# Question
Title: Why does sensory deprivation cause hallucinations?
John C. Lilly performed the seminal experiment about sensory deprivation. The author isolated people in a sensory deprivation tank and they reported having experienced hallucinations.

Richard Feyman reported about his own experiences with isolation tanks in the collection of essays Surely You're Joking, Mr. Feynman!

I am curious about the reason of this effect. If we are deprived of our senses (being perfectly sane and without drugs), why do we start to hallucinate? What happens inside our brains?

# Answer
According to the article The Brain’s Voices: Comparing Nonclinical Auditory Hallucinations and Imagery (Linden et al. 2011):

> Spontaneous activation of sensory areas (Hunter et al. 2006) has been described in cases of sensory deprivation or during epileptic seizures. Local spontaneous activity may underlie certain types of hallucinations, for example, visual hallucinations of Charles Bonnet syndrome (Ffytche 2005) and possibly imagery of music without lyrics (Kraemer et al. 2005).

An example, from Neural activity in speech-sensitive auditory cortex during silence (Hunter et al. 2006) states that the auditory cortex has a propensity to spontaneously “activate” during silence. Specifically, from their study

> suggest that, within auditory regions, endogenous activity is modulated by anterior cingulate cortex, resulting in spontaneous activation during silence. Hence, an aspect of the brain's “default mode” resembles a (preprepared) substrate for the development of auditory hallucinations. These observations may help explain why such hallucinations are ubiquitous.

In the article Visual hallucinations in psychologically normal people: Charles Bonnet syndrome (Teunisse et al. 1996), states that this syndrome, where healthy people can experience visual hallucinations undergoing sensor deprivation, is more common than first realised, their study suggests that under conditions of sensory-deprivation, the slightest amount of arousal triggered the hallucinations.

This is discussed further in Spontaneous and driven cortical activity: implications for computation (Ringach, 2009), where their study suggests

> the lack of a stimulus generates a weak feedforward drive and the cortical state is determined largely by its own intrinsic dynamics and top-down expectations. This explains why spontaneous activity is not noise. Further, if the attractor has been shaped (via evolution or developmental rules) to represent the manifold of natural signals, it is easy to see how sensory deprivation or weak input can lead to “hallucinations” during deprivation

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Additional references:

Ffytche D, Visual hallucinations and the Charles Bonnet syndrome. Curr Psychiatry Rep 2005;7:168-179.

Kraemer D, Macrae C, Green A, Kelley W . Musical imagery: sound of silence activates auditory cortex. Nature 2005;434:158.
> 9 votes

# Answer
first, i commend you on your reading choice.

> **Did you know? Fun John Lilly Factoid**
>
> Despite identifying as a male, later in life Dr Lilly elected to have breast implants. Those who knew him would later note that his breasts appeared to be rotting off. Oh, that's John for ya!

for many years john lilly was my intellectual hero and i spent a lot of time pursuing his work.

i recommend you read the following, both by lilly:

the human biocomputer - really hard to follow, but it goes into the theoretical approach he took in investigating sensory deprivation

the scientist: a metaphysical autobiography - a much lighter read. very interesting things about his experiences, particularly with ketamine.

> I am curious about the reason of this effect. If we are deprived of our senses (being perfectly sane and without drugs), why do we start to hallucinate? What happens inside our brains?

now, onto sensory deprivation. being such a self-indulgent wanker, i've told enough people about sensory deprivation to write it from memory. unfortunately, i have no references for you:

**Background**

At the time, there was a Freudian theory that sleep is a form of unconsciousness that is instantiated once sensory input is withdrawal from the body. To test the theory, Lilly decided to construct an enclosure that attenuated all input as maximally possible.

**Sensory deprivation protocol**

Lilly though about this matter systemically and proceeded in a perfectly logical manner. Let's go through them one by one as it's a good way to appreciate that his goal attenuate sensory input as maximally as possible without causing any organic damage to his body. Here are the pertinent specifications:

*Sight.* The enclosure is completely lightproof.

*Smell.* Lilly was a smoker. First, smell would be detectable and be a distraction for him. However, after enough time passes e.g. 30 minutes, we tend to habituate to smells.

*Touch.* Conceptually, this is the most interesting. Lilly filled the enclosure up with water, then added a ridiculous amount of salt. At a density of 1.30 g/ml, the human body will float in the water as though it's weightless. Initially, salt water was used, but Lilly switched over to Epsom salts (MgSO4). A solution of Epsom salt is very silky on the skin and very therapeutic.

*Temperature.* Temperature is controlled with a thermostat set to 34.5 C. It was at this temperature that Lilly found that if he stayed still, he would perceive the water to be neither hot nor cold.

*Sound.* If sound is generated outside in the medium of air, then it needs to travel across the enclosure, into water before hitting the eardrums. Lilly found that if ge floated on the surface of the water, but with his eardrums just below the surface, the different mediums through which externally generated sound would have to travel would be dampened.

**Phenomenology of sensory deprivation**

I think that's it.

Now, when one enters the tank and starts floating in complete silence, the body will start to miss its normal sensory input. Just remember, your body is used to this. It's as though there is tonic firing of neurons at a particular regularity: your brain has constructed a map of what input it is meant to over the entirely of your life, but now that baseline input is gone.

Slowly, over time, your brain will start seeking sensory input. It will start by instantiating a behavioural response amenable to you giving it input e.g. you will feel like you want to move your hand somewhere, or maybe scratch yourself. Something. This is all occurring below our conscious awareness. You will probably catch yourself generating sensory input.

Now, if you stay still in the water, and your skin cannot detect either hot or cold, what happens is that the representation your brain makes of your body in space starts to lose sharpness. i.e. You will not know where your body ends, and where the water starts. In some sense, it's like when you use your smartphone and it asks you to calibrate the accelerator by rotating it and what have you. It needs to have a conception of gravity and acceleration in order for it to accurately construct a representation of your body.

Anyways: eventually, your brain finally has enough: if you aren't going to furnish it wish sensory input, then it'll make some on its own. And so, it will start generating int.

In short: you start hallucinating because your brain is used to a certain level of sensory input. In the absence of that bare minimum input from the sensory modalities, it will start generating whatever sensory input necessary, probably just so it can process it.

My impression is that if you research the phenomenon of seeing tracers when the lights are off, an account of the neurobiological substrate of this will be reminiscent of what the the brain experiences under conditions of sensory deprivation.

> **Did you know? Fun John Lilly Factoid**
>
> It was while he was floating that Dr Lilly came to formulate the belief that an extraterrestrial superconsciousness was communicating with him. During such communications, the beings instructed him to commence administering intramuscular injections of ketamine and await further instructions. So dedicated was he to honouring the wishes his guests that at his peak, he maintained a dosing schedule of 50 mg i.m. ketamine per hour, 20 hours a day, for three weeks. What selflesslessness!
> 0 votes

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Tags: hallucinations
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# Question
Title: Comprehensive list of cognitive techniques in CBT
I'm not a cognitive science student, but I'm interested in CBT (Cognitive Behavior Therapy) and I'm using it to overcome some of the problems I have.

However, I have difficulty in finding resources online for it. AMAIK CBT has a list of **cognitive errors**, which I prefer to call **dysfunctional mental sceneries**. You can simply Google for *common cognitive errors* and you end up with like 20 good results.

To overcome those errors, people are encouraged to use some techniques like **reality testing** for example. But I can't find a good comprehensive list of techniques used in CBT. Here are the links to sites I've found:

http://cognitivetechniques.com/what-is-cognitive-behavioral-therapy-cbt/ http://www.calmclinic.com/anxiety/treatment/cognitive-techniques http://brownbackmason.com/articles/5-common-techniques-of-the-cognitive-behavioral-therapist

However they barely provide more than 5 techniques. In comparison to the lists of cognitive errors, it seems that there are not enough cognitive techniques proposed by cognitive psychologists. I've heard somewhere that we have more than 100 cognitive techniques, and I can't find more than 5 on the Internet.

Is it that I've misunderstood *techniques* part of CBT? Or is it that techniques are not free to be published online? Can anyone clarify me here, or show me a comprehensive list of cognitive techniques?

# Answer
You might want to check out http://www.anxietyonline.org.au/. It's free for the eTherapy version and it's funded by the Australian federal government.

A colleague of mine gave a presentation and it looks really good. From the website:

> Anxiety Online is a comprehensive online mental health service offering information, assessment, online diagnosis and treatment programs ("eTherapy") for the anxiety disorders:-

Once you have gone through the fairly long diagnostic process, you get access to a range of eTherapy resources. In particular, you can use it to learn more about CBT. It has exercises and videos.
> 3 votes

# Answer
The issue is that there are many variations of cognitive behavioral therapy, and each variation has its own techniques (as well as some that overlap with other therapies). A lot of the time, when people are speaking about cognitive behavioral therapy, they are considering cognitive behavioral therapy as conceived by Aaron Beck. However, there have been many different "variations" of cognitive behavioral therapy, which some envision as having come in three waves. I wrote an article that I considered to be a good list of cognitive behavioral therapy techniques. However, I am now planning extensive revisions and possibly a couple of additional articles to clarify the following:

1. There are many variations of CBT (and I shall write an article explaining that and listing them)
2. In total, there are over 70 techniques of CBT when you consider all the different versions of it. I shall write an article listing them.
3. I will either rewrite or revise my current article to reflect that it mainly accounts for CBT as conceived by Aaron Beck.
> 3 votes

