# Question
Title: Do people like those who are similar to them and why?
### Questions

* Is it true that people 'like' those who are similar to them?
* Why is it so? Is there an evolutionary explanation?

# Answer
You may want to read up about "homophily". It is often summarised with the phrase "birds of a feather flock together". "Heterophily" relates to when people are attracted to those that are different to them.

There was a review article by McPhereson et al (2001) which you might like to read. To quote the abstract:

> Similarity breeds connection. This principle—the homophily principle—structures network ties of every type, including marriage, friendship, work, advice, support, information transfer, exchange, comembership, and other types of relationship. The result is that people’s personal networks are homogeneous with regard to many sociodemographic, behavioral, and intrapersonal characteristics. Homophily limits people’s social worlds in a way that has powerful implications for the information they receive, the attitudes they form, and the interactions they experience. Homophily in race and ethnicity creates the strongest divides in our personal environments, with age, religion, education, occupation, and gender following in roughly that order. Geographic propinquity, families, organizations, and isomorphic positions in social systems all create contexts in which homophilous relations form. Ties between nonsimilar individuals also dissolve at a higher rate, which sets the stage for the formation of niches (localized positions) within social space. We argue for more research on: (a) the basic ecological processes that link organizations, associations, cultural communities, social movements, and many other social forms; (b) the impact of multiplex ties on the patterns of homophily; and (c) the dynamics of network change over time through which networks and other social entities co-evolve.

### References
> 10 votes

# Answer
Since you mentioned that you want an evolutionary explanation, there is one available. In biology the effect of providing benefit towards potential non-kin based on an arbitrary marker is known as the green-beard or armpit effect. In a social human setting, if the marker is arbitrary social construct it is usually known as ethnocentrism. This sort of behavior is studied in game theory in the context of cooperate-defect games (typical example: Prisoner's dilemma) and usually called *conditional altruism*.

It has been shown that conditional altruism evolves in a simple spatial agent-based model and promotes cooperative behavior (Hammond & Axelrod, 2006a 2006b). The effect does not create cooperation, but if there is another mechanism for creation of cooperation (say spatial factors in the H&A model) then ethnocentrism helps maintain it and extend the range of parameters under which cooperation can occur (Kaznatcheev & Shultz, 2011).

In humans, this ability to cooperate only with others of similar culture is believed to require a significant amount of cognitive ability. In fact, some even suppose that it could have been one of the factors that drove towards the increasing complexity of our brains. Unfortunately, Kaznatcheev (2010a) shows that the ethnocentrism of the sort present in the H&A models is not robust to increase in the cost of cognition. Thus, in humans (or simpler organisms) the mechanism allowing discrimination has to have been in place already (and not co-evolved) or be very inexpensive.

The above examples dealt with the prisoner's dilemma (PD) which is a typical model of a competitive environment. In the PD cooperation is irrational, so there conditional altruism allowed the agents to cooperate irrationally (thus moving over to the better social payoff), while still treating those of a different culture rationally and defection from them. This doesn't seem as bad, but Kaznatcheev (2010b) shows that the mechanism of ethnocentrism is robust across different games (not just PD) including ones where cooperation is rational. In those games conditional altruism produces an irrational defection from the out-group. Thus, from an evolutionary stand-point this is a two-edged sword: it can cause unexpected cooperative behavior, but also irrational hostility.

### References

* Hammond, R., & Axelrod, R. (2006a). Evolution of contingent altruism when cooperation is expensive. Theoretical Population Biology, 69, 333-338.
* Hammond, R., & Axelrod, R. (2006b). The evolution of ethnocentrism. Journal of Conflict Resolution, 50, 926-936. (pdf)
* Kaznatcheev, A. (2010a). The cognitive cost of ethnocentrism. In S. Ohlsson & R. Catrambone (Eds.), Proceedings of the 32nd annual conference of the cognitive science society. (pdf)
* Kaznatcheev, A. (2010b). Robustness of ethnocentrism to changes in inter-personal interactions. Complex Adaptive Systems - AAAI Fall Symposium. (pdf)
* Kaznatcheev, A., & Shultz, T.R. (2011). Ethnocentrism Maintains Cooperation, but Keeping One's Children Close Fuels It. In L. Carlson, C, Hoelscher, & T.F. Shipley (Eds), Proceedings of the 33rd annual conference of the cognitive science society. (pdf)
> 13 votes

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Tags: social-psychology, evolution
---


# Question
Title: Using natural language processing for traffic monitoring from video
I am stuck trying to learn how to use video processing as explained in the linked papers in the area of human behavior detection or traffic surveillance (any kind of monitoring activity). In particular, I do not know how to formulate the problem using any available models.

I have found two papers (Haag & Nagel (2000; Paper 1) and Arens, Gerber, & Nagel (2008; Paper 2)) which illustrate, with an example, using natural language for traffic monitoring by using image sequences of videos. My question are

1. Under what assumptions are the actions generated?What is the advantage of nlp here or in any application apart from the fact that it gives a hierarchical representation of information/knowledge?
2. How are the actions and graphs (labelled as Situation Graph Trees by the author) generated (under what assumptions) in Fig2 of Paper 1 and Fig1 of Paper 2?
3. Has the Table5 in paper1: Incremental recognition of traffic situations from video image sequences and subsequent tables been generated using some programming tools?

### References

Haag, M., & Nagel, H.-H. (2000) "Incremental recognition of traffic situations from video image sequences". *Image and Vision Computing* 18(2): 137-153.

Arens, M., Gerber, R., & Nagel H.-H. (2008) "Conceptual representations between video signals and natural language descriptions". Image and Vision Computing 26: 53–66.

