# Question
Title: What are the laws of female physical attractiveness?
Though sometimes beauty is in the eye of the beholder there must be certain physical traits that humans consistently find attractive. What are these physical beauty traits for women in modern developed countries? An example is large eyes. Ethnicity or country of origin doesn't matter. Provide your sources if possible.

# Answer
> 3 votes
There is an excellent paper at Evolutionary considerations of facial attraction which you may find useful. Neoteny is also a useful discussion.

My off the cuff summary would be that humans do appear to have retained much of their juvenile characteristics in comparison with other primates. Across cultures female faces with more neoteny (more childlike) are considered more attractive. As a general rule, the less masculine, the more feminine, so you can negate the masculine markers, i.e., larger jawbones, more prominent cheekbones, thinner cheeks, to increase femininity perception. That would, of course, include less facial hair, since that is a general neoteny character that would be more attractive. My recollection of several studies of so-called "baby face ratings" might pertain also, in that larger eyes, more prominent eyebrows, smaller chin, are typically perceived as innocent or less threatening, so I would guess that would also fall into the normal feminine perception category.

In general terms, symmetric faces are more attractive (right hand left hand comparison on the midline), so that would apply to women also. Averageness, surprisingly, is also more attractive, in that the more closely a face resembles the majority of faces is perhaps a sign that the person is less likely to have deletrious alleles. Facial averageness seems to be associated with medical health. Skin color is also a measure of perceived health. Typically pallor is perceived as possible illness. Texture of facial skin is a marker, smoother being more attractive.

There is an interesting paper Cosmetics as Extended Phenotype that examines how cosmetics may be used to exaggerate cues to sexual dimorphism. Another paper, Face is not an empty canvas discusses how the morphology of faces is more desirable when it tends to heighten the expected emotions for the particular sex role, for example, the rounded baby face with larger eyes is perceived as more approachable and warm and more feminine generally. Finally, this article Aspects of Facial Contrast Decrease with Age and are Cues for Age Perception discusses how aspects like wrinkling and loss of luminance contrast between the eyes and surrounding skin and the lips and surrounding skin increases the perception of aging and decreases the attractiveness of female faces.

# Answer
> 1 votes
Attractiveness has shown to be related to symmetry. A study that used a computer to simulate perceptive systems showed that a visual system designed to recognize an object from multiple positions would most quickly identify symmetrical figures. (Enquist, 1994) In addition, some research suggests that familiarity, attraction, and preference have been shown to operate on similar mechanisms. (Reber, et al)

**Reference**

Enquist, Magnus, and Anthony Arak. “Symmetry, Beauty and Evolution.” Nature 372.6502 (1994): 169–172. Web.

Reber *et al*., Processing fluency and aesthetic pleasure: Is beauty in the perceiver's processing experience? *Personality and Social Psychology Review* ( 2004);

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Tags: physical-attraction
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# Question
Title: Does a split brain affect the inner voice?
In the Nature link provided, split brain reportedly alters the processing of **sensory input** (*e.g.*, an aberrant performance on monocular visual tasks under laboratory conditions), and impairs **motor output** execution (*e.g.*, impaired ability to make goal-directed movements).

Now my question is whether **a split brain (*corpus callosotomy*) affects the ability to have an internal monologue in any way?**

I'm curious of that because I heard about "Bicameral mind" theory (although I didn't read the book) and that on of the reasons of "bicameralism" was weak connection between hemispheres. I couldn't find anything about formation of inner voice and decided to ask.

<sub>**Source**
**-** Nature News, 2012</sub>

# Answer
Short answer: Probably not.

Let's first keep in mind that very few split-brain patients have ever been studied. Add to this that inner speech is not a well studied area in general. As the resulting Venn diagram suggests, there is next to nothing known about inner speech in split-brain patients.

Second, remember that one of the key reasons why inner speech is problematic to investigate is because up until recently, our main data source has been self-reports, considered notoriously unreliable as a methodology. This is especially exacerbated in patients with awareness deficiencies such as split-brain.

Having said that...

Split-brain patients in general report no significant post-operative changes in their cognitive function, sense of self, or conscious experience. Internal monologue remains intact, and appears to function as normal. However testing under lab conditions demonstrates that subjects do in fact experience significant changes in awareness - effectively neglecting half of their perceptual experience.

If self-reports of awareness are so significantly inaccurate, then what are we to make of split-brain patients' self-evaluation of conscious experience and other cognitive functions? The truth is, we just don't know.

Relatively recently, new techniques for studying inner speech have been developed, such as fMRI imaging of subjects instructed to or prevented from engaging in self-reflection and internal monologue. Such studies suggest that inner speech is primarily localized to Broca's area (LIFG, on the left side of the brain), just as is outer speech (McGuire, 1996; Morin & Hamper, 2012; Wikipedia). These findings are consistent with other evidence that inner speech is a form of silent (simulated) outer speech, and thus uses the same physical mechanism.

In the split-brain paradigm experiments, subjects are able to articulate stimuli presented to their right field of view (left hemisphere, where Broca's area is), but unable to do so for stimuli presented to their left side (right hemisphere, where language is lacking). To communicate with the right hemisphere, researchers have subjects use their left hand to gesture responses in some way.

These experiments were instrumental in localizing language function in the brain, and they demonstrated that language capabilities are largely lateralized in the left hemisphere. However, the right hemisphere has sufficient language understanding capabilities to gesture meaningful responses without the left hemisphere's awareness.

So although it's tempting to suggest that inner speech, localized in Broca's area on the left side of the brain, should be unaffected by corpus callosotomy, as reported by split-brain patients, the language capabilities of the right hemisphere leave open the possibility that a separate experience may exist there, potentially implying some reduction in function of (outer and inner) speech in the left side.

And indeed, while language function is highly lateralized in 90% of right-handed people, function is more evenly distributed amongst the hemispheres in other cases. By some stroke of luck, this was the case in a particularly interesting split-brain patient by the name of Paul S.

Remarkably, in the experiments conducted with Paul, he was able to use his left hand to spell out single word answers using Scrabble pieces to express what his right hemisphere was thinking (LeDoux et al, 1977). As with other split-brain subjects, his right hemisphere had a quite different experience from his left, but unlike other patients, Paul was able to demonstrate a slightly different personality residing in his right brain, with different opinions, preferences, and decisions.

Could this mean that Paul S. had a second, independent internal monologue in his right hemisphere that the left hemisphere was unaware of? The dual-consciousness interpretation of this case study has been the subject of much debate, but most scholars suspect that this is unlikely: Language function is simply too rudimentary in the right hemisphere, even in this remarkable case, to plausibly support this hypothesis.
> 3 votes

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Tags: neuroscience, language, lateralization
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# Question
Title: How do I obtain recordings of the P300 wave of the event-related potential in the EEG?
I am trying to understand how to analyze the ERP (Event-Related Potentials) from EEG recordings and in particular the P300 wave.

I have come up with a few questions which I hope you might be able to help with:

1. I assume that the number of repetitions of the stimulus should give better results, but I am not sure why. On the one hand, it should help, because averaged results are usually better in electrophysiology. On the other hand, maybe there is some unwanted adaptation effect in the subject? So, are repetitions wanted in this kind of experiment?
2. There are time points in which I didn't expect P300 but the brain activity was not 0. I understand that there is always a background activity in the brain, but maybe there is more to it? And if so, are there certain frequencies that are expected in the EEG?
3. When I analyze the data using an average response, should I assume anything on the P300 response?
4. What is the recommended sample Rate I should use? I guess there should be an advantage for high sample rates to increase resolution, but I am not sure about that. Am I right, or maybe a lower sample rate has advantages that I am not aware of?

# Answer
The **P300** wave is a positive deflection in the human event-related potential (ERP). A common experiment in which it is analyzed is the "oddball" paradigm, where a subject detects an occasional target stimulus in a regular train of standard stimuli. The P300 wave only occurs if the subject is actively engaged in the task of detecting the targets and its amplitude varies with the improbability of the targets. Its latency varies with the difficulty of discriminating the target stimulus from the standard stimuli. A typical peak latency when a young adult subject makes a simple discrimination is 300 ms. The P300 wave may represent the transfer of information to consciousness, a process that involves many different regions of the brain (Picton, 1992).

Your questions:

* ad. 1: Averaging reduces the random background EEG activity (**noise**), as well as **artifacts** due to movement or eye blinks. Random events will average out, while the ERP itself, being highly synchronized with the stimulus, will persist in the signal. In short: averaging increases the **signal-to-noise ratio** (SNR). `Is this wanted?` \- That depends on the SNR you wish to obtain. The more averages, the better the SNR. `[M]aybe there is an unwanted adaptation effect of the subject` \- if you are afraid of **adaptation** \- do repeated measures and analyze single ERPs, or small chunks of averages across the recording - it will give you an idea whether there is adaptation, and if yes, how much. I wouldn't worry about it too much. The long time scale of P300 recordings (second-range) allows the nervous system plenty of time to recover.
* ad. 2. There is always background EEG, except in (brain) dead subjects - and these subjects won't be too cooperative. `[A]re there certain frequencies that are expected in the EEG` \- ERPs are not analyzed in the frequency domain, but in the time domain. If you are interested in the frequency content of the EEG; it is much dependent on the state of the subject. An awake, vigilant test subject with their eyes open will show **beta activity** (6 - 31 Hz band).
* ad. 3. Averaging doesn't change the timing characteristics of the ERP, barred the recording is properly time-locked with the stimulus.
* ad. 4. Higher sampling rates are generally better. If your system allows it, crank it up. You can always downsample later. Downsampling may have the advantage of smoothing high-frequency noise and enhancing the ease of handling of the data. ERPs are slow responses, so you don't need 100 kHz signals. For EEG generally 500 Hz is used, because according to the **Nyquist criterion** you need at least twice the numbers of samples than your highest frequency of interest. The **gamma band** is 32+ Hz, so 500 Hz is pretty safe (De Haan, 2013). For ERPs, 200 Hz may be sufficient. Wikipedia suggests higher rates for EEG.

