night. Despite the extra recovery nights, performance still failed to return to baseline levels. In a second group that extended their sleep prophylactically to 10 hours of time in bed before the period of sleep restriction, performance declined at a slower rate and recovered to baseline more quickly, suggesting that sleep restriction and recovery vary as a function of prior sleep. Therefore, sleep extension or supplemental nap sleeps can be used as a prophylactic measure or countermeasure to lessen the performance effects of sleep deprivation during periods of extended wakefulness or sleep deprivation.

Looking at the actual article, the 5 recovery days were 8 h TIB (probably because the author works at an army hospital), which for me personally would still count as mild sleep deprivation (less than 8 hrs actual sleep = TST), and which is somewhat odd contrast with opening statement in the paper that 8 hours of actual sleep are considered non-deprived. But that seems to be the only study using a longer recovery period to date. Below is a graph from that paper:

The two tests are part of PVT. And description of the two groups:

> “Extension” group (nightly TIB = 10 h) or a “Habitual” sleep group (usual nightly TIB).
>
> To determine Habitual Sleep schedules for volunteers assigned to the Habitual Group, actigraphic estimated total sleep time on weeknights (Sunday through Thursday nights; nights excluded if followed by a holiday or weekend) was determined, and 15 min were added to the average (to avoid inadvertently sleep restricting volunteers) and rounded up to the nearest 5 min for the final TIB amount. Bedtime was determined by subtracting TIB from the 07:00 rise time (i.e., a subject averaging 7 hours 15 min of sleep would have a bedtime of 23:45).

Frankly I find that being able to bank on sleep prior to deprivation, not just recover it thereafter, even more interesting. Also despite the obvious (and statistically significant) difference in PVT between groups,

> No group differences in subjective sleepiness were evident during any phase of the study.

And also another finding

> For both PVT variables, younger individuals showed a steeper slope of performance deterioration during sleep restriction and steeper slopes of improvement during the transition from sleep restriction to recovery and during recovery compared to older individuals.

Honestly I'm a bit concerned about overfitting because this was a small study (two dozen participants). However they say in their discussion of related research that this observed interaction/influence (of age) is consistent with other studies. Perhaps it goes along with the received wisdom that older people \[need to\] sleep less.

Another paper derived from the same study of Rupp et al. looked at math throughput and task acquisition (tested using ANAM, which presents a significant learning effect) and found that their observations mostly mirror those for PVT, except that presleep wasn't as significant as recovery sleep for this math/learning test.

Finally, it's generally accepted (see e.g. Pilcher and Huffcutt) that sleep deprivation influences mood even more than either cognitive or motor performance, however it seems that the recovery is quicker (perhaps owing to the hormonal one?), at least in older people, cf. Reynolds et al.:

> While the increase \[in Total Mood Disturbance -- my note\] tended to be greater in women, in both groups self-ratings of mood returned to baseline after 1 night of recovery sleep.

References:
> 8 votes

# Answer
http://thechart.blogs.cnn.com/2010/08/02/%E2%80%98recovery-sleep%E2%80%99-can-make-up-for-lost-zzzs/

Everything up to 1:25 of this clip should answer your question. It looks like the general answer to your question is "No".

"\[...\]says Dr. David F. Dinges, one of the study authors and Chief of the Division of Sleep and Chronobiology at the University of Pennsylvania School of Medicine." Should give your more information on where to find the specific study they performed. Unfortunately, the name of this study was not given.
> 3 votes

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Tags: sleep
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title: How can tacit knowledge be measured?

text:
# Question
Title: How can tacit knowledge be measured?
**Question 1:** If tacit knowledge is that which can't be written as declarative facts or communicated easily, then how can scientists measure how much of it someone has in a lab?

**Question 2:** Is it true that tacit knowledge can never be declarative or written down?

**Example:** Knowledge like "never tell your immediate boss in this organization what you feel about TPS reports, or you won't be able to get your complaint past upper management" seems like tacit knowledge. But yet it's written down as a declarative fact.

# Answer
> 5 votes
**Short answer**
Because tacit knowledge is defined as knowledge we cannot describe, researchers apparently adopt a strategy of just interviewing and listening for signs of tacit knowledge, as far as I understand it.

**Background**
Tacit knowledge can be curtly defined as ‘**that which we know but cannot tell**’.

For example, a person may be very aware of being able to ride a bicycle and able to describe how they learned to do it. However, the person may not be able to describe critical aspects of biking, such as swift, reflex-driven adjustments due to imbalance, and subjects like the steadying effect of the gyroscopic motion of the wheels, may not be consciously realized either.

Still tacit knowledge can be made explicit by either making the knower to learn to tell, or by the researcher telling and seeking respondent. In other words, one has to facilitate the ‘telling’ of the untold. Both methods require the researcher to construct an account.

Eraut (2000) claims that tacit knowledge can be examined through **regular interactions, encouraging persons to freely describe what they know**. This can be facilitated by an **informal relationship**, where one can freely **interact with the person about their knowledge**.

<sub>**Reference**
**-** Eraut, *Brit J Edu Psychol* (2000); **70**: 113–36</sub>

# Answer
> 1 votes
TLDR version: the authors (philosophers mostly) who use that ineffable defintion don't measure anything. The authors (psychologists, economists) who do measure "tacit knowledge" use a much more tractable operational definition, generally defined as just not-yet-codified or non-doctrinal knowledge, which is measured like any other knowledge, starting with writing it down.

---

Frankly, the notion isn't anywhere near as clear or uncontroversial as (say) the Wikipedia article presents it. The fact that one encounters the notion more in management publications than in psychology ones... is a fair warning given the amount of management fads known to mankind.

