# Question
Title: Are men subject to optimism bias when it comes to assessing their sexual/romantic appeal?
Intuitively, I imagine that men are strongly subject to optimism bias when dating, and in particular facing rejection. (ie. not believing that she's really not attracted to him).

My question is:

* How well studied is this? What methods of study do they use?
* How prevalent is it amongst men? (Are all men subject it it?)
* How strong is the bias? By how much do men overvalue their attractiveness?
* How does this compare with women?

# Answer
Short answer: Yes, but not really...

**Self-enhancement:**

Self-enhancement (sometimes referred to as positive illusions) refers to a general preference for positive self-views (in men and women alike). It includes several common strategies, such as: The "above average effect" (aka illusory superiority), self-serving bias, and optimism bias. Optimism bias however refers to perceived risk, whereas this question is about illusory superiority:

> ... a cognitive bias whereby individuals overestimate their own qualities and abilities, relative to others. This is evident in a variety of areas including intelligence, performance on tasks or tests, and the possession of desirable characteristics or personality traits.

Self-esteem is a particularly dicey subject matter - it seems to refer to a conglomerate of fairly independent / mildly correlated factors. So when we examine say, self-perceived sexual attractiveness (sex appeal), the results are different from a variety of other similar sounding - but independent - constructs such as self-perceived physical attractiveness, sexual self-schema, self-valuation, sexual self-esteem, sexual satisfaction, sexual performance, body image, self-image, etc...

Therefore, to keep the scope of this question manageable, I'll focus on gender differences in illusory superiority with respect to sexual attractiveness, though as will be discussed, physical attractiveness will come into play as well.

**Research methodology:**

Self-esteem factors such as perceived sexual attractiveness are measured using surveys / self-reporting. For sexual attractiveness in particular, there doesn't appear to be a well-established scale in common use, so researchers tend to develop questionnaires as needed for their particular studies. Furthermore, there is evidence that many confounding factors exist that cannot be easily controlled for, such as societal changes. So unfortunately, some questions of validity and reproducibility of the results exist, as is common in many facets of social psychology and personality research.

Another issue is the extricability of sexual attractiveness from physical attractiveness. Studies have shown that these are in fact two different constructs. However, different scales used by different researchers emphasize physical attractiveness in sexual attractiveness measures to different degrees, making the separation difficult.

As suggested in the question, self-enhancement is known in general to increase when under threat - Wikipedia says:

> This motive becomes especially prominent in situations of threat, failure or blows to one's self-esteem.

and:

> Positive illusions are a form of self-deception or self-enhancement that feel good, maintain self-esteem or stave off discomfort at least in the short term.

To manipulate self-esteem in the lab, subjects can be presented with a comparison point (contrast), such as a photo or video of someone else that may be highly attractive, or unattractive. An ego-threatening contrast may affect self-enhancement differently from an unthreatening scenario.

**Summary of results:**

As expected, both men and women report a "better-than-average" bias for sexual attractiveness - ie, the average rating compared to others is higher than average. The bias is slightly greater for men than women on some scales, and not significantly different on others, eg:

> ... on the dimensions of Sexual Attractiveness, Sexual Restraint, and Sexual Orientation ... no significant sex differences \[were\] found.

Here is an example where women actually rated themselves higher than men:

> ... we found that males rate themselves higher on explicitly sexual dimensions (e.g., sexually responsive, experienced) and females perceive themselves to be more romantic and sexually attractive.

It would be good to see a meta-analysis of such studies to get a better idea of the overall effect, but the bottom line is that it's not clear - it may depend on the particular scale used, or any number of other confounding factors.

Some examples of such factors: Black men rate themselves higher than white men, but women do not; men and women base their ratings on physical traits to different degrees; self-esteem affects females differently from males; and effects vary in cultures where physical attractiveness is more or less emphasized. That is, it appears that gender differences vary based on societal changes, such as before and after the feminist movement, differences in idealized representations in the media, cultural changes in messages such as "black is beautiful", etc. And gender differences also vary depending on the incorporation of physical attractiveness.

**Physical attractiveness:**

In the 1980's and 90's, there was a flurry of research on self-perceived body image and physical attractiveness related to increased diagnosis of anorexia/bulemia, so much more is known about these measures. In line with suggested epidemiology for anorexia, that is most associated with young women, body image is typically lower in females than males, and females are more often subject to a "lower-than-average" effect, while males more often rate their physical attractiveness as better than average.

As before, there are many confounding factors, including some of the same ones to do with skin colour, cultural context, different physical traits, and self-esteem. Nonetheless, the effect suggested in the question is perhaps more pronounced for physical attractiveness than sexual attractiveness / romantic appeal. And since self-perceived physical attractiveness often constitutes an important component of sexual attractiveness, then some of the differences in results may depend on how heavily a particular study incorporates physical attractiveness into their own measure of sexual attractiveness, and how important physical attractiveness is as a component of sexual attractiveness for the particular group studied. With this factor removed, and limiting findings to modern Western culture, it may turn out that men and women do not differ in self-enhancement of sex appeal, or even that women do so to a greater degree.
> 7 votes

# Answer
Respectfully, I believe there might be a flaw in the thinking behind the question insofar as you are assuming that "attractiveness" is a relatively static property in an individual.

This might be a male perspective because the way that males are programmed to feel attraction for females is based on female attributes which are relatively slow to change.

Females, however, are programmed very differently than males. The amount of attraction or repulsion that she feels can change significantly very quickly because it is largely based on the behavior of the male. This is a concept that most males find hard to grasp because it is not the way that they are programmed so it is not a part of their experience of reality.

An explanation ...

The field of evolutionary psychology suggests that much of animal behavior - including and especially our attraction and repulsion systems is hardwired into our genes.

For example, when a cat hears the squeaking of a mouse, the behavior of the the cat will be somewhat predictable. How is this possible? The belief is that cat has been genetically programmed by evolution to feel an emotional compulsion to behave in a very specific way when it receives a very specific auditory signal. This behavior gives it an evolutionary advantage over those cats which did not have it because it will eat the mouse and the nourishment will give it a better chance of surviving to pass on its genes.

Evolutionary psychology suggests that much of animal behavior - including and especially mate selection choice - is similarly hard-wired. Those who make good choices for selection of mates are more likely to have their genes survive.

However, the programmed mating strategy of males and females is very different for the simple reason that the optimal strategy for the survival of the genes of the male is different than the optimal strategy for the survival of the genes of the female.

In particular the male mating strategy might be described as seeking high “replication value” whereas the female strategy is to seek high “survival value”.

Men have the advantage of being able to make quick and relatively permanent assessments of female attractiveness because all they need is a visual signal to assess her “replication value” and that assessment - before the advent of plastic surgery - is relatively permanent. Females, however, cannot assess the “survival value” of a prospective mate so quickly. She has to get to know you in order to make an accurate assessment. The level of attraction that she feels for you will be based nearly entirely on how you behave during that “getting to know you” time.

A popular book on the evolutionary psychology of attraction is "The Evolution of Desire: Strategies of Human Mating" by David M. Buss.

Evidence to support the belief that the attraction mechanism of females is rooted in male behavior is given by the (admittedly non-scientific) experience of “pick-up artists”. For example “Eric Von Markovic” aka “Mystery” wrote a famous book called “The Mystery Method” in which he describes how a male can alter his behavior to “create attraction” in women by behaving in ways that exude the desirable traits and not behaving in ways that exhibit the undesirable traits.

I realize this is not a rigorous scientific source. Someone should do a study to validate the claims. But I personally have a great deal of certainty that the method works because I was a dating coach in a former life, taught it to dozens of men, and saw it work with my own eyes over and over again in the field.

This brings me to my second point.

One of the most important behavioral traits that women seem to be programmed to seek out in men might be described as “self confidence”.

So if you, as a male, have a genuine “optimism bias”, females will actually feel more attracted to you because you are more self-confident. Women are attracted to men who have this trait and feel aversion to those who don't have it.

I do not have a scientific reference to support this. However, all that I have experienced tells me that it is true. You might consider doing a simple survey of women to verify.

In his book, von Markovic suggests that women seem to be programmed to run a “testing” algorithm to ascertain if you really are the attractive mate who can fulfill her needs that you seem to be. If a male “behaves” correctly, her attraction will increase. If he behaves incorrectly, the female’s attraction will decrease.

So all men are punished and rewarded by their life experiences to develop the attractive behavioral traits - including and especially “self-confidence”. It would seem, therefore, that men are *rewarded* for having the trait of “optimism bias” and *punished* for not having this trait. Therefore a male who fails to find a way to generate self confidence with respect to his desirability is putting the survival of his genes in jeopardy by severely limiting his mating opportunities.

Are all men subject to it?

All men are compelled by their life experiences to develop it. Though many give unskillful meaning to and draw the wrong lessons from their painful experience and are thus much slower to develop the correct behaviors.

How is it different for women?

Men are not biologically programmed to punish women for lacking self confidence because we are not looking for her to be our "protector and provider". Women are therefore not compelled to develop this trait by their life experiences.
> -2 votes

---
Tags: bias, sex-differences
---


# Question
Title: A definition of hatred towards your own nation
There are such things as xenophobia, nationalism, etc. In other words, various forms of hating and diminishing the foreign and the foreigners.

My question is, is there a term meaning hatred and disparagement towards your own people or culture? Some kind of your-own-nation-phobia?

I don't mean xenophilia, because that's affection towards foreign, it doesn't mean hatred towards your own. I mean exactly hatred towards your own people/nation/culture/etc.