<sub>**References**
**-** De Haan, *Infant EEG and Event-Related Potentials*; Psychology Press (2013)
**-** Picton, *J Clin Neurophysiol* (1992); **9**(4): 456-79</sub>
> 5 votes

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Tags: eeg, electrophysiology, event-related-potential
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# Question
Title: Are there empirical studies showing that one sex is more sexually selective than the other?
Initial research: I've found papers by Clark and Hatfield (1989) and Buss and Schmidt (1993) that seem to lend support to the idea of heterosexual females being more selective than heterosexual males.

Motivation: I have constructed a game theoretic model of romantic advances. Within this model, it is possible to show that certain Nash equilibria are Pareto improvements upon others depending on which sex is more selective. Thus, I'm looking for empirical evidence as to which (if any) sex is more selective

Does anyone know of any other empirical studies that support or go against the idea that heterosexual women are more selective in who they date, have sex with or have relationships than heterosexual men?

**References**

Buss, D. M., & Schmitt, D. P. (1993). Sexual strategies theory: an evolutionary perspective on human mating. *Psychological Review*, *100*(2), 204.

Clark, R. D., & Hatfield, E. (1989). Gender differences in receptivity to sexual offers. *Journal of Psychology & Human Sexuality*, *2*(1), 39-55.

# Answer
> 5 votes
As noted above, evolutionary theories suggest that (heterosexual) females should be more choosy than males, because they typically invest far more resources in raising offspring (men have enough time and sperm that their genes are going to be more successful if they adopt a scattergun approach!).

A **disclaimer** here is that, in humans, research on sex preferences is difficult because it is mostly based on self-reported preferences, and because these are likely coloured by cultural and historical norms. However, there is significant empirical evidence that females are more choosy. Searching on google scholar for "sex differences" and "mate preference" or similar will give you lots of options. Here are a few.

Here is a study which summarises, across many cultures, some sex differences in self-reported mating preferences. As predicted by Buss and others, the authors find that across all cultures men report that they *desire* more sexual partners than women. This is not a small effect. They also find that men are more likely to consent to sex after a brief period of time, and that men everywhere are more likely to be seeking short-term partners.

Here is a more experimental paper where they changed the attractiveness and implied wealth of potential partners and found that men were more likely to go for short term, multi-partner strategies than women who were more likely to go for long term, committed relationships.

Of course, there are also many studies from other species, some of which show the conditions in which men become more choosy. This paper even includes a video of a female beetle trying to reject a male!

This paper proposes a mathematical model which might also be helpful. Modern models are much more nuanced about how male and female choice interact.

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Tags: reference-request, sexuality, sex-differences
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# Question
Title: What is the mental state called when I forget my thoughts?
Suppose I am talking to someone and while talking more thoughts come to my mind that I wish to talk about. I postpone those thoughts, however, to tell everything synchronously, *i.e.*, I wish to tell the old thoughts first and then the new thoughts in sequence. But by the time I finish telling previous thoughts and try to come to those new thoughts that I postponed to tell, some are vanished. This must be a very common phenomenon, as everyone has experienced the dreaded

> ***What on earth was I about to say...?***

What is the term for this mental state, or of the process mentioned?

# Answer
**Short answer**
The key term in your question is working memory.

**Background**
**Working memory** is involved in information-processing functions such as encoding, storing, and retrieving data and it is a system that temporarily stored and manages information required to carry out cognitive tasks, such as learning, reasoning, and comprehension.

One relatively straightforward test to assess working memory is **memory span**. In this test the number of items (usually words or numbers) is determined that a person can hold onto and recall. In a typical test of memory span, an examiner reads a list of random numbers aloud at about the rate of one number per second. At the end of a sequence, the person being tested is asked to recall the items in order. The average memory span for normal adults is 7 items (source: Medicine Net).

Note that the definition of working memory, as opposed to short-term memory and, to a lesser extent, long-term memory are not that well defined. In fact, Medicine Net links two identical webpages to short-term memory and working memory. The difference between working memory and short-term memory is indeed subtle. Working memory is generally thought to rely on short-term memory, but to additionally involve processes to effectively *use those memories* during cognitive tasks. The difference may be explained as (Cowen, 2008):

> \[W\]orking memory includes short-term memory and other processing mechanisms that help to make use of short-term memory.

The difference between short- and long-term memory stores is based on a difference in their *duration* and in their *capacity* (Cowen, 2008). Long-term memory, not surprisingly, is of longer duration and it can hold much more information. However, it cannot be accessed as readily compared to short-term and working memory.

<sub>**Reference**
**-** Cowen, *Prog Brain Res* (2008); **169**: 323–38</sub>
> 3 votes

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Tags: cognitive-psychology, psychology
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# Question
Title: How do neurons limit their input current?
I know that many neurons have an input current-spiking frequency (I-F) relationships, e.g. as seen here.

However, all the I-F curves I've encountered show the input current in a fairly small range (few pA or nA), suggesting that there is no limit to this behavior.

However, if the current is increased indefinitely, there is a point where the membrane voltage does not recover to the resting, or smaller, potential. For example, here are voltage traces of a simulated mitral cell:

**At 0.1nA**:

**0.5nA**:

**1nA**:

**10nA**:

How do neurons limit the amount of current that enters the cell? If the cell is large, with many incoming synapses, it seems like there would be stimuli that could result in "too many channels" open at the same time. **How do cells ensure the input current remains within the acceptable range?**

# Answer
Current is Voltage (driving potential) times conductance. As the membrane potential approaches the Nernst potential of the conductance, the current approaches 0. Conductances can be turned on or off through receptor binding, but there is no such thing as voltage-independent current injection (at least under physiologically relevant conditions).

Indeed, it is the case that if you artificially inject large amplitudes of current into neurons, you observe voltage traces similar to your simulations. This will very quickly lead to cell death.
> 1 votes

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Tags: neuroscience, theoretical-neuroscience, computational-modeling, electrophysiology
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# Question
Title: What does it mean to say that mental illness is a modern-day leprosy?
I was reading about mental illnesses and then thought one day that the uninformed regard mental illnesses the same way leprosy was regarded.

I looked up about leprosy and some papers and articles about how mental illness is a modern-day leprosy, but I can't seem to find as to what exactly is the relation, if they are even thinking the same thing I am.

So far I know, it is observed that the uninformed are not giving them the treatment they need. Specifically, why are the uninformed not giving them the treatment they need?

Is it accurate and precise to say that mental illness is regarded as modern-day leprosy since:

1. In ancient times (or Jesus's time), uninformed people believed people who had leprosy had leprosy because they committed a grave sin or sins
2. In modern times, uninformed people believe people who have mental illnesses have mental illnesses because they committed gravely immoral actions (see how I avoid the non-secular word "sin") ?

Take for example a drug or gambling addict. Drug and gambling addictions are mental illnesses, but an uninformed person would look at a drug or gambling addict and say that the reason that they have these sicknesses is that they started taking drugs or gambling, the immoral action.

However maybe an informed person would say that the reverse is the case: the immoral actions of starting to take drugs or gamble is caused in part by the illness that the person had or the biological, psychological or environmental predispositions that the person had.

Other examples would include procrastination, overeating or hyperactivity.

Bottom line, is it accurate and precise to say that the term "modern leprosy" is in reference to thinking:

> You're crazy because you did evil things

rather than

> You did evil things because you're mentally ill ?

This question may not be very clear so please recommend how I can improve this question.

# Answer
This term depicts a wide spread problem in society that the term 'mental illness' carries with it stigmas and negative connotations.

Firstly, From a psychologist's perspective, we want people with mental illnesses to recognise them and seek help/treatment so that the problem can be solved. However, negative labels often cause people to ignore signs of mental illness. The effect is that fewer people with problems are seeking help from them, causing them and those around them to suffer for it.

Secondly, mental illnesses carry no moral significance or worth. An individual afflicted by a mental illness has done nothing to deserve it. It is unfair on them to be ostracized for something beyond their control, however this is often what happens with mental illnesses.

Leprosy has been greatly feared and shunned for thousands of years by humans everywhere. An individual with leprosy would be separated from the society and would be forced to survive on their own or find a leper colony if they were lucky. This is similar to how many people suffering mental illness suffer today. Often they cannot take care of themselves, and are shunned regardless of their suffering.
> -1 votes

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Tags: abnormal-psychology, terminology, addiction, adhd
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# Question
Title: Why can't hemineglect patients be trained to actively pay attention to their neglected side?
I'm still having a hard time understanding the symptoms of hemineglect, mainly because perception and attention has been two peas of a pod for most of my experiences.

A Scholarpedia article states that a hemineglect patient is likely to shave just one side of their facial hair (thus having left half of their beard intact).