# Answer
Wikipedia has a long list.

1. Acceptance and Commitment Therapy is a "third wave" behavior therapy, developed by Stephen Hayes based on relational frame theory.
    2. Anxiety Management Training was developed by Suinn and Richardson (1971) for helping clients control their anxiety by the use of relaxation and other skills.
    3. Applied Behavioral Analysis, described by Baer, Wolf and Risley in 1968, is the science of applying experimentally derived principles of behavior to improve socially significant behavior.
    4. Behavioral activation is a behavioral approach to treating depression, developed by Neil Jacobson and others.
    5. Behavior modification is a term originally used by Edward Thorndike in 1911.
    6. Behavior therapy
    7. Cognitive therapy was developed by Aaron Beck\[3\]\[4\] and has become of the most studied psychosocial treatments.
    8. Cognitive analytic therapy
    9. Cognitive behavior modification
    10. Cognitive behavioral analysis system of psychotherapy
    11. Cognitive Emotional Behaviour Therapy
    12. Cognitive processing therapy for Post traumatic stress disorder
    13. Computerised Cognitive Behavioral Therapy
    14. Contingency Management
    15. Dialectical Behavior Therapy
    16. Demartini Method
    17. Direct therapeutic exposure
    18. Exposure and response prevention
    19. Functional Analytic Psychotherapy
    20. Interactive Cognitive Subsystems
    21. Mindfulness-based Cognitive Therapy
    22. Multimodal Therapy
    23. Problem-Solving Therapy
    24. Prolonged Exposure Therapy
    25. Rational Emotive Behavior Therapy, formerly called Rational Therapy and Rational Emotive Therapy,\[5\] was founded byAlbert Ellis and is "regarded by many as one of the premiere examples of the cognitive-behavioral approach"
    26. Reality Therapy
    27. Relapse Prevention
    28. Self Control Training.
    29. Self Instructional Training was developed by Donald Meichenbaum, influenced by the developmental psychology ofAlexander Luria and Lev Vygotsky, designed to treat the mediational deficiencies of impulsive children
    30. Self-talk Identification, Questioning & Revision (SIQR)
    31. Stress Inoculation Training
    32. Systematic desensitization is an anxiety reduction technique, developed by Joseph Wolpe.
    33. Systematic Rational Restructuring was an attempt by Marvin Goldfried to reanalyze systematic desensitization in terms of cognitive mediation and coping skills.

This book also seems like a good resource for learning more about techniques.
> 0 votes

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Tags: cognitive-psychology
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# Question
Title: Can a bipolar EEG signal be converted to a monopolar (unipolar) one?
I have bipolar EEG signal of Fpz-Cz of EEG sleep data which I have downloaded from physionet. I would like to have Fpz signal for my sleep study.

Is there any way I could convert a bipolar EEG signal to a monopolar (unipolar) EEG signal?

# Answer
> 1 votes
**Short answer**
As far as I can see - no you can't.

**Background**
In EEG systems, unipolar signals are measurements against a distant reference electrode, for example Fpz (Fig. 1). So suppose I have recorded *unipolar* EEG signals, say O1 and O2 against Fps, then I can obtain a bipolar measurement offline by subtracting O1-O2 (source: Biopac).

However, if you start with a bipolar measurement, *e.g.* O1-O2, then you can never reduce those recordings back to O1-Fpz and O2-Fpz as the O1 and O2 signals are independent of Fpz.

Further, 'the' Fpz signal is non-existant, as an electrophysiological potential (and in fact *any* potential), is a potential *difference* between 2 points. There *is no* potential difference on one electrode.

PS. I am not proficient in **principal component analysis**, but I do know that by cross-correlating various electrode-pairs a source analysis can be done. Perhaps you could somehow extract the unipolar signal from bipolar signals, but I must say that a Google Scholar search using the search terms 'principal + component + analysis + eeg + bipolar + to + unipolar' did not yield any useful hits, at least at first glance.

Fig.1. EEG montage. source: Kemp *et al*., 2003

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Tags: methodology, eeg, electrophysiology, signal-processing
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# Question
Title: Do children learn to play musical instrument more easily than adults?
People say that it is harder for adults to learn to play instrument, because *their muscle became stiff*. Is there evidence for this claim?

# Answer
> 4 votes
Roughly speaking, most forms of learning become harder as one ages. Probably the most relevant aspect for your question is learning fine motor skills:

> most studies revealed that performance gains in fine motor tasks are diminished in older adults

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Tags: learning, music
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# Question
Title: Does mental rigidity cause psychological problems?
Is there a correlation between mental disorders and mental rigidity?

I suspect that when people have very strong beliefs and it happens that this beliefs are dysfunctional they can incur into mental disorders. To further clarify the question it can be also reformulated in another way. Is it possible to state that most of people change their beliefs to become adaptive to the requirements of society while stubborn people don't?

Is that correct?

# Answer
> 1 votes
Philip gave a pretty good answer (+1). There's also a phenomenon called "belief perseverance", typically defined as

> maintaining a belief despite new information that firmly contradicts it

This IMHO is a little closer to "mental rigidity"; jumping to conclusions is sometimes done because one is biased toward his "rigid" (prior) idea, i.e. a form of confirmation bias, although certainly other forms of cognitive deficits can lead to incorrect inferences.

The two-factor \[theoretical\] approach to delusions basically includes belief perseverance, at least in an extreme pathological form:

> Central to the two-factor approach is that the presence of any delusion, regardless of theme or medical context, must be accounted for by answering two distinct questions: 1) how did the unusual thought content first arise?; and 2) having once entertained the idea, why does the patient fail to reject it?

Thus the question of whether "mental rigidity" causes other "psychological problems" is a bit circular because (in extreme forms) perseverance in *unusual* beliefs is one of the symptoms of mental disorders that include delusions (schizophrenia, psychotic depression etc.), which are defined operationally, so in terms of symptoms. And we're getting a bit further afield here, but I do think it's worth mentioning that some of the debate of whether delusions are socially constructed hinges on what beliefs are sufficiently unusual in a given society:

> it can be extremely difficult to develop an operational way of determining what is or is not a part of normal experience, and it is correspondingly difficult to distinguish clearly between a belief that is truly delusional and one that is merely unusual, arcane or irrational

Some psychiatrists have even investigated the perseverance in common (but non-factual) beliefs like racism from a delusional-phenomenon perspective. Religious beliefs are also commonly brought into discussion:

> In clinical practice, no clear guidelines exist to distinguish between "normal" religious beliefs and "pathological" religious delusions. Historically, psychiatrists such as Freud have suggested that all religious beliefs are delusional, while the current DSM-IV definition of delusion exempts religious doctrine from pathology altogether. From an individual standpoint, a dimensional approach to delusional thinking (emphasizing conviction, preoccupation, and extension rather than content) may be useful in examining what is and is not pathological. When beliefs are shared by others, the idiosyncratic can become normalized. Therefore, recognition of social dynamics and the possibility of entire delusional subcultures is necessary in the assessment of group beliefs. Religious beliefs and delusions alike can arise from neurologic lesions and anomalous experiences, suggesting that at least some religious beliefs can be pathological.

And even further out, some famous atheists have argued that some religious beliefs can make a society as a whole more dysfunctional.

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Now if you actually want to define stubbornness as not adapting one's beliefs to those of those around him (like in your second-to-last sentence/question)...

> Is it possible to state that most of people change their beliefs to become adaptive to the requirements of society while stubborn people don't?

... the more common term for \[the opposite of\] that is (social) conformity:

> the act of matching attitudes, beliefs, and behaviors to group norms

But do note that conformity may include machiavellianism etc., so not really changing one's inner beliefs, but pretending to do so for the purpose of fitting better in society.

Even glossing over that, some nonconformists (e.g. schizophrenics) may exhibit belief perseverance, but other non-conformists may exhibit huge cognitive flexibility, much more so than most people around them. In particular, think of those non-conformists that pioneered new fields of science, etc. So I think the final part of your question is conflating "mental rigidity"/stubbornness with non-conformism, but the two are not really the same concept, although overlap/intersection is certainly possible in some individuals.

# Answer
> 3 votes
I've read that a tendency to "jump to conclusions" has an impact on certain psychological afflictions, such as having delusions. As you may know, the definition of a delusion is as follows (this is just from Google dictionary):

> an idiosyncratic belief or impression that is firmly maintained despite being contradicted by what is generally accepted as reality or rational argument, typically a symptom of mental disorder.

I am assuming that that sort of uncritical thinking is at least part of what you meant by "mental rigidity."

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Tags: cognitive-psychology
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# Question
Title: Does wealth cause (or correlates with) narcissism?
In the mental health field, narcissism is viewed as personality trait/disorder, which suggests little changes during the life of the subject.

Nevertheless, one mass media article (based on a book) is titled The age of entitlement: how wealth breeds narcissism, and claims that rich people are more inclined than the poor to engage in quite a number of anti-social behaviors from violating traffic rules to plain stealing. (At least as far traffic violations are concerned, the rich can usually afford the fines more easily, and even if they have their license suspended, can better afford to pay someone else to drive them.) Another indicator was that the rich tended to draw themselves as bigger circles in relation to the world. (But if you think of yourself mainly in terms of net worth, then perhaps that's not surprising or unjustified.)

Most of this was was based on the research of Paul Piff by the way. And at least one of his studies really does suggest causality, it's not a matter of him being misinterpreted by the press:

Is there a categorical confusion here in lumping these behaviors with narcissism? Or is it really the case that the richer do these because they are more narcissistic? Or perhaps the rich narcissists are more overt and the poorer narcissists more covert? Are there experimental studies that try to separate these concerns?