EDIT1: Just one of the examples of how this phenomena may work. An international conference. A person from, say, Russia, talks to a group people from various countries. Suddenly, another Russian joins the group. Our hero realizes that (either he knew that that person was a Russian beforehand or reads that on their badge) and an anger and disgust start boiling within him. He starts to be prejudiced and a bit aggressive towards his compatriot because that person is his compatriot.

# Answer
The word "Oikophobia" has several different definitions. In psychology, it usually means an aversion to home surroundings, or to objects in the home. However, the British philosopher Roger Scruton coined a new meaning, which is exactly what you are looking for:

> The disposition, in any conflict, to side with 'them' against 'us', and the felt need to denigrate the customs, culture and institutions that are identifiably 'ours'.
> \- Roger Scruton, quoted on Urban Dictionary

Wikipedia has a more detailed description of the term:

> Scruton uses the term as the antithesis of xenophobia. In his book, Roger Scruton: Philosopher on Dover Beach, Mark Dooley describes oikophobia as centered within the Western academic establishment on "both the common culture of the West, and the old educational curriculum that sought to transmit its humane values." This disposition has grown out of, for example, the writings of Jacques Derrida and of Michel Foucault's "assault on 'bourgeois' society result\[ing\] in an 'anti-culture' that took direct aim at holy and sacred things, condemning and repudiating them as oppressive and power-ridden."
>
> "Derrida is a classic oikophobe in so far as he repudiates the longing for home that the Western theological, legal, and literary traditions satisfy. . . . Derrida's deconstruction seeks to block the path to this 'core experience' of membership, preferring instead a rootless existence founded 'upon nothing.'"
>
> An extreme aversion to the sacred and the thwarting of the connection of the sacred to the culture of the West is described as the underlying motif of oikophobia; and not the substitution of Judeo-Christianity by another coherent system of belief. The paradox of the oikophobe seems to be that any opposition directed at the theological and cultural tradition of the West is to be encouraged even if it is "significantly more parochial, exclusivist, patriarchal, and ethnocentric." Scruton described "a chronic form of oikophobia \[which\] has spread through the American universities, in the guise of political correctness."
>
> Scruton's usage has been taken up by some American political commentators to refer to what they see as a rejection of traditional American culture by the liberal elite. In August 2010 James Taranto wrote a column in the Wall Street Journal entitled Oikophobia, Why the liberal elite finds Americans revolting in which he criticized supporters of the proposed Islamic center in New York as oikophobes who were defending Muslims who aimed to "exploit the 9/11 atrocity".
> \- Wikipedia
> 5 votes

# Answer
There is some research in social psychology that has investigated when people dislike a group they belong to. Thus, this research is more general in that it is not limited to nationality, but about any kind of social group.

Usually, people have a tendency for ingroup bias, that is, they prefer their own group over other groups (outgroups). One important theoretical perspective that has guided much research on this phenomenon is Social Identity Theory, which posits that people derive their self-concept from the groups they belong to, and strive for positive distinctiveness from other groups.

Sometimes, however, people have a strong dislike for their own group, e.g., because these groups are stigmatized, because a larger ingroup discriminates a smaller subgroup they belong to, because an ingroup violates important personal moral standards, or when people move to high status positions in disadvantaged groups (for a review, see Becker & Tausch, 2014). This phenomenon has been labeled with different terms such as "**ingroup hate**", "**outgroup favoritism**", or "**disidentification**".

To my knowledge, the most comprehensive account of explicit dislike of ingroups has been proposed by Becker and Tausch (2014), who have developed a scale to capture this phenomenon. They distinguish between different components of **disidentification** and show that their scale can predict negative emotional and behavioral reactions toward the ingroup. Citing from their abstract:

> This research introduces a multi-component model of ingroup disidentification that distinguishes three disidentification components (detachment, dissatisfaction, and dissimilarity). In Studies 1a (N = 168) and 1b (N = 215), the authors developed a measurement scale that assesses these components, and examined alternative factorial structures. Study 2 (N = 115) provides evidence that the disidentification scale performs better at distinguishing between disidentification and nonidentification than an established identification scale. Using additional data from Studies 1b and 2, Studies 3a and 3b examined emotions and behavioral intentions as correlates of disidentification and revealed that the disidentification components predict negative ingroup-directed behavioral intentions (active harm, passive harm, and passive facilitation) and identity concealment over and above measures of identification.

**References**

Becker, J. C., & Tausch, N. (2014). When group memberships are negative: The concept, measurement, and behavioral implications of psychological disidentification. Self and Identity, 13(3), 294–321. http://doi.org/10.1080/15298868.2013.819991
> 3 votes

# Answer
I like the word misanthropy...

Misanthropy is the general hatred, distrust or disdain of the human species or human nature. A misanthrope or misanthropist is someone who holds such views or feelings. The word's origin is from the Greek words μῖσος (misos, "hatred") and ἄνθρωπος (anthrōpos, "man, human"). The condition is often confused with asociality.
> 0 votes

---
Tags: social-psychology, phobia
---


# Question
Title: Can we use a scale even if one of the answer levels was not added?
I have a set of 20 participants for a study who were given a 7-point Likert scale that was made incorrectly by a graduate student. The student accidentally did not add the 6th answer level. The scale for these 20 participants arguably has no validity now. However, I am hoping there is a way to use it for a pilot or preliminary poster. The study will continue for a couple years and is proposed to have 300 participants. But I would like to use these 20 participants for a small pilot or preliminary poster. Is there a way for me to still use that scale (missing the 6th answer option) and the 20 participants?

I don't know if I can impute it because the data is not MCAR, the answer level was not added to the scale as it should have been. But can I weight the low and high-ends of it or something still? I would like to see if the measured construct from that scale relates to either another variable (such as Engagement) or the outcome variable. It is a longitudinal study, they come in once a week for three weeks. Each time they come in to the lab and use the online intervention they take the scale three times (i.e., Baseline, after first half of website, and then after second half of website), which means we have each participants using the scale 9 times.

# Answer
I think you'll come unstuck if you don't have a balanced scale.

If you consider a typical five-point scale:

* Strongly disagree
* Disagree
* Neither agree nor disagree
* Agree
* Strongly agree

If we forget to put `Strongly disagree` on the scale, it is positively biased, because it is heavier on the `Agree` side of the scale. If we forget to add `Strongly agree` we have a negatively biased scale.

If you intend the questionnaire to be used for research purposes, you'll need to ensure the scale is correct - otherwise it may affect your findings, and it will definitely cause people to question whether the outcome would have been the same as if the correct scale was used.
> 3 votes

---
Tags: measurement
---


# Question
Title: Neurophysiological indications of focus and motivation
Is there any way to detect a subject being focused or highly motivated (assuming that these two states are essentially the same) using any sort of external detection, such as fMRI or EEG? How would the accuracy of these measurements be compared? I have a hard time imagining what the "ground-truth" of these measurements might be.

# Answer
Focus and motives are very different cognitive processes. Essentially focus would be attention, while motivation is a complex neurocognitive process, such as hunger or thirst, which drives attentional orientation.

I'm going to have to break this down a bit further because motivation is largely considered two processes 'wanting' and 'liking'. 'Wanting' is the drive to obtain a motivational object, such as food. While 'Liking' is the assessment of the motivational object. So if a digestive tract is empty of food it will typically send chemical signals telling the brain its empty, amongst a whole host of other factors but lets not get into that. As a result we will 'want' food, and this alters the hedonic value of food, which ultimately influences its salience (how much it grabs your attention). And its representation in the brain, all of this is done to draw your attention towards the motivational target, or make us seek it out. Once the target i.e. food, is obtained it is consumed, this is the point at which it is assessed for how much we 'like' it. All of this is done by a neural system, often referred to as the reward circuit. The reward circuit is made up of a number of brain areas (nuclei), so many it would take an dissertation to write about them all however the main constituents are: Nucleus Accumbens, Ventral Tegmented area and the parabracial nucleus. Changes in these structures appear to influence activity in the cingulate cortex (likely to do affective assessment and memory) and orbitofrontal cortex (attention, inhibition, hedonic value, etc). As you can see this is just gross anatomy, these structures are involved in a variety of cognitive processes.

Going by your question I imagine you are interested in the drive to behaviour or determination. The nucleus Accumbent shell is considered responsible for this, although I think thats like saying wembley is responsible for one of two teams winning a football match. The resolution in functional signals has a long way to go. Anyhow endocannabinoids are thought to be responsible for modulating the increase in eating or rather 'wanting' to eat, they do this by increasing the hedonic-value of the motivational target. Hence cannabis give people the 'munchies' and can make them feel sexually aroused.

So to answer your question can we measure this? Yes and no. fMRI can detect motivation-related activity in NA shell, but there is alot going on in that area so there is bond to be noise that must be controlled for in any design. But essentially you can show someone images of food before and after eating and measure their neural responses. However I must stress that the NA is not the only area involved in this motivational process.

As for EEG, research is a bit inconsistent and I would feel uneasy recommending anything from this area. This is mostly because motivational processing is largely conducted in subcortical structures, which EEG isn't really the best method of investigation for. However it can be used for detecting arousal, but cognitive arousal can occur as a result of merely interesting or treating stimuli.

Another method are implicit cognitive measures and eye tracking, this is a growing field. Measures include, visual-search tasks, dot-probe, stroop, go/n-go, attentional blink tasks etc. What this area tends to show is that people are more attentive to motivationally-relevant stimuli i.e. more attentive to food when they are hungry. Although some research shows that people attend to such stimuli regardless of motivational state, the methods here are constantly being updated as they are still relatively new methods.

Finally and importantly do any measures discriminate between levels of motivation? No, not any of the neural or cognitive measures I know of anyway, most are lucky to detect differences between fasted and fed states. There is work going on in this area, but so far differences in levels of motivational state are only collected on explicit measures such as VAS scales asking someone what there level of motivation is.