I also know that while hemineglect patients have harder time attending to the side contralateral to the lesion location, external effort to bring attention to the contralateral side can bring attention to the contralateral side temporarily.

If that is the case and the patient is still familiar with the concept of body symmetry, then my question is:

**Why doesn't the patient use their concept of symmetry to force themselves to pay attention to the contralateral side?**

Is even the concept of bilateral symmetry affected, possibly because any memory of an object brought up from long-term memory also loses the contralateral side?

# Answer
> 3 votes
**Short answer**
Symptoms of hemi-neglect are often accompanied by additional layers of cognitive deficits that make rehabilitation challenging. Logic reason is often dissociated from these patients' perceptions, or they simply dismiss there is a problem altogether.

**Background**
Hemineglect is the impaired or lost ability to react to, or process sensory stimuli presented in the hemispace contralateral to a lesion of the human right or left cerebral hemisphere. Besides this *sensory neglect*, *motor neglect* may occur, manifesting itself as a reduced use or even non-use of a contralateral extremity. Finally, there is *representational neglect*, referring to impaired spatial imagination (Kerkhoff, 2001).

In terms of **rehabilitation treatment of neglect**, it seems indeed logical to suggest the patient to actively start paying attention to the neglected side in tasks of everyday life. In fact, this is an accepted rehab strategy used, which can be regarded as a coping strategy. Though this approach is intuitively the most straightforward way to rehab these patients, it often proves to be difficult for therapists, because often additional, more global cognitive deficits exist besides the hemi-inattention (Marshall, 2009). As you indicate, **anosognosia** (deficit of self-awareness, *i.e.*, a disability to acknowledge the existence of his or her disability) is seen in hemineglect patients in up to 20% to 58% of cases. When the patient dismisses the problem, treatment is next to impossible. **Personality changes** such as apathy, emotional instability, disinhibition and agitation further complicate rehab. Finally, although perception may be abnormal, and it can be pointed out to them (*e.g.*, '*this arm that you claim is not yours can be traced back to your body*), they are often unable to reconcile logic of the situation with abnormal perceptions. An example is given by Marsshall (2009), where a patient is described who reported that his hospital room was the “*only one to have telephones with 2 columns of numbers.*” On a line bisection task, a hemineglect patient may be trained to move the gaze leftward to identify a cue at the left extent of a line, confirming that the whole line is in view, and yet, that patient may still bisect the line to the right of midpoint as the gaze tracks rightward.

Hence, there is a **dissociation between perception and logic**. This was examplified by Ramachandran *et al*. (1999). They investigated twelve patients with left hemineglect caused by right hemisphere stroke by showing them a mirror. A mirror was placed on their right side (their 'good'side), while an object was held out for them on their left (their neglected side). The patients were made explicitly aware that the object was on their left and that the mirror was just a reflection of the object. And still, a substantial subset of patients (no numbers are provided in the article, unfortunately; it is a pilot-report) repeatedly reached for the object’s reflection on the right, even going so far as to say, “it’s behind the mirror.”

Thus, brain injury may result in more that just a hemi-inattention. Other cognitive deficits add to the complexity to the syndrome and pose challenges to devise effective rehab treatments (Marsshall, 2009).

<sub>**References**
**-** Kerkhoff, *Prog Neurobiol* (2001); **63**(1): 1–27
**-** Marshall, *The Neurologist* (2009); **15**(4): 185-92
**-** Ramachandran, *Med Hypotheses* (1999); **52**(4): 303-5</sub>

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Tags: neuroscience, vision, attention, neurology
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# Question
Title: What models/mechanisms exist for the brain to chain movements together?
Motor Sequence Learning is the study of the cognitive ability to chain various motor sequences together. The most intuitive example of this is learning to play a sequence of notes on a piano. Initially, each note will be played hesitantly while consulting the sheet music for guidance. However, with practice, more and more of the sequence becomes memorised and can be played smoothly. Additionally, sequences that are learned can be transferred to other contexts.

What is the most comprehensive model or description of neurophysiological mechanisms of this cognitive ability?

# Answer
> 2 votes
In the paper "Control of automated behavior: insights from the discrete sequence production task" a task similar to piano playing is discussed. The task, shown in the figure below, involves a user pressing a key corresponding to visual input.

One of the most interesting results from the paper is, as shown below, after learning, the response times of certain series of movements have lower reaction times. They also seem to be organised in specifically sized chunks.

The model of how this works is called the Dual Processor Model (DMP), which claims that two processors, one cognitive and one motor, race each other to execute a task. It is only described at a high level and never built into a model.

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Tags: learning, theoretical-neuroscience, computational-modeling, motor
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# Question
Title: Is "Biophysics of Computation" still a good book?
Currently I'm studying mathematics (2nd year) and I think I'm pretty into neuroscience. To "test" this, I purchased Principles of Computational Modelling in Neuroscience and am considering to get Biophysics of Computation: Information Processing in Single Neurons which seems to fit my interests fairly well, as I'd want to steer a middle course: Learn about the biological structure and manner of functioning of neural cells and thus be able to derive and develop models that do not only fulfill one special task (like most machine learning, ... now - an algorithm for face recognition will never challenge its own functioning), but rather resemble our brain.

As *Biophysics of Computation* was published in 1998, I wanted to know if it is still a good read, or already considered too outdated?

# Answer
> 1 votes
I've looked through that book briefly but never really got into it... if I could suggest some others, though: Dayan and Abbott's *Theoretical Neuroscience* is a standard text in computational neuroscience but if I understand your question correctly, you might enjoy Kevin Murphy's *Machine Learning: A Probabilistic Perspective*, or David MacKay's *Information theory, inference, and learning algorithms* a bit more. Trappenberg's *Fundamentals of computational neuroscience* is also one of my favourites, but moreso on the neuroscience side of things.

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Tags: reference-request, theoretical-neuroscience, computational-modeling
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# Question
Title: What is the difference between 'stereoscopic depth' and 'crossed/uncrossed disparity'?
What is the difference between *stereoscopic depth* and *crossed/uncrossed disparity*, and specifically in terms of their use in the methods to manipulate visual stimuli to investigate depth-perception?

# Answer
**Short answer**
Stereoscopic vision is the perception of depth via disparity. Disparity is the mechanism that the visual system uses to create binocular depth perception.

**Background**
A dictionary definition of Stereoscopic is the following:

> \[N\]oting or pertaining to three-dimensional vision or any of various processes and devices for giving the illusion of depth from two-dimensional images or reproductions, as of a photograph or motion picture.

So stereoscopic depth perception refers to the ability of perceiving depth in a 2D image.

A more visual-scientific description of *stereopsis* is the following (Kalloniatis & Luu, 2016):

> Stereopsis refers to our ability to appreciate depth, that is the ability to distinguish the relative distance of objects with an apparent physical displacement between the objects. \[...\] **Stereopsis** is an important **binocular cue** to depth perception. **Stereopsis cannot occur monocularly** and is due to **binocular retinal disparity** \[where\] two objects stimulate \[...\] disparate (**non-corresponding**) retinal points \[...\].

Monocular cues include occlusion, lights & shade, among others. Binocular cues, *i.e.*, stereoscopic cues are caused by the slightly offset retinal images on our two eyes due to the distance between them. This is called disparity. Disparity depends on the focal distance, and in a nutshell, uncrossed disparity refers to points in space closer than the focus distance and crossed disparity to points more distant than the focal distance (source: Heeger, New York University).

**Hence, long story short, stereoscopic depth is a perception, disparity is the mechanism that the visual system uses to create that perception.**

<sub>**Reference**
**-** Kalloniatis & Luu, Perception of Depth. In: The Organization of the Retina and Visual System, Utah University (2016)</sub>
> 2 votes

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Tags: neuroscience, perception, vision
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# Question
Title: What is the most unified functional model of the hippocampus?
There are many different incremental models of the hippocampus and it's role in learning as shown by a quick search. However, have there been any efforts to combine these various models into a single unified functional model?

# Answer
I myself have not come across a complete end-to-end hippocampal model, but I would imagine that such an implementation would be quite broad in scope. Edmund Rolls has some nice papers on the hippocampus, one of which is a particularly informative and recent review:

Kesner RP, and Rolls ET. A computational theory of hippocampal function, and tests of the theory: New developments. *Neuroscience and Biobehavioral Reviews* 48 (2015) 92-147 PDF here (Second page missing?)

I'll be very interested to read other answers to your question.
> 3 votes

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Tags: reference-request, theoretical-neuroscience, computational-modeling
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# Question
Title: What is a good example of a psychological theory that became formalized into neural and computational terms?
As far as I see it the goal of cognitive sciences is to find a description of mental processes in terms of neural computations that can be eventually formalized by a mathematical theory to generate accurate predictions. However, I was wondering whether we got to such a point in any area.

The first positive examples that came to my mind were vision and the Gestalt rules of perception or decision-making. But what about other processes?

# Answer
> 5 votes
Check out all of the videos in this playlist
https://www.youtube.com/watch?v=lrppe54fixc&list=PL1hKzFfV5qJlVTjD8XWzyiaHxBZZ7iWs9&index=3

The particular video I linked gives the example of the "Papez circuit". Other interviewees mention other examples as well.

# Answer
> 3 votes
I have one particular area to offer as a potential example. Keep in mind that likely no formalization of psychological concepts has heretofore been comprehensive (and the utility of a comprehensive "model" may be questionable, but I'll leave this for my more philosophical colleagues to consider).