# Answer
I think you misunderstood, in a lot of ways, what Haag & Nagel (2000; what you call Paper 1) did and how Arens, Gerber & Nagel (2008; Paper 2) extended it. Fig. 1 of AGN08 is a good summary of HN00. What HN00 did was build a system that could watch a video of an intersection, detect cars, and translate the car behavior into a conceptual framework. As inspiration for their system, they used their idea of how humans represent the task:

> ﬁve levels of representation seem to be involved: (i) a representation of the geometry of spatiotemporal developments in the road traﬃc scene, comprising both a 2D-one in the image plane and a 3D-one relating to the depicted scene, (ii) a representation of driving maneuvers closely coupled to particular traﬃc situations, (iii) a conceptual representation of visible bodies, their attributes, and their elementary movements, (iv) generic conceptual representations of spatiotemporal body conﬁgurations and their expected temporal developments, and (v) one or more versions of a natural language representation of developments centred around the current point in time.

In other words, the goal of HN00 was to look at a 2D image of an intersection, from it construct a 2D/3D representation of the scene. In that scene identify and label objects and describe them in a conceptual language called SIT++. Once in that conceptual representation (as situation trees) they could conduct logical inference (using Fuzzy Metric Temporal Horn Logic) on their representation in order to decide what the agents they identified are trying to do.

Note that HN00 involved no natural language processing (NLP) at all. Although they did have to use lots of pattern recognition and various machine learning algorithm that would be familiar to NLP practitioners. However, their domain was transforming a visual scene into a conceptual (not natural language) internal representation.

How did AGN08 extend beyond this? They changed what they wanted to do. Their task was not simply to view a scene and transform it into an internal representation, but to then output that internal representation in a **natural language description**. Thus, they were adding a natural language generation system to HN00. Generating natural language from an internal representation is obviously an important part of NLP.

In the process of adding this functionality, AGN08 had to extend the internal representation in several ways. This was due to the fact that more internal information was required to generate good natural language output, and because they wanted to deal with more complex scenes than HN00. The paper focuses on this aspect of the work (extending the internal representation) and only tangentially touches on natural language output. They go into detail of the natural language output in:

R. Gerber, Naturlichsprachliche Beschreibung von Straßenverkehrsszenen durch Bildfolgenauswertung. Dissertation,Fakultat fur Informatik der Universitat Karlsruhe (TH), Karlsruhe, January 2000

Unfortunately, I am not willing to learn German and read a whole thesis in order to give you a more complete answer about the details. Before you try to do that yourself (hopefully you already know German) or look into more recent papers, I recommend learning some basics of NLP. A good source is the following question:

Looking for a good beginners reference to learn computational linguistics
> 3 votes

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Tags: cognitive-modeling, computational-modeling, agent-based-modeling, nlp
---


# Question
Title: How do responses to Likert type response scales vary across countries and cultures?
I gave an answer here on stats.stackexchange.com about how to analyse ordinal items, such as those on Likert type response scales (e.g., Strongly disagree to Strongly agree). Someone asked whether there were differences between countries and cultures in how respondents use such scales. I remember reading research about this many years ago. I can remember something about certain countries preferring extreme responses. Such differences naturally have implications for cross-cultural comparisons of levels of like life satisfaction, personality, and presumably any self-report measure that uses such response scales.

### Questions

* How does use of Likert type response scales vary across countries and cultures?
* What explains any such differences?
* How are differences in response style differentiated from differences in levels of the underlying construct?

# Answer
> 6 votes
### Culture reference effects

Heine et al (2002) discuss how people in different cultures often answer questions relative to a reference group in their own culture. Thus, for example, if a culture is more collectivistic in general, measured cultural differences may less when people within a culture answer test items relative to their own cultural reference group.

To quote the abstract:

> Social comparison theory maintains that people think about themselves compared with similar others. Those in one culture, then, compare themselves with different others and standards than do those in another culture, thus potentially confounding cross-cultural comparisons. A pilot study and Study 1 demonstrated the problematic nature of this reference-group effect: Whereas cultural experts agreed that East Asians are more collectivistic than North Americans, cross-cultural comparisons of trait and attitude measures failed to reveal such a pattern. Study 2 found that manipulating reference groups enhanced the expected cultural differences, and Study 3 revealed that people from different cultural backgrounds within the same country exhibited larger differences than did people from different countries. Crosscultural comparisons using subjective Likert scales are compromised because of different reference groups. Possible solutions are discussed.

### Cultural differences in response tendencies

Lee et al (2002) summarised some of the empirical literature on cross-cultural differences in use of response scales:

> Only a few researchers have addressed the issue of cultural differences in rating scales empiri- cally. Wong, Tam, Fung, and Wan (1993) found no difference in the way Chinese participants in Hong Kong responded to an odd versus an even number of response choices. Johnson (1981) found no difference in how readers of Horizons USA who resided in Great Britain, Italy, the Philippines, and Venezuela responded to bipolar scales. Stening and Everett (1984) found that Japanese managers responding in Japanese were more likely to choose the midpoint than were American or British managers responding in English. Chen, Lee, and Stevenson (1995) found the same effect for Japanese and to a lesser extent for Taiwanese in a sample comparing 11th-grade students in Japan, Taiwan, Canada, and, in the United States, Minneapolis. Iwata, Saito, and Roberts (1994) and Iwata, Roberts, and Kawa- kami (1995) reported that junior high school students in Japan and the United States responded similarly on negative items but that Japanese were less likely to endorse positive items.