Now quoting from a paper by Kabir, N. (2013) (whose only merit is that it ranked high a google search), "Tacit Knowledge, its Codification and Technological Advancement":

> Several prevailing views regarding conceptual notion of the term tacit knowledge exist. The first view is that tacit knowledge is part of knowledge that has not been codified as yet (Ambrosini and Bowman, 2001; Boisot, 1995; Davenport and Prusak, 1998; Leonard and Sensiper, 1998; Nonaka and Von Krogh, 2009). This epistemological dyadic perception places tacit knowledge as a phenomenon directly opposite to explicit knowledge.
>
> The second view is tacit knowledge by very definition is tacit – ineffable. Any attempt to convert it to explicit is a futile effort. Tacit knowledge is the background or subsidiary knowledge of the focal knowledge of the act at hand. Because of this, it is not reducible to the level of explicit as it is only relevant to a specific context (Tsoukas, 2006: 410; Tsokas and Vladimirou, 2001: 973‐93; Cook and Brown, 1999; Brown and Duguid, 2000; Jones and Miller, 2007).
>
> The third view that corresponds with our suggestion in this paper: In any context where knowledge is applied, a part of tacit knowledge, which is overlaid on top of all the knowledge being utilized, will always stay ineffable and cannot be codified. We can call this fragment of knowledge the “meta tacit”. Apart from this, most tacit knowledge, depending on the degree of difficulties in codification, its viability of codification and the availability of required resources could be codified. Collins shows eight different possible reasons or "Cannot" ranging from inconvenience to impossibility to clarify what types of tacit knowledge are not explicable. (Collins, 2010 pp. 88‐96)

So yeah, pick your poison. And measure the ineffable or some such.

Another paper which calls out some of the (obvious) issues is by Lowney, C. (2011), Ineffable, Tacit, Explicable and Explicit: Qualifying Knowledge in the Age of “Intelligent” Machines:

> There would appear to be problems with any formulation of tacit knowledge, be it Collins’ or Polanyi’s. First of all, to a critical reader, the term itself can appear to be an oxymoron. Isn’t all knowledge necessarily explicit? If something is not explicit but somehow veiled in silence, can it properly be called “tacit knowledge”? There is a second problem as well. If tacit knowledge, somehow operative in the background, can be made explicit, can it then properly be called “tacit knowledge”? Isn’t the term merely a placeholder for something unknown that, we hope, will someday become known? Putting both these problems together, “tacit knowledge” seems to present a dilemma: either it is tacit or it is knowledge, but not both.
>
> Collins begins mainly by addressing the second horn of the dilemma. He agrees with Polanyi that “tacit knowledge” is not merely a way station on the road to explicit knowledge. For Collins, the proper use of the word tacit, directly opposes the explicit—it is that which cannot in a strong sense become explicit. Background knowledge and bodily skills that can become explicit are “explicable” and therefore are not properly called “tacit” for Collins. So riding a bike or mastering a craft are not, in the end, proper examples of tacit knowledge, although the experience we have when we ride a bike, drive a car, or learn how to make a good pair of shoes can fool us into thinking those tasks are inexplicable

So yeah, according to Collins and his followers, Alice's example (bike riding) is not proper. So what is proper tacit knowledge for the purist then?

> Collins \[...\] separates Relational Tacit Knowledge (RTK), e.g., learning the skill of a master craftsman; Somatic Tacit Knowledge (STK), e.g., riding a bike; and Collective Tacit Knowledge (CTK), e.g., knowing when it is appropriate to laugh at a joke. Collins rank-orders these phases on a scale ranging from easiest to explicate (RTK), to more difficult (STK) or impossible to explicate (CTK). But ultimately, for Collins, both STK and RTK are, in principle, explicable, so without a use for “tacit” as that which may become explicit, there would be no relational or somatic tacit knowledge per se. Only collective tacit knowledge would remain. Collins thus widens his use of “tacit” to include the explicable, but he will occasionally remind us that the proper understanding of tacit comes from its contrast with the paradigmatically explicit

This to me is reading far more like philosophy than science.

To conclude this, what's tacit knowledge in the military? Well it's

> knowledge not well supported by doctrine or formal training

You can certainly measure that (first by writing it down, and then asking questions about it of others)... and they do just that. So it depends how you define it... philosophically or operationally.

And in fact, the latter definition is prevalent in economics as pointed out by Cowen et al., (2000):

> Tacit knowledge thus has come to signify an absolute type, namely: “not codified” knowledge. As such, however, the label now covers the implicit complement of a category of containing a various forms of information and social knowledge, but which itself usually is left undefined and undifferentiated

So it depends who you ask.

<sub> Kabir, N. (2013). Tacit knowledge, its codification and technological advancement. Electronic Journal of Knowledge Management, 11(3).
Lowney, C. (2011). Ineffable, tacit, explicable and explicit: qualifying knowledge in the age of “intelligent” machines. Tradition and Discovery: The Polanyi Society Periodical, 38(1), 18-37.
Cowan, R., David, P. A., & Foray, D. (2000). The explicit economics of knowledge codification and tacitness. Industrial and corporate change, 9(2), 211-253. </sub>

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Tags: intelligence
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# Question
Title: What electrical stimuli do brain implants use?
I was reading about artificial eyes and came to think about how the brain works. More specifically, what "signals" it uses in the case of cortical visual prosthetics in blind people? Cortical prosthetics apply current stimulations through electrodes placed on the surface of the visual cortex.

Now suppose I would want to let a blind person wearing a cortical prosthesis to see the color red, what signal would I send through the electrodes? Would a sine wave of 200 Hz do the job?

# Answer
**Short answer**
The track record of cortical visual prosthetics is limited. However, a lot more is known on auditory prostheses (mainly cochlear implants) and retinal prostheses. In these implants, biphasic, charge balanced pulse trains are generally applied, mainly for safety reasons and to reduce current spread through the neural tissue. Sine waves have been tested in cochlear implants, but have long since been abandoned as useful stimulus. Color perception in visual cortical prosthetics is uncovered ground so far, but in retinal implants some limited data is available that color perception can be manipulated by altering the shape and frequency of the electrical pulse trains.

**Background**
First off, neural prosthetics (including auditory and visual prosthetics, as well as pace makers) in general operate through biphasic pulses instead of sine waves.