## Reinforcement Learning

I am not a psychologist, but from what I can tell, both classical and instrumental conditioning are formalized in reinforcement learning. For instance, many but not all aspects of classical conditioning may be captured by models such as the Rescorla-Wagner rule. One of the most successful models of instrumental control has been the temporal-difference learning algorithm (Sutton & Barto 1998), which contributed significantly to our understanding of the computational function of mesencephalic dopaminergic neurons in several species (Schultz, Dayan, and Montague 1997; Schultz, 2015; Eschel et al 2015). The mathematical details will not be presented here since excellent treatments exist elsewhere (Sutton & Barto 1998; Dayan & Abbott, 2001). Briefly put, not only has the temporal difference learning rule mathematically formalized elements of psychological theories of behavioural control (mapping from behavioural to algorithmic level), but its critical element (the reward prediction error) has also been successfully mapped to neural substrates. (For many years, these neural substrates were independently thought to be involved in reward learning.)

### A note on further implications

I know you didn't ask directly about this, but I can't help myself :P

Of particular interest in recent years relates to the fact that instrumental control can be further subdivided into model-free (MF; aka "habitual") and model-based (MB; "goal-directed") systems (Dolan & Dayan, 2013), and that humans ostensibly use a combination of the two during sequential planning tasks (Daw et al. 2011). Probing the balance of MB/MF control in healthy controls and neuropsychiatric patients has suggested that deficits in goal-directed control may, in fact, be a cross-cutting neuropsychiatric symptom dimension spanning eating disorders, obsessive-compulsive disorder, and addiction (Gillan et al. 2016).

## References

1.Sutton & Barto. *Reinforcement Learning: An Introduction* (1998)
2. Schultz, W., Dayan, P., & Montague, P. R. (1997). A neural substrate of prediction and reward. *Science* (New York, N.Y.), 275(5306), 1593–1599.
3. Schultz, W. (2015). Neuronal Reward and Decision Signals: From Theories to Data. *Physiological Reviews*, 95(3), 853–951.
4. Eshel, N., Bukwich, M., Rao, V., Hemmelder, V., Tian, J., & Uchida, N. (2015). Arithmetic and local circuitry underlying dopamine prediction errors. *Nature*.
6. Dayan, P., & Abbott, L. F. (2001). Theoretical Neuroscience: Computational and Mathematical Modeling of Neural Systems. Computational and Mathematical Modeling of Neural Systems. Cambridge, Massachusetts: MIT Press.
6. Dolan, R. J., & Dayan, P. (2013). Goals and habits in the brain. *Neuron*, 80(2), 312–325.
7. Daw, N. D., Gershman, S. J., Seymour, B., Dayan, P., & Dolan, R. J. (2011). Model-based influences on humans’ choices and striatal prediction errors. *Neuron*, 69(6), 1204–1215.
8. Gillan, C. M., Kosinski, M., Whelan, R., Phelps, E. A., & Daw, N. D. (2016). Characterizing a psychiatric symptom dimension related to deficits in goal-directed control. *eLife*, 5, 1–24.
9. Voon, V. et al. (2014). Disorders of compulsivity: a common bias towards learning habits. *Molecular Psychiatry*, 20(October 2013), 1–8.
10. Voon, V. et al. (2015). Motivation and value influences in the relative balance of goal-directed and habitual behaviours in obsessive-compulsive disorder. *Translational Psychiatry*, 5(11), e670.

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Tags: theoretical-neuroscience, computational-modeling
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# Question
Title: The art of exploiting people and taking advantage of them
As one ages he/she will definitely encounter a lot of people who will do their best to make the most out of him/her.

Are there any books regarding this ??

# Answer
From a hackers perspective I would recommend to check out a term called "social engineering". This is all about manipulating people in order to get sensitive information.

A great book about this is called The Art of Human Hacking
> 1 votes

# Answer
Look for persuasion methods. Read any book written for sales people. They use these methods a lot. Every time when I came across a sales person I bring my shield up because I know for a fact that most of them are well trained in these methods. For them it is a way of living
> -1 votes

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Tags: cognitive-psychology, social-psychology
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# Question
Title: What is the concordance rate for schizophrenia in monozygotic and dizygotic twins?
What is general level of concordance for twins and is it higher for monozygotic twins? What research is available on this?

# Answer
> 2 votes
The Wikipedia article seems to provide a summary of this information with links to the primary literature

http://en.wikipedia.org/wiki/Causes\_of\_schizophrenia#Genetics

> Concordance rates between monozygotic twins vary in different studies, approximately 50%; whereas dizygotic twins was 17%. Some twin studies (Koskenvuo et al; Hoeffer et al) have found rates as low as 11.0%–13.8% among monozygotic twins, and 1.8%–4.1% among dizygotic twins, however.

### References

* Koskenvuo M, Langinvainio H, Kaprio J, Lönnqvist J, Tienari P; Langinvainio; Kaprio; Lönnqvist; Tienari (1984). "Psychiatric hospitalization in twins". Acta Genet Med Gemellol (Roma) 33 (2): 321–32. PMID 6540965.
* Hoeffer A, Pollin W; Pollin (November 1970). "Schizophrenia in the NAS-NRC panel of 15,909 veteran twin pairs". Arch Gen Psychiatry 23 (5): 469–77. doi:10.1001/archpsyc.1970.01750050085012. PMID 5478575.

# Answer
> 0 votes
You could check out the Meta-Analysis of Twin Correlations and Heritability (MATCH) website which is fully interactive and searchable.

The following image is a screenshot from their results on Schizophrenia, which shows that generally the concordance (here reported as correlation) of diagnosis between MZ twins is generally quite a bit higher than across DZ twins:

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Tags: abnormal-psychology, genetics, nature-nurture, twin-study
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# Question
Title: Does knowing a word for an emotion cause a person to feel the emotion more frequently?
I am aware of the Frequency Illusion which makes it more likely for us to notice a new word if we just heard about it recently, but I was wondering if this is true for emotions as well.

Logically, I assume it would be yes because you are more aware about your emotions and hence more likely to notice that you are experiencing the emotion. Have there been any conclusive studies done on this subject?

I don't know much about linguistics but if, say, a certain isolated tribe has not come up with a word for "happiness", would they ever feel happiness in the same way that we do, or feel it less frequently?

# Answer
> 2 votes
The answer would be no. To go along with the comments babies feel emotions however do not know words. As they grow adults help them organize their emotions for example a baby cries with frustration and anger because they may be hungry as you get older you have learned how to deal with that experience. As it is impossible to feel any emotion without having a thought first, emotions stem from what we are thinking which would be mostly concepts we don't think in random words. Therefore if we like to be happy we will think about things or do things that make us such. We are made to feel a wide range of emotions and they come and go. Knowing a word is not going to help someone know happiness better. Learning to control thoughts would be much more helpful. Just as a baby feels all emotions it does not yet understand them. What good would a huge vocabulary be if we could not put together concepts.

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Tags: emotion, language, bias, linguistics
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# Question
Title: How does the inner ear encode sound intensity?
Different areas of the inner ear (the cochlea) are sensitive to different acoustic frequencies. Hence, the cochlea basically performs a fast Fourier transform on the audio signal. This spectral information is subsequently sent to the auditory cortex. But **how does the cochlea encodes the intensity of an acoustic stimulus?**

# Answer
**Short answer**
Hair cells in the cochlea can code sound intensity via the amount of neurotransmitter they release. Higher sound levels result in more neurotransmitter release and in turn to higher firing rates in the spiral ganglion cells of the auditory nerve.

**Background**
Sound waves are picked up by the **mechanoreceptors** in the inner ear: the **hair cells**. Hair cells release the excitatory neurotransmitter glutamate. Dependent on the direction of the deflection of the hairs (stereocilia) on the hair cells, the hair cell releases more neurotransmitter (activation) or less (inhibition) than at its resting state (Fig. 1). The released glutamate activates the primary sensory neurons that connect to the hair cells, namely the **spiral ganglion cells** (SGCs). The axons of the SGCs combine to form the auditory nerve (Fuchs, 2005).

Fig. 1. Hair cells are activated when their stereocilia are bent in one direction (depolarization) or inhibited when the cilia bend to the other direction (hyperpolarization). source: Yanowski

The hair cell cilia contain mechanoreceptor proteins, that open or close, dependent on the direction in which the cilia bend (Fig. 2).

Fig. 2. Mechanoreceptors in the cochlear hair cell. source: Hudspeth (2014)

Because sound waves have sinusoidal shapes, hair cells undergo cycles of activation and inhibition, closely following the input waves. Louder stimuli cause the cilia to bend further. This causes larger responses in the hair cell and larger amounts of neurotransmitter to be released in the depolarizing phase of the auditory stimulus. This in turn leads to **higher spike rates** in the spiral ganglion cell axons (Fuchs, 2005). Spike rate in the spiral ganglion cells are thought to primarily encode sound intensity (Heil *et al.*, 2011)

A secondary mechanism of loudness coding *may* be related to the fact that increased sound levels activate a larger area in the cochlea, due to the low-frequency tail (Kiang & Moxon, 1974). Hence, more neurons start firing at higher sound levels when the tone frequency is the same. However, although it is a plausible mechanism, it is a secondary intensity code, if any.