# Answer
> 4 votes
I found a review in a relatively obscure journal, but it seems a reasonable summary of the existing research, except for the fact that income and wealth aren't necessarily the same:

> A review of literature regarding income and altruism revealed mixed evidence. Chen, Zhu, and Chen (2013) showed that, under a dictator game setting, pre-school children from higherincome families give fewer stickers (endowment of the game) to others compared to kids from lower-income families. Miller, Kahle, and Hastings (2015) altered the game so that the tokens (endowment of the game) had to be earned via work and the kids were told that the recipients of their donation would be other sick kids who were not able to make it to the venue on that day. They still found that kids from richer families are less likely to donate their tokens compared to kids from poorer families. Piff, Kraus, Côté, Cheng, and Keltner (2010) conducted experiments on adults using economic games and scenarios and found that individuals of lower socioeconomic status appeared to be more generous, more trusting, and more compassionate.
>
> On the other hand, Hoffman (2011) investigated historical data during the World War II on people’s decision to rescue the Jews. He found that the higher the income of the people, the more likely they were to rescue the Jews. Holland, Silva, and Mace (2012) used a lost-letter experiment. They dropped letters on pavements in different neighborhoods in the United Kingdom and found that letters dropped in the richer neighborhoods were more likely to be returned to the address listed on the letters. Looking into this issue more thoroughly, Andreoni, Nikiforakis, and Stoop (2017) designed a more complicated version of the lostletter experiment. Under their setting, the envelopes used were thin enough so that contents of items in the envelopes (cash, or bank transfer cards) could be seen from the outside. The letters were mis-delivered to rich and poor households in the Netherlands. Their initial results revealed that the rich were more likely to return the envelopes compared to the poor. However, with further investigations, the authors found that the rich were not more altruistic than the poor. The fact that the rich were more likely to return the envelopes was because they faced lower financial constraint and had lower marginal utility for the found money.
>
> The above evidence showed that the relationship between income and altruism may be ambiguous. Thus, it cannot yet be concluded whether the degree of altruism \[...\] should be higher for the rich or for the poor.

Unfortunately, that may not be as relevant as I had hoped because

> It is unfortunate that a false dialectic between narcissism and altruism is in common usage. The two entities regularly co-exist. Vaillant, in his longitudinal study of healthy males, found that altruism increases significantly in the second half of life – not simply because we become more selfless as we age, but rather because helping others becomes more rewarding to us. A neuroimaging study demonstrated that those who are altruistic directly benefit from their altruism. Participants had to choose to endorse or oppose societal causes by anonymous decisions to donate or refrain from donating to real charitable organizations. The mesolimbic reward system was engaged when one donated money in the same way as it was when one received monetary awards. In other words, altruism activates brain centers that are associated with selfish pleasures like sex or eating.

Unfortunately the narcissism-wealth link alone has received less attention, perhaps because most researchers were interested in outward behavior (like altruism). Or in more prosaic terms, most people don't care how long you look at yourself in the mirror as long as you give them money :P

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Tags: social-psychology, personality
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# Question
Title: Effectiveness of implicit measures of deception (e.g., sweating, eye focus, EEG) when filling out online questionnaire
I'm working in my master thesis on a method of detecting user deception or lying when answering online questionnaires using his implicit feedback like sweating, eye focus, EEG etc.

I would like if you could recommend me some related works or books or give me some tips on which implicit feedback should I focus.

# Answer
> 2 votes
If you want to estimate/classify using implicit measures, whether a user is being deceptive while filling out an *online* questionnaire ... then methods such as EEG are not suitable.

Recording EEG data takes a lot of preparation and at least one experimenter to prepare the "user" (in your case the person filling out the questionnaire). And if you are talking about *online* questionnaires, I do not see a point in having an experimenter visit the user.

On the other hand, using (often toy-like) dry-electrodes that could be prepared by a single person, will not yield a sufficient data quality.

I think the easiest might be to consensually access the webcam of a user and evaluate the video stream for e.g., eye blinks, or other tentative variables.

Generally, this sounds like a very difficult task that will probably result in a high number of false positives and false negatives.

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Tags: cognitive-psychology, experimental-psychology, eeg, deception
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# Question
Title: What is the origin of the belief that the heart plays a role in influencing the emotions?
In many religious scriptures, novels, fictions you read about this battle between heart and brain. If till date we are using this in our daily conversations and history is full of these examples then there must be some origin of this concept?

# Answer
> 3 votes
In the 4th century B.C., **Aristotle** identified the heart as the most important organ of the body, and claimed that it was the seat of intelligence and sensation. Aristotle described it as a three-chambered organ that was the center of 'vitality' in the body. Other organs surrounding it (e.g. brain and lungs) simply existed to cool the heart (source: Stanford University). Since then it has been associated with emotions, although in the middle ages during the Enlightenment it already became clear that he heart was a pump, and not the seat of emotions.

A fact, however, is that intense emotions, such as love, fear and anger have pronounced effects on heart rate, mainly because of the release of adrenaline and other (stress) responses regulated by the **hypothalamic–pituitary–adrenal axis** (HPA) axis (source: Penn State University). The brain sends signals to the adrenal gland, which then secretes hormones and then they go to the heart which causes the heart to beat faster.

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Tags: social-psychology, emotion
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# Question
Title: How common are single-author research articles in cognitive psychology?
Are single-author research articles looked down upon?

# Answer
To target the question in the question body here:

This question is quite opinion-based, because everyone can decide to frown upon something. However, I think that, in general, it's much more about:

* **Who the author** is, *i.e.*, what is their track record in the field;
* What their **affiliation** is;
* What the **quality of the article** is;
* What the **quality** (*e.g.* impact factor) **of the journal** is.

These considerations are, at least to me, much more important than how many authors follow or precede someone in the author list. I would never judge an article on the number of authors *per se*. Lastly, (invited) review papers are often authored by just one author, even in the STEM sciences.
> 1 votes

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Tags: cognitive-psychology
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title: Name of false answer effect in surveys

text:
# Question
Title: Name of false answer effect in surveys
I'm looking for research I've read about a well known effect that happens when participants complete a survey, where they do not answer what they think is right, but what they think the researchers are expecting from them. It can be a survey but it can also be something else...

# Answer
This is called "demand characteristics":

> ... an experimental artifact where participants form an interpretation of the experiment's purpose and unconsciously change their behavior to fit that interpretation.

An example is:

> The good-participant role in which the participant attempts to discern the experimenter's hypotheses and to confirm them. The participant does not want to "ruin" the experiment.

Demand characteristics are a type of response bias:

> ... a general term for a wide range of cognitive biases that influence the responses of participants away from an accurate or truthful response. These biases are most prevalent in the types of studies and research that involve participant self-report, such as structured interviews or surveys.

Another related type of response bias is the "social desirability bias":

> ... the tendency of survey respondents to answer questions in a manner that will be viewed favorably by others.
> 4 votes

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Tags: social-psychology, measurement, bias, survey
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# Question
Title: How likely is it that rate-of-test-taking impacts on WM tests?
Rate-of-test-taking (also known as r9) is one of the main subsets of processing speed, so is tested via e.g. the symbol digit coding task. I believe it is affected by e.g. depression.

How likely is it that rate-of-test-taking impacts on WM tests, the digit span test etc,?

It was pointed out in this answer that tests of WM should create a "bottleneck" so that other cognitive processes are implicated less. What about r9?

# Answer
According to "The neuroscience of working memory capacity and training" by Christos Constantinidis & Torkel Klingberg asserts that training can increase WM capacity, however this does not translate into better reasoning power:

> Ongoing research aims to elucidate the extent to which the improvements also translate to various other abilities, such as academic abilities, that statistically correlate with WM capacity. Indeed, transfer to reasoning ability has been reported to be small, with inconsistent findings.

However, transfers to attention seem more promising:

> More-encouraging transfer results are seen for attention: several randomized, controlled trials, some of them including children with ADHD, show decreases in inattentive behaviour in every-day life after WM training

They cite to support this:

> Klingberg, T. et al. Computerized training of working memory in children with ADHD — a randomized, controlled trial. J. Am. Acad. Child Adolesc. Psychiatry 44 , 177–186 (2005)
>
> Brehmer, Y., Westerberg, H. & Backman, L. Working- memory training in younger and older adults: training gains, transfer, and maintenance. Front. Hum. Neurosci. 6 , 63 (2012).
>
> Green, C. T. et al. Will working memory training generalize to improve off-task behavior in children with attention-deficit/hyperactivity disorder? Neurotherapeutics 9 , 639–648 (2012).
>
> Bigorra, A., Garolera, M., Guijarro, S. & Hervas, A. Long-term far-transfer effects of working memory training in children with ADHD: a randomized controlled trial. Eur. Child Adolesc. Psychiatry http:// dx.doi.org/ 10.1007/s00787-015-0804-3 (2015).
>
> Conklin, H. M. et al. Computerized cognitive training for amelioration of cognitive late effects among childhood cancer survivors: a randomized controlled trial. J. Clin. Oncol. 33 , 3894–3902 (2015)
> 1 votes

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Tags: working-memory
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# Question
Title: Do the feelings related to Transference always originate from parents?
As I understand,

> Transference is a phenomenon which is related to human behavior where humans unconsciously redirect/transfer their feelings about a subject in the past to apply it to a subject in the present.

Is this definition correct?

Does the `subject in the past` always have to be **Parents**? What did Freud say about this?

# Answer
**Short answer**
Transference is often related to feelings felt toward parents, but not always.

**Background**
**Transference** (Hughes & Kerr, 2000) is

> the phenomenon whereby we unconsciously transfer feelings and attitudes from a person or situation in the past on to a person or situation in the present. The process is at least partly inappropriate to the present

According to (Ladson *et al*., 2007), transference are

> unconscious feelings that are transposed onto another significant individual.

These feelings can be beneficial for therapeutic purposes, but intense, sexualized transference can be disadvantageous. Sexualized transference is

> any transference in which the patient's fantasies about the analyst contain elements that are primarily reverential, romantic, intimate, sensual, or sexual.