When reviewing the literature on cross-cultural differences in response style Hamamura et al (2008) stated that:

> Compared to North Americans of European-heritage, higher levels of extreme responding have been observed in African–Americans (Bachman & O’Malley, 1984) and Latino Americans (Hui & Triandis, 1989). In contrast, East Asians seem to show more moderacy than samples of European-heritage (Chen, Lee, & Stevenson, 1995)

### References

* Bachman, J. G., & O’Malley, P. M. (1984). Yea-saying, nay-saying, and going to extremes: Black–white diﬀerences in response styles. Public Opinion Quarterly, 48, 491–509.
* Chen, C., Lee, S. Y., & Stevenson, H. W. (1995). Response style and cross-cultural comparisons of rating scales among East Asian and North American students. Psychological Science, 6, 170–175.
* Hamamura, T., Heine, S.J. & Paulhus, D.L. (2008). Cultural differences in response styles: The role of dialectical thinking. Personality and Individual Differences, 44, 932-942.
* Heine, S.J. and Lehman, D.R. and Peng, K. and Greenholtz, J. (2002). What's wrong with cross-cultural comparisons of subjective Likert scales?: The reference-group effect. *Journal of personality and social psychology, 82*, 903, PDF
* Hui, C. H., & Triandis, H. C. (1989). Eﬀects of culture and response format on extreme response style. Journal of CrossCultural Psychology, 20, 296–309.
* Iwata, N., Roberts, C.R., & Kawakami, N. (1995). Japan–U.S. comparison of responses to depression scale items among adult workers. Psychiatry Research, 58, 237–245.
* Iwata, N., Saito, K., & Roberts, R.E. (1994). Responses to a self-administered depression scale among younger adolescents in Japan. Psychiatry Research, 53, 275–287.
* Johnson, J.D. (1981). Effects of the order of presentation of evaluative dimensions for bipolar scales in four societies. Journal of Social Psychology, 113, 21–27.
* Lee, J.W. and Jones, P.S. and Mineyama, Y. and Zhang, X.E. (2002). Cultural differences in responses to a Likert scale. Research in nursing & health, 25, 295-306.
* Stening, B.W., & Everett, J.E. (1984). Response styles in a cross-cultural managerial study. Journal of Social Psychology, 122, 151–156.
* Wong, C.S., Tam, K.C., Fung, M.Y., & Wan, K. (1993). Differences between odd and even number of response scale: Some empirical evidence. Chinese Journal of Psychology, 35, 75–86.

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Tags: measurement, cross-cultural-psychology, attitudes
---


# Question
Title: Whether to ask satisfaction and importance questions for each item in a survey?
Job satisfaction and opinion surveys ask respondents to provide ratings on a set of items. One response scale might be a five point rating scale measuring satisfaction (e.g., 5-point strongly dissatisfied to strongly satisfied) with the item content (e.g., "Opportunities for promotion"). Some tests also gather for each item "importance" ratings.

* What are the psychometric properties of importance versus satisfaction scales?
* To what extent is the incremental information provided by importance ratings justified?

# Answer
### Computing overall satisfaction

There is discussion in the literature about whether measures of overall satisfaction should be calculated as some form of weighted composite of facet satisfaction where weights are derived from importance ratings. These debates have been applied to various types of satisfaction including life, job, and customer. In this context, it does not seem like weighting by importance makes much difference, and it may even be detrimental.

For examples, Trauer et al (2001) state that:

> Many Quality of Life (QoL) instruments ask respondents to rate a number of life domains in terms of satisfaction and personal importance, and derive weighted satisfaction scores by multiplying the two rat- ings. This paper demonstrates that this practice is both undesirable and unnecessary. QoL domains are selected on the basis of their inherent importance, rendering separate importance rating partially redun- dant. Weighted scores present difficulties in interpretation. Further, we show that multiplicative composites have undesirable psychometric properties. There is evidence that multiplicative composites have little or no advantage over unweighted ratings in correlational or predictive studies. Apart from the face validity and the intuitive appeal of multiplying satisfaction ratings by importance ratings, there appear to be no sound reasons for doing so, and several good reasons not to do so.

A similar critique of importance ratings in the job satisfaction domain can be seen in Blood (1971).

Nonetheless, this all assumes that importance measurement is a means for forming an overall composite. In some instances, measurement of importance is of substantive interest. Trauer et al (2001) acknowledge this when they write:

> It is not suggested that the assessment of the importance of domains of satisfaction is inconsequential. It has been shown that domains that are closer to the personal core (e.g. health, marriage, family) are typically judged as more im- portant than more peripheral domains (e.g. membership of organizations)...

### Study of mean importance ratings

Importance ratings can be used to assess average perceptions of importance which might inform causal hypotheses regarding what is influencing satisfaction.

Take for example, Rice et al (1991) among many other things, they report importance ratings of various job facets. Among other things the authors asked 97 employed college students to rate

> facet importance on a 9-point scale with two verbal anchors: not at all important and extremely important (e.g., "How important to you is the amount of opportunity for promotion?").

If we sort the results reported in Table 1 by importance we see the following:

```
Job Facet                     Mean Importance
Hourly pay (dollars)              7.4
Hours per week                    7.3
Control over schedule             7.3
Opportunity to learn skills       6.7
Decision making                   6.4
Promotion opportunity             6.3
Mental effort required            6.1
Conversation with co-workers      6.0
Customer or client contact        5.7
Physical effort required          5.4
Supervisor contact                5.3
Commuting time (minutes)          4.3

```

This is presumably an interesting empirical finding in itself.

### Relationship between importance and satisfaction

Some researchers have explicitly studied the relationship between importance and satisfaction to see whether there is a relationship. E.g., Borg (1991) provides an example of job satisfaction exploring how intra-individual variability in facet job satisfaction relates to facet importance. They find support both for the idea that more important facets are deemed more satisfying and for a u-shaped relationship where it is the most and least satisfied facets that are the most important. This variation depends on the domain being studied.

### References

* Blood, M.R. (1971). The validity of importance.. Journal of Applied Psychology, 55, 487.
* Borg, I. (1991). On the relationship between importance and satisfaction ratings on job aspects. Applied Psychology, 40, 81-92.
* Rice, R.W., Gentile, D.A. & McFarlin, D.B. (1991). Facet importance and job satisfaction.. Journal of Applied Psychology, 76, 31.
* Trauer, T. & Mackinnon, A. (2001). Why are we weighting? The role of importance ratings in quality of life measurement. Quality of life research, 10, 579-585.
> 2 votes

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Tags: social-psychology, io-psychology, measurement, attitudes
---


# Question
Title: What is the correlation between objective indexes and aggregated self-report measures of life satisfaction?
The Better Life Index and other indices seek to overcome the limitations of GDP in assessing social progress. They provide a composite score with which to rank nations on a range of indicators such as safety, environment, health, employment, economic activity, and so on.