Biphasic pulses have the advantage that they can be very short (in the order of tens of microseconds in the case of cochlear implants, and hundreds of microseconds in retinal implants). This is advantageous, because the typical biphasic pulse has two identical phases but of opposite polarity. This means that the injected current is quickly neutralized within microseconds. Note that direct current is damaging to the delicate neural tissues. That's why charge-balanced pulses are used in modern cochlear implants to avoid direct current (DC) stimulation that may damage neural tissues (Bahmer & Baumann, 2013).

Sine waves have been used in **cochlear implants** (Clark, 2006), as most of the acoustic speech information is conveyed in frequencies between 500 and 400 Hz. Indeed, the auditory nerve does show phase locking when the electrical (or acoustic) stimulus is about 100 Hz or lower. However, biphasic pulse train are the norm nowadays, because it is safer, more power efficient and more effective, as pulses on adjacent electrodes can be alternated to prevent electrical current to summate on closely spaced electrodes. This is called interleaving and has been used widely since the 1990's as it came known as the **continuous-interleaved sampling** (CIS) strategy (Wilson *et al*., 1993). A CIS-like strategy has been adopted in retinal implants too, for example the **Argus II prosthesis**.

Visual prosthetics in general deliver visual perceptions on a gray scale. Cortical prosthetics have not been investigated much. However, retinal implants are currently commercially available from at least two companies. In retinal implants, phosphenes appear mostly as white spots of light, but yellow has been reported too (Stronks & Dagnelie, 2014b) as well as red to orange phosphenes (Humayun *et al*., 2003). Interestingly, in retinal prostheses it has indeed been shown that by carefully adjusting the pulse rate and pulse shape some crude form of color perception could be induced (Stronks & Dagnelie, 2014a). However, the only consistent result seem to have been that high-pulse rates resulted in blue phosphenes when the stimulation was stopped (OFF response) (Humayun *et al*., 2003). The thought is that different stimulus characteristics stimulate a different set of fibers in the retina but this is very preliminary at this stage. In cortical implants research has not even touched upon color sensations as yet, as far as I am aware.

<sub>**References**
**-** Bahmer & Baumann, *Hear Res*, **306**: 123-30
**-** Clark, *Philos Trans R Soc Lond B Biol Sci* (2006); **361**(1469): 791–810
**-** Humayun *et al*., *Vis Res* (2003); **43**(24): 2573-81
**-** Stronks & Dagnelie, *Exp Rev Med Dev* (2014a); **11**(1): 23-30
**-** Stronks & Dagnelie, Encyclopedia of Computational Neuroscience (2014b): 1-4
**-** Wilson *et al*., *J Rehabil Res Dev* (1993); **30**(1): 110-6</sub>
> 2 votes

# Answer
This question is frankly a bit vague, but generally speaking (i.e. answering the question from the title) the brain uses electrochemical signaling. The trouble is, of course, we are far from fully understanding what goes on in there, or how those signals achieve all that we can do. Presently we can simulate tiny fragments of a rat's brain, as reported in Nature news, 2015.

To answer the question form the body, "if I hooked up some electrode\[s\] to a blind persons visual cortex and wanted them to see the color red, what would i send through the el\[e\]ctrodes?" The answer is we don't know. That's because, as Conway et al. 2007, state:

> On a gross level, it remains disputed whether color is localized to a particular brain region; on a microscopic level, it is uncertain what contribution single cells make to the perception of specific hues. While some brain-imaging studies have suggested that color processing may be localized within the extrastriate brain \[...\], single-cell electrophysiological studies, which have higher spatial and temporal resolution than imaging, have produced conflicting results \[...\] and cast doubt on the notion of a specialized color center \[...\].

Now if you're asking about artificial eyes... there are many kinds of proposed prosthesis, but if we talk about\[bypassing the optical nerve completely such as bionic eye brain implants as reported by MIT Technology Review, 2017, then currently that only works for black and white... and even then

> The patient was able to see spots of light with no significant adverse side effects. \[...\]
>
> “If we could figure out how to process and filter visual information to correctly stimulate the electrodes we could eventually improve the type of image that person will be able to perceive,”

So it seems to be an open problem, even without color.

<sub> Conway, B. R., Moeller, S., & Tsao, D. Y. (2007). Specialized color modules in macaque extrastriate cortex. Neuron, 56(3), 560-573. </sub>
> 1 votes

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Tags: vision, neurophysiology, brain, brain-computer-interface
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# Question
Title: Is acceptance of the science of global warming by politicians primarily a result of the bandwagon effect?
While denial of global warming is without a doubt from bandwagon appeal furthered by campaign donations, I get the impression that the acceptance of global warming by politicians is also primarily a result of the bandwagon effect. The bandwagon fallacy being

> \[An *argumentum ad populum*\] that concludes that a proposition is true because many or most people believe it: "If many believe so, it is so."

The main reason I think so is because it is not a major issue for most of them. I get the impression that if they knew how serious it is, then it would be a major issue for them, and they would have made more efforts to combat it.

# Answer
> 1 votes
First off, political agendas in Western democratic countries are, of course, shaped by the masses.

Secondly, global warming is becoming a science in its own right. Climatology is important and is based on models based on historical data to predict the future, taking into account current greenhouse gas concentrations, melting of the polar caps, sea levels, population growth and what not. In other words, it is far too complicated a subject to be completely understood by the regular ground folks.

Thus, indeed, \[intelligent, capable\] politicians rely on scientists to do the thinking for them. In turn, politician's agendas are shaped by the populace so their focus is, and *should* be guided by the masses.

This should, however, *not* be a reason to adhere to hypotheses and theories to be correct or incorrect based on the people's opinion. And hence I do not agree that politician's opinions in general are shaped according to the bandwagon appeal.

# Answer
> 1 votes
If we stay with the Western democracies, the politician's agenda(s) are shaped *mostly* by their own desire to remain in power (i.e. self-interest) more so than to satisfy the needs of the electorate. If it behooves the politician to accept "global warming" to received more votes, than the politician will support such a cause or viewpoint. Hence, they will join the "global warming" bandwagon irregardless of its scientific validity.
This is unfortunate and certainly not the ideal or preferred behavior of our elected officials. Nevertheless, even a cursory review of US history shows us that the political mind, when at work, prefers "popularity" over "science" or "reason". After all, our elections are about popularity more than anything else. And political agendas are shaped mostly by the power structures within society that "shape" the masses (via media, education, etc.)