The authors give an example of projections of sexual feelings experienced during early childhood relationships.

So although transference *per se* is often described in relation to parental feelings of submission, vulnerability and openness in a relation between therapist and client, transference can take other shapes.

<sub>**References**
**-** Hughes & Kerr, *Advances in Psychiatric Treatment* (2000); **6**(1) 57-64
**-** Ladson *et al*., *Psychiatry (Edgmont)* (2007); **4**(3): 47–50</sub>
> 2 votes

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Tags: psychiatry, therapy, transfer, freud
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title: Books on Neurological functions?

text:
# Question
Title: Books on Neurological functions?
Are there any books anyone can recommend that do not have any or much in the way of prerequisites but go through the anatomy of the central nervous system while laying out in detail the functions of the various regions of the brain *especially the higher brain*. I do not mean a book that merely cuts the brain into brain stem, the mid brain and higher regions like the cortices and then simply divides those regions into a dozen or so further categories. I am looking for something that is a lot more detailed and focuses on the functions of thought, emotions, sensations, perceptions, and memory and the cellular anatomy that goes along with them.

I realize it might be difficult to find a textbook without any prerequisites, so let me say as few prerequisites as possible.

# Answer
> 3 votes
Any basic Neuroscience book would suffice, really. For example, a really good and widely used book is

**Principles of Neural Science** from Kandel *et al*. I read it nearly from cover to cover, and it details the workings of the nervous system from bottom to top. Parts IV to IX are probably most relevant to you:

* Part IV: The Neural Basis of Cognition
* Part V: Perception
* Part VI: Movement
* Part VII: The Unconscious and Conscious Processing of Neural Information
* Part VIII: Development and the Emergence of Behavior
* Part IX: Language, Thought, Affect, and Learning

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Tags: neuroscience, cognitive-neuroscience, reference-request, consciousness, neuroanatomy
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# Question
Title: Why are EEG markers usually sent over the parallel port?
Usually, a study participant is viewing stimuli on a computer screen while their EEG is recorded through the hardware provided by a manufacturer. To later synchronize the EEG data to stimuli, an experimenter will send so-called 'markers' from the stimulation computer to the EEG hardware so that the markers are encoded in realtime together with the EEG data.

Why do most manufacturers use the old-fashioned parallel port for that?

I know, that the parallel port allows for a *parallel* transmission of up to 8 bits (i.e., 255 possible marker values and one '0' marker to indicate 'no marker') ... however, while that is a clear advantage, it comes at the cost of using a legacy port that is not available on modern computers.

Couldn't we just use a USB port to send data serially (in smaller bit packages) ... and then join these bits to a byte (8bits) to get the same number of possible markers? USB would in theory be fast enough to even compensate for the extra time needed to 'buffer' single bits and then encoding them as a byte.

Am I getting something wrong?

Why is the parallel port still so prevalent for this specific application (EEG)?

# Answer
I think this is for scientists who like to design their own setups. I doubt medical EEGs have a parallel port. You do not always want to sync to a computer. You will often want to synhcronize it to a photodiode, an eyetracker, a tactile stimulator etc. With a parallel port you just plug that trigger to a given pin then you know that everytime your get an integer containing 2^(pin number) you have received a trigger on that pin: for ex. trigger on pin 0 if you are reading 1, on pin 4 if you are reading 16, and on pins 1, 3 and 6 if you are reading 74. Yes, you could read your triggers with a micropchip, then use a serial-USB converter, but that's needlessly complicated and less accurate. USB have surprisingly unreliable timings for a port that can work at such a high baudrate. So it's usually better to synchronize everything to an external input. I usually synchronize an eeg and an eyetracker to a photodiode, then I know they are synchronized perfectly (yet they often have a 1msec difference for some reason).

On top of that, I'm sure there must be some backward compatibility issues. If you are a small lab that has built a complicated setup over the years, you might not want to change your EEG if it means changing your entire apparatus.
> 5 votes

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Tags: eeg
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# Question
Title: Long term effects of a high self monitor who voluntarily chooses a contradictory self-presentation
Are there any cases or studies of a `high self monitor` who intuitively chooses to act "by impulse" in order to reform said impulse?

In other words when the HSM behaves as a `low self monitor` they selectively and willingly embrace a `low self presentation` in order to challenge (or embrace flaws) within their own pride, ego, or some other aspect of psychology.

**Additional questions**

* What else can be said of this situation?
* What other questions, or background is necessary to analyze this occurrence?
* Is this behavior indicative of other problems worth investigating? (e.g. morally flawed premise for taking such action)
* What negative effects could there be on the ego and super-ego by behaving this way over long periods of time?

**Edit**

At a young age, this HSM may have discovered that behaving as a low-self-presentation allowed them to abdicate responsibility. This was later corrected in adulthood when the subject decided to actively pursue accountability on past and present behavior... thus leading to overall character improvement.

# Answer
> 2 votes
So basically the question eventually became about the influences of on-line activities on changing (improving in this case) one's behavior if not downright one's personality in real life.

There is a body of evidence that this is not uncommon, especially with children, adolescents and young adults. It's not an incredibly well research topic, so I'll mention a few papers and their findings:

> Prosocial behavior of anonymous peers (confederates) exerts a profound influence on college students’ participation in a signature campaign and money donation, whereas the reading of a prosocial paragraph has no effect. Furthermore, no participants reported peer influence as a reason for engaging in prosocial behavior.

> The experimental study using U.S. university undergraduates demonstrated a short-term causal impact of playing prosocial games on helpful behavior (and of playing violent games on hurtful behavior). Short-term experiments like this are especially important for at least two reasons: (a) they provide a strong case for causality; (b) they reveal underlying processes likely to influence long-term effects. The correlational study using Singaporean junior high schoolers demonstrated the predicted associations among video game habits and “real world” prosocial and antisocial behaviors and traits. Such correlational studies are important because: (a) they provide an opportunity for a theoretical model to fail; (b) they allow tests of the predicted association with long-term consequential behavioral patterns and traits; and (c) they allow tests of some plausible alternative explanations. The longitudinal study using Japanese children and adolescents demonstrated effects of earlier prosocial game play habits on later prosocial behavior. Such studies allow strong causal inferences, primarily by ruling out many alternative explanations that rely on individual differences in trait aggressiveness and in interests that exist at the first assessment time period; they also allow testing of the theoretical model with consequential real-world outcome measures. The bi-directionality of the present longitudinal results also demonstrates that the often-asked chicken and egg question is overly simplistic. These data suggest that playing prosocial games tends to increase prosocial behavior tendencies, and that prosocial tendencies tend to lead to selection of prosocial games. This clearly has implications for the parallel argument about violent media and aggression.

A bit of an aside here, but their conclusions about violence are a bit simplistic. From a later study:

> Research on video games has yielded consistent findings that violent video games increase aggression and decrease prosocial behavior. However, these studies typically examined single-player games. Of interest is the effect of cooperative play in a violent video game on subsequent cooperative or competitive behavior. Participants played Halo II (a first-person shooter game) cooperatively or competitively and then completed a modified prisoner's dilemma task to assess competitive and cooperative behavior. Compared with the competitive play conditions, players in the cooperative condition engaged in more tit-for-tat behaviors-a pattern of behavior that typically precedes cooperative behavior. The social context of game play influenced subsequent behavior more than the content of the game that was played.

I haven't found the exact study this refers to, but the Guardian says

> Joseph Kahne, a professor of education at Mills College in California, studied 400 teenagers over three years. Kahne found that teens who participated in fan or hobby sites were more likely than other kids to do real-world volunteering. Interestingly, this wasn't true of being on Facebook.

The findings about Facebook are fairly consistent with another paper though, i.e. it has a weak impact on "real life" behavior.

There might be more research on which (other) kinds of online communities facilitate "real life" pro-social behavior, I'm not terribly familiar with this area.

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Tags: cognitive-psychology, experimental-psychology, self, self-control, self-discipline
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# Question
Title: Effect of Physical Exercise on Intelligence/IQ
I am interested in empirical research relevant to answering the following questions:

* What is the effect of physical exercise on IQ/intelligence?
* Does any such effect vary by type of exercise? e.g. aerobics, weights
* Are there any forms of physical exercise that can stimulate brian growth?

# Answer
> 14 votes
My general sense from reading the intelligence literature is that I would not expect there to be much of a relationship between exercise and intelligence. For example, if you read Neisser et al (1996) you can get an overview of the intelligence literature. From the review, you can get a sense of just how difficult it is to systematically increase intelligence, especially over longer periods of time. This includes many cognitive interventions. It seems likely to me that cognitive interventions are targeting intelligence more directly and thus if anything should be more effective than more indirect interventions, such as those targeting physical activity. That said, aerobic, strength, and general physical health is presumably related to energy levels and as studies suggest below may also be related to a range of cognitive and motivational processes relevant to effective life functioning.

## Exercise for sedentary adults

Colcombe and Kramer (2003) performed a meta analysis on sedentary older adults and found that performance on cognitive tasks improved by .48 standard deviation relative to to .16 standard deviation improvement for control groups. The average improvement in cardiovascular only programs was 0.41 standard deviations, and the average improvement for combined programs (i.e., including resistance training) was .59 standard deviations. These studies used a variety of psychomotor and cognitive tasks. However, it did not appear that the studies used intelligence tests.

I take from these studies that exercise can have a beneficial effect on psychomotor functioning. However, I'm not persuaded yet that it exercise has a major effect on intelligence.

## Exercise for children

For a review of research on exercise on children's cognitive function and academic achievement, see Tomporowski et al (2008). The authors conclude that "similar to adults, exercise facilitates children’s executive function (i.e., processes required to select, organize, and properly initiate goal-directed actions)." They provide a narrative review of many existing studies on the topic.