Other researchers obtain self-report measures of happiness of life satisfaction (e.g., Diener's popluar Satisfaction with Life Scale). With care these scales can be aggregated over individuals to form a group-level measurement. For example, with careful sampling, a nation level estimate can be obtained.

I'm curious about these things:

* What is the correlation between aggregated self-report measures and objective indexes of life satisfaction?
* What explanation is provided for the size of the correlation in terms of how they are similar or different in what they measure?

# Answer
The World Values Survey seems like a good starting point for examining nation level life satisfaction and then correlating it with other indicators.

Diener (2000) summarises this research on

> mean levels of life satisfaction for selected nations from the World Values Survey (World Values Study Group, 1994), conducted with representative samples of approximately 1,000 respondents per nation between 1990 and 1993. The purchasing power parity figure is the percentage of purchasing power (based on a standard "basket" of goods) that the average person in each country can buy with his or her yearly income, compared with the average purchasing power of individuals in the United States. The **correlation between mean purchasing power income and mean life satisfaction was .62 across all nations in the survey**. The finding that wealthier nations have higher levels of reported well-being has been replicated several times (see Diener & Suh, 1999). One reason that wealthy nations may be hap- pier is that they are more likely to fulfill basic human needs for food, shelter, and health, as well as to have better human-fights records (Diener et al., 1995).

### OECD Life Index

I performed a quick analysis of data from up to 36 countries from the OECD Better Life Index Site. You can download the datafile used directly from http://www.oecdbetterlifeindex.org/. The R code, data file, and output of this draft set of analyses is available here, along with a list of the included countries.

I obtained the following correlations between other variables and self-reported life satisfaction (r is correlation; n is number of countries):

```
##                                               r  n
## Rooms.per.person                           0.70 30
## Personal.earnings                          0.67 34
## Employment.rate                            0.63 36
## Households.income                          0.59 32
## Water.quality                              0.59 36
## Long.term.unemployment.rate               -0.58 34
## Self.reported.health                       0.58 34
## Life.expectancy                            0.57 36
## Dwellings.with.basic.facilities            0.54 32
## Social.network                             0.50 36
## Time.devoted.to.leisure.and.personal.care  0.43 21
## Household.financial.wealth                 0.41 31
## Voter.turn.out                             0.36 36
## Educational.attainment                     0.22 35
## Students..skills                           0.21 36
## Air.pollution                             -0.18 36
## Housing.expenditure                        0.12 32
## Years.in.education                         0.12 35
## Consultation.on.rule.making                0.12 35
## Employees.working.very.long.hours         -0.09 33
## Job.security                               0.08 32
## Homicide.rate                             -0.07 36
## Assault.rate                              -0.02 36

```

### References

* Diener, E. (2000). Subjective well-being: The science of happiness and a proposal for a national index. American psychologist, 55, 34.
* Diener, E., Diener, M., & Diener, C. (1995). Factors predicting the subjective well-being of nations. Journal of Personality and Social Psychology, 69, 851-864.
* Diener, E., & Sub, E. (1999). Societies we live in: International compar- isons. In D. Kahneman, E. Diener, & N. Schwarz (Eds.), Well-being: The foundations of hedonic psychology (pp. 434-452). New York: Russell Sage Foundation.
* World Values Study Group. (1994). World Values Survey, 1981-1994 and 1990-1993 \[Computer file, ICPSR version\]. Ann Arbor, MI: Institute for Social Research.
> 1 votes

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Tags: social-psychology, well-being, cross-cultural-psychology
---


title: Is The magical number 7 still valid?

text:
# Question
Title: Is The magical number 7 still valid?
George A. Miller published *"The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information"* in 1956 and is one of the most highly cited papers in psychology. It *supposedly* argues that the number of objects an average human can hold in working memory is 7 ± 2. This is frequently referred to as Miller's Law.\[1\]

I've learned this in school as well, and I often use the magic number seven when it comes to grouping of elements in more logical units. However recent research question Miller's Law stating that the correct number a human being can hold in working memory is three or four\[2\]. In my daily life, I can see that this is more likely. When I go shopping, I need to write a shopping list if there are more than four things I need to buy and by this not forget what it was I'm supposed to buy. *One could argue that my working memory is worse than average, but I would never agree to such a statement.*

But the question remains and is puzzling my mind... **Is The magical number 7 still valid?**

---

\[1\] Wikipedia article on Miller's Law

\[2\] Jeanne Farrington EdD, *"Seven plus or minus two"*

# Answer
As far as I recall, the "magic" of the number seven is that George Miller had to give a 1h-presentation while not having enough research on one particular topic to talk about this long. So he tried to connect unrelated lines of research, with the only connection between them being that they show cognitive limitations of similar magnitude ("7+/-2 items"). However, the comparison was not very serious and mostly rhetorical. So I guess the short answer is: No it is not valid, and it has never really been.

Here is an short article that answers your question in more detail:

> Cowan, N., Morey, C.C., & Chen, Z. (2007). The legend of the magical number seven. In S. Della Sala (Ed.), Tall tales about the mind & brain: Separating fact from fiction (pp. 45-59). Oxford, U.K.: Oxford University Press.