**References**
**-** Fuchs, *J Physiol* (2005); **566**(1): 7–12
**-** Heil *et al.*, *J Neurosci* 2011; **31**(43): 15424-37
**-** Hudspeth, *Nature Rev Neurosci* (2014); **15**: 600–14
**-** Kiang & Moxon, *JASA* 1954; **55**(3): 620-30
> 7 votes

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Tags: neuroscience, perception, sensation, neurophysiology, hearing
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# Question
Title: How does the brain structure 3D visual data?
Adobe Illustrator has taken over five minutes (and counting) to render a vector 2D image rotated 18° in 3D on my computer. And yet, I and nearly anyone else can easily visualize the subject rotated almost instantaneously, and with little effort rotate the object continuously in real time in the mind's eye.

I'm not asking how the brain *stores* representations of objects, as that's clearly up for debate. But how does the brain *structure* its internal representation of 3D visual data?

It's almost definitely not in some pixel-based format, as can be shown by simply visualizing an object of some sort, and then zooming in mentally on some detail and noticing the image retains its sharpness. It's probably not breaking down objects into geometric shapes either, because at least I personally don't visualize my friends as stick figures. It could be a vector format, but then it should be easier to visualize complex shapes that are mathematically simple, like this one:

So it would seem that the brain uses some other format. To the best knowledge of modern cognitive, how does this work?

# Answer
This question cannot be answered in the form in which you asked it both because of the limits of current neuroscientific theories and methodologies when it comes to determining the structures of complex neural representations (although we have made headway in a few cases such as place cells and grid cells), and because neural representations are not really analogous to our colloquial concepts of simple mappings from numbers to images (ex. pixel, vector, wavelet, etc. bases for digital image representation).

I would encourage you to think, not only in terms of these representational formats privileged by Von Neumann style computer architectures (i.e. normal computers) with separate processing and digital memory systems, but in terms of a neural computer with distributed computation and memory. Neuroscientists typically think of neural representation in visual perception as occurring at a number of stages of increased abstraction. At the retina, the image is represented roughly in terms of what you might think of as pixels, but it is really just a set of photosensors and attached neurons that are activated due to light hitting the retina in different places at different frequencies and amplitudes. In V1 or primary visual cortex, the representation is in terms of what can be thought of as "edge detectors." In V2, the cells are tuned for a variety of slightly more complex properties such as such as orientation, spatial frequency, color, and binocular disparity (an important piece of information for 3D perception.) As you go up through V3, V4, V5, and V6, the representations becomes more and more complex until they contain information about the structure of the underlying concept itself.

The 3-dimensionality does not come in until the visual information from both eyes is combined with top-down information about how things tend to be in the world (which comes from other senses and experiences as well) in order to infer the likely shape of the object. It is unclear whether there is any place in the brain where an image is represented explicitly as a 3D model of a visual object. More likely the raw perceptual data such as colors and patterns is represented in one area and is associated with the more object-centric structural representation in another area and this association causes the co-activation of all the neurons relevant to the perception of the object in it's three dimensional form. The information is neither represented in one area of the brain nor in one scheme but is distributed across a large number of neurons with different degrees of activation.

We can also think of this in terms of the contemporary theory of enactive perception, which states that the brain represents information in terms of state-action-observation contingencies. In this theory, there is no "image" present at all, but only a set of neural activations which correlate with prior experience (where the correlations are stored in terms of associative links between neurons creating a causal activation path along which "information" travels) and relationships between potential actions (either low level motor actions of the retina or other muscles, or higher level actions such as taking a step forward) and their likely consequences (both low level perceptual consequences such as the expected changes in the sensory data when an action such as moving the head is taken and higher level perceptual and conceptual consequences such as a cup falling when you choose to open your hand and the associated experiences.) In this more comprehensive picture, visual information cannot be strictly separated from from conceptual and multi-sensory information and so three-dimensional visual information is represented both in terms of neural activations causally associated with the structure of the perceived object as well as the activations associated with all the other conceptual beliefs and perceptual expectations that relate.

If you want to read more, these sources should be a good start: distributed neural memory, distributed neural representation of a higher order process, perception as associations between actions and observations

There are also a few sources that offer direct experimental evidence towards your question, but do not provide as much of a conceptual introduction to neural computation and representation. See "Neural computations underlying depth perception", Binocular depth perception and the cerebral cortex as a start.

Your question also makes reference to rotating an object "in the mind's eye." There is also a very large body of research on this phenomenon, which is called "mental rotation." The wikipedia article is a good place to start but there is a lot more to say about this interesting phenomenon, so feel free to ask a related question if you are curious!
> 6 votes

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Tags: cognitive-neuroscience, vision, cognitive-modeling, visualization
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# Question
Title: Any link between IQ and a person's ability to create or mimic sounds?
Reading some articles about animals and speech, and it just brushes a bit of the neurology of it, but that got me curious:

Is there any link between a person's (or an animal's) mimicry skill and/or their ability to create complex noises just by manipulating their body to their overall intelligence?

**Note**, I'm not referring to "speech", ie. the actual comprehension and assignment of value to those noises; I'm just curious if the *ability* and/or the creativity of making and/or mimicking those noises has any correlation.

# Answer
> 2 votes
According to Howard Gardner and his theory of Multiple Intelligence, I can propose that there is no link between IQ and the ability to mimic sound.

The IQ test (originating in the work by Alfred Binet) is not a measure of intelligence pre-se, but rather a measure of the ability of the subject to comprehend in the manner expected. \[Look for Gardner's explanation of the Hammer, Screw Driver and Nail question.\] Gardner proposes that we have the ability to either master or lack in 7 different types of intelligence. (Not as in one stronger than the other, more like at different levels for each one.)

IQ measures some elements of linguistic, mathematical and spacial intelligence, but does not measure the others. According to Gardner, the musical intelligence is the ability to comprehend tones, and patterns in sound quicker than others. I thus propose that mimicking should have some direct correlation with Musical Intelligence, and since Musical Intelligence in not a measure in the IQ test there will be no link.

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Tags: cognitive-neuroscience, intelligence, hearing, evolutionary-psychology, auditory-discrimination
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title: Do women have fetishes?

text:
# Question
Title: Do women have fetishes?
As in title; is it possible/common for women to have fetishes?

It always seemed to me that fetishes are related to men only. Is it true?

# Answer
For a non-clinical sample in a study on paraphilic sexual interests, Dawson et al. (2016) report that

> Fisher’s exact test of proportions revealed that a significantly greater proportion of men reported arousal to activities related to voyeurism, fetishism, sadism, biastophilia, and urophilia compared with women (all ps \< .05). A greater proportion of men were also more likely to endorse items related to frotteurism, hebephilia, and pedophilia compared with women (all ps \> .05 and \< .10). Similar proportions of men and women reported being aroused by activities involving exhibitionism, scatologia, transvestic fetishism, masochism, scatophilia, and zoophilia (all ps \> .10). \[Absolute numbers are reported in table 4 on page 13 of the PDF.\]

*A fortiori* the answer is **yes**, women do »have fetishes«.

• Samantha J. Dawson/Brittany A. Bannerman/Martin L. Lalumière. 2016. Paraphilic Interests: An Examination of Sex Differences in a Nonclinical Sample. Sexual Abuse: A Journal of Research and Treatment 28(1), pp. 20–45.
> 10 votes

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Tags: developmental-psychology, sexuality
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title: Blocking out unwanted sound sources

text:
# Question
Title: Blocking out unwanted sound sources
Suppose you are in a room with two other persons, both of them talking. If you want to hear one of them, you are able to block out the other even though he is talking (although not very loud). How our brain does this as if the other person is not talking, even though the sound waves from both the persons are entering your ears?

# Answer
You're not really blocking them out. It's more that you're processing the language of the person you're focusing on.

You could do exactly what you describe at reasonably high volume levels.

Though the level is not equal for all people. Young children and people with attention difficulties Why it's Difficult to Listen to two People
> 2 votes

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Tags: hearing
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# Question
Title: What is the effectiveness of self-prescribed marijuana for depression?
How common is it for patients diagnosed with depression to self-prescribe themselves marijuana after trying prescription anti-depressants? Is there any evidence that this self-treatment is effective or satisfies some need that is not filled with typical prescription medication?

# Answer
> 4 votes
Question 1: I am unaware of any studies directly addressing the epidemiology of self-medication with cannabis in cases of treatment-resistant depression (it seems like that is what you are asking about). However, there are several lines of therapy that have demonstrated effectiveness in depression beyond the first line antidepressants (CANMAT Depression Guidelines). None of these include marijuana or cannabinoids.

Question 2: There is (to my knowledge) absolutely no evidence that marijuana is an effective treatment for depression. The article by Volkow et al. (2014) although titled "Adverse Effects," also reviews conditions for which evidence of effectiveness exists for *symptomatic* treatment with marijuana or cannabinoids. These conditions include glaucoma, nausea, AIDS-associated anorexia and wasting syndrome, chronic pain, inflammation, multiple sclerosis, and epilepsy (Volkow et al. 2014). That being said, the quality of that evidence is unclear to me.

It must also be mentioned that studies will generally be limited by heterogeneous cannabinoid content in the active compound. Not all cannabinoids are created equal, and from what I understand one of the potentially most medically useful cannabinoids is cannabidiol (CBD; Curran et al., 2016); THC and CBD may have opposing effects, with THC generally associated with *impairments* across several psychological functions (Curran et al. 2016). On the other hand, small studies have suggested a potential role for CBD (but **not** THC) in augmenting psychotherapeutic treatment of some anxiety disorders. The evidence thus far seems to suggest that marijuana would not have a role in treatment of psychiatric disorders in general, let alone depression, but that further research about the effects of isolated CBD might be warranted.