### References

* Tomporowski, P. D., Davis, C. L., Miller, P. H., & Naglieri, J. A. (2008). Exercise and children’s intelligence, cognition, and academic achievement. Educational Psychology Review, 20(2), 111-131. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2748863/
* Neisser, U., Boodoo, G., Bouchard Jr, T. J., Boykin, A. W., Brody, N., Ceci, S. J., ... & Urbina, S. (1996). Intelligence: Knowns and unknowns. American psychologist, 51(2), 77. PDF
* Colcombe, S., & Kramer, A. F. (2003). Fitness Effects on the Cognitive Function of Older Adults A Meta-Analytic Study. Psychological science, 14(2), 125-130.

# Answer
> 1 votes
You also ask

> Does any such effect vary by type of exercise? e.g. aerobics, weights
>
> Are there any forms of physical exercise that can stimulate brian growth?

There is one large study in male Swedish adolescents (army conscripts), which found that cardiovascular fitness but not muscle strength was associated with IQ.

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Tags: cognitive-psychology, intelligence, iq
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# Question
Title: How do I measure ratio of EEG frequency band for a few electrodes in decibels?
I wanted to calculate the ratio of Theta/Beta ($\Theta$/$\beta$) in decibels for a couple of electrodes in AF3 AF4 and Cz

I was able to get these in microvolts, but would like to convert them to decibels but am unsure what is the appropriate way to do so.

For instance, should I convert it like:

$$ratio\_1 = 10.log\left( \frac{\Theta\_{AF3} + \Theta\_{AF4} + \Theta\_{Cz}}{\beta\_{AF3} + \beta\_{AF4} + \beta\_{Cz}}\right)$$

or

$$ratio\_2 = 10.log\left(\frac{\Theta\_{AF3}}{\beta\_{AF3}}\right) + 10.log\left(\frac{\Theta\_{AF4}}{\beta\_{AF4}}\right) + 10.log\left(\frac{\Theta\_{Cz}}{\beta\_{Cz}}\right)$$

# Answer
> 2 votes
Decidels are ratios in log scale. Usually the ratio of powers (in the physical sense). Powers sum up, but not dB. For example, a sound source at 70dB SPL means its power is approximately 3200 times higher than the reference sound source of dB SPL. If you have 2 sound sources both at 70dB, their power add up but their total sound pressure is going to be only 76dB SPL.

The appropriate way to answer your question depends on the assumptions you make. Your first equation compares the overall power within the Theta frequency band to the overall power within the Beta band, across recording locations. Your second equation compares power ratios at each location independently (although I would take the mean, not add them). Whether the first or the second equation is more appropriate is a scientific question.

Also note that dBs are usually defined in log10 scale ($\frac{ln(x)}{ln(10)}$), but it doesn't really matter.

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Tags: measurement, eeg, signal-processing
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# Question
Title: How do I determine whether my EEG signal needs denoising?
I recently start to work on sleep study.
For my research i download sleep EEG data from physionet. The EEG data has 100 HZ sampling rate and was recorded from 2 bipolar EEG site.

When i start the preprocessing stage, i encounter a simple problem, **how should i know if my signal has an artifact or noise?**

It should be noted, based on nyquist theorem and my signal's sampling rate, the maximum frequency of my signal is 50 HZ, so i did not filter unnecessary EEG frequency.
In general i only used a simple notch filter at 50 HZ, and used simple threshold method in order to remove the epochs that were grossly contaminated by muscle and/or eye movement artifacts.

Back to the main question, how should i know if i need to uses more complicated method for removing EMG or EOG artifact from my signal?

# Answer
Your recording necessarily has noise. That's a property of any physical apparatus, and you are recording the activity of noisy neurons. The other property of noise is that, by definition, it will average out. So don't do anything about that. 100Hz is quite a low frequency. Artifacts (e.g. blinks, but I doubt you would have that in sleeping subjects) would typically have a higher frequency than that so (1) it's unlikely it has been recorded by your system at all, (2) you can low-pass filter your signal to remove both the 50Hz artifact and possible other artifacts. Other artifacts such as sleeping position would have very low frequencies. So you can high-pass your signal to get rid of them. I'm not familiar with sleep EEGs but I would not worry too much about it. You can also check few papers and see how they filtered their signal.
> 3 votes

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Tags: eeg, signal-processing
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title: Does dreaming cuts our sleeping hours?

text:
# Question
Title: Does dreaming cuts our sleeping hours?
If I am dreaming a lot at night, how many effective hours am I sleeping at night? After dreaming heavily at night, when I wake up in the morning I feel sluggish as if I haven't slept properly.

Does dreaming cuts our sleeping hours?

# Answer
One small study (2015) in otherwise healty subjects, found no correlation between nightmares and the quality of sleep measured using widely used objective methods, or more precisely

> sleep measures obtained by ambulatory polysomnographic recordings revealed no group differences in (a) overall sleep architecture, (b) sleep cycle duration as well as REM density and REM duration in each cycle and (c) sleep architecture when only nights with nightmares were analyzed.

Nonetheless the subjects who experienced nightmares reported worse *self-reported* sleep quality. Granted, in a study like this, there's always a chance the authors failed to consider some objective sleep measure not commonly known/used today. Anyhow, the author's' conclusion was that

> nightmares result in significant impairment which is independent from disturbed sleep architecture

And thus they suggest one seek specialized treatment for nightmares... which are correlated with quite a few psychiatric disorders, PTSD, anxiety, depression, or borderline personality disorder, to name a few.

Another caveat of this study is that the authors deliberately excluded people with diagnosable psychiatric conditions from the sample. So this study does not exclude the possibility that subjects with (say) PTSD actually do have worse objective sleep... owing to nightmares.
> 3 votes

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Tags: sleep, dreams
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# Question
Title: What is the difference between a bias and a heuristic explained in layman terms?
Can anyone explain the difference in a way which can be explained to some one who does not a have a clue about psychology? May be examples could help.

# Answer
> A heuristic is an approach to problem solving, a bias is a prejudice; so in what way do these terms confuse you?

I respectfully disagree. I have noticed that the term bias and heuristic are used interchangeably in the literature that could lead to confusion. The difference between them is subtle.

> Can anyone explain the difference in a way which can be explained to some one who does not a have

Heuristics, biases and algorithms are all related terms. The simplest way to describe them is as follows:

A ***heuristic*** is a rule, strategy or similar mental shortcut that one can use to derive a solution to a problem. A heuristic that works all of the time is known as an ***algorithm***. Consider the following scenario: you get lost in a maze, what can you do to escape? The solution is to place your hand on the outer edge of the maze and keep walking until you find the exit. Heuristics can help us make sense of the world in a reliable way and reduce our mental load. However, they aren't always perfect and there is also a tendency to use them inappropriately to form beliefs. A systematic error that results from the use of a heuristic is called a ***cognitive bias***.

**EDIT:**

Per suggestions, the following should be noted:

While the use of heuristics of can lead to cognitive biases, not all cognitive biases are the result of heuristics. Generally, however, when an error in judgement or belief is identified empirically or anecdotally, there will be an attempt to account for it using heuristics.

Additionally, and more broadly, there is just as much ambiguity regarding the definition of cognitive bias in the literature.

For example, in this account of attribution biases, the following definition is provided:

> ***Cognitive biases refer to systematic mistakes that derive from limits that are inherent in our capacity to process information.*** Because we are not capable of perceiving everything in our environment, our focus is automatically drawn to the most prominent or “eye-catching”—that is, perceptually salient—stimuli. This can lead us to formulate biased and inaccurate causal attributions (Taylor & Fiske, 1975). Specifically, we are prone to equate the most perceptually salient stimuli with the most causally influential stimuli.
>
> `Shiraev, E. B., Shiraev, E. B., & Levy, D. A. (2016). Cross-cultural psychology: Critical thinking and contemporary applications. Taylor & Francis.`

Similarly:

> ***When the correct answer is described, they see for themselves how their own judgment is biased in systematic ways.*** Such personal demonstrations make Tversky and Kahneman's points in a salient, simple, and powerful way. What was innovative about their work was that it drew a connection between heuristics and biases: A heuristic is a rule of thumb used as such in different contexts. A cognitive bias is a systematic error in our thinking.
>
> `Morvan, C., & Jenkins, W. J. (2017). Judgment Under Uncertainty: Heuristics and Biases. CRC Press.`

However:

> Heuristics are the "shortcuts" that humans use to reduce task complexity in judgment and choice, and biases are the resulting gaps between normative behavior and the heuristically determined behavior (Kahneman et al., 1982).
>
> `Chipman, S. E. (Ed.). (2016). The Oxford Handbook of Cognitive Science. Oxford University Press.`

Ditto:

> ***Cognitive biases are subconscious deviations in judgement leading to perceptual distortion, inaccurate judgement and illogical interpretation.*** From an evolutionary point of view, they have developed because often speed was more important than accuracy. Biases occur due to information processing shortcuts (or heuristics – see Box 5.1), the brain's limited capacity to process information, social influence, and emotional and moral motivations.
>
> `Cooper, N., & Frain, J. (Eds.). (2016). ABC of clinical reasoning. John Wiley & Sons.`

Although this isn't a psychology reference, the definition is a tad weird:

> Architects rely on precedent knowledge to design their next building, believing the past buildings worked well and the knowledge can be transferred to their new design, promising similar performances. ***Cognitive biases (illusions) and potential errors can occur when using precedent knowledge for analogical, pre-parametric and qualitative design thinking.***
>
> `Zarzar, K. M., & Guney, A. (Eds.). (2008). Understanding Meaningful Environments: Architectural Precedents and the Question of Identity in Creative Design (Vol. 4). IOS Press.`

Although I am speculating, I would suggest the following explanation: strictly speaking, an error in normative reasoning need only occur once for it to potentially be the result of a cognitive bias. However, a cognitive bias would need to occur in a systematic manner in a study sample before it could be identified in empirical research and reported in the literature.