I don't particularly like this situation -- but there it is.

Here also is some further reading that I found interesting though there is much in the article to disagree with.

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Tags: social-psychology, bias
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# Question
Title: Can One Have a Temporary Manifestation of Dyslexia?
I have a friend who said he was taking a test in college that involved many calculations (similar to a math test). He inexplicable mixed up numbers, for example, he switched 16 to be 61. Although he did all of the steps correctly, he got the wrong answers due to this mixup. This did not just happen once on this test, but repeatedly. He says that he has not had any issues with dyslexia throughout his life. But his sister does have it.

What might be going on here? Is it possible that he has a very mild form of dyslexia that does not manifest itself except in certain circumstances (I don't know, but perhaps he was nervous/anxious when taking the test)?

# Answer
> 10 votes
The jury is still out on temporary dyslexia, but apparently astronauts can experience it on a temporary basis on return to earth.

However, mixing up (anagramming) digits or letters is not dyslexia. And this is confirmed from another source:

> A common myth closely associates dyslexia with mirror writing and reading letters or words backwards.

At least when done with letters/words, e.g. reading smile as slime, this type of anagramming error is (sometimes) called a "migration error" (or more elaborately, transposition of letters within words). Furthermore, doing this on a regular basis is called Letter position dyslexia (LPD), a peripheral dyslexia. Some people with dyslexia also exhibit LPD, but LPD alone is not widely reported, no doubt in part because LPD is not that well studied: the first study of the developmental form appeared in 2007, while the first study of the acquired form came out in 2001, as far as I can tell. The only known cases of acquired LPD are following brain damage.

People with developmental LPD (but not full dyslexia) fail to be identified as such in standard tests of reading in English because typical reading tests don't have enough "migratable" words, c.f. a 2012 paper that was the first to look at LPD in English (with just 3 cases though). Also of note, one of the three cases discussed there was also officially diagnosed with attention deficit disorder and another one was suspected.

One interesting aspect is that LPD is *not* caused by swapping phonemes; for instance someone with LPD can read *cloud* instead of *could* (even though there's no *ell* heard in *could*). Based on this it seems plausible to me it could affect number *reading* as well, but I haven't found any published research on migrating digits in numbers. A 2nd (2014) study of LPD in English included a *verbal* digit span test, but the LPD children did not have any problems with this test; they were actually above average on verbal digit span. The paper does not report any number reading tests, unfortunately.

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Tags: learning
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# Question
Title: Can drugs cause positive reinforcement for undesirable tasks?
For this example, I will use alcohol as an example drug, since it's legal and increases dopamine.

Can drinking alcohol when performing unpleasant tasks, such as homework, cleaning, or laundry confuse the brain into associating those tasks with positive feelings, and thus increase the desire to perform those tasks, even in the absence of alcohol?

For example, I noticed some of the songs I first heard of while drinking sounded particularly good, but also sound great when not drinking.

# Answer
> 1 votes
Sure. Any introduction of a positive stimulus can reinforce any associated actions. However, alcohol is a depressant, and as such will negatively impact performance on activities such as homework, cleaning, or laundry, to name a few.

The Wikipedia page on operant conditioning explains it well:

> Positive reinforcement and negative reinforcement increase the probability of a behavior that they follow, while positive punishment and negative punishment reduce the probability of behaviour that they follow...Positive reinforcement occurs when a behavior (response) is rewarding or the behavior is followed by another stimulus that is rewarding, increasing the frequency of that behavior. For example, if a rat in a Skinner box gets food when it presses a lever, its rate of pressing will go up. This procedure is usually called simply reinforcement.

# Answer
> 2 votes
**Short answer**
Aversive stimuli can drive drug seeking.

**Background**
Central to your question is the dopamine circuit of the **limbic system** (Fig. 1), being crucial to the reward circuitry in the brain. One notorious way of powerfully activating the reward system is through intake of highly addictive dopaminergic drugs like **cocaine**, heroin and amphetamines, but also alcohol, albeit less potently. They are so addictive because they evoke strong euphoric, hedonic feelings and the notorious 'crash' when their effects wear off. The euphoric state is a powerful positive reinforcer, the crash a potent negative reinforcer.

Stressors negatively impact emotional state and can drive drug seeking by modulating the activity of the mesolimbic dopamine system. In rats this was tested by stressing them with the administration of the bitter compound quinine. Rats stressed in this way had a decreased dopamine tone in their limbic system. This was accompanied by an increased tendency to seek and use cocaine. This increased cocaine-seeking behavior resulted in increased dopamine levels in the limbic system, at least partially counteracting the stressful quinine shots (Twining *et al*., 2016).

Admittedly these findings do not directly answer your question

> \[When\] performing unpleasant tasks \[can drugs\] confuse the brain into associating those tasks with positive feelings \[?\]

My answer shows that

> Unpleasant tasks can lower dopamine in the brain and drive drug seeking behavior \[and cause addiction\] when drug intake is associated with \[more\] positive feelings

Fig. 1. Dopamine pathways in the reward center of the brain. source: Lieff J.

**Reference**
**-** Twining *et al*., *Addiction* (2007); **102**(12): 1863–70

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Tags: cognitive-neuroscience, memory, psychopharmacology
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# Question
Title: Do action potential thresholds vary in "capacity" significantly, and if so, does input frequency correspond to action potential thresholds?
To clarify, I'm asking if the level of stimulation / polarization required for a neuron to reach action potential / excite the neuron varies significantly from neuron to neuron- even differing in neurons of the same type.

And if so, I'm curious to know whether the number of the neurons feeding into a neuron (and the frequency by which they normally fire) corresponds to the level of stimulation required for excitement. I'm wondering if neurons' thresholds for action have sensitivities (levels of input required to reach action potential) based on the number of neurons feeding into them in order to create a balance of input rate / excitement rate.

To rephrase the question, I'd like to know if the action threshold of a neuron changes to fit the frequency with which it's excited.