And here is Millers original article, it's actually fun to read:

> Miller, G. A. (1956). "The magical number seven, plus or minus two: Some limits on our capacity for processing information". Psychological Review 63 (2): 81–97.
> 33 votes

# Answer
Most others have already pointed to some great papers on this and the fact that the literature has moved on from these claims now (as usual, 'bold' claims so often end up being false), but there's a great and very recent review on visual memory by Brady etal (2011) that gives a great deal of detail and is available via open access online here :

To quote the abstract:

> Traditional memory research has focused on identifying separate memory systems and exploring different stages of memory processing. This approach has been valuable for establishing a taxonomy of memory systems and characterizing their function but has been less informative about the nature of stored memory representations. Recent research on visual memory has shifted toward a representation-based emphasis, focusing on the contents of memory and attempting to determine the format and structure of remembered information. The main thesis of this review will be that one cannot fully understand memory systems or memory processes without also determining the nature of memory representations. Nowhere is this connection more obvious than in research that attempts to measure the capacity of visual memory. We will review research on the capacity of visual working memory and visual long-term memory, highlighting recent work that emphasizes the contents of memory. This focus impacts not only how we estimate the capacity of the system—going beyond quantifying how many items can be remembered and moving toward structured representations—but how we model memory systems and memory processes.

### References

* Brady, T.F., Konkle, T. & Alvarez, G.A. (2011). A review of visual memory capacity: Beyond individual items and toward structured representations. Journal of Vision, 11. FULL TEXT
> 11 votes

# Answer
While their answer may not be any more useful in everyday life and while the results are within the specific domain of visual short-term memory, Sims, Jacobs, & Knill, 2011 provide a more detailed (and less arbitrary) answer than either "7 +/- 2" or "about 4" items by using rate distortion theory to model optimal lossy compression.
> 10 votes

# Answer
Pavel has already given a pretty good answer, and I agree that not even Miller was very serious about 7 +/- 2 being a useful or accurate conclusion. As for the limit of three or four items that was suggested in the question, I'm not entirely certain about that myself, as it still isn't entirely clear what constitutes an "item", nor is it clear how information on items is stored in working memory.

I'd recommend looking at the current debate between the "Discrete-Slots" and "Distributed Resources" models of Working Memory (which is far from being resolved) to get a better understanding of the issue. Some good examples include work by:

* Luck and Vogel "The capacity of visual working memory for features and conjunctions" (1997, Nature)
* Bays and Husain "Dynamic Shifts of Limited Working Memory Resources in Human Vision" (2008, Science)
* Awh, Barton, and Vogel "Visual working memory represents a fixed number of items regardless of complexity" (2007, Psychological Science)
* Bays, Catalao, and Husain "The precision of visual working memory is set by allocation of a shared resource" (2009, Journal of Vision)
* Gorgoraptis, Catalao, Bays, and Husain "Dynamic updating of working memory resources for visual objects" (2011, The Journal of Neuroscience)
* Rouder, Morey, Cowan, Zwilling, Morey, and Pratte "An assessment of fixed-capacity models of visual working memory" (2008, Proceedings of the National Academy of Sciences)
* Wheeler and Treisman "Binding in short-term visual memory" (2002, Journal of Experimental Psychology: General)
* Wilken and Ma "A detection theory account of change detection" (2004, Journal of Vision)
* Zhang and Luck "Discrete fixed-resolution representations in visual working memory" (2008, Nature)

That being said, measures of "effective" capacity, such as Cowan's K (Cowan "The magical number 4 in short-term memory: A reconsideration of mental storage capacity", 2001, Behavioral and Brain Sciences) suggest that the capacity of visual working memory is about 4.
> 10 votes

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Tags: memory
---


# Question
Title: How does evolution help in Minsky's theory of a resourceful mind?
I've read Minsky's book *The Emotion Machine*, where he explains how the mind can be seen as a set of resources interacting and self-interacting based on several levels of change. The explanation is in fact a little deeper, but I won't be able to do the book justice in three sentences.

However, it seems to me that when it comes down to the *why*, Minsky backs himself up by saying "evolution did so", but hasn't provided tests or studies that verify such claims.

**How does the evolutionary mechanisms help prove/disprove Minsky's theory?**

# Answer
> 7 votes
Evolution does not help Minsky's theory of a resourceful mind. Although he tries to frame his discussion in loose evolutionary terms in the Emotion Machine and the book it is based on: Society of Mind (here is a good review/summary). As you noted during your reading:

> Minsky backs himself up by saying "evolution did so", but hasn't provided tests or studies that verify such claims

There are several reasons why he can't back himself up, and these are not unique to him but common throughout evolutionary psychology. The fundamental reason why Minsky (and other evolutionary psychologists) can't provide biologically convincing defenses for their evolutionary statements is because they are buildings **theories of the mind, not the brain**.

Biological evolution (at least in the modern synthesis) acts on genes. It is already hard enough to provide evolutionary descriptions on this level (see for instance issues surrounding the green-beard effect). However, biologists are sometimes able to go one step past this and start talking about basic physiology and the phenotypes and how selection acts on them. These are discussions about phenotypic traits. The traits that are most easily linked to the genes that express them are the ones that we can study effectively.

The brain is not easily linked to the genes that express it. Thus questions about the brain are already difficult enough to talk about from an evolutionary perspective (although some try). The mind is one more level of description higher up. Thus, in order to have a precise evolutionary statements about the mind we would need to solve the whole chain: genes --\> protein expression --\> physiology of the brain --\> function of the brain --\> function of the mind. We haven't solved any of these arrows, so it is not surprising that Minsky does not have hard evidence to support himself.

Lastly, when you read Minsky (and other evolutionary psychologists) be wary of teleological arguments. For us to have some trait doesn't mean that the trait needs to have been selected for at some point (in fact, some make a whole ruckus over what it even means to 'select for a trait'). Especially when you are considering such epiphenomena as the basic agents (or resources in the new book) of the mind. Take a look at genetic drift and genetic hitchhiking as starting point.