And that, my friends, concludes my demonstration on *overkill*.
> 7 votes

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Tags: bias, behavior
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# Question
Title: Can I read what the person thinking through electrodes or something similar?
First of all I'm not a medical student so I may miss some points here.

I know that EOG (electro-oculography) works on the corneo-retinal dipole. The cornea (front of eye) is slightly positively charged and the retina (back of eye) is slightly negatively charged. When I apply electrodes on the temples and ground circuit to my forehead (helps to stabilize readings and get rid of some 60Hz interference).

So I used that(I wrote a program) to read these signals and control some thing by moving my eyes, and follow the signals change according to my eyes movement.

Now my program can read this simple electrecity signals and convert it in order to control something else.

But this doesn't make much sense, I need to make it more understandable, for example I'm wondering if there someway to read alphabets the person thought about and receive a unique signal for it, and I mean by (someway) not just through eyes maybe with brain waves or something else I don't know about it.

# Answer
> 5 votes
I take it you want to use eye movements for data input (rather than reading people's thoughts, which would be silly to consider). It's not the greatest idea, efficiency wise, but may have its strengths in terms of convenience. From a fairly recent (2014) review of eye based HCI:

> It should be noted, though, that gaze control of WIMP is noticeably slower and more error prone than control by conventional mouse and keyboard (e.g. gaze typing reaches about 20 wpm which is far from the 80 wpm by a touch typist, see Majaranta et al. 2009a).

And the 2009 paper they refer to for state of the art is "Fast Gaze Typing with an Adjustable Dwell Time". It's basically displaying a large virtual keyboard (like your phone/tablet does) and uses a specialized algorithm to reduce errors. I'm not familiar with the details of the latter, you'll want to read the paper for that.

Microsoft Research has a more recent (2017) paper using a cascading virtual keyboard and it claims improvements for the average user. The latter paper also makes me wonder if the previous research overstated its results, because

> Participants were able to achieve typing speeds of 12.39 WPM on average with our cascading technique, whereas participants were able to achieve typing speeds of 10.62 WPM on average with a static dwell time approach.

I don't know what discrepancies are due to; methodology or what is being reported, I guess.

By the way, there's a HCI stack exchange where I'm sure there are more knowledgeable people on this.

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As for the title of your question "Can I read what the person thinking through electrodes or something similar?". This is a somewhat different topic, and perhaps too broad to address here. Most of the results in this latter area are much more experimental in nature, i.e. farther from a practical technology right now. Wikipedia's article on thought identification is probably a resonable start.

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Tags: electrophysiology, brain, brain-computer-interface, brain-waves
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# Question
Title: Theorem of uncertainty in cognitive science
Recently, reading one book I have come across such paragraph:

`"[...] The operation would require de facto to create a complete record of the mind and build the brain again - an impossible thing for absolutely fundamental reasons. Cognitive science has its own theorem on uncertainty, the law proving the impossibility of reducing the mental structure to numerical data."`

I am guessing, that the author was referring to the Heisenberg's uncertainty theorem, but that is the only thing that came to my mind (my knowledge about cognitive sciences is very limited). Do you know, what the author might have meant? Or maybe it was just fiction?

# Answer
As you say in your last comment, this is clearly fictional as a theorem, but the argument has been raised in less fictional works. The "theorem on uncertainty" phrase probably is intended to hint to the uncertainty principle and/or the no-cloning theorem from quantum mechanics. For instance, Scott Aaronson writes

> Does quantum mechanics (specifically, say, the No-Cloning Theorem or the uncertainty principle) put interesting limits on an external agent’s ability to scan, copy, and predict human brains and other complicated biological systems, or doesn’t it?
>
> I regard the above as an unsolved scientific question, and a big one. Many people seem to think the answer is obvious (though they disagree on what it is!), or else they reject the question as meaningless, unanswerable, or irrelevant.

Note that he is far from being the first to ask the question (e.g. Alan Turing did in 1951), although Aaronson did perhaps help sharpen it.

So with respect to brain function, this "theorem" is just a hypothesis, and it may well prove to be false. The empirical evidence on the relevance of quantum processes for understanding brain functioning is questionable at best, although you do see occasional "breakthroughs" reported in the press, e.g. on Orch OR; see the long list of comments under the abstract for a review paper for more. On the other hand, other researches continue to pursue brains simulators like the Blue Brain Project, although it's computatinally very expensive just to simulate a part of a rat's brain.
> 1 votes

# Answer
It looks like fiction to me. I think it's quite clear that mental structure can be reduced to numerical data. **If anything, you can start with atoms, their distance from each other and angles between any three of them and inductively work up through molecules and nerves to the whole brain structure.**

Yes, such technology is not available to us today but it might tomorrow. Just look at CRISPR crisping small DNA molecules.

Then there might be a difference between what the author perceives as "mind" and brain. That field is rather metaphysical and philosophical in nature.

But that doesn't necessarily mean such feat is fundamentally impossible.

Don't take my opinion too seriously though, in the end, I am only a layman. Maybe somebody else will provide a different view on the subject.
> 0 votes

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Tags: cognitive-modeling, brain
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# Question
Title: Platforms to make online experiments with counterbalancing
There are a number of different interfaces to make an place experiments online, e.g. in questions Software for online psychological experiments that don't require users to download anything or Open source software for running Internet psychological experiments that collect reaction time data.

We have an experimental design that we'd share online, but we've found that one feature may be quite rare - namely counterbalancing. We have 4 conditions, and we'd like participants to be placed in these conditions so that we have more or less equal amount in each by the end. This can be difficult for web studies since it should only count the participants that successfully completed the trial.

Free and open source would be best, we don't have a designated budget to pay for setting up an experiment.

# Answer
> 3 votes
You could try www.gorilla.sc It's cloud based software specifically designed for running cognitive psychology experiments online without needing to code. It's not free, but it is affordable - £0.75 per participant.

Counterbalancing of various sorts is built in; randomisers, stimuli set counterbalancers, order counterbalancers. It sounds like the simple **randomiser** set to **balanced** will do what you want. As long as you stay on top of rejecting Ns that drop out, you'll get a balance in each condition.

There is a GUI questionnaire builder, task builder and experiment tree builder. So you don't need to do any coding. The vast majority of cognitive science task can be created in it very easily.

Full disclosure, I created Gorilla.

# Answer
> 2 votes
Qualtrics (survey software) and Inquisit (more sophisticated stimulus presentation software) both run online. Both tools support counterbalancing. Inquisit has extensive support for both randomisation of stimuli in a variety of ways and between-subjects allocations to orders and so on. They both require payment, but some universities have subscriptions to one or both services (especially Qualtrics).

I'm not sure about how you'd solve the issue of drop out to get perfectly even numbers in each group ordering.

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Tags: methodology, experimental-psychology, software, internet
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# Question
Title: EEG segmentation and denoising which one should done first?
Because of EEG nature, in EEG analysis often researcher use Windowing/segmentation method.

As i currently work on sleep study, and in my study i need to analysis EEG data, i came to a problem.

**My problem:** should i filter and Denise my EEG signal and then segment it or no i should firstly segment my EEG and then filter and denoise each epoch separately?

And as extra question, is there any difference between these two in signal processing view?

# Answer
Depending on whom you ask, you get both answers. That's mostly dependent on the denoising algorithm. If you're using an adaption of GST, you are segmenting first with an n-1 overlap.

If you're using S3P I'd recommend not segmenting, since (in my experience) there is a slight difference, with unsegmented data having slightly closer results to Fernandez and Li, 2003 and Frangakis and Hegerl, 2001.
> 2 votes

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Tags: eeg, signal-processing
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# Question
Title: Converting Big 5 questionnaire data to Big 5 scores using R
I'll preface this with I have no knowledge of psychology, but my goal is to produce some graphics dealing with correlations, and one example that I had thought of is how the Big 5 personality traits correlate with each other. I came across the R dataset \`\`qgraph" which has the results of a 240 item questionnaire (48 questions per Big 5 trait), but this only gives me the responses to questions. I want to be able to aggregate the questionnaire data in such a way that I can accurately assign Big 5 trait percentile scores to each respondent; however, it is not at all clear to me how this should be done. What is the process of taking questionnaire data and getting percentile values for each of the Big 5 traits for the respondents? Alternatively, if there's a dataset that already include percentile scores for the respondents, I'd be interested in that.

# Answer
Here are some resources that will show you how to score the Big 5 using R.

The main function that I like is called `scoreItems` in the `psych` package. It handles item reversal, imputation, and multiple scales. It will also give you things like alphas and item total correlations.

William Revelle has this tutorial: http://personality-project.org/r/psych/HowTo/scoring.pdf

I have this video ( which has an associated github repository): https://www.youtube.com/watch?v=iFFW5sK3Bhk

See in particular, this bit of the code: https://github.com/jeromyanglim/score-tests-with-r-exercise/blob/master/finished-analysis/munge/01-munge.R

```
sc <- scoreItems(meta.bfi[,v$scales], ccases[,meta.bfi$name])
ccases[,colnames(sc$scores)] <- sc$scores

```
> 3 votes

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Tags: big-five
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# Question
Title: What does 'Mean Diffusivity' tell me about the connectivity of cortical areas?
I am reading an article about changes in thalamic volume and connections in relation to age and I understand that thalamic volume decreases with age. The authors find that mean diffusivity (MD) in thalamo-cortical projections increased with age.

I'm not familiar at all with diffusion tensor imaging so I have trouble understanding what the ramifications are for the function/anatomy of the white matter tracts.