## Reference

1. Volkow, N. D., et al. (2014). Adverse Health Effects of Marijuana Use. *New England Journal of Medicine*, 370(23), 2219–2227.
2. Curran, H. V, Freeman, T, P., Mokrysz, C., Lewis D, A., Morgan, C, J, A., & Parsons, L. H. (2016). Keep off the grass? Cannabis, cognition and addiction. *Nature Reviews Neuroscience*, 17(5), 293–306.
3. Baldwin, D. S., Anderson, I. M., Nutt, D. J., Allgulander, C., Bandelow, B., den Boer, J. a, … Wittchen, H.-U. (2014). Evidence-based pharmacological treatment of anxiety disorders, post-traumatic stress disorder and obsessive-compulsive disorder: a revision of the 2005 guidelines from the British Association for Psychopharmacology. Journal of Psychopharmacology (Oxford, England), 28, 403–39.

# Answer
> 1 votes
I've had several patients who asserted that marijuana use improves their anxiety or depressive symptoms. Some report an increase in motivation. I'm not aware of any evidence that cannabis is safe and effective for depression, but I wouldn't rule out the possibility that some subset of patients might benefit from it's use.

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Tags: abnormal-psychology, clinical-psychology, psychopharmacology
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# Question
Title: Severe depression/anxiety can't be treated with CBT
Is there any evidence that supports the idea that a severe depression/anxiety can't be treated with CBT?

Since, it's in severe state, and one has to use anti-depressants to lower the level, and then obviously CBT can help reduce a moderate to low level depression. Is a severe depression/anxiety too strong to be healed by CBT, and it makes the usage of anti-depressants necessary?

# Answer
Yes, that is the consensus view among psychiatrists and clinical psychologists (*e.g.*, Parker *et al*., 2012). A commonly referenced authoritative guideline for treatment of major depressive disorder is the NICE guide.

**Reference**
Parker *et al*., *Acta Psychiatr Scand* (2013); **128**(4): 271-81
> 4 votes

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Tags: cognitive-psychology, depression, anxiety
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# Question
Title: Does the meta-analytic literature overestimate the relationship between conscientiousness and job performance?
There are quite a few meta-analyses of the relationship between personality and job performance (for a review, see Barrick & Mount, 2012; and specific meta-analyses: Barrick & Mount, 1991; Murray R Barrick, Michael K Mount, & Timothy A Judge, 2001; Hurtz & Donovan, 2000; J. Salgado, 1997; Tett, Jackson, & Rothstein, 1991).

These often come up with raw meta-analytic mean correlations between conscientiousness and job performance of around r = .15.

However, there is a lot of discussion in general at the moment about replicability and publication bias. In particular, if papers that showed a correlation between personality and job performance, were more likely to be published, then this would inflate the meta-analytic estimate.

Alternatively, there have been quite a few studies of personality and performance with huge sample sizes (10,000+) and these would quite likely be published regardless of the exact results, and they also would have sufficient statistical power to detect even small effects. And for most meta-analyses, large sample size studies get a greater weighting in the estimation process.

I seem to remember reading a paper a few months back that examined this question. If I recall, the authors concluded that the meta-analytic estimate of relationship between conscientiousness and performance might be inflated slightly. However, I can't remember what was the reference.

### Questions

* What research has been conducted on publication bias or other factors that might influence the accuracy of the meta-analytic estimate of the relationship between personality (and conscientiousness specifically) and job performance?
* What is the evidence for and against this?

# Answer
I'm posting a summary here (thanks to @DJ Sims for directing me to the paper of interest). Kepes and McDaniel (2015) re-analysed data from an existing meta-analysis. The existing meta-analysis had been examining various moderators of the relationship between big 5 personality and job performance. Kepes and McDaniel performed a range of sensitivity analyses.

They summarise their results as follows:

> Publication bias analyses demonstrated that the validity of conscientiousness is moderately overestimated (by around 30%; a correlation difference of about .06). The misestimation of the validity appears to be due primarily to suppression of small effects sizes in the journal literature.

As evidence for publication bias, they show that the average validity for conscientiousness is lower in unpublished samples:

> The results for the sub-group distributions of samples from journal articles (k = 67) and non-journal sources (k = 46) \[indicate that\] samples published in journal articles reported larger average effect size estimates ( $\bar{r}\_{oRE}$ = .19) than samples from non-journal sources ( $\bar{r}\_{oRE}$ = .12.

### A few critical comments:

When publishing results showing the relationship between big 5 personality and performance, there are five correlations presented. Assuming that publication bias sometimes led to a requirement to have at least one significant correlation, then the publication bias should be less.

The study does not cite or discuss other common meta-analyses on the Big 5 and job performance, which interestingly have often obtained meta-analytic estimates similar to what they say is the correct value. For example, the famous early meta-analysis by Barrick & Mount (1991) using 12,893 cases and 92 correlations obtained a mean raw correlation between conscientiousness and job proficiency of $\bar{r}$ = .13. In a meta-analysis by Hurtz and Donovan that exclusively used correlations for measures using the big 5, they obtained an overall validity for conscientiousness of $\bar{r}$ = .14. This also is very close to what might be expected.

These traditional estimates of validity from previous meta-analyses are sample weighted means. Thus, they naturally weight large samples more. So, for example, one study with 2000 participants would be weighted as much as 20 studies each with 100 participants.

There are good reasons to assume that publication bias would have less of an effect on large sample studies (e.g., n \> 1000). First, when the sample size is sufficiently large, the results become intrinsically interesting. Reviewers can not argue that it was merely a lack of statistical power. Second, such studies generally have sufficient power to detect correlations in the r = .10 area. For example, assuming a population correlation .10, alpha of .05, and a two-tailed test, to have at least 90% power to detect a significant correlation you would need at least 1,046 participants.

My take away from the paper:

* There is probably publication bias in the literature in relation to small sample studies. I imagine this publication bias is relative. If I were to guess, I'd say strong bias at n \< 100; moderate bias n \< 200, and progressively less as you move to 500+.

### References
> 2 votes

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Tags: personality, performance, io-psychology, selection-recruitment
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# Question
Title: How to compare IAT (Implicit Association Test) results of two different groups?
I already have the recommended algorithm to analyse IAT data. It allows to compare within-subject differences in response latency in the congruent versus non-congruent condition. However, in addition to analyzing the within-subject differences, I also need to know if the differences between two groups are statistically significant. How should I go about it?

# Answer
I assume IAT gives you a score for each person.

I imagine you could just do an independent groups t-test to assess whether the means of the two groups significantly differ.
> 1 votes

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Tags: statistics, data
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title: How to use EEG on dogs?

text:
# Question
Title: How to use EEG on dogs?
I need to take EEG readings on dogs for BCI and seizure prediction research. To do so do I need special equipment?

Is there an accepted approach in terms of frequency, electrode size and placement, etc?

# Answer
After a quick google search I (surprisingly) found that it already has an application: the No More Woof headset.

I believe the most important part is that you have a headset that fits and does not move when a dog walks or turns his head. Then it does not matter that much where and how the electrodes are oriented. The only thing you need to do is map the locations of the available electrodes to correct brain-regions of a dog. For human studies there are many different layouts of EEG caps (FieldTrip), which is fine, because they have such a clear mapping to brain areas.

How a dog's brain looks like and what frequencies can be expected I do not know, however. Perhaps you can follow up on the "No More Woof" to see what references they used to base their approach on.
> 2 votes

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Tags: eeg, animal-cognition
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# Question
Title: Does a mental disorder exist where people think someone else is sick?
Is there a known disorder where the subject thinks someone *else* or other people around them are sick or dying, say exo-hypochondria?

In this case I am thinking of a wife pathologically convinced that her husband is dying or seriously ill of some unspecified condition and that he knows this and is deliberately concealing it from her.

# Answer
There is a condition called ***hypochondriases by proxy*** (*e.g.*, Moreira & Moreira, 1999). It is also referred to as vulnerable child syndrome (Pacurar *et al*., 2015). The parent, particularly if (s)he is inexperienced or unsupported, might see symptoms and illness in a child where in fact there are none. For instance, the parent might be convinced that a common cold is a respiratory infection, or that a simple headache is a brain tumor. In such a scenario, the parent might exaggerate the child's symptoms in order to get the physician to take her fears seriously. This would then be akin to a "cry for help" rather than an intentional desire to malinger (Mart, 1999).

Hypochondriases by proxy is reported to be related to Munchausen syndrome and Munchausen by proxy syndrome, which belong belong to a group of diseases called factitious disorders. In these disorders, a healthy person feigns to suffer from disease, illness, or psychological issues to draw attention or sympathy, or they can project a disease or illness upon to another person, asking or requiring medical intervention for them, respectively (Pacurar *et al*., 2015).