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Tags: evolution, philosophy-of-mind, connectionism
---


# Question
Title: Why is it easier to remember the correct response for problems with many options rather than just two?
Sometimes it seems easier, at least for me, to remember an answer, when there are more than 2 options to choose from.

For example, I easily remember my pin (14 bit), but hardly the lighter switch (up or down- 1 bit) for "on".

Why is that? Or is it just a wrong impression?

# Answer
There are at least three phenomena, which may play the role:

A too short information can easily interfere. So if it is on/off, it may interfere with its state a few days before, or with if the iron is on or off.

Moreover, things are remembered with redundancy. So, for example, one can remember not only PIN as numbers visually, but also as words, as a 'snapshot' of numbers written on a letter, as a sequence of finger moves, etc. So in case one is lost or inactive, all other can be used instead.

Also, one there is a piece of information, you can relate (consciously or not) to other objects. E.g. you can additionally remember that there are two digits from your birthdate and there is 8, a number you like very much, ...

Actually, mnemonic techniques base on the three observations, to make it easier to learn or harder to forget.

As a side note, computational analogues (esp. number of bits) are usually very misleading when it comes to human mind. The later does not work as an easy in/out device storying faithfully digital information.

(BTW: very likely, still it is much easier to remember 4 digits (of base 10) than 14 zeroes/ones.)
> 6 votes

# Answer
The simple fact of the mater is you're talking Short Term Memory (STM) for the light switch versus Long Term Memory (LTM) for the PIN.

From Wikipedia's definition of Long Term Memory (which is fairly accurate, if simplistic)

> Long-term memory (LTM) is memory in which associations among items are stored, as part of the theory of a dual-store memory model. According to the theory, long-term memory differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 20–30 seconds and can be recalled easily. This differs from the theory of the single-store retrieved context model that has no differentiation between short-term and long-term memory.

You never encode simple things like light switch positions into Long Term Memory because it would be useless; it's going to change and it's not that important (you can always check it's state readily). You pay very little attention to the light switch meaning you will likely not even keep it in Short Term Memory.

Your PIN on the other hand you have rehearsed dozens of times, tried very hard to remember, gotten some sleep (which helps the encoding process into Long Term Memory) and have built up many associations (this number gives me money, reminds me of my wallet, ect).

All forms of human memory are limited, so it's very important that we bias our memory toward important stuff; in STM you have to keep working with an item constantly to remember it; "call bob call bob call bob". But once you've elaborated on that item (I need to call bob at 3PM because he owes me money), rehersed it repeatedly, written it down (maintenance and elaborative rehearsal) it might slip into long term memory. But, since unlike your PIN, it will eventually be lost to forgetting (hopefully) since you don't continue to dwell on it, and the information stops being useful.
> 7 votes

# Answer
The short term v. long term memory answer is a good one. But what if they are both long term memory?

An alternative is that you just aren't counting bits correctly. Your 14 bit PIN is static. Once it is set one might actually argue it contains 0 bits within a given context. It has no probability of being anything else. The light switch is not static. You don't encode one instance of a light switch being on or off but multiple ones over time. The last episode of your kitchen light being on or off is one in a long string. If you were to consider the current state of your light at home being just the last of a very long list of times you had to remember that then the light switch actually contains vastly more information.

Another interpretation (sometimes used to further explain the one above) is not to consider information so much as interference. If you have one PIN# that you use within a given context then there's no interference from competing information. However, the extensive proactive interference from past traces of the state of the light switch limit your certainty about it's state. You might want to look up interference theory on wikipedia.
> 4 votes

# Answer
A few thoughts:

* **Automaticity and consistency:** It is much easier to automate a response that is consistent. Thus, if all the lights that you interact with follow the same rules then you will make the correct decision more often and you are more likely to automate the response.
* **cost of not recalling:** The cost of not recalling your password can be high. This is particularly true for credit cards and so on. The cost of not knowing what is "on" on a light is minimal, just try the other option.
* **contingent responses**: There are different ways that you can perform tasks. With the light switch, you could have a decision rule that says if I want to have light on and light is off, toggle switch. Such a decision rule does not require knowledge of which state is on and which is off. In particular, if your life is filled with inconsistent light switches then the toggle decision rule may be more adaptive.
* **automaticity and recall:** If you have automated a response, you may even forget in a declarative sense what you are doing.
> 4 votes

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Tags: cognitive-psychology, memory
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# Question
Title: Theoretical limit to the use of mental faculty of the brain
A lot of articles stress the importance of having to train the brain (By training the brain, I mean the cognitive faculty of the brain for learning things and not brain's normal functions) since the brain is a muscle and training it would improve its cognitive abilities.

Since using anything beyond a limit is detrimental to it, is there a theoretical limit to the use of brain beyond which it would be detrimental to the brain?

# Answer
`nrz` is on the right track with the epilepsy example. One of the limiting factors in the use of our brain is the amount of free molecules of the neurotransmitter glutamate. Having too much free glutamate can cause a phenomenon known as excitotoxicity. This phenomenon is also seen in conditions such as stroke, where damaged cells release their entire load of glutamate due to hypoxic damage.

Once glutamate has been bound with a post-synaptic cell, it must be taken up by neuroglia (supporting cells), which are present in great number in the surrounding milieu, metabolized into glut\*amine\* (inactivated), and recycled for repackaging and reuse in the neighboring neurons \[1\].

In the case of epilepsy (or in the theoretical case of your question, overusing your brain), the glial cells proliferate rapidly, which paradoxically causes a *slowing* of the transformation of glutamine back into glutamate. This is presumably a homeostatic mechanism\[1\].

So, from my own reckoning, it would seem like a rapid increase in function would cause excitotoxic damage in the short term, and lead to a slowdown in the metabolism of fresh transmitter in the long. Granted, there are other transmitters that are active in the cortex, but glutamate is the most abundant.