# Answer
> 2 votes
**Short answer**
The mean diffusivity (MD) in diffusion tensor imaging is a sensitive, yet a rather non-specific measure. Changes in MD tell you that water movement is altered, yet why and how will have to be answered through additional studies.

**Background**
Diffusion MRI relies on the fact that water diffuses better parallel to axons than across them in the brain. Hence, in white matter that consists mainly of bundles of parallel oriented axons, water primarily moves in one direction, *i.e.*, parallel to the fibers therein. In contrast, in the brain’s gray matter and the extracellular space, water moves freely in many directions. By taking advantage of the differences in diffusion rates, the white matter can be imaged in the brain. This technique is used diffusion tensor imaging, or DTI. DTI has been used to study disruptions in brain structure caused by trauma and white matter diseases, such as multiple sclerosis (Chi, 2014).

Now, there are several outcome measures in DTI and one of them is the mean diffusivity (MD). MD describes the magnitude of water diffusion within brain tissue and can be used to examine differences in brain structural integrity. Differences in MD may reflect variations within the intra- and extracellular space, a reduction in neuropil (basically, gray matter), and/or global increases in CSF (Clark *et al*., 2011). For example, increased tissue water in edema will increase the MD, whereas cell proliferation (tumor) may decrease the MD. In complex diseases like multiple sclerosis (MS), brain regions may experience an unpredictable combination of demyelination, axon loss, gliosis, and inflammation, which could result in competing influences on the diffusion tensor (Alexander *et al*. (2007).

**MD is a sensitive but rather non-specific measure** that can be affected by any disease process that **affects the barriers that restrict the motion of water, such as cell membranes**. (Clark *et al*., 2011).

In your linked article (Hughes *et al*., 2012), the only thing they really say about the MD is

> MD increased in both thalamo-frontal and thalamo-parietal regions with increasing age \[...\]. These observed changes \[in\] white matter tracts occur in parallel with an age related decrease in frontal cortical volume and the volume of related thalamic regions.

Indeed, I think in itself the change in MD tells you only that *something* has changed and that the MD *may* be a predictor for aging in the thalamocortical system.

<sub>**References**
**-** Alexander *et al*., *Neurotherapeutics* (2007); **4**(3): 316–29
**-** Chi, *The Scientist* (2014)
**-** Clark *et al*., *J Psychiatr Res* (2011); **45**(7): 980–8
**-** Hughes *et al*., *NeuroImage* (2012); **63** (3): 1134-42</sub>

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Tags: neuroscience, neuroimaging, neuroanatomy, fmri, aging
---


title: Classical or Operant Conditioning?

text:
# Question
Title: Classical or Operant Conditioning?
I'm working on a conditioning experiment for my psychology class in which I tap my finger three times on a table and then ask my friend to sharpen a pencil for me. If she finishes the task I give a reward (ex. part of a cookie). However, I'm not sure if this would be classified as classical or operant conditioning because although it's a voluntary behavior, it's prompted by a stimulus. I think it's operant conditioning, but I just wanted to be sure. Any advice for this?

# Answer
> 3 votes
This is homework. But it's still interesting.

> However, I'm not sure if this would be classified as classical or operant conditioning because although it's a voluntary behavior, it's prompted by a stimulus. I think it's operant conditioning,

There are multiple learning processes involved. Some of them have already been established e.g. asking your friend for something is already a salient motivational cue.

Anyways, what you're describing is reminiscent of the learning phenomenon classical-to-instrumental transfer (CIT), which is also referred to in the literature as Pavlovian-instrumental transfer (PIT). Essentially, its the phenomenon by which a conditioned stimulus (CS) eventually acts as a signal or a predictor of a reward contingency (or vice-versa). Think of it as motivation/focus/salience modifier.

It has particular relevance to relapse in drug dependency after a period of abstinence. An individual who has quit smoking, for example, would be more likely to relapse after years of abstinence if they are exposed to any stimuli that were present when they typically smoked. In fact, there is nothing stopping an anti-smoking billboard acting as that stimulus.

# CLIFF'S NOTES SUMMARY

This is how you would break down your homework problem. However, you should note that this is NOT the way you would want to structure the training of CIT.

Also, I'm going to assume that the end game here is to get your friend to sharpen your pencil through mere desk tapping.

**1. INSTRUMENTAL LEARNING**

Sharpening your pencil results in receiving a cookie. By linking a desired behavioural repertoire with a positive outcome, you increase the likelihood of the behaviour being repeated:

```
[response-outcome]   pencil sharpening => cookie

```

Your friend will eventually learn that pencil sharpening is something that is rewarded.

**2. CLASSICAL CONDITIONING**

Now it's time to add additional stimuli to the learning condition.

There are two parts to this. First, your friend will learn that you asking her to sharpen your pencil will be rewarded, but in its absence, she won't. It would be done along the lines of:

```
CS+ (asking)   sharpening => cookie

CS- (no asking)   sharpening => [no reinforcement]

```

Then, through simple conditioning of the two stimuli, tapping and asking will also become paired:

```
[classical conditioning]   tapping => asking

                                      sharpening => cookie [operant conditioning]

```

**CLASSICAL-TO-INSTRUMENTAL TRANSFER**

I will spare you the intricacies of how the training is performed, but needless to say, eventually you could expect to observe the following:

1. Tapping alone should instantiate the sharpening behaviour.
2. Ditto asking.
3. As a motivational cue, sharpening should become more *vigorous* in the presence of tapping.
4. I suspect, but am not certain, that asking while tapping would have some effect on the *vigour* of sharpening observed in #3.
5. Tapping should produce spontaneous recovery after extinction of the sharpening =\> cookie contingency.

Below is an outline of how classic-to-instrumental transfer is demonstrated experimentally. If you note, you have an additional stimulus pairing (tapping=\>asking) but it does not make this any more different to the following:

**References**

Domjan, M. (2014). The principles of learning and behavior. Nelson Education.

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Tags: learning, psychology, conditioning
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# Question
Title: What is the history of self-experimentation in cognitive science?
I am looking for a source on the history of self-experimentation in the cognitive sciences, or experimental psychology in general. I am specifically interested in knowing when it stopped being the norm.

The Wikipedia article on self-experimentation has no sources for psychology.

# Answer
> 1 votes
**Short answer**
Based on the general developments in drug and medical device development research, 1970 was a major milestone, as randomized controlled trials were marked as compulsory for new drugs to be marketed through the FDA regulations.

**Background**
The question is quite broad, but in terms of clinical trials I can say that since 1970 the FDA required that drug producers submit randomized controlled trials (RCTs) results with new drug applications, heralding a new era of the RCT in drug approval regulations (Meldrum (2000); Bothwell & Podolsky (2016)). An RCT is defined as

> \[A\] type of scientific (often medical) experiment which aims to reduce bias when testing a new treatment. The people participating in the trial are randomly allocated to either the group receiving the treatment under investigation or to a group receiving standard treatment (or placebo treatment) as the control. Randomization minimizes selection bias \[...\]. The RCT is often considered the **gold standard for a clinical trial**.

Now you are referring to questions on Cognitive Sciences or Psychology in general. Drug research and medical device investigations include the widely used psychoneuropharmaceuticals such as the antidepressants and antipsychotics, as well as medical devices such as deep brain stimulators and sensorineural implants to treat *e.g.*., epilepsy and deafness/blindness, respectively. All of these can be included in the disciplines of Cognitive Sciences and Psychology.

<sub>**References**
**-** Bothwell & Podolsky, *N Engl J Med* (2016); 375: 501-04
**-** Meldrum, *Hematology/Oncology Clinics of North America* (2000); **14**(4): 745-60</sub>

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Tags: reference-request, psychology, history-of-psychology
---


# Question
Title: Is there a known mechanism by which people fall asleep less easy after watching TV?
It's my experience that people (I am one of them) tend to fall asleep while watching television. Afterwards, when lying in bed, sleep doesn't come as easy as when they were watching television.

Is this because only the "small" part of the brain that is involved in watching television (and when you experience that what you're watching ain't worth looking at, so you fall asleep before you can switch the canal) and the other parts "wake up" when you're lying in bed, which makes it harder for you to fall asleep? Or is it just linked to being tired (in which case you would expect to fall asleep easy in bed)?

You can examine this by letting a group of people (**or** men **or** women, not both) of about the same age, physical health, etc. letting perform the same things (like eating, waking up at the same time, doing the same physical tasks), and before going to sleep letting them watch the same movie on TV. I think doing this a month suffices. After a month of collecting data (from questions asked and physical examinations), you're maybe able to say something useful.

# Answer
What you describe is rather common for a certain type of insomnia, called psychophysiologic.

> The patient has evidence of conditioned sleep difficulty and/ or heightened arousal in bed as indicated by excessive focus on, and heightened anxiety about, sleep; difficulty falling asleep in bed at the desired bedtime or during planned naps, but no difficulty during other monotonous activities when not intending to sleep

And more from *Therapy in Sleep Medicine*:

> Insomniacs often report that they fall asleep easily when watching television or reading in the living room, but become aroused upon going to bed. In addition to the previously mentioned tendency of insomniacs to associate bedroom stimuli with frustration, falling asleep when reading or watching TV may also result from the fact that doing so keeps the body in a quiet and relaxed position, and keeps the mind focused away from frustrating attempts to fall asleep. Support for the habit of reading or TV in bed is derived from Gallup polls, which indicate that about one third of all U.S. adults read themselves to sleep or fall asleep watching television in bed. Watching television has also been associated with falling asleep more easily on multiple sleep latency testing (MSLT). Nevertheless, there is considerable controversy regarding this recommendation, focused mainly on the success of Bootzin’s rules when used as a whole. Clinicians may, therefore, first advise the use of the bed only for sleeping, but if that does not help, they may suggest a trial of reading or watching TV in bed.