# Answer
The key to determining if depolarizing a neuron will result in an action potential is the threshold potential of the cell. The threshold potential is basically the voltage, around -55 mV, at which the Na+ channels open. A number of factors (covered in Wikipedia) affect the exact threshold potential.
> 2 votes

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Tags: neuroscience, cognitive-neuroscience
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# Question
Title: What does "non-linear processing" mean, exactly?
In the following sentence from "How does the brain solve visual object recognition?" by DiCarlo et al.:

> In sum, our view is that the “output” of the ventral stream is reflexively expressed in neuronal firing rates across a short interval of time (~50 ms), is an “explicit” object representation (i.e., object identity is easily decodable), and the rapid production of this representation is consistent with a largely feedforward, **non-linear** processing of the visual input.

I'm familiar with "feed-forward" but not with the meaning of "non-linear processing" in a neuroscience context. What does "non-linear processing" mean, exactly?

# Answer
The idea of linear/non-linear in neuroscience is the same as in mathematics. A process $f(x)$ is linear if $f(\alpha x) = \alpha f(x)$ and $f(x+y) = f(x)+f(y)$ for all $x$, $y$, and $\alpha$.
> 5 votes

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Tags: cognitive-neuroscience
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title: Matching patterns in auditory signals

text:
# Question
Title: Matching patterns in auditory signals
How do people match audio signals from memory? For example, consider the simplest case where there is a single channel sound being applied to one headphone. If the subject was previously presented a set of audio signals and then has to identify if the presented signal was present in the set, what features do humans tend to focus on? Is amplitude (volume), frequency (pitch) or something else entirely? Alternatively, a reference to what this type of experiment is called would be appreciated.

# Answer
I don't know if there is a name to this type of experiment, but this basically sounds like a test of recognition memory.

The features that subjects focus on would depend entirely on the task. If you ask them to match volume, they would pay attention to volume. If you ask them to detect a frequency match, they'll focus on pitch. If you run an experiment without specifying a feature, humans generally tend to weight the different features according to their reliability (signal-to-noise ratio). So if pitch is more informative in detecting a match, they would focus largely on pitch.

For example: https://link.springer.com/article/10.1023/A:1026557704054
> 1 votes

# Answer
There are two categories of audio signal memory retrieval/recognition that appear to be being researched.

# Noise Identification

In "Long Term Memory for Noise: Evidence of Robust Encoding of Very Short Temporal Acoustic Patterns", the subject were asked to discriminate 1s cyclic noises (where the two halves are equivalent) or 1s random noises. Four weeks later, target cyclic noises that were shifted or chopped+shuffled were presented in an another discrimination task. The discrimination for intact cyclic noise was significantly better than for novel cyclic noise presented four weeks later.

However, this doesn't address what aspects of audio signals people tend to focus on.

# Melody Identification

From the abstract of "Contributions of pitch contour, tonality, rhythm, and meter to melodic similarity" (emphasis mine):

> In this study, **pitch contour (pattern of ups and downs)** served as pitch surface information, and **tonality (musical key)** as pitch structure; in the temporal dimension, surface information was the ordinal duration ratios of **adjacent notes (rhythm)**, and **meter (beat,** **or pulse)** comprised the structure. Factorially manipulating the preservation or alteration of all of these forms of information in 17 novel melodies (typifying Western music) enabled measuring their effect on perceived melodic similarity. In Experiment 1, 34 participants (varied musical training) rated the perceived similarity of melody pairs transposed to new starting pitches. **Rhythm was the** **largest contributor to perceived similarity, then contour, meter, and** **tonality**. Experiment 2 used the same melodies but varied the tempo within a pair, and added a prefix of 3 chords, which oriented the listener to the starting pitch and tempo before the melody began. Now **contour was the strongest influence on similarity ratings, followed by** **tonality, and then rhythm; meter was not significant**.
> 0 votes

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Tags: cognitive-psychology, memory
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# Question
Title: Can alter-personas of a person with MPD/DID have mental diseases of their own that other 'alters' don't have
**Context:** We are making a short film on different mental disorders.

**The Question:** If it is realistically feasible for a 'alter-persona' of a person with Multiple Personality Disorder to have different mental disorders of their own such as schizophrenia and depression.

# Answer
Yes. For example, people suffering from DID can also suffer from depression.

See DID

Since, by definition "dissociative identity disorder is characterized by the presence of two or more distinct or split identities or personality states that continually have power over the person's behavior. ... ", then the other disorder (e.g. depression) can be unique to a persona.
> 2 votes

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Tags: cognitive-psychology, personality-disorder
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# Question
Title: Is there a named psychological condition for people who find every bad thing to be someone's "fault?"
Suppose person X is looking for something he has lost. Instead of thinking he left it somewhere, he is convinced that person Y has taken it. X is so convinced of this that he will not even look for the object. Instead, he badgers person Y for the location of said object.

In another example, person X is sitting in the rear of a vehicle. He feels cold. The temperature for the rear of the vehicle is controlled by a panel of buttons immediately in front of X. Instead of changing the temperature, he gets angry at person Z. His first instinct is to assume that person Z changed the temperature so he would be cold.

This behavior almost reminds me of Capgras syndrome. Person X attributes every negative circumstance to the malevolent intent of another individual, usually someone close to him he fears or sees as oppressive. He thinks of most people around him this way, and he sees himself as their victim. X responds this way to everything: lost items, a hamburger served differently than he ordered it, tripping and getting hurt, changes in cellular reception while driving along a freeway, etc. While some of these may be someone's fault, he attributes fault to the wrong person.

Is there a name for this type of behavior?

# Answer
> 3 votes
I thing what you are looking for is scapegoating :

> Scapegoating is the practice of singling out any party for unmerited negative treatment or blame as a scapegoat. Scapegoating may be conducted by individuals against individuals (e.g. "he did it, not me!"), individuals against groups (e.g., "I couldn't see anything because of all the tall people"), groups against individuals (e.g., "Jane was the reason our team didn't win"), and groups against groups.
>
> A scapegoat may be an adult, child, sibling, employee, peer, ethnic, political or religious group, or country.
>
> ...
>
> Unwanted thoughts and feelings can be unconsciously projected onto another who becomes a scapegoat for one's own problems. This concept can be extended to projection by groups. In this case the chosen individual, or group, becomes the scapegoat for the group's problems.