> \[1\] Coulter, D.A., Eid, T. (2012) Astrocytic Regulation of Glutamate Homeostasis in Epilepsy. Glia., 2012 May 16. doi: 10.1002/glia.22341. \[Epub ahead of print\]
> 9 votes

# Answer
Intensive stimuli may trigger epileptic shocks in some individuals. At least prolonged epileptic shocks may damage neurons, I'm not sure about short epileptic shocks. So the answer is yes, using your brain eg. your extended visual system to process excessively intensive visual stimuli may cause epileptic shocks and thus be detrimental to the brain.

However, as far as I know, visual stimuli are not able to cause epileptic shocks to everyone (susceptibility to epilepsy is a requirement), so I'm not sure if there is any proven way how by you could cause brain damage only by brain function (without aid of any voluntary motoric movements) in *any* individual.

As intensive visual and auditory stimuli are a part of our natural environment - whereas lack of stimuli (sensory deprivation) is an unnatural state - I think triggering epileptic shocks by intensive stimuli can not be considered only as a self-caused way of damaging the brain.
> 9 votes

# Answer
A few thoughts:

### Brain training

> A lot of articles stress the importance of having to train the brain

Much of this literature is used to sell computer games and crossword puzzles. In a recent review, Owen et al (2010) concluded that the proposed benefits of brain training lack empirical support. There is a vast literature which suggests that practice is the basis of skill acquisition but that skill acquisition tends to be focused on what is practised. Thus, if you want to get skilled at crossword puzzles, then do crossword puzzles; if you want to get good at a computer game, practice the computer game.

### Learning and normal function

> (By training the brain, I mean the cognitive faculty of the brain for learning things and not brain's normal functions)

Learning is a normal function of the brain.

### Brain as muscle

> since the brain is a muscle and training it would improve its cognitive \> abilities.

As mentioned by @John, *brain as muscle* is a metaphor. The brain does forget things, and forgetting can be adaptive. Thus, if you want to maintain or develop particular skills, then you should practice them.

### Limit to brain training

> Since using anything beyond a limit is detrimental to it, is there a theoretical limit to the use of brain beyond which it would be detrimental to the brain?

This seems like a big question. There is plenty of research on fatigue and stress which would suggest that getting adequate rest is important to maintaining optimal cognitive functioning.

### References

* Owen, A.M. and Hampshire, A. and Grahn, J.A. and Stenton, R. and Dajani, S. and Burns, A.S. and Howard, R.J. and Ballard, C.G. (2010). Putting brain training to the test. Nature, 465, 775-778.
> 6 votes

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Tags: neuroscience, philosophy-of-mind
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# Question
Title: Perception of probability of being right
The probability that people percept may be different from the real one due to a number of factors, including the form in which their are presented, their context and biases (due to misinformation or wishful thinking).

My question if there is any research showing the subjective probability judgement of being correct ($p\_\mathrm{perceived}$) as a function of actual probability of correctness ($p\_\mathrm{real}$) for situation were people estimate the chance that they are right in a test/trial (e.g. in a two answers forced choice task)?

Also, I am interested mathematical models with foundation in experimental data.

# Answer
> 7 votes
You'd probably want to take a look at signal detection theory. This is a set of tools that you use to analyse how well a person (or an animal, or a machine) is able to discern trials where there is a signal present (e.g. a picture is shown that has been shown before, a tumour is present in an x-ray image, a dot on a radar is an enemy aircraft) from trials where there is no-signal present (e.g. a picture is shown that hasn't been shown before, a tumour is not present in an x-ray image, a dot on a radar is not an enemy aircraft).

Whether a person perceives a signal or not is not always easy to discern. There will always be a certain interplay between the hit rate and the false alarm rate (in that you for example, if you always answered "signal", would have a perfect hit rate, although your false alarm rate would be terrible), and based on a number of criterias (time pressure, instructions, reward structure et cetera) one can manipulate the response patterns of a certain individual.

There has been attempts to create models where accuracy, speed and certainty all are taken into concideration; see for example Plescak and Busemeyer (2010).

# Answer
> 3 votes
Unless I'm mistaken, it sounds like you're actually interested in meta-cognition and type-2 signal detection theory (the form of SDT that Speldosa has pointed to is type-1 signal detection theory). It's used to study our ability to reflect on our own knowledge, or what we think about what we think.

This wikipedia article might get you started on meta-cognition in general.

A type-2 SDT task might involve asking participants to detect a stimulus, as would be the case in a type-1 SDT task, giving hits and false alarms. However, the difference is that, in a type-2 SDT task, after reporting whether they thought the stimulus was present or absent, participants are then asked a second question. This second question asks them how confident they were that they were right in their decision.

With this additional information, type-2 SDT tasks can then probe the extent to which participants can tell the difference between when they have the correct answer and when they have the incorrect answer, which I believe is what you are interested in.

Here's a sample paper that explores this in detail, albeit related to a different task, but should be enough to get you started:

Higham, P.A. (2007) No Special K! A signal detection framework for the strategic regulation of memory accuracy. Journal of Experimental Psychology: General, 136(1): 1-22.

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Tags: mathematical-psychology
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# Question
Title: How to obtain Fritz Perls' Eye Witness to Therapy film?
I am reading Fritz Perls' book called "Eye Witness to Therapy" which contains film transcipts that Perls thought would be useful to learn Gestalt therapy.

For me it is a very deep and interesting reading, but I'm wondering whether seeing the actual films would benefit me.

I was searching around but I couldn't find any reference on how to get those films. If anyone could help that would be very much appreciated. Thanks.

# Answer
This youtube channel has videos labeled "Fritz Perl ClipN" where N = 1,2,3, 4.0 and 5:
> 3 votes

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Tags: reference-request, psychiatry
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# Question
Title: Can one "understand" emotions, yet not "feel" them?
Prometheus Viral Clip #3 - David is a good clip of a fictional character in a science-fiction movie that helps frame my question; but I am interested in the general question, not the specifics of this movie.