For more on Bootzin's rules see this page for instance.

Unfortunately, not much can be said about 'why'; from the first source:

> there are little to no data relating specifically to the etiology and pathophysiology of psychophysiological insomnia.

Having said that, it's also known from studies on night-shift workers that 20-mins to 1-hour nap improves alertness (cf. the *Therapy* book, which cites several studies e.g.), so it's rather common/expected that if you fall asleep at the TV you'll have a harder time falling asleep later, even if you don't have insomnia. The distinction is one of degree/intensity, I suppose.
> 3 votes

# Answer
I found a very useful quote from a book by Ray Schilling. The book is called "Healing gone wrong, healing done right". Here's the quote:

> Your brain is working overtime when you watch TV. You do this for several hours and your brain thinks it should be active. Then you turn the TV off and want to fall asleep. Your brain thinks, no, I am activated now. Let’s have some fun: what about pupils flashing, and why not activate your eyelids: now you got eyelids jerking. Then the brain recalls some of the noises and thinks: “I can do that too” Bingo: You got high pitched heavy white noise; that’s when you over impose all of the various noises you heard on TV into one. I suggest you experiment alternative ways of handling the TV. You could give yourself 2 hours or so after finishing TV, before you go to sleep. Alternatively, you may want to not watch TV for one evening and see whether things are better. There is another thing: When you watch TV, you stimulate your adrenal glands to produce more cortisol, which is the waking hormone. Cortisol counteracts melatonin, which is the sleeping hormone. So, when you decide to go to bed, your hormones disagree with you. The circulating cortisol will prevent you from falling asleep and inactivate the melatonin that is released from your pineal gland when the environment around is dark. Total darkness is the trigger normally to pour out melatonin, which inactivates the still circulating cortisol. But if there is too much cortisol circulating you are still in a fight/flight mode of thinking, which was needed for daytime stress. But all of this will settle when you follow my advice above. If you still have problems falling asleep, take 3 mg of melatonin from the health food store about 30 minutes before bedtime. If this does not put you to sleep within 20 to 30 minutes, you are thinking too much. At that point, you would benefit from 500 mg to 1000 mg of valerian root (that’s in addition to the melatonin you already took). The valerian root calms your nerves and you will fall asleep. If you still can’t sleep, you should see your physician for a possible sleep study.

I think this is a very enlightening piece of writing. I deduce from this that when you watch TV, your attention is only directed to the TV, shutting down other parts of the brain that would be active if you weren't watching. These other parts "wake up" when lying in bed \[if you go to bed directly after watching your flat (or non-flat) screen\], and start "shouting" louder than normal, which causes the difficulty of falling asleep. There is more cortisol, which competes with the melatonin. This applies of course to people who have no psychologic issues. What happens on the molecular level (which I think is the scientifically accepted answer) I can't say, though melatonin and cortisol are chemicals of which the balance for sleeping well is disturbed.
> 0 votes

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Tags: sleep, attention
---


# Question
Title: Evidence and arguments for and against bounded rationality?
Can anyone point me to a couple prominent papers on Simon's concept of bounded rationality (i.e., that human rationality is shaped by limitations in our ability to ingest and process information)? Specifically, I'm looking for empirical evidence for or against and arguments against (I'm content with Simon's own arguments for.) I know the literature on this is extensive; I just need a very high-level overview with some credible scholarly support.

# Answer
> 1 votes
*The Paradox of Choice* is probably the area best supported by empirical evidence that argues for \[the existence of\] satisficiers. If you'd rather read a shorter paper, "Maximizing versus satisficing: happiness is a matter of choice." with the same lead author (Barryt Schwartz) has \> 1K citation in Google Scholar; there's a free pdf in CiteseerX. And on the flip-side of that, Scheibehenne et al.'s "Can There Ever Be Too Many Options? A Meta-Analytic Review of Choice Overload" "a meta-analysis of 63 conditions from 50 published and unpublished experiments (N = 5,036), we found a mean effect size of virtually zero but considerable variance between studies". The latter paper has about 500 citations in GS, but it's also published in 2010 vs 2002 for the Schwartz et al. paper. That might not be the last word in this matter, because 2015 brought us Chernev et al.'s "Choice Overload: a Conceptual Review and Meta-analysis" while agreeing with the zero overall effect from the 2010 meta-analysis, does a meta-regression to obtain as significant explanatory variables for the variance: choice set complexity, decision task difficulty, preference uncertainty, and decision goal. As the names of these are not always self-explanatory, here's the authors' details:

> (1) The complexity of the choice set describes the aspects of the decision set associated with the particular values of the choice options: the presence of a dominant option in the choice set, the overall attractiveness of the options in the choice set, and the relationship between individual options in the decision set (alignability and complementarity); (2) The difficulty of the decision task refers to the general structural characteristics of the decision problem: time constraints, decision accountability, and number of attributes describing each option; (3) Preference uncertainty refers to the degree to which individuals have articulated preferences with respect to the decision at hand and has been operationalized by two factors: the level of product-specific expertise and the availability of an articulated ideal point; and (4) The decision goal reflects the degree to which individuals aim to minimize the cognitive effort involved in making a choice among the options contained in the available assortments and is operationalized by two measures: decision intent (buying vs. browsing) and decision focus (choosing an assortment vs. choosing a particular option). In this context, we expect higher levels of decision task difficulty, greater choice set complexity, higher preference uncertainty, and a more prominent, effort-minimizing goal to produce greater choice overload.

The latter paper is too new to assess its impact but insofar it has about 70 citations in GS, which is not too shabby.

---

Another highly cited paper is Kahneman's "Maps of Bounded Rationality: Psychology for Behavioral Economics". Although it has "Bounded Rationality" in its title and pays homage to Simon in the opening paragraph, this is farther from Simon's own ideas of satisficing as the basis of bounded rationality. Kahaneman proposes that "(i) that most judgments and most choices are made intuitively; (ii) that the rules that govern intuition are generally similar to the rules of perception". The kinds of problems used to illustrate the latter (e.g. the bat and ball problem) are not necessarily the choice problems that Simon had in mind.

---

And on a somewhat (but not entirely) contrarian note, Camerer's book *Behavioral Game Theory* (\>5 K citations if GS is correct) (see this for a review), which has a sort of precis in a paper of his (much less cited thatn the book though), states:

> Even though strategic thinking is limited, behaviour can approximate equilibrium predictions surprisingly well if people can learn over time (or through imitation or some other adaptive process).

And he has some experimental data to prove it. I'm a bit surprised computer scientists don't stroke their ego more often with the result from 'table 1' in this paper of Camerer. I guess it's not that well known (only about ~100 citations).

Anyway, my point here is that unlike the one-off experiments with choice or puzzles, iterated versions tend to produce results suggesting that the bounds on human rationality are farther than might be conceived in simpler experiments. But simultaneously this finding is also an argument for bounded rationality, at least a computational version thereof.

And speaking computational interpretations, there have been some theoretical works examining (arguing for) bounded rationality from the latter perspective, e.g. Kao and Velupillai; the latter author also has a book-length exposition titled *Computable Economics*. Frankly the only people who seem to argue against any bounds (as opposed to just bounds in some 'homo economicus' experiments) are those who argue for a non-computational theory of mind, like Penrose so forth; SEP has a good review of these.

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Tags: cognitive-modeling, cognitive-load
---


# Question
Title: Physiologically speaking is anxiety and adrenaline the same?
I am wondering from a physiological perspective what is anxiety. From my experience anxiety feels like muscle tension and lots of suppressed energy. For what I know the only thing that can make the body feel like that is adrenaline. So I am wondering if the two are the same or if anxiety is caused by different hormone. However what doesn't seem right about my hypothesis is anger increases adrenaline, but I don't think anger feel like anxiety for the general population. It would be helpful if someone could clarify me what causes the physiology of anxiety.

# Answer
> 3 votes
Not quite the same, although there is some overlap.

What's colloquially known as an "adrenaline rush" (e.g. what you'd experience in a roller coaster or more generally in a fight-or-flight situation) is the result of the body's fast reaction system to stress, sometimes called the sympathetic-adrenal-medullary (SAM) axis. SAM activation causes the adrenal medulla to release epinephrine (adrenaline) and norepinephrine (noradrenaline);.

On the other hand, sustained/chronic stress (eventually) activates the slower stress-response axis, known as the hypothalamo-pituitary-adrenocortical (HPA) axis. In humans, HPA activation releases cortisol from the zona fasciculata of the adrenal cortex. (The adrenal cortex is the outer layer of the adrenal gland, while the adrenal medulla is the inner area of the gland.) One of the actions of cortisol is to contain the activation of the SAM axis. (*Textbook of Anxiety Disorders*, 2nd ed., p. 571 citing the highly influential paper of Munck et al.) Cortisol has its own negative-feedback loop.

So, in a panic attack you'd experience mostly SAM activation, or at least this will be the dominant effect. On the other hand, anxiety generally refers to a broader class of reactions to stress, including long-term ones. E.g., \[older\] people with generalized anxiety disorder (GAD) may experience elevated cortisol, and this is reduced by SSRI medication. Other anxiety-related disorders such as PTSD have a much more complicated picture; cortisol levels are not terribly useful in distinguishing PTSD patients from controls. Recent research suggests however that a dysfunctional cortisol feedback loop may be present in PTSD; administration of cortisol after a potentially traumatic event seems to reduce later symptoms.

What I said above is a pretty simplified picture, in which I completely glossed over the complex pathways of stress-mediation in the brain, which actually make studying/treating anxiety disorders much less trivial.

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Tags: physiology, anxiety
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