Hostile Attribution Bias is another possibility, defined as the tendency to interpret the behaviour of another as having hostile intent even when the behaviour is ambiguous, neutral or benign.

References :

* Roy F. Baumeister & Kathleen D. Vohs, 2007, Encyclopedia of Social Psychology
* Berkowitz and Green, 1962, the stimulus qualities of the scapegoat, Journal of Abnormal and Social Psychology, 7, 202-207
* Gemmill, G., 1998, The dynamics of scapegoating in small groups, Small Group Behavior, 20, 406-418

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Tags: social-psychology, abnormal-psychology, behavior, aggression, cognitive-dissonance
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# Question
Title: What is there in learning to ride a bicycle?
Why do we need to learn to ride a bicycle? We just need to pedal and move the handle. I don't think balancing needs to be learnt. What is the thing we need to learn to ride a bicycle or is it just telling the brain that it is ok? And why do we not forget cycling? Thank You.

# Answer
Riding a bicycle is the clasical example of procedural memory.

> Procedural memory guides the processes we perform and most frequently resides below the level of conscious awareness. When needed, procedural memories are automatically retrieved and utilized for the execution of the integrated procedures involved in both cognitive and motor skills, from tying shoes to flying an airplane to reading. Procedural memories are accessed and used without the need for conscious control or attention.
>
> Procedural memory is created through procedural learning or, repeating a complex activity over and over again until all of the relevant neural systems work together to automatically produce the activity. Implicit **procedural learning is essential for the development of any motor skill or cognitive activity**.

When we learn to ride a bicycle, the brain is learning the motor movements necessary to maintain balance. This learning occurs mostly at the unconsious level, and this is probably the reason why you have the illusion that nothing is learnt.

> Motor control is the process by which humans and animals use their brain/cognition to activate and coordinate the muscles and limbs involved in the performance of a motor skill.

The procedural memory is a type of long term memory which has a long lasting effect.
> 2 votes

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Tags: perception, learning
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# Question
Title: What is the rationale for the normal distribution of intelligence?
What is the rationale for the normal distribution of intelligence?

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I'm asking what the rationale is for saying that 68% of variance within intelligence falls within 1 standard deviation either side of the mean, and 95% within 2, etc.. That's just what "normal distribution" means. Here is a picture:

Why not suppose that intelligence is e.g. a uniform distribution? You can see clearly, in the picture below, that if it's modeled in that way:

* someone's deviation from the mean will be equal to the probability of their score.

# Answer
**Short answer**
IQ scores are distributed normally, because they follow the central limit theorem.

**Background**
When we measure **IQ scores** in sufficiently large populations, they will be normally distributed. This holds for healthy controls, as well as groups of people with ADHD or reading disabilities (Kaplan *et al*., 2000), and also in people with mild to moderate mental retardation (Bellugi *et al*. (2003).

Many biological variables follow a normal distribution quite well. This is a result of the **central limit theorem**, which says that when you take a large number of random numbers, the means of those numbers are approximately normally distributed (McDonald, 2012). When for example the weight distribution is sampled in a population, it will vary with age, nutrition, disease status *etc*. The addition of these independent random variables result in the variable (in this case weight) to become normally distributed ("bell shaped"), even if the original variables themselves are not normally distributed (source: wikipedia).

Hence, your statement `Do we as a society have the right attitude to variation in human intelligence? Because it seems to me we are either over-nurturing the extremes, or should not represent it as a normal distribution` doesn't really apply here, as IQ score distributions have nothing to do with 'us as a society having the right to do something'.

**References**
**-** Bellugi *et al*., *Enfance* (2003); **3**(55): 237-49
**-** Kaplan *et al*., *J Learning Disabilities* (2000); **33**(5): 425-32
**-** McDonald, *Handbook of Biological Statistics*, 3rd ed. (2012). Sparky House Publishing, Baltimore, Maryland
> 7 votes

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Tags: intelligence, statistics
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# Question
Title: A doctor told me that cephalic index can be used to measure human intelligence, is it true?
I am roommates with a maxillofacial surgeon. He told me that during his studies he read that cephalic index can be used to measure intelligence.

And he further explained that as Africans and women have smaller brains according to cephalic index, so they are less intelligent than Caucasian and Asian men.

I just want to know how much of this is true, if any? And please explain.

# Answer
> 6 votes
No, the index and its correlation to intelligence is not strong.

See the medchrome.com description on cephalic index:

> * The underlying assumption of craniometry is that skull size and shape determine brain size which determines such things as intelligence and capacity for moral behavior. Empirical evidence for this assumption is not very strong.
> * Cephalic index consistently produced a very low or negative correlation with mental ability.

See also this article on Smithsonian.com: Why Brain Size Doesn’t Correlate With Intelligence

Healy and Rowe (2007) provide a critique of comparative studies of brain size.

<sub> Healy, S. D., & Rowe, C. (2007). A critique of comparative studies of brain size. Proceedings of the Royal Society of London B: Biological Sciences, 274(1609), 453-464. </sub>

# Answer
> 3 votes
(It wouldn't let me just comment) I would add, there are multiple cases where the apparent size of the skull and therefore brain do not correlate with intelligence, and this is across different species of the planet. If it were true, why are humans one of the apparently most intellectually evolved creatures? Consider whales. This cannot be explained by the aforementioned method. If one were to look at brain size in the human population they appear to actually be decreasing in size over time, which could lead one to conjecture people aren't getting less intelligent but that the density of neurons is changing. The density is increasing. We can justify the lack of decreasing intelligence by the intelligence metrics that exist today, regardless of how flawed they may actually be, they show an average increase compared with the past. So, in the human case, if you were take density into consideration then this altogether and at once dismisses the idea you speak of as being patently false.