Sorry for lack of references SE only allows you two references on the first post in a new area of SE.
> 4 votes

---
Tags: measurement, eeg, fmri
---


# Question
Title: is it true that people who code think differently?
I code websites and I believe the way I think is totally different from most of the others. Not that I think in a better way(a possibility though) but I'm only saying "differently". Do you think it's true? if yes, why?

# Answer
> 2 votes
Well, let's considering what you're asking here.

You're asking if people who code think differently. Well, let's consider those who know how to program. Some people plan what they are going to do, while others take a more dynamic approach. Some people create a 'skeleton' of what they are about to build before they fill in the missing pieces (and will debug each piece as they go), and yet others will create one new method at a time until they have one giant bug-filled product to deal with at the end.

Now pick two arbitrary coders. Do they think differently from each other? Probably. They probably have different approaches, interests, strengths, and weaknesses. But sure, they probably think differently than, say, someone who works in a grocery store.

But then again, take the person who works in a grocery store. They probably have different methods for dealing with shoppers, they probably use different greetings, they may have different strengths and weaknesses, etc.

In fact, I would argue that **in instances where you are given a choice, it isn't what you do that teaches you to think; rather, the way you think determines what you do**. You may pick up on certain methods out of habit (maybe you see people as variables, or maybe you're quick to decompose your thoughts like you would a program), but on top of learning new skills, those habits you pick up are probably further emphasizing the ways in which you **currently** think.

---
Tags: philosophy-of-mind, theory-of-mind, thought
---


# Question
Title: How are real life events translated into dream symbolism?
I'm interested in **how significant events from daily life get encoded or translated into dream content**. A personal observation can help clarify my question:

> I've observed that for me, "significant, futile mental effort" translates into dreams of me being in a classroom in my old middle school. The kind of mental effort dictated which classroom I will see \- history, language or math.

It took me years to make the connection, as the frequency of the dream was rather high while attending school and college. It is only after I started working that I noticed dreams of classrooms were gone and only reappeared following intense, but perceived as pointless mental effort to learn or grasp or produce something.

I'm familiar with the Freud's theories on how wish fulfillment and repressed sexual desires show up in dreams. On the other hand I'm aware of the much discredited concept of "dream interpretation" with dictionaries of dream symbols.

Have there been studies that lay in between the two extremes listed above and **attempted to elicit connections between daily events and how they appear in dreams?** Maybe attempts to create personal dream dictionaries, like the one I described in the example?

# Answer
We do not know a lot about how dreams work yet. However, there are some theories out there. One theory of particular interest is that are dreams are a means of reverse learning.

> In 1983 Francis Crick of the Salk Institute in La Jolla, Calif., and Graeme Mitchison of the University of Cambridge in England proposed the idea of reverse learning. Working from the Hobson-McCarley assumption of random neocortical bombardment by PGO waves and their own knowledge of the behavior of stimulated neural networks, they postulated that a complex associational neural network such as the neocortex might become overloaded by vast amounts of incoming information. The neocortex could then develop false, or “parasitic,” thoughts that would jeopardize the true and orderly storage of memory. According to Crick and Mitchison’s hypothesis, REM sleep served to erase these spurious associations on a regular basis. Random PGO waves impinged on the neocortex, resulting in erasure, or unlearning, of the false information. This process served an essential function: it allowed the orderly processing of memory. In humans, dreams were a running record of these parasitic thoughts—material to be purged from memory.

At any rate, it seems that dreams are less a representation of an event and more a byproduct of random impulses coming from the brain stem. These may be made less 'random' (seemingly) only because the things we think about most and spend most our energy on are probably more likely to be 'happened upon' in the dream state.

Any further tendency to recognize a certain dream pattern after a certain event may be an occurrence of this, as well as an instance of selective remembering, or remembering the instances that support your case and neglecting the instances that don't. Having dreams of a classroom in college is normal because you are in classrooms (and you are unconsciously forced to remember the topics you have picked up on in your own middle school classrooms, which may be later 'dream material'), and associating these dreams with futile mental effort is a broad case, considering that college is essentially a four-year cycle of seemingly-futile mental effort. ;)
> 2 votes

---
Tags: cognitive-psychology, cognitive-modeling, sleep, dreams, long-term-memory
---


# Question
Title: What are other methods to induce ego depletion besides using emotional videos and thought suppression?
Muraven and Baumeister (2000) proposed that self-control is a limited resource akin to strength or a muscle, to deplete this limited resource leads to subsequent self-regulatory failure. Ego depletion, the temporary depletion of self-regulatory capacity by an initial act of self-control, has a significant effect in decreasing performance in self-control tasks (Hagger et.al, 2010).

I would like to know the methods to induce ego depletion, so far I only come across studies using emotional videos and thought suppression (Baumeister et.al., 2003) to achieve this cognitive process.

1. Baumeister, R. F. (2003). Ego depletion and self‐regulation failure: A resource model of self‐control. Alcoholism: Clinical and Experimental Research, 27(2), 281-284. DOI: 10.1097/01.ALC.0000060879.61384.A4
2. Hagger, M. S., Wood, C., Stiff, C., & Chatzisarantis, N. L. (2010). Ego depletion and the strength model of self-control: a meta-analysis. Psychological bulletin, 136(4), 495. http://dx.doi.org/10.1037/a0019486
3. Muraven, M., & Baumeister, R. F. (2000). Self-regulation and depletion of limited resources: Does self-control resemble a muscle?. Psychological bulletin, 126(2), 247. http://dx.doi.org/10.1037/0033-2909.126.2.247

# Answer
In the supplemental materials (Appendix A) of the meta-analysis by Hagger et al. (2010), you can find a comprehensive **taxonomy of different methods that have been used to induce ego depletion**. As the table summarizes a great variety of different paradigms, I will only list a few examples of methods and papers here. The references can be found in this document.

Hagger et al. sort the methods into 3 "task spheres" depending on whether they focus more on affective or cognitive processes:

1. **Affective**

* **controlling emotions** \- for example *reading book passage aloud in emotionally expressive fashion* (Gailliot, Schmeichel, & Maner, 2007, Study 1), *regulating negative affect when describing a situation* (Bruyneel et al., 2009, Studies 3 & 4)
    * **controlling impulses** \- for example *crossing-out-letters task* (e.g., Baumeister et al., 1998, Study 4), *modified Stroop task performance* (e.g., Bray, Ginis, Hicks, & Woodgate, 2008), *Appetizing/unappetizing food taste perception task* (e.g., Baumeister et al., 1998, Study 1)
2. **Cognitive**

* **controlling attention** \- for example *focusing attention on subject and not displayed words while watching a video* (e.g., DeWall et al., 2008, Study 2), *arithmetic task with/without auditory interference* (e.g., Alberts, Martijn, Greb, Merckelbach, & de Vries, 2007, Study 2)
    * **cognitive performance** \- for example *paced forward (low fatigue)/backward (high fatigue) counting task* (e.g., Wright et al., 2007), *easy/difficult labyrinths task* (e.g., Alberts et al., 2007)
    * **controlling thoughts** \- for example *suppressing thoughts of death* (e.g., Gailliot, Baumeister et al., 2007, Study 8), *suppressing thoughts of previously-viewed emotive video* (Ostafin et al., 2008)
    * **choice and volition** \- for example *making product choices* (Bruyneel, Dewitte, Vohs, & Warlop, 2006), *forced-choice essay task* (e.g., Baumeister et al., 1998, Study 2)
3. **Affective and cognitive**

* **social processing** \- for example, *high-maintenance social interaction tasks* (e.g., Finkel et al., 2006), *other-race/same-race social interaction task* (e.g., Richeson & Shelton, 2003)

**References**

Hagger, M. S., Wood, C., Stiff, C., & Chatzisarantis, N. L. D. (2010). Ego depletion and the strength model of self-control: A meta-analysis. Psychological Bulletin, 136, 495–525. doi:10.1037/a0019486
> 4 votes

---
Tags: cognitive-psychology, motivation, cognitive-modeling, ego-depletion, self-control
---


# Question
Title: What stimulus features determine the psychophysical power law exponent?
Following the work of Stanley Stevens, psychophysical functions of stimulus intensity are commonly assumed to follow power laws, as illustrated below:

This appears to be true for a wide variety of different types of stimuli and sensations. A table that is often presented to illustrate this generality is from Stevens, 1975:

However, it is not obvious from perusing this table what kinds of stimuli tend to be associated with what kinds of power exponents -- in particular, what kinds of stimuli tend to be associated with *positively accelerated* psychophysical functions of intensity vs. *negatively accelerated* psychophysical functions of intensity. Indeed, the exponents in the table above appear to be distributed rather haphazardly to me, and I have not seen any mention of work suggesting it is otherwise in my admittedly limited literature search.

**So my question is:** Is anyone aware of research that attempts to characterize what kinds of stimuli tend to be associated with what kinds of psychophysical functions of stimulus intensity? If so, what is the basic summary from this research, and what are some suggested readings? As hinted above, I am particularly interested in stimulus features that predict positively vs. negatively accelerated psychophysical functions of stimulus intensity, but references to and descriptions of more specific research questions are also quite welcome.

**Update:** I thought it might help to say just a little bit more about exactly what I'm interested in finding out here, in as clear and concise a way as I know how. What I am looking for are any references to review papers and/or research articles that are about (or even that just mention) predicting the form of the psychophysical power law across a range of different stimuli, using stimulus-level predictors. It is hard to extract any general conclusions about this from Stevens's table above, given that the power law exponent appears to vary widely, sometimes being \>1 and sometimes \<1, *even for stimuli on the same psychological continuum*, as in the cases of "Taste" and "Warmth." The point of the table (and indeed the body of research that it is based on) is just to show that these functions follow power laws of some kind or other -- while this is mildly interesting, what I really want to know is how well we can predict what *kinds* of power laws different stimuli will follow. Please let me know if I can offer any additional clarification.