<sub>**References**
**-** Mart, Am J Forensic Psychol (1999); **17**(1): 69
**-** Moreira & Moreira, *J Pediatr (Rio J)* (1999); **75**(5): 373-6
**-** Pacurar, *Romanian J Pediatrics* (2015); **LXIV**(3): 252-8</sub>
> 7 votes

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Tags: abnormal-psychology
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# Question
Title: Are animal instincts and preferences based on some brain micro structures?
I'm thinking about the mechanism by which an animal has built in preferences for some visual objects in the real world. The most well known example is the seagull chicks and pecking at a red dot or stripe:

I can think of other examples that expose preferences:

* Human male preference for nubile females
* Human baby preference for human face over a rock
* Human observers being able to predict election results based solely on photos of candidates

It seems that in each case there's some very rapid analysis of visual features taking place, and in case of newborn babies, there's not enough time to be "taught" to perceive something specific. This makes me ask:

**Are there any structures (adaptations) within the human brain which are responsible for our built in instincts and preferences?**

# Answer
There is the structure called the Fusiform-face area (FFA), which is located in the low tempero-parietal region. In human studies, the FFA has shown to highlight strongly when you look at a human face, as opposed to any other (inanimate) object. This is what the region got its name from.

However, it is believed that the FFA is not necessarily a face area (See "Function and Controversy" on the Wiki page). Instead, researchers argue that the area is a visual expertise area. Where we, as humans, are experts in recognizing faces, zebras, for instance, are incredibly good at distinguishing the stripes of other zebras.

This even goes for within-species differences. Western people that have never worked with Chinese symbols will show little to no activation in the FFA, whereas Chinese people that use it daily will show this activation. This would also explain cross-race recognition (thanks Josh) i.e. it is easier to distinguish people from the same race then someone from different races.

With regard to your question about preferences: I don't know for sure. I have heard that people like what they know. That would imply that whatever the FFA is expert in, is more preferable to the person/animal. I have no reference, so if anyone does have some, I welcome you to edit my answer or post your own.
> 2 votes

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Tags: social-psychology, perception, perceptual-learning, preferences
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# Question
Title: Is prior experience necessary to perceive the Kanizsa triangle illusion?
We know the Kanizsa Triangle.

Kanizsa Triangle

I was socialized in a "western" world, where I learned mathematics for about 13 years; I have designed products surrounding me using geometric forms and so forth.

**I wonder if somebody would see the triangle who never or rarely saw a triangle before?**

# Answer
> 4 votes
It's a difficult question to answer. My educated guess is that the appearance of the triangle, and **illusionary contours** in general, would persist, even in individuals who have never seen a triangle before in their lives. I *think* they would perceive the illusionary contours, but it might just not make sense to them, as the shapes may be unfamilair to them. In other words, they would not **associate** the form with something meaningful. The reason why I *expect* previous experience with geometrical shapes is unimportant for illusiuonary contours to be perceived is two-fold:

1. Illusionary contours are generated in the secondary visual cortex (V2), which is a low-level part of the visual system. It performs relatively simple processing such as the coding of orientations, contours and the perception of background and foreground (Anzai *et al*., 2007). Such **low-level processing** is, expectedly, **largely innate**.
2. The neural representations of illusionary contours have been shown in a variety of species. Admittedly, most electrophysiological evidence comes from primates (*e.g.*, Heydt, 1984), but **illusionary contours have even been shown to be recognized by cuttlefish** (Zylinsk *et al*., 2012). Hence, given the fact that relatively uncomplicated species like cuttlefish are able to successfully perceive illusionary contours, I doubt that prior experience in the geometry of the illusionary contour is a critical factor in perceiving it.

**References**
**-** Anzal *et al*., *Nature Neurosci* (2007); **10**: 1313 - 21
**-** Heydt, *Science* (1984); **224**(4654): 1260-2
**-** Zylinsk *et al*., *Proc Biol Sci* (2012); **279**(1737): 2386–90

# Answer
> 3 votes
**First**, in the context of your reference to cultural context, one aspect of your question appears to be whether or not a person who has never had experiences of triangles before can have a triangle experience. **Second**, it is of interest whether that experience can be brought about by a configuration of shapes which is considered appropriate to elicit the perception of illusory contour.

**As to the second question**, you seem readily inclined to take the view that someone who has previously seen triangles, knows what triangles are, and can also verbally express that experience (»I'm seeing *a triangle*!«), can indeed have a triangle experience when looking at the Kanizsa figure. (This is not to be taken for granted. Taking a gestaltist view however will grant that perception at least some kind of actual reality. Consider the question whether you see a second triangle constituted by black lines *behind* the ›illusory‹ one.)

Now, if we are willing to allow this, then we can actually **reduce the whole question to the first part**. A common psychological stance on perception, taking input from philosophy of mind, assumes a perceptual episode to be constituted by an object providing stimulation to the senses, leading to a ›perception‹ that is not conscious, which is then somehow translated into a conscious perception that corresponds to a phenomenon, which again is fully *recognized* in the sense of a perceptual judgement. Here, of particular interest is the difference between perceptual experience and perceptual judgement (you might also ask yourself whether a cat can see a triangle):

> \[W\]e must be careful to distinguish such a perceptual judgement from a perceptual experience. A person may have a perceptual experience of seeing a table to be rectangular without necessarily being willing, or even able, to form the perceptual judgement that he sees that a certain table is rectangular. \[…\] \[T\]he person may be *unable* to form the perceptual judgement in question because he lacks the requisite concepts. Thus, for example, one might be prepared to attribute a young child a perceptual experience of seeing a table to be rectangular and yet doubt whether the child is capable of forming the perceptual judgement that *it sees that* a certain table is rectangular \[…\]. (Lowe 2000, pp. 132–133)

**Summing it up**, the answer is **yes, that person could justifiably be said to see a triangle**, however, depending on particulars of the question, the answer might differ.

**Taking a different approach**, we can take the question to mean: **Given which previous experience are we capable to perceive illusory contour?**, and there is evidence that the visual system's capability to recognize simple shapes is largely innate (notwithstanding the fact that lack of any visual input will prevent vision to develop in the first place). See Christiaans answer for some more detail. A particularly interesting question in this context, which relates to the difference between perceptual experience and perceptual judgement discussed above, is **at what age is a person capable of perceiving illusory countours?** In this regard, Ghim (1990) concludes that »infants as young as 3 months of age are able to perceive subjective contours«, and in a related study, Curran et al. (1999) conclude that »by 2 months of age, the infant's visual system contains the nonlinear mechanisms necessary to extract an illusory contour from aligned terminators«.

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References:

* W Curran, OJ Braddick, J Atkinson, J Wattam-Bell, R Andrew. 1999. Development of illusory-contour perception in infants. *Perception*, Vol. 28, pp. 527–538.
* H-R Ghim. 1990. Evidence for perceptual organization in infants: Perception of subjective contours by young infants. *Infant Behavior and Development* 13(2), pp. 221–248.
* EJ Lowe. 2000. *An Introduction to the Philosophy of Mind*. Cambridge University Press.

# Answer
> 1 votes
I think that illusory contours could be experienced independently of cultural influence: a person would see a figure but she would not know it is a "triangle". The reason is that illusory contours as the ones you see in the figure share many of their properties with illusory phenomena that could be obtained with simple alignments of image features. As such, the illusion of a contour can be obtained also with overall irregular shape, although the regularity of the figure could facilitate the occurrence. There are several examples of irregular figures with illusory contours. See for the phenomenon of neon color spreading. Displays in this case easily allow more complex patterns, see for example:http://www.blelb.ch/oldblelbsite/english/blelbspots/spot05/expspot05\_en.htm

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Tags: perception, vision, philosophy-of-mind, gestalt-psychology
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# Question
Title: is Lewin's field theory still used in modern psychology? If yes, what are its applications?
I recently stumbled upon Kurt Lewin's field theory. However, not being very familiar with gestalt psychology, I could not assess whether Lewin's theoretical framework is still used today and if yes, what its applications are.

In other words: Is it still a recognised psychological theory? If yes, what are its application in psychological research and applied psychology? If no: Is it because Lewin's ideas have been proven wrong, because they've been forgotten or because they were never actually accepted within psychology?

# Answer
I've come across Lewin's theory of organisational change a lot. It is often presented in introductory courses on organisational behavior, I/O psychology, and organisational change. It is a three stage theory that talks about unfreezing, making a change, and refreezing.
> 1 votes

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Tags: social-psychology, gestalt-psychology
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# Question
Title: Do dissatisfaction with a job and relationships share the same mental mechanism?
The modern world has two new ways of finding abundance of employment and relationships:

* Job boards, career sites and recruiters for finding jobs
* Online dating sites for finding dates

While seemingly different, they share a couple similarities ~ 20% top performers and 20% top attractive people have really easy time finding the next job or romantic partner.

For **example**, a talented engineer working at Apple may have 50 recruiters knocking on his door, trying to "poach" him to the next hottest job or startup. An attractive woman on Tinder would match with just about any guy she wants and be swamped with messages from guys. **Both of these people can find a great (but not perfect) job or a partner easily**

From what I've been reading and observing, the ease with which the needs for job/partner can be fulfilled by top percentile of people makes these people devalue the experience. The good things are overlooked once negatives start to show up. This can make a person experience rapid build up of dissatisfaction with the current situation and want to "trade up".

This makes me ask: **Are the experiences of dissatisfaction with job and relationships, as experienced by people who "have it easy" related?** Do they use the same mental mechanism?

In a sense, this question is a continuation of this one: How long can a person stay happy, excited and motivated about something new? I'm asking if there's a universal mechanism by which a person starts to seek "something better"

# Answer
> 3 votes
In general, personality traits correlate with most measures of satisfaction. Most notably, there is a large literature showing that personality correlates with life satisfaction (see Steel et al). In general, neuroticism is the biggest correlate followed by extraversion and conscientiousness.