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Tags: intelligence
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# Question
Title: Why ADHD instead of ADD? / Why predominantly hyperactive-impulsive instead of predominantly-impulsive?
The types of Attention deficit **hyperactivity** disorder are:

1. predominantly inattentive
2. predominantly **hyperactive**-impulsive
3. combined

Not sure I understand. People with ADHD are hyperactive because of the H in ADHD. So what's the point of the word "hyperactive" being in both "predominantly hyperactive-impulsive" and "Attention deficit hyperactivity disorder" ? Why not just say predominantly impulsive or attention deficit disorder?

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Edit to justify this question not being a duplicate:

I think one of the terms unnecessarily uses the word "hyperactive":

1. AD**H**D
2. predominantly **hyperactive**-impulsive

Why do we use **hyperactive** twice? Why not

1. ADD has 3 types: predominantly inattentive, predominantly **hyperactive**-impulsive, combined

or

2. AD**H**D has 3 types: predominantly inattentive, predominantly impulsive, combined?

# Answer
ADHD used to be called just ADD in DSM-III (released in 1980), with the subtypes ADD/H (ADD with hyperactivity) and ADD/WO (ADD without hyperactivity). However, by 1987 when DSM-III-R was published, it turned out there was not enough empirical evidence to support the multidimensional view of ADD from DSM-III, so DSM-III-R adopted a unidimensional view, which was reflected in the name change to ADHD. This change was not without criticism, and it turned out that the criticism was well founded, because by the time DSM-IV came about (it was published in 1994), enough empirical evidence had accumulated for the multidimensional view, however the dimension space was refined into inattention and hyperactivity-impulsivity, and allowed for a combined type as well. From empirical research it turned out that the DSM-III diagnoses of ADD/WO and ADD/H correspond fairly closely with the DSM-IV diagnoses of ADHD predominantly inattentive type and combined type, respectively (cf. Morgan et al.)

Now for the terminology, the proper name howadays is attention-deficit/hyperactivity disorder (i.e. with the slash), which correctly reflects the equal importance of the two dimensions (from DSM-IV and 5) in the name. If you want to be really nitpicky, the proper, unambiguous abbreviation of this name should be something like {AD/H/AD+H}D or ADD/HD/AD+HD, though of course nobody writes it like that for reasons of parsimony.

If you propose to say that "ADD has 3 types: predominantly inattentive \[...\]" you're still semantically repeating inattentive which means attention deficit, so I don't get the parsimony you propose at 1 as it asymmetrical, i.e. you're still repeating something in the first subtype from the title name even though you avoid it for the 2nd subtype.

As for proposal 2 "ADHD has 3 types: predominantly inattentive, predominantly impulsive", you're now calling the hyperactive-impulsive just impulsive. This is more a matter of how do you want to call the hyperactivity-impulsivity subtype. There is probably not enough empirical evidence to to have 3 dimensions (inattention, hyperactivity and impulsivity) for ADHD, nevertheless DSM-IV distinguished between the latter two for reasons not entirely clear to me, but which I suspect are a matter of calling a spade a spade:

> Hyperactivity: (a) often fidgets with hands or feet or squirms in seat (b) often leaves seat in classroom or in other situations in which remaining seated is expected (c) often runs about or climbs excessively in situations in which it is inappropriate (in adolescents or adults, may be limited to subjective feelings of restlessness) (d) often has difficulty playing or engaging in leisure activities quietly (e) is often “on the go” or often acts as if “driven by a motor” (f) often talks excessively
>
> Impulsivity: (g) often blurts out answers before questions have been completed (h) often has difficulty awaiting turn (i) often interrupts or intrudes on others (e.g., butts into conversations or games)

For diagnostic purposes these two are combined, i.e you need 6 of any of these for hyperactive-impulsive diagnosis. Nevertheless it seems somewhat awkward to say that someone who has difficulty awaiting his/her turn is hyperactive rather than impulsive. There may be more history behind this sub-subheading split without diagnostic consequences; the DSM is designed by a committee so there may have been more to it, but I wasn't able to find out. What seems obvious is that lifting hyperactive rather than impulsive to the disorder name is appropriate given that most criteria for the subtype are of the hyperactive kind. Calling it "attention-deficit/hyperactive-impulsive disorder" seems really a mouthful.

It turns out there's at least one 2005 paper that partially agrees with your criticism though:

> Not only is “ADHD without hyperactivity” (ADHD of the predominantly inattentive type) an awkward locution, but it also tries to squeeze ADD into a box in which it does not belong. The term ADHD should be reserved for when hyperactivity is present (as the term implies), regardless of whether inattention is also present.

As it's evident in the above, abbreviations don't capture alternatives. So ADHD is hard to read as {AD|H}D. Nevertheless the DSM-5 committees were not convinced and the name remained what it is. Although some changes were made to the ADHD diagnosis the DSM-5:

> The retention of the ADHD symptom domains and 18 core symptoms likely reflects a judgment that the DSM-IV definition of ADHD has largely withstood the test of time.

However

> The change in nomenclature from “subtypes” in DSM-IV to “presentations” in DSM-5 reflects increasing evidence that symptoms are often fluid within individuals across their lifespan rather than stable traits. DSM-IV ADHD subtypes change across development due to the heterotypic continuity of symptom trajectories over time. For example, since inattention is relatively stable across development while hyperactivity/impulsivity often wane with age, many children diagnosed with ADHD, Combined eventually transition to ADHD, Predominantly Inattentive \[...\]. The “presentation” terminology better reflects that the symptom profile represents the person’s current symptomatology, which may change over time. The “type” terminology implied more stable, trait-like characteristics.
> 2 votes

# Answer
You are partly right. In older patients, there is usually just attention deficit without hyperactivity.

Hyperactivity is term which describe behavior, and attention is the word which describes cognitive processes.