# Answer
> 5 votes
Mainly: the choice of variables.

Beware that the exponent depends on the choice of parameters; or even worse - relations can change from power-law to linear, logarithmic or exponential, with redefining variables.

E.g. you can measure sound volume in either amplitude, energy density (square of the amplitude) or dB (logarithm of the first one). None of it is privileged. Moreover, "psychological magnitude" needs exact definition, for the same reason (so not only to specify which type of reaction is that but what is the exact physical quantity being measured).

In general, if you consider only qualitative parameters, then you can look at only at qualitative behaviour of the relation (e.g. if it is monotonous). To calculate exponents (or even - to claim that a certain relation is a power function) it is not enough.

Of course, there are many adaptations to make sensitivity higher (e.g. edge detection) or lower (e.g. to see well in lighting conditions differing by order of magnitude, in terms of light intensity). But to compare their exponents, for the comparison to make sense, you need to have a very good justification for the right choice of variables.

# Answer
> 1 votes
Those responding make some very good points about being specific about operational definitions and such. However, I've argued -- in an evolutionary psych textbook -- that there is a probably a reason why discomfort from cold and electric shock have power laws with exponents greater than perceived brightness (at low stimulus intensities), for example. It's adaptive to be highly sensitive to intense levels of things that can kill or harm you -- to avoid frostbite or death from electrocution, for example. This would also suggest that the psychophysical exponents for normally harmless dimensions such as brightness and loudness would go up for very bright lights or very loud noises (that could damage your eyes or ears, respectively).

Psychologist Martie Haselton has made very similar arguments in her research on "error management theory." Roy Baumeister has made similar points in his Psychological Bulletin paper entitled something like 'Bad is stronger than good."

Brett Pelham

---
Tags: perception, sensation, psychophysics
---


# Question
Title: Why do we always wake up at the climax of our dreams, even when it is an alarm that wakes us?
I know that it probably has something to do with the fact that our dreams didn't really end at the same time our alarm clock rang, our brains just make us think so for some reason.

# Answer
There are two possibilities. One is that we do tend to wake up more at the climax of dreams, and that somehow our dreams can sync up with external input like an alarm clock so that the climax of the dream occurs at the same time as the alarm going off. The second is that this doesn't actually happen; the alarm is just as likely to go off at the climax of the dream as it is at any other point.

If the second situation is true, then why do you end up feeling like you always wake up at the climax of the dream? One explanation is **confirmation bias**. This is an established bias of human memory, in which we selectively remember events that confirm our ideas, and neglect the events that disconfirm them. In this situation, you have the idea that you always wake up at the climax of dreams, so your memory is biased towards times where you actually did wake up at the climax of dreams. However, there are likely many times where you woke up not during the climax of the dream, but these are less memorable because they don't fit your expected pattern.
> 8 votes

# Answer
I'd reckon this can be due to the chance of you remembering the dream when you wake up. When your dream was mundane (i.e. emotionless), you probably have no reason to remember it - when awake. (see The neuropsychology of REM sleep dreaming for more on the noradrenergic and serotonergic influences on sleeping)

While sleeping, only small time-periods (usually 90 minutes) you're actually dreaming, which can result in short of (speculating) time-gaps between periods of the dream. When you were dreaming of something climatically, you can (just as well) leave your dream state, without you noticing it (Waking up properly: is there a role of thermoregulation in sleep inertia. So when the alarm bells ring, you think you were just in a climaxical (word?) dream, while in real life the clock went on.

I must say, this sounds like an interesting research question, although it might be hard to test, because you need the right kinds of dreams (perhaps TMS can provoke them during sleep). Since dreaming happens during REM sleep, we should are able to tell whether you dreaming (regardless of whether or not you will remember later), based on your brain waves (or using EOG).

Finally, since dreams are pretty familiar to us, they are just as mysterious, so one might think of loads of reasons for it (Dreaming and the brain: from phenomenology to neurophysiology, or, or)... Worth while thinking of it
> 4 votes

# Answer
From my personal interest and research into dreaming over 12 years, I ask you to consider that **the climax of a dream may actually be caused by the alarm ringing.**

There has been long standing hypothesis that real life content gets incorporated into one's dreams. This phenomenon is rather unpredictable, and an example would be seeing lightning strikes in a dream in response to real life light flashes.

From personal experiences - I've frequently been puzzled by waking up a second or so ahead of perceived alarm going off. I hypothesize that this perception is false, and the alarm has been going off for some time before I awoke. **Due to the high intensity of an alarm, I hypothesize that the awakening process somehow influences the intensity of dream imagery.**

Regarding the confirmation bias - it can also play a part in your question. Once again, from anecdotal evidence, there are many occasions where the dream just fades into blackness and a person slowly gains the sensation of laying in bed (no alarm).
> 2 votes

---
Tags: memory, sleep, dreams, bias
---


title: Is there such a thing as word synonyms?

text:
# Question
Title: Is there such a thing as word synonyms?
I'm an English teacher and participate in the English Language forum. The question of word synonyms is very frequent. People ask if words can be substituted in sentences and still retain meaning, etc.

I feel that there is no such thing as "synonyms" because the pictures created in the mind of listeners and speakers are different for different words, and to complicate matters putting the words in sentences will produce different mental pictures / movies.

For example, if I ask 100 native English speakers what they imagine when they hear these two sentences, I feel that very different mental pictures / movies will be produced:

a) Please wash your hands. b) Please clean your hands.

Some would argue that "wash" and "clean" are synonyms, and that the meaning of both sentences are the same; remove dirt from you hands in whatever way you choose. I feel that they are not the same. I'm sure there are better examples to help my point. The words garbage, waste, pollution, trash, and rubbish, were discussed in another post.

I read Benjamin Bergen's book. I am an ESL teacher, and a big problem I have found is that students don't have the same mental pictures as native speakers for words. If I ask them what a word means they can say, but if I ask them what they imagine, the results don't always match or coincide with what native speakers would likely imagine, and I know that they will end up using the word incorrectly.

My questions are:

1) Does it really make sense to talk about "synonyms" in light of what we now know about how people process language?

2) Are there books besides Bergen's that explore the topic of language processing in the way his book did, i.e. language as a mental movie produced in the listener and speaker's mind?

# Answer
> 3 votes
Technically no two words are identical, especially between speakers, but the term is still useful. Here's my answer borrowing from a few disciplines:

Semantics:

It may be useful to think of words in terms of their *sense* and *reference*. You can think of reference as the thing that the word/phrase 'points to' in the world, and sense as additional meaning conveyed by a word/phrase. If for example, you were to refer to your friend's dog as "Lassie", the reference of Lassie in this context is simply your friend's dog. If you referred to your friend's dog as a "mutt", then the reference of "mutt" is still your friend's dog. Both "Lassie" and "mutt" share elements of the same meaning--in that they have the same reference, but they differ in their sense. You could make the same argument for "wash" and "clean", though they may have the same *reference* they have different *senses*, therefore, they are not the exact same.

Cognitive Science:

How do we define words and phrases? It cannot be just a dictionary definition, because we know much more about what constitutes a word than what a dictionary attempts to do. One could extend the idea of a dictionary definition and compose a set of necessary and sufficient conditions that encapsulate a word's meaning (for example a dog could be something that is furry, four-legged...etc.) But this is problematic--for one it does not account for *gradation* across categories. Secondly, it is almost impossible to fully define categories such as "dog" and "chair" using necessary and sufficient conditions. (You could fill a book with conditions that could satisfy "chair" but can never work out a contingent system), finally, it leads to infinite regress. (For example, if we define a "dog" as something that is "furry", what then is are the necessary and sufficient conditions of "furry"?)--thus necessary and sufficient conditions don't have much use in natural language. An alternative is *prototype theory* (see: Eleanor Rosch), which asserts that a concept's meaning is graded around an idealized core. For example, you may have an idealized concept of "dog" (say, a golden retriever), and all other examples of dogs you see in the world lay on a spectrum in relation to your idealized representation of a dog. The farther away, or more different, the object is from the idealized core, the less "dog-like" it is. The interesting thing about prototype theory is that the idealized core is arbitrary--it varies from person to person. So one person's idea of a "dog" is not the same as another person. That means that the word does not mean the exact same from speaker to speaker, despite having very similar senses and references. From this we could conclude that no two speaker's englishes are the same. So even when comparing the same word, their meanings are not truly the same. The processes that involve how prototypes form in the first place are as much dependent on individual variation, as they are culture and language.

Phonology:

The Bouba-Kiki effect shows that speech sounds themselves may come to have meaning (see: sound symbolism). So the fact that your synonyms "wash" /waʃ/ and "clean" /klin/ have different phonological realizations means that they also have differing semantic implications.

Bringing it together:

As an ESL teacher you may be working with children who may have learned english explicitly--this is in stark contrast to native english speakers who learned english passively. ESL speakers may be comparing their native language (and prototypes) to english, thereby producing different conceptualizations of the semantic space english expressions explore.

So cognitively no two words are identical. From this you could claim that there are no "true" synonyms--but that *doesn't* mean that the term "synonym" is useless. Even though all words have multiple complex layers of meaning, some words have more semantic similarities than others, and that still bears pointing out as an interesting feature in language.

# Answer
> 0 votes
I think you asked a couple of very interesting questions.

Here is my thought to the first question you mentioned.

People have different levels of knowledge/capability on things.