The following table from Grant et al summarises two major meta-analyses on the correlation between big 5 personality and various measures of well-being including life satisfaction:

From a theoretical perspective, personality represents an interpretative lens through which people experience the world. Some people are generally more positive or more negative. Some people focus on problems, others focus on what they have. Of course, eve

### Personality and Job Satisfaction

I've seen similar correlations looking at personality and job satisfaction (see Judge et al), although in general these correlations are smaller than for life satisfaction. This may reflect the greater role of context. Here is the table of meta-analytic correlations from Judge et al between big 5 personality and job satisfaction.

### Personality and Relationship Satisfaction

Here is the meta-analytic estimate of the correlation between personality and intimate partner relationship satisfaction from Malouff et al (2008).

### General Comments

In general, the two tables above look somewhat similar to each other. Neuroticism correlations are the largest in both (r = -.22, r = -24). However, extraversion and conscientiousness may be slightly more relevant to job satisfaction.

### References

* Grant, S., Langan-Fox, J., & Anglim, J. (2009). The big five traits as predictors of subjective and psychological well-being 1.Psychological reports, 105(1), 205-231.
* Judge, T. A., Heller, D., & Mount, M. K. (2002). Five-factor model of personality and job satisfaction: a meta-analysis. Journal of applied psychology, 87(3), 530.
* Steel, P., Schmidt, J., & Shultz, J. (2008). Refining the relationship between personality and subjective well-being. Psychological bulletin, 134(1), 138.
* Malouff, J. M., Thorsteinsson, E. B., Schutte, N. S., Bhullar, N., & Rooke, S. E. (2010). The five-factor model of personality and relationship satisfaction of intimate partners: A meta-analysis. Journal of Research in Personality, 44(1), 124-127.

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Tags: cognitive-psychology, emotion, motivation, behavioral-economics
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title: How do we hear our inner voice?

text:
# Question
Title: How do we hear our inner voice?
How do we perceive inner speech? Does it follow the same neural pathways as normal acoustic speech? If yes, what is the extent of overlap between the two neural pathways?

# Answer
No, inner speech does not follow the same neural pathway as speech coming in from outside.

Rather, inner speech uses the same neural mechanism as outer speech - that is, speech going out. The neural mechanisms of inner speech can be studied using recently developed technologies such as fMRI imaging of subjects instructed to or prevented from engaging in self-reflection and internal monologue. Such studies suggest that inner speech is primarily localized to Broca's area (LIFG, on the left side of the brain), just as is outer speech (McGuire, 1996; Morin & Hamper, 2012). These findings are consistent with other evidence that inner speech is a form of silent (simulated) outer speech, and thus uses the same physical mechanism. This is based on private speech theories originating in the 1920s and 30s by Jean Piaget and Lev Vygotsky, that inner speech is actually outer speech that children learn to internalize.

However, if inner speech uses the same mechanism as outer speech rather than the incoming auditory system, then how is it that we "hear" it? One proposal is based on the attenuation mechanism involved in normal speech production. This mechanism filters self-generated sounds from other sounds. It is believed to work analogously to noise cancellation technologies - by predicting self-generated sound and modulating audio processing accordingly. Experiments by Scott (2013) and Scott et al (2013) demonstrate that this attenuation is also active in inner speech, and suggests that perhaps what we "hear" is the prediction of our own voice by this system.

Another approach by Alderson-Day et al (2016) distinguishes between multiple kinds of inner speech - monologic inner speech of the type traditionally studied as above, and dialogic inner speech that adds a second voice (an interlocutor). Brain scans of subjects engaging in dialogic inner speech show additional activity in areas associated with auditory hallucinations, and may therefore be "heard" in a similar way. This is still a very active area of research, so stay tuned!
> 12 votes

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Tags: perception, cognitive-neuroscience, hearing, speech
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# Question
Title: Do many people have an "Accompanying Voice" - an equal they converse with?
A hypnosis professional told me this is true, so I am asking: is it a fact of psychology that many people have a voice that they talk with "in their head" which talks back to them and helps solve problems? I find that this voice often has a perspective I never had and presents ideas I had not thought of. But it does not just tell me what to do. When I really get in a fix, it backs off and lets me solve the problem "by myself". I am about 50 and it has been there as far back as I can recall.

**Is it common to have an "Accompanying Voice" and conversations where both voices appear to have equal standing and independence?** Is there research which shows this is something other than a hallucination? (After all, an internal monologue is not a hallucination. Why not have two voices in your mind?) The prevailing idea is that voices are hallucinations, but it seems that they could just be parts of the self. This is a cornerstone of Transpersonal Psychology, which uses a dialog method to help people improve self-awareness and solve inner issues.

**Addition:** Here is some info from a site about this topic, although it does not address my question directly:

> Because of prevailing attitudes psychiatry and within society as a whole, it is important to point out, that there are many people who hear voices who can cope with their voices and regard them as a positive part of their lives. Neither is it the case that voices have always been regarded as a negative experience, throughout history and even today there are people who hear voices who find their voices inspirational and comforting.
>
> These are facts, that on the face of it are hard to square with the negative way that the experience is regarded by psychiatry.

**More Addition:** Here is a bit about the Voice Dialog technique used in Transpersonal Psychology:

> Voice Dialogue Technique
> The Voice Dialogue technique allows a client to gain a deeper sense of inner wisdom and gives them the opportunity to identify and examine the voices within. Being armed with this powerful knowledge provides a greater resource from which the client can draw upon when faced with difficult circumstances. The Voice Dialogue guides a client into realizing that there are parts of their inner being that propel them, but they are separate from those parts. They begin to understand that they are made up of many parts and each serves a function and has an energy force that sustains it. With this awareness, a client is able to create a balance among all of his corresponding and correlating parts and can determine which ones to silence and which ones to accentuate.
>
> The "Aware Ego" in Voice Dialogue
> In Voice Dialogue, this heightened sense of awareness is referred to as the "aware ego." An aware ego is not a trait that one possesses, rather it is a process by which we begin to know all of the layers of our consciousness on an intimate level. Because there is an negative for every positive, the aware ego assumes that you can experience both the beneficial part of your consciousness and its opposite. With enough insight into your own identity, you can choose freely which one will serve you better, and can adjust, alter, and align the parts within to meet your goals for healing.

To me, this is about using a process which gets underneath assumptions, especially unconscious ones. The biggest assumption is that we are one singular thing that is consistent and understandable. Not So. But we can become master of ourselves.

# Answer
> 1 votes
Most people (including myself) do not hear or speak with inner voices, but it is not unheard of, see Hearing Voices Network.

Ego State theory is a theory of multiple personality facets (ego states). In their book "Ego States: Theory and Therapy", John G. and Helen H. Watkins transcribe several hypnosis sessions, where they communicate with different ego states of a person. Ego States are often mentioned in the context of trauma or multiple personalities, but they also exist in the average person.

I think that extreme cases help to understand normal phenomena, so I'd also recommend "The Flock" by Joan Frances Casey, a journey from multiple personalities that do not know of each other to working together to one integrated personality.

# Answer
> 5 votes
From a quick search online I see no reason why you distantiate what you describe from auditory hallucinations:

> a form of hallucination that involves perceiving sounds without auditory stimulus.

Given the article you link to, which arguably *does* address your question (yes, some people report experiencing this), you mainly seem to be concerned that this would unequivocally be considered a mental illness. Your actual question thus seems to be "**Is hearing multiple voices always considered a mental illness?**".

Judging from the Wikipedia article (and its subheading 'Non-disease associated causes') this is seemingly not the case.

> However, individuals may hear voices without suffering from diagnosable mental illness. (Thompson, 2006)

The article by Thompson mentions a study for which unfortunately no source is provided, thus I would take the following with a grain of salt:

> But studies by Dutch researchers that began in the 1990s found that some healthy people also regularly hear voices. ... Many of the people who contacted them did not find the voices disruptive and had never felt the need to consult mental health services. ... The resulting studies found that more people might hear voices than psychologists had thought, perhaps around 4 percent of the population.

It might, however, set you on the right path to finding the actual studies, or more recent work in regards to how many people report hearing voices not attributed to the self without considering them a mental illness.

<sub> Thompson, Andrea (September 15, 2006). "Hearing Voices: Some People Like It". LiveScience.com. </sub>

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Tags: consciousness, hallucinations, thought
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title: An Overview of Priming in Psychology

text:
# Question
Title: An Overview of Priming in Psychology
I am looking for a comprehensive overview of priming literature in psychology and cognitive science. A survey article or a book would be a great start. More specifically, I am interested to learn about different types of priming, stimuli, and applications in which priming is used, in addition to some common methodological practices in this field. Any help would be greatly appreciated.

**Update for those who think this question is not specific enough:** Which book do you recommend to a person interested in learning about priming in depth?

# Answer
> 2 votes
This should be rather easy to find on google scholar, especially with the recent replicability crisis in social psychology. In particular, Bargh and Cesario has a few things to say in 'defense' of priming.

You can start with Bargh's article, which is a response to this article by Bower.

Cesario's article is here, and for an overview of the whole issue surrounding priming and replicability, you can try Pashler and Wagenmaker's article.

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Tags: cognitive-psychology, social-psychology, behavioral-economics, priming
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