These processes are not the same although they depend on each other because neurotransmitter dopamine.

http://www.dsm5.org/documents/adhd%20fact%20sheet.pdf

EDIT: Control of impulses and hyper-activity are in behavioral domain. hyper means "a lot of" activity". Because of this reasons hyperactivity is diagnosed: \- appears to be always on the go \- excessively talks \- has severe difficulty waiting for their turn \- squirms in their seat, taps their hands or feet, or fidgets \- gets up from a seat when remaining seated is expected \- runs around or climbs in inappropriate situations \- is unable to quietly play or take part in leisure activities \- blurts out an answer before a question has been finished \- intrudes on and interrupts others constantly
> 0 votes

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Tags: abnormal-psychology, terminology, adhd, psychology
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# Question
Title: Does Machiavellianism concept attempt to combine different personalty types?
Wikipedia states that:

> Machiavellianism has been found to be negatively correlated with Agreeableness and Conscientiousness

Next, agreeableness article has following words:

> The lower-level traits, or facets, grouped under agreeableness are: ***trust***, straightforwardness, altruism, compliance, modesty, and tender-mindedness.

And article on Machiavellianism in some way is contradictory:

> It was found that in a ***trust*** game, those with high MACH-IV scores tended to follow homo economicus' equilibrium strategies while those with low MACH-IV scores tended to deviate from the equilibrium

In simple words that means that high machs are closer to optimal strategy in trust games than low machs. If they are mistrustful, why are they better in trust games?

That's not the only contradiction. Let's look at conscientiousness article:

> People who score low on conscientiousness tend to be ***laid back***, ***less goal-oriented***, and ***less driven by success***

And now again Machiavellianism article:

> High Machs admitted to focusing on unmitigated ***achievement*** and ***winning at any cost***.

But enough Wikipedia, there is more ambiguousity in this research article (that references a bunch of other articles):

> There are at least **two** main paradigms of partner selection and both can be evidenced with previous research to be relevant to the partner selection of Machiavellians. On the one hand, similarity in level of affiliation, intimacy needs and personality traits has particular importance in ideal standards and mate choice. Previous studies provided countless evidence supporting the similarity hypothesis
>
> ...
>
> Accordingly, it is also possible that a dominant high-Mach who demands attention can form the most stable – though dysfunctional and asymmetric – relationship with a submissive and permissive low-Mach partner who he or she can manipulate and exploit

Again ambiguousity. The only explanation I can propose is that there is no such thing as Machiavellianism. There are \[at least\] two types of personality which Machiavellianism tries to describe. Is there any concept that tried to resolve these issues? Obviuosly, Mach-IV can't separate these two types of personalities. So, are there any tests that can do it?

P.S. I expect that those "machiavellianists" who are good in trust games usually tend to choose similar \[to themselves\] partners for relationships and possibly, they are more goal-oriented (and should they really be a part of dark triad?). Also I won't be surprised if these two types of "machiavellianists" will differ greatly in emotional intelligence and mind theory.

# Answer
"If they are mistrustful, why are they better in trust games?"

From the abstract of the actual paper:

> We argue that Christie and Geis’s Machiavellianism scale (Mach-IV) is an instrument that allows the identification of types who vary in cooperativeness. We use that test to predict the behavior of participants in a two-person one-shot constituent game in which subjects face a choice between trust and distrust, and between reciprocation (trustworthiness) and defection. We find that the Mach-IV scale does not predict trusting behavior. It does, however, predict reciprocity. Over one half of those who score low to average on the scale reciprocate trust. High scorers overwhelmingly defect when it is to their advantage to do so.

In other words, high Mach's know when it's to their advantage to stab you in the back and do it. Big surprise there.

The game played, annotated with the results, is reproduced below.

I'll not give a full explanation (read the paper if you are unfamiliar with game theory, it explains it "for dummies"), but suffice to say that the high Mach (H) overwhelmingly moved down as P2, i.e. maximized their own profit even if that meant screwing over the P1 player who was nice to them, whereas average-to-low (AL) Mach players reciprocated (about half the time) as P2 even though that's not the dominant strategy as P2. In other words, AL felt like reciprocating for a past favor, even though that buys them nothing in this game. High Machs (mostly) did not repay a favor in such circumstances.
> 2 votes

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Tags: abnormal-psychology, personality
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title: How to prime gammatone filters?

text:
# Question
Title: How to prime gammatone filters?
A set of gammatone band-pass filters are often used to model the filtering performed by the human inner ear. For example, "BatSLAM: Simultaneous Localization and Mapping Using Biomimetic Sonar" Jan Steckel and Herbert Peremans, as well as "Biologically inspired methods in speech recognition and synthesis: closing the loop" by Trevor Bekolay both use them. However, like all filters, if you start the input signal with silence, the gammatone filter responds differently than if you started the input signal with some sort of noise. Similarly, mammals are very rarely submerged in absolute silence. The environment and internal organs generate what I would imagine to be some sort of low frequency noise. Maybe it's a low-pass filtered white-noise?

If you are trying to use gammatone filter in a model, what do you prepend the start of your signal with? In other words, how are gammatone filters typically "primed"?

# Answer
Mostly it depends on the kind of experiment you're doing. If you're interested in speech (as I was), most of the important information is in the 300-3000 Hz range, where low-frequency noise will have little effect unless it's extremely loud. If the experiment you're doing deals with static or other sounds with broad power spectra, then low frequency noise could have a significant effect.

As with most questions of perception, what matters most isn't really the signal itself but how the signal is changing. It's a big change to go from from silence to loud static. It's a lesser change to go from quiet static to loud static. That difference is more significant than the difference between going from silence to speech and going from quiet static to human speech, because speech is similar to neither silence nor static.
> 1 votes

# Answer
Priming the filters (or setting the initial state) is essentially unimportant for studies of audition. In a typical study, the signal is presented at 70 dB and the background noise of a quality double-walled sound both might be 20 dB. This gives a 50 dB SNR. That means if the amplitude of the filter response to the signal is 1, the response to the noise would be 10^-5 (0.00001).

If you are using the filter bank to study absolute detection, where the signal is small relative to the background noise, then you need to worry about the ongoing background noise (but should probably also include some sort of internal noise in the model). Even in these cases, the effect of priming will be small for signals of reasonable duration since the filters die out in a few milliseconds. So unless you are looking at absolute detection of brief signals, there is probably no reason to worry about "priming" the filter.
> 1 votes

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Tags: cognitive-modeling, hearing
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