For example, for a toddler who is showing off his/her color recognition skills, it is probably all right to use 'red' for a range of colors from pink to magenta. However, for a professional graphic designer, it is not OK.

This applies to language skills too. 'Synonyms' to ESL students (for example: myself) may not necessarily be 'synonyms' to native English speakers. Similarly, 'synonyms' to native English speakers may not 'synonyms' to Shakespeare.

If you quantify the similarity among words, say, you give a score to a pair of words to indicate their similarity, then you certainly can define that all pairs of words with degree of similarity more than 128.57 (just a mock up number) are 'synonyms' and all pairs of words with degree of similarity less than 13.78 are antonyms. Of course, different people may assign different scores between two words. An ESL student may assign 250.12 between 'wash' and 'clean': that makes them become 'synonyms'. Whereas you, an export in English language,may assign 110.01 or less between the same two words, which make them not 'synonyms' to each other.

So, I guess, my comment to your first question is that: yes, it does make sense to talk about 'synonyms' but at the same time, people also need to keep in mind that the degree of similarity is different for different people.

Best regards,

Chris

---
Tags: language-processing
---


# Question
Title: What is the mechanism behind recurring or looping thoughts?
I'm interested in what is the mechanism that explains the recurrence or looping of thoughts within a person's mind. Unless very strongly distracted, such thoughts can creep up back or mutate slightly while maintaining the same overall theme - action is required.

From my understanding both positive and negative thoughts can loop, although thoughts with the themes of fear, anxiety, compulsion or desire can be more disturbing when looping.

**What is the mechanism behind looping or recurring thoughts?** In particular I'm interested if such thoughts are chemically induced through a release of some kind of neuromodulator (like fight or flight response is based on Adrenaline).

A few examples, where rational thought is used to counter irrational fear or anxiety thought:

* Did I forget to do X?
* I really have to go to Y, but what if I did not do X?
* \[Imagination a horrible scenario when X is not done\]
* I better go check on X.
* Check on X reassures the person, resulting in no new thoughts creeping in.

What interests me is what happens when the person either cannot go and check or will incur significant cost for doing so (ex: being late to work) or will try to resist the urge to check. In this case recurring thoughts can eventually reemerge and start to invade one's awareness:

* Did I forget to turn the stove off?
* I really have to go to work.
* But the house can burn down
* I believe that nothing bad will come out of it
* You can't know that
* The stove has a pilot light - gas will just keep burning
* But the cat can jump on a stove and get burnt
* Cat is smarter than that
* But the house can burn down
* You can become homeless
* Do you have fire insurance?
* \[Repeat/mutate\]

# Answer
I think what you're talking about is **worry** and/or **rumination**, both of which describe a perseverative and repetitive thinking style (e.g., Watkins, 2008). Worry is future-oriented whereas rumination is past-oriented. We don't understand the mechanisms all that well at the level of analysis you're interested in, but I'll present some brain-level theories/data about these processes.

## Rumination

Rumination is associated with functional hyperconnectivity between the default mode network (DMN) and subgenual prefrontal cortex (sgPFC), which may be mediated by connections with the medial dorsal thalamus (Hamilton, Farmer, Fogelman, & Gotlib, 2015). The DMN is involved with affective self-referential thought and the sgPFC supports affective behavioral withdrawal. Together, the DMN and sgPFC might produce a ruminative state that is "self-focused, valenced, and withdrawn" (Hamilton et al., 2015, p. 227). Other analyses also reveal structural and resting state abnormalities associated with rumination, involving areas related to cognitive control (Kuhn, Vanderhasselt, de Raedt, & Gallinat, 2012). Rumination and cognitive control deficits (e.g., in working memory; Joormann, Levens, & Gotlib, 2011) are strongly related, explaining why trait ruminators have difficulties with disengaging from their repetitive, intrusive thoughts.

## Worry

Worry seems to be associated with increased activation of anterior cingulate and dorsal medial prefrontal cortex, involved with mentalizing and self-reflection. And pathological worry (in GAD) may be associated with prolonged activation of these areas, possibly representing difficulties inhibiting worrying thoughts (Paulesu et al., 2010). Hyperanxious individuals also tend to show greater amygdala and insula activity to emotional stimuli (Etkin & Wager, 2007). This may indicate that pathological worry arises from dysfunctional salience processing ("Is this stimulus biologically relevant to me?") and emotional processing/reactivity.
> 7 votes

---
Tags: cognitive-psychology, behavior, thought
---


# Question
Title: Is there a term to describe the tendency to attribute the cause of a bad outcome to a recent event?
I've noticed that when something goes wrong, people have a tendency or a bias to associate its cause with a recent event. The following may not be a great example but here goes.

Imagine a game of Jenga where players remove blocks from a tower. Early in the game I remove two blocks from near the bottom of the stack, destabilizing the foundation of the tower. We have some skilled players so we manage to make it four or five more moves before the tower falls. Although I destabilized the tower from the beginning, there will be those who perceive that the move prior to the last one was the main contributing factor.

I ask because this is a pattern that I see in my job and I'm trying to communicate it to someone. We see projects fail because the foundation work done months prior was not of good quality. Nevertheless, the blame seems to go to the last person who touched it. I can't help but think there is an established term that describes this psychology and would love to be able to reference it.

# Answer
I don't know of a single term for it, but what you're describing is, in essence, causal inference driven by "statistics", "co-variation", "co-occurrence", or "contiguity" (the terms are largely interchangeable).

If you're interested, there's a quite in-depth discussion review of theories of different theories of causal inference, including statistical models, here.

I think your example can be tied in quite nicely with "dual process" theories too, which propose two kinds of thinking: automatic, *intuitive* processes, which are sensitive to things like co-variation, and more effortful *reflective* processes, needed for more abstract relational reasoning. In your case, intuitive thinking easily makes a causal inference based on co-occurance:

> "Mark touched the tower, and then the tower fell, so the tower must have fallen because Mark touched it"

while more effortful reflection is needed to construct a causal model involving foundational work done months ago. I don't know of any specific application of this intuitive/reflective distinction to causal reasoning, but I'm sure it's been done somewhere.

**EDIT:** I've just remembered this paper, which discusses a similar idea, but in "multiple cue probability learning", a specific kind of causal learning. I feel a little obliged to plug this, because one of the authors is my PhD supervisor.
> 5 votes

# Answer
I think Daniel Kahneman calls this the Availability heuristic, a cognitive bias explaining the tendency to weigh more recent (more available) information as more pertinent when making beliefs, reasoning or drawing causal relations.
> 4 votes

# Answer
You can also research Aaron Beck and his principles of thinking distortions. In evidence based cognitive thinking models for thought and behavior changes it describes what you are referring to as a common thinking distortion called lack of time perspective. It defines it by explaining that when this thinking distortion is being used by an individual they are confusing cause and effect. In terms of criminal and addictive behavior the distortion allows a person to continually find justifications. Everyone has thinking distortions, the separation is between those who act on them and those who don't.
> 1 votes

---
Tags: cognitive-psychology, social-psychology
---


title: How to get anatomical masks?

text:
# Question
Title: How to get anatomical masks?
I recently read a paper called `"An automated labeling system for subdividing the human cerebral cortex on MRI scans into gyral based regions".` I want to use the method of this paper to apply to my dataset in order to get anatomical masks. I already installed fsl on my Linux system. But I still cannot fully understand this paper. Specifically, I want to get `Temporal Occipital Fusiform gyrus (TOFC)` and the `lateral occipital Cortex (LOC)` region of interest. Anyone can help me?

# Answer
> 5 votes
I'm a TMS, but not an fMRI, researcher but I have experience using anatomical masks. I can guide you through the steps to make an anatomical mask, but unfortunately I don't have any code to offer you.

First of all you need a set of x, y and z co-ordinates that specify where TOFC or LOC are. One way to find these is to find a paper that reports the x,y,z values corresponding to a voxel that contains the peak BOLD signal change co-ordinates within the LOC or TOFC. An alternatively way, might be to find some anatomical studies that provide these co-ordinates for you. I cannot recommend one or the other to you; this is a decision for you to make based on the analyses you are doing.

Once you have found some LOC or TOFC co-ordinates you are happy with, you can create a mask based on them using FSLView (type in fslview in the Linux terminal to open it).

First of all, open FSLView and open one of the standardized brain images. You can enter your TOFC or LOC co-ordinates (in MNI or Talairach space - I'd recommend MNI) in FSL using the x, y and z boxes in the bottom left corner. This will move a crosshair on top of the peak voxel. Then click file - create mask. This will enable you to use the toolbar, on this toolbar you will see an icon shaped like a pencil. Use it to mark voxel the crosshair is pointing at, making it sure it corresponds to the voxels you entered earlier. Do this separately for both site

You can then save this you will have an image containing an anatomical mask indicating where LOC and TOFC are. If this is unclear, try this blog - an fMRI researcher in my lab found it really useful.

http://andysbrainblog.blogspot.co.uk/2012/11/creating-masks-in-fsl.html

Good luck!

---
Tags: cognitive-neuroscience, cognitive-modeling, fmri
---


# Question
Title: Why are some people good at algebra and bad at geometry and vice versa?
I've met people who say they did very well in algebra but were terrible at geometry in high school and some people who say they did very well in geometry but were terrible at algebra in high school.

I'm curious if people who do well in geometry are right-brained thinkers while people who do well in algebra are left-brained thinkers? Why is there a difference in ability, when algebra and geometry are just branches of the same subject, mathematics?

# Answer
> 4 votes
In short, algebra and geometry are different type of cognitive abilities. Geometry is more spatial and algebra more verbal-logic.

Kestenbaum, C., Williams, T. D., Handbook of Clinical Assessment of Children and Adolescents, NYU Press, 1988.

# Answer
> 2 votes
I'm one of those people who was good at Geometry, but bad at Algebra. Eventually I caught up and was good at both. The question why did bother me for a long time, and it's good to see that I'm not alone.

It seems to me that middle and high school algebra is mostly about memorization. Typical questions have **only one solution**. You have to remember how to expand polynominals, and if you are faced with an equation and don't a specific rule, you are going to fail:

> What is the remainder when f(x) = (x - 2)54 is divided by x - 1?

In terms of Geometry, not only is it more visual, but **there are multiple ways to arrive at a solution**. Multiple rules can be applied in different order to arrive at a solution. It can take longer, be less effective, but a solution can be found.

---
Tags: mathematical-ability
---


# Question
Title: Can positive self-affirmation improve mood?
Most people get "depressed" every now and then - nothing serious, but people sometimes feel down. I am wondering if positive self-affirmation can make you happier by physically increasing the serotonin levels in your brain, or by some other mechanism.

**Can positive self-affirmation improve mood?**

# Answer
Self affirmations is a kind of meditation, that is a specific state of mind, guided consciously. This kind of activity itself amends the person into a more direct and ordered state, actively improving the balance between the functioning of the sympathetic and parasympathetic systems.

This brings in the feeling of improvement and serves as a reward which helps to repeat self affirmation again. The more calm and ordered state of body lends even more control to the intellect which starts solving things, which also improves mood. This is widely used in medicine, for example, during child birth where the women are instructed to breathe calm and control the breath, which brings improvements of vital importance.

That being said, it is impossible to say, if self affirmation is primal. Maybe the fact itself of the sympathetic system function subsiding, gives birth to the feeling of improvement which is verbally perceived as a positive self affirmation. However, if free will is real then positive self affirmation is a good way to manifest it.

In any way the mechanism is complex and involves changing brain EM rhythms, probably with many other processes coming into play.
> 1 votes

---
Tags: clinical-psychology, mood
---


# Question
Title: Why do people want what they don't have now?
There are many examples of people wanting what they don't have. For example, a single man may want to have a girlfriend, but after some time of having a girlfriend, he may want to be single again. Or for example, people in the city may want to live in the village and villagers may want to live in the city.

**What causes individuals to desire something they don't have and once they have it we desire to have something else -- or something which we left behind a while ago -- again?**

# Answer
The reason for desire or want or liking is Pleasure. Various people have various things to get pleasure: from Money, from Power, from Love etc. etc.

But this pleasure is always based on comparison. For ex: I may have money, power, wealth and love. I am satisfied with all these. When I encounter another person who has all these things but with another proportion, then I tend to "HAVE/POSSESS" that. The reason could be, "THAT" appears more pleasurable to me than what I have.

There is no absolute answer to this question 'Why man seeks pleasure? or Where it comes from?'. We may need to understand the nature of pleasure, how it occurs etc etc. Read this link and you may understand scientifically what is want/desire/liking/pleasure.

There is also a philosophical answer to your question which is related to mind. As put by Hindu philosophy, Mind always seeks pleasure. This pleasure, found in external things, is always in the form of self satisfaction. It feels happy with possession of things outside.

But once it turns inward and looks at itself, it understands its nature. This comes out of intelligence. Then it gradually seeks inner calmness rather external cravings. Resting in inner peace and calm is more happier and blissful to Mind. But it is under illusion that it finds pleasure in things in the external world. The reason being mind, as put by Hindu/Buddhist philosophers, identifies itself with the body and it thinks it has a separate individuality - "I", "ME","MINE". When there is a separation like this, automatically there is a comparison. When comparison exists, desire sprouts. You better read about mind in Google. Lot of notes and articles are there.
> 0 votes

# Answer
This is more along the lines of **novelty**.

As you mentioned, once you have it, you **want** something else you **don't have** and on and on and on it goes.

Reason being, once a subject acquires the object longed and desired for, the **novelty** level within the subject is diminished and must be refilled.

To be more specific, what needs to be refilled is dopamine. Novelty produces dopamine and dopamine is well know as the brain's fuel driving satisfaction. So remove that and guess what your going to try to reproduce?

Check out:
> 12 votes

# Answer
Why do we want what we don't have? There are **many different answers stemming from diverse theoretical approaches**. I will list a couple, drawing heavily on a older review by Lynn (1992) who has collected different ideas about why desirability can sometimes be increased when something is unavailable to us.

1. We perceive things that few people have as important **resources that signal social status**. This can be seen in people's tendency for **conspicuous consumption** (Veblen, 1899), in other words the tendency to buy positional goods, which promise being superior to others (e.g. Solnick & Hemenway, 1998)
2. Researchers such as Snyder and Fromkin (1977) posit that people can perceive similarity to others as a threatening. Therefore, scarce and unavailable things are desirable because they promise to fulfill a **need for uniqueness**.
3. Unavailable resources often imply that having them means to have **power** over others (Emerson, 1962)
4. Social comparisons can give rise to **specific emotions** that motivate us to seek things that are unavailable. People deliberately engage in downward comparisons (Wills, 1981) to enhance their self-esteem. Having something that not everybody has may thus give rise to **pride**. Upward comparisons with others (who have something we want) may cause **envy**, which can increase desire (Crusius & Mussweiler, 2012, Van de Ven et al. 2011)
5. **Scarcity** has been portrayed as a **heuristic cue that signals desirability** (Cialdini, 1993), for example, because rare things are perceived to have a higher quality (Ditto & Jemmott, 1989)
6. Sometimes, we don't have things because we are denied to have them. Such threats to our freedom cause **reactance** which **increases our desire** to have what we can't have (e.g., Brehm, Stires, Sensenig, & Shaban, 1966)
7. Trying to attain something which is difficult to get increases **arousal which fuels desirability** (Brehm et al, 1983)

It stands to reason, however, that we are often quite good in rationalizing why we don't want the things that we don't have (e.g., Kay, Jimenez, & Jost, 2002).

**References**

Brehm, J. W., Stires, L. K., Sensenig, J., & Shaban, J. (1966). The attractiveness of an eliminated choice alternative. Journal of Experimental Social Psychology, 2, 301–313. doi:10.1016/0022-1031(66)90086-2

Brehm, J. W., Wright, R. A., Solomon, S., Silka, L., & Greenberg, J. (1983). Perceived difficulty, energization, and the magnitude of goal valence. Journal of Experimental Social Psychology, 19, 21–48. doi:10.1016/0022-1031(83)90003-3

Brock, T. C. (1968). Implications of commodity theory for value change. In A. G. Greenwald, T. C. Brock, & T. M. Ostrom (Eds.), Psychological foundations of attitudes (pp. 243–275). New York: Academic Press.

Cialdini, R. B. (1993). Influence: Science and practice (3rd ed.). New York: HarperCollins.

Crusius, J., & Mussweiler, T. (2012). When people want what others have: The impulsive side of envious desire. Emotion, 12, 142–153. doi:10.1037/a0023523

Ditto, P. H., & Jemmott, J. B. (1989). From rarity to evaluative extremity: Effects of prevalence information on evaluations of positive and negative characteristics. Journal of Personality and Social Psychology, 57, 16–26. doi:10.1037/0022-3514.57.1.16

Emerson, R. M. (1962). Power-dependence relations. American Sociological Review, 27, 31-41.

Kay, A. C., Jimenez, M. C., & Jost, J. T. (2002). Sour grapes, sweet lemons, and the anticipatory rationalization of the status quo. Personality and Social Psychology Bulletin, 28, 1300–1312. doi:10.1177/01461672022812014

Lynn, M. (1992). The psychology of unavailability: Explaining scarcity and cost effects on value. Basic & Applied Social Psychology, 13, 3–7. doi:Article

Snyder R., C., & Fromkin, H. L. (1977). Abnormality as a positive characteristic: The development and validation of a scale measuring need for uniqueness. Journal of Abnormal Psychology, 86, 518–527. doi:10.1037/0021-843X.86.5.518

Solnick, S. J., & Hemenway, D. (1998). Is more always better? A survey on positional concerns. Journal of Economic Behavior & Organization, 37, 373–383. doi:10.1016/S0167-2681(98)00089-4

Van de Ven, N., Zeelenberg, M., & Pieters, R. (2011). The envy premium in product evaluation. The Journal of Consumer Research, 37, 984–998. doi:10.1086/657239

Veblen, T. (1899). The theory of the leisure class. Amherst, NY: Prometheus Books.

Wills, T. A. (1981). Downward comparison principles in social psychology. Psychological Bulletin, 90, 245–271. doi:10.1037/0033-2909.90.2.245
> 8 votes

# Answer
Why we want things is a very broad question. As to why we specifically want things we don't have, I commented in jest that it does not make sense to want something you already have. Basically if you attach value to something you have, you would say that you “like” it, not that you “want” it but the distinction might not necessarily reflect a difference in some fundamental psychological process.

The immediate reason could be that these things provide us with “reward” or “pleasure” – which is certainly often true at a phenomenological level and can possibly be associated with specific brain structures – but that's not explaining much. As Greg mentioned, there are also many empirical results and theories suggesting that, to a point, we seek novelty and stimulation for their own sake. That could be a reason to want things specifically *because* we don't have them already or at least in part because we don't have them already. (The idea is very old and has been expressed in various ways, e.g. the Yerkes-Dodson law.)

On the specific point of regret and wanting to go back, one thing is that we are not always good at gauging how we will feel about something we have not experienced yet. Research on this goes under the name “affective forecasting”. Once you have it/did it/experienced it, you might realize that it is not as good as you expected and reverse your decision (or not, incidentally). Also, the notion that we seek novelty implies that the novel stimulus will become less pleasurable with repetition (but the opposite process has also been observed, e.g. in “mere exposure” research). At some point, we might become “bored” and find any change attractive, even if it is to come back to something we tried before.
> 2 votes

# Answer
In economic terms this can also be defined in terms of marginal utility of a thing, experience etc (von Neumann and Morgenstern, 1944). As soon as you have (enough of) something and/or got used to having it, something novel and/or relativelively scarce that might be useful will seem attractive. Maybe because it's evolutionary fit to strive for the optimal combination to increase pleasure.

von Neumann J, Morgenstern O. Theory of Games and Economic Behavior. Princeton University Press; 1944.
> 1 votes

# Answer
Most frequently people want a different version of what they already have or have liked in the past. That's why there are countless "clones" of video games, movies and books.

Coolidge Effect explains why people devalue past sexual partners over time (as in your girlfriend example) and seek novel partners instead.

Another explanation is that people want whatever spikes their serotonin and dopamine reward systems the most.
> 1 votes

---
Tags: social-psychology, emotion, motivation, consumer-psychology
---


# Question
Title: How fast can the brain react in order for someone to pull a trigger?
Just out of curiosity, regardingly highly unlikely situations of ever needing to disarm someone - using neuroscience to make informed self defence decisions:

How fast can the brain recieve a visual or reflexive (seeing me beginning to move my hand, or feeling my hand hit the wrist -- I suspect the two impulses might have differing response times) signals from the body, to the moment of signaling the finger muscles?

# Answer
**Short answer**
The motor response latency to a visual stimulus is approximately 210 ms.

**Background**
You are basically asking for the **visually induced reaction time of a motor response**. Reaction times have been assessed many times in various studies. In a very recent study with an impressive subject population of more than 1400 (aged 18 - 65), the motor response latency to a visual stimulus was estimated at an average of 213 ms. Reaction times increased with age, but were unaffected by sex or educational level. Old age mainly affected the motor latency, and not so much the visual processing speed.

<sub>**Reference**
**-** Woods *et al*., *Frontiers Human Neurosci* (2015); **9**:131-12p</sub>
> 3 votes

# Answer
It seems that if response is trained enough long that it happens unconsciously. Also if you want to be precise in forms of neuroscience, if you have longer arms, but less myellinated neuro fibers then your reflexes will be slower then unconscious visual reaction.

Kibele, A., Non-consciously controlled decision making for fast motor reactions in sports—A priming approach for motor responses to non-consciously perceived movement features; Psychology of Sport and Exercise; November 2006, Pages 591–610

http://www.sciencedirect.com/science/article/pii/S1469029206000537
> 0 votes

---
Tags: reaction-time
---


# Question
Title: Why do dreams lose clarity quickly over time after we awaken?
Right after you wake up from a dream, you seem to be able to remember most if not all of the details. Then, over time, these details fade and often disappear.

Is this a form of regression? Why is it harder to solidify memories of dreams?

# Answer
> 16 votes
Short answer: Because areas of the brain needed for remembering are turned off during dreaming.

**Dream Amnesia:**

The process of converting perception into a memory construct that can be stored is called encoding, and is essentially the same during both wakefulness and sleep: That is, the same factors can hamper or promote successful encoding when awake or dreaming. During sleep, the brain undergoes cyclical changes in which activity in some parts of the brain increases (hyperactive), while other areas decrease in activity (hypoactive). Some areas of the brain associated with memory encoding are hypoactive during dreaming, resulting in most dreams being forgotten.

Red = hyperactive; Blue = hypoactive; F = prefrontal cortex

The most prominent area implicated in memory encoding of episodic memories is the prefrontal cortex (PFC). Activity in this region is correlated with memory in studies conducted in awake subjects, and is similarly correlated with dream amnesia: During dreaming, this area is typically hypoactive (turned off), and its level of activity is predictive of dream recall. Activity in the PFC during sleep may be modulated by levels of acetylcholine, dopamine, and other neurotransmitters.

**Vanishing Memory:**

Nir & Tononi (2010) review the issue:

> Unless the dreamer wakes up, most dreams are forever lost. Upon awakening, memory for the dream often vanishes rapidly unless written down or recorded, even for intense emotional dreams. It is not clear why this is the case since from a neuroimaging perspective, limbic circuits in the medial temporal lobe that are implicated in memory processes, are highly active during REM sleep. Perhaps the hypoactivity of prefrontal cortex, also implicated in mnemonic processes, plays an important role in dream amnesia.

Theoretically, waking up reactivates the areas of the brain that are turned off during sleep, allowing for memories to be encoded. This process is unreliable, as memory encoding in both awake and sleeping subjects is modulated by attention - also a function of the PFC - so how much and how well dream content is remembered also depends on how much attention is given to it during waking. Without attention, the memory trace fades quickly. This interpretation is consistent with the reduced dream recall in awakenings from deep (slow-wave) sleep, that are characterized by disorientation and lower PFC activity, and with higher dream recall of lucid dreaming, characterized by awareness, control, and higher PFC activity.

Note: The above is certainly an over-simplification of a complex and poorly understood system, but it does suggest that any factor affecting the processes involved in memory encoding and attention (such as certain neurotransmitters, psychoactive drugs, lesions, mood disorders, training, experience, etc) may impact dream recall. On the other hand, NMDA, a neurotransmitter involved in long-term memory consolidation (LTP) - a different activity that is increased (hyperactive) during dreaming - is less likely to be implicated in dream amnesia.

# Answer
> 7 votes
State dependent memory could play a role in quickly forgetting dreams after awakening.

See my question here: What is the scientific term for unexpected, spontaneous dream recall? I ask about a phenomenon where dream recall happens much later potentially weeks or months after awakening.

I would venture to hypothesize that **Melatonin** might play a role as a state dependent cue that alters the state of memory for recall. Melatonin supplementation can produce extraordinarily vivid dreams that rapidly lose their grandeur upon awakening and subsequent recall.

Personally I take a melatonin supplement at night and can drift off to sleep while recalling dozens of dreams (seems to correlate with melatonin levels rising). My understanding is that Melatonin is suppressed by blue light, so bright lights in the morning may rapidly reduce melatonin concentration and hamper recall.

# Answer
> 2 votes
My suggestion would be that, as with all forms of mental imagery, short-term working memory circuits are responsible for keeping dreamt images active, i.e. in consciousness. Distraction by competing perceptual representations would cause immediate disruption of one's dreamt images; without such distraction, imagery in short-term memory typically starts to rapidly fade after about 8 seconds, unless it's highly relevant to one's immediate situation on waking, and hence promptly acted on.

---
Tags: memory, consciousness, dreams
---


# Question
Title: Avoiding Cognitive dissonance,is it a necessity?
I want to know how strong is the pain of going through cognitive dissonance. Is it really so that changes in humans can be brought about by severity of cognitive dissonance struggle/pain ? Can I have a neurological perspective about it that might throw some light on the parts of the brain that are involved and the neurochemicals that might be playing a role in it ?

# Answer
> 1 votes
I think you're confusing science with politics. The APA and other such professional organizations have not, to my knowledge, concluded that cognitive dissonance should be avoided or even minimized. I'm unaware of any evidence that suggests that cognitive dissonance directly causes distress or suffering.

The position of psychology, as a science, is that cognitive dissonance is a phenomenon that exists and has certain properties. There is no normative stance from the field as a whole.

What happens in these cases is that political groups engage in activism and argue that such things should be minimized; the same is true of stereotyping, for instance. You may agree with the dominant political opinion, but it's not a scientific question, *per se*.

# Answer
> 0 votes
I will try to answer even if I'm not an expert, I hope who is willing to downvote will instead write his own better answer or improve this one.

I've experienced cognitive dissonance many times. It's something very annoying and easy to understand. Imagine a guy which has a wife. He loves her but he has a strong neurotic need to change her. He intuits he could change himself but he feels this task as really hard. She doesn't change of course. And she suffer from this guy trying to change her.

The guy feels guilty, he feel responsible of a bad action, but he doesn't like this feeling. This is the moment in which cognitive dissonance acts.. She should change. the guy will focus on the reasons why SHE is guilty to feel less guilty. It's not a real pain, it's an intense emotion..

The dissonance itself is a functional mechanism. The best action is to reduce the neurotic needs of him and her.

---
Tags: cognitive-psychology
---


# Question
Title: How does a human classify or cluster data?
Here, what I mean by DATA are text documents.

I am going to do a research on text clustering algorithms by the help of artificial neural networks (ANNs). But first of all I need to know how our brain (neural system) cluster (or classify) text data while we are reading a document.

Imagine we are reading some uncategorized and scattered news articles around the internet (For example on a weblog). Here, when we read an article, we'll easily find out that what it is about or what group it goes under: Politics, Sports, Economic, etc. We'll know it by the help of words inside the article, I know.

How does our brain cluster these data inside itself. How do we make clusters/categories inside our brain, and then assign data to them?

# Answer
> 2 votes
Here is an article written on a study on the measured effects of blood flow in the brain from "two hours of movie trailers that contained over 1,700 categories of actions and objects". A video (attached in the article) describes the methods used and the results of the study. They found that the brain tended to categorize things that shared similar functions or is-a relationships. This can be seen in the resulting chart, where the nodes representing "mammals", "people" and "communication verbs" are closely related. The brain also seemed to separate things that moved or were considered to be alive and inanimate objects.

This study was done using only 5 participants so it's fair to say that more research needs to be done before we can uncover more of the truth concerning this topic.

To answer your second question, regarding how information is stored in the brain, we need to understand a process called "encoding". I don't fully understand how this process works on a biological level, but as a gross explanation the brain stores sensory information it deems important and then goes through a secondary process called "consolidation". This process aims to stabilize the trace of a memory after it is initially encoded. The final process, "retrieval" is the act of remembering the information. During this stage the brain reconstructs the memory or information and thereby strengthens the neural pathway that makes up that memory.

So in short, the brain stores information through complex neural connections. These neural connections are tied to the sensory information that was initially perceived, which is reconstructed when you remember it.

Hope I was able to clear up some of your questions :)

---
Tags: cognitive-neuroscience, theoretical-neuroscience, neural-network
---


title: High Density Signal Meaning

text:
# Question
Title: High Density Signal Meaning
When I was reading an article, I found that it describes the EEG signal as a *high-density signal*. So what is that mean?

> EMG is high temporal resolution and moderate spatial resolution (comparable to high-density EEG)

# Answer
> 1 votes
"High-density EEG" refers to the number of electrodes in the array. Typically, any EEG rig with more than 64 electrodes is considered to be high-density electroencephalography.

---
Tags: eeg, signal-processing
---


# Question
Title: Why is my SPM batch job printing a warning repeatedly?
I'm aware of the ambivalence of cogsci.stacexchange with regards to asking questions about code, but this question really is about SPM, specifically, so I think that the domain-specific nature of my inquiry makes it suitable for this forum. I do apologize if this is in poor form.

I'm trying to run a custom batch script on some fMRI data. The relevant code is presented below:

```
cfg = config();  % a struct that holds a few parameters, namely paths and regexps

for isub = 1:length(cfg.subdir)
    subdir = cfg.subdir(isub);
    rundirs = fullfile(subdir, regexpdir(subdir, cfg.regex.rundir));

    matlabbatch{isub}.spm.spatial.realign.estwrite.data = regexpdir(fullfile(subdir), cfg.regex.funcscan);
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.quality = 1.0;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.sep = 4;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.fwhm = 5;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.rtm = 2;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.interp = 2;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.wrap = [0 0 0];
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.weight = '';
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.which = [0 1];  % [0 1] = create mean images only; [1 1] crt all imgs + mean
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.interp = 4;  % 4th degree bspline interp
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.wrap = [0 0 0];
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.mask = 1;
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.prefix = 'r';
end

```

This loop, which performs slice realignment for all subjects, is called via `spm_jobman('serial', 'myscript.m')` where `myscript.m` is the script shown above.

`regexpdir` is available on the matlab file exchange for those who wish to examine it, but it returns an Nx1 cell array of strings, which correspond to paths matched by the regex parameter.

Running this code doesn't seem to produce any errors, per se, but rather prints the following several thousand times:

```
Item 'Session', field 'val': Value must be either empty, a cellstr or a cfg_dep object.

```

The variable name `cfg_dep` makes me think of SPM's "dependency" construct, often used in the visual batch tool. The code above is taken from said visual batch tool's code exportation feature, so it's possible that I'm referencing a dependency that somehow got omitted when I refactored the exported code... but damned if I can find where...

Any thoughts or advice would be greatly appreciated!

# Answer
Below is a corrected version of the script. SPM seems to be quite finicky about the structure of the data passed to `matlabbatch{...}.spm.spatial.realign.estwrite.daat{...}`.

---

```
%%job_realign.m  SPM batch module.
% SPM's spm_jobman function will eval this file, and automatically launch a
% batch job if the parameters are valid.  Cryptic errors out of spm_jobman
% are usually an indication of a runtime error in batch modules.

%% Get configuration

cfg = config();

%% Get data
include = cfg.subdir(find(cfg.submask));

for isub = 1:length(include)
    subdir = include{isub};
    fprintf('In directory %s:\n', fileparts(subdir));

    runs = regexpdir(subdir, cfg.regex.rundir, false)';
    runs = [runs regexpdir(subdir, cfg.regex.locdir, false)'];
    runs = [runs regexpdir(subdir, cfg.regex.retdir, false)'];

    for irun=1:length(runs)
        rundir = runs{irun};
        scans = regexpdir(rundir, cfg.regex.funcscan, false);
        fprintf('Scans:  %d\n', size(scans, 1));

        matlabbatch{isub}.spm.spatial.realign.estwrite.data{irun} = scans;
    end

    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.quality = 0.9;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.sep = 4;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.fwhm = 5;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.rtm = 1;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.interp = 2;
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.wrap = [0 0 0];
    matlabbatch{isub}.spm.spatial.realign.estwrite.eoptions.weight = {''};
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.which = [0 1];    % [0 1] creates mean image only; [1 1] creates all images + mean
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.interp = 4;       % 4th degree B-Spline interpolation
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.wrap = [0 0 0];
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.mask = 1;
    matlabbatch{isub}.spm.spatial.realign.estwrite.roptions.prefix = 'r';
end

```
> 3 votes

---
Tags: fmri, spm, analysis
---


# Question
Title: What happens in your brain when you see a dinosaur in this stenographic image?
You might have come across stereographic Images like the one shown below (found here):

* What happens in your brain when you observe the dinosaur? (as you put your face on the image by touching your nose and then slowly withdrawing from the image.)
* Is this perception a particular trick that my eye performs or is it processing the visual data in an alternative way?
* Is the effect of this percept measurable by an EEG?

# Answer
The source I have quoted below gives an example of the following stenographic image:-

**Is this perception a particular trick that my eye performs or is it processing the visual data in an alternative way?**

> Stereograms can be viewed as three-dimensional images by providing two side-by-side views of a three-dimensional scene, rendered from slightly different viewpoints. Stereoscopes facilitate focusing of the eyes depths other than the surface of a two-dimensional stereogram image, allowing the two separate images to overlap in the center of the field of vision (Kimmel, 2002). Once the correct depth is achieved, it may seem to the viewer as if the two images are different due to the horizontal retinal disparities. Then the two images can fuse into a coherent three- dimensional percept where horizontal disparities in the images provide important depth cues.

**Is the effect of this percept measurable by an EEG?**

> Autostereograms have been used in recent research to investigate three-dimensional depth perception. These efforts have improved understanding of the various visual cues involved in forming three-dimensional percepts, perceiving motion in depth, attention- switching in the depth of field, and the neural correlates of forming and maintaining a unified three-dimensional structure in awareness.
>
> Revonsuo and colleagues (Revonsuo, et al., 1997) used neural synchronization to investigate the neural correlates of three-dimensional percept formations. They confirmed that autostereoscopic perception is primarily mediated by right parieto-temporal activity. Their research indicated a region of synchrony spanning portions of the right temporal, parietal and occipital lobes, with maximum power in the gamma (36-44Hz) frequency range. Also employing electroencephalogram (EEG) recording, Burgess, Rehman, and Williams (2003) located particular brain regions, including the left frontal (F7) and the right and midline occipital (Oz, O2) clusters, exhibiting functional clustering during autostereoscopic perception. Overall, neural complexity was highest with the most functional clustering of responses during observer awareness of the three-dimensional object. Additional clustering analyses revealed functional clusters of scalp recordings in the aforementioned areas that correlated with both phases of three-dimensional perception (search to three-dimensional and three-dimensional maintenance).

---

**Sources**
> 11 votes

---
Tags: perception, vision, eeg, optical-illusion
---


# Question
Title: Attributing change in DV to IV manipulation: between-groups (control group) vs mixed-model (pre&post measure)
One often sees researchers attributing a change in the dependent variable to their experimental manipulation, semingly without considering whether this change in DV occurs between or within groups.

For instance, in the classical Bargh et al. (1996) paper on behavioural priming, subjects in an experimental group were shown word primes recalling stereotypes of old age (e.g. "forgetful"), while subjects in a controlg group were shown neutral words. Everyone's walking speed as they left the experiment was measured, and because the first group's was slower, it was concluded that priming people with words relating to a certain concept (in this case: old age) makes them unconsciously take on characteristics of that concept (in this case: walking more slowly).

The question that comes to my mind is, however: how do we know that the mean difference in walking speed is not just due to pre-existing (baseline) differences between the groups? How can we be sure it is due to the IV manipulation (different word primes)?

To me, believable evidence for this claim would be if they had measured everyone's speed pre&post-experiment, and then found an interaction showing that, while controls' speed stayed the same pre-to-post, that of the old-age-primed group had decreased. Without such an interaction (involving the use of a mixed between-within model), is the authors' between-groups-only inference statistically correct?

# Answer
> 3 votes
There's a short straightforward answer, and a more nuanced answer.

The **short answer** is that people were *randomly assigned* to the two groups. Any baseline differences between people will be equally likely to affect both groups. Will there still be differences? Absolutely. This is why researchers use statistical inference to rule out the possibility that baseline differences are responsible for the observed difference.

The **more nuanced answer** is that we can't be certain that the observed differences aren't due to these random baseline differences. In any experiment, there will always be noise that causes differences in the groups. When researchers use statistical inference, they aren't able to say with certainty that the effect was due to the manipulation. They are merely assessing the probability that random noise could account for the data. If the probability that random noise can explain the data is very low, then researchers claim that the manipulation had an effect. However, this is a probabilistic inference and sometimes the researchers will be wrong and the difference really is due to noise. Within-subject designs help remove some of this noise, but not all of it, because people change over time, even over the short timescale of a social priming experiment.

# Answer
> 2 votes
Excuse my english, I'll try my best to explain. The key concept here is "randomization", which involves randomly allocating the subjects across the different groups. If randomization is well done, this ensure that your groups are "equivalent" on all other factors that have not been explicitly accounted for in the experimental design. Thus, in theory, there should not be any difference in your pre-test betweens groups, and the difference between groups in the post-test should only be accounted by the manipulation of your VI.

---
Tags: experimental-psychology, statistics, priming
---