An robot named David claims to "understand human emotions, although \[he\] does not feel them \[himself\]."

I personally feel as though his claim is false - I would argue that to be able to state an understanding of human emotions, one must \[have the capacity to?\] feel them oneself. **Is there existing knowledge or papers on this matter?**

When asked what makes David sad, he responds with things like war and poverty. When asked if David would like to supply any additional statements before ending the feed, he expresses "gratitude" explicitly. **If one "is" sad, isn't one by definition, "feeling" sadness?**

---

### Related questions

Are there emotions that only some people can feel?

# Answer
> 7 votes
There are two ways to approach your question: with or without dualism. I will highlight the dualist approach since it is more salient. Keep in mind that I do not find this approach reasonable, and doubt my summary will do it justice.

You might be interested in the concept of philosophical zombie, it is a modal argument against physicalism in the spirit of Saul Kripke that was polished by David Chalmers in *The Conscious Mind*. The basic idea is that you can have a *zombie* which is behaviorally equivalent to a human (including making utterances like "Ouch, I feel pain") yet it does not actually *experience* those emotions. There is nothing that if "feels like" to be a zombie. A zombie can say "I feel sad" and act like it *is* sad, but it doesn't *feel* anything.

If you adopt this stance it often becomes impossible to make a good theory-of-mind since everyone except yourself could actually be a zombie. In fact, Chalmers takes this further by talking about a whole parallel Z-universe where all creatures are zombies (including a copy Chalmers that goes around talking about a parallel universe). **From this perspective, David's statement can be perfectly valid.**

A second approach is looking at this point from the polar opposite perspective: behaviorism. Here, "to understand human emotion" would mean to be able to make predictions of human behavior based on knowledge that the human asserts to be in a certain emotional state. To "feel human emotion" would not be as well defined, but would be roughly equivalent to make the same patterns of behavior as a human that asserts to feel a certain emotion would usually make.

It is easy to see how **David's statement can be perfectly valid from this perspective**: if David simple stood in the corner and wrote down predictions of what the humans around him would do, then a behaviorist would say that David "understands human emotion". However, since standing in a corner and making predictions while your crew is eaten by aliens is not a typical human response, the behaviorist could conclude that David does not "feel human emotion" (if the behaviorist was tricked into using the word 'feel').

What I provided are two extreme philosophical stances, and each individual lays somewhere in between the two in terms of their personal philosophy on this issue (and maybe some lay on other extremes I did not imagine). Unfortunately, a scientific answer will come down to definitions and semantics. It will depend on what definition of 'feeling' the scientists in question find more reasonable.

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Tags: social-psychology, emotion, philosophy-of-mind, artificial-intelligence
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# Question
Title: What is the term for a psychological effect which does not have a neurobiological/genetic basis?
When a psychological condition is the result of irregular brain structures or neurotransmitter imbalances we say the condition has a neurobiological basis; this is analogous to the classic **Nature** in the Nature vs Nurture discussion.

What is the term for a condition which does *not* have this sort of (apparent) neurobiological basis? This would be a condition caused by **Nurture** effects such as psychologically traumatic events.

*Is there* a distinction? Technically both would induce physical changes in the brain, but I often see "neurobiological basis" used as if there were a different sort of basis for a condition.

# Answer
> 6 votes
**psychological sequelae** might be a word you're looking for if you forgive that it's somehow still neurobiological; it is however, not genetic or developmental or something somebody was born with:

```
Chronic kidney disease, for example, is sometimes a sequela of diabetes,
and neck pain is a common sequela of whiplash or other trauma to the cervical
vertebrae. Post-traumatic stress disorder may be a **psychological sequela** of rape.

```

Of course, this is a specific kind of pathological condition (a clinical one that requires attention!), not a general term for "psychological effect".

http://en.wikipedia.org/wiki/Sequelae

As Artem pointed out, you will have a hard time separating neurobiology from psychological effects if you want to maintain a reasonable/empirical/scientific approach.

Epigenetic is the word for "an addition to" genetics, so you can find out a lot with that search term. Particularly, **behavioral epigenetics** might be what you're interested in (note that it's still a molecular basis, just not genetic):

http://en.wikipedia.org/wiki/Behavioral\_epigenetics

Environmental influences, as opposed to intrinsic influences (but still somehow neurobiological, as the biological system has to detect, interpret and respond to external stimuli for them to be significant) have many different names and are a large part of psychology in general. Richard Wilkinson has an excellent talk on how income disparity leads to unhappiness through the psychological conditions it imposes on the poor (another example of Sequelae):

http://www.ted.com/talks/richard\_wilkinson.html

# Answer
> 6 votes
As I alluded in the comments, I think your question is underpinned by a more fundamental worry of the "best level of description" for psychological phenomena. If you a **reductionist** then you believe that all of psychology is best explained in terms of the activity of neurons (or systems of neurons if you are of the system perspective; note that some do not consider this reductionist. However, it does reduce to the physical basis).

On the other hand, Putnam and Fodor (and I suspect most proponents of strong AI) argue for **multiple realizability**: mental states and psychology can be implemented in various physical substrates, not just biological neurons. If you subscribe to this view, then it is natural to expect the best level of description of psychology to be independent of the specifics of a physical implementation (think algorithm-analysis in theoretical computer science). Since brains are physical things that implement minds, you would believe that a neurobiological basis does exist, but its details are irrelevant to your theory. Note that many theories in psychology can be viewed at the macro- or **behaviorist** level and as I suggested earlier: many theories in cognitive science lack a solid neuronal grounding.

If you have a physics background, then the weak analogy I would make is *thermodynamics versus statistical mechanics*. Thermodynamics is a macro-level theory that can exist without micro-level detail. However, eventually thermodynamics found a micro-level grounding in statistical mechanics. Does that mean we abandon thermodynamics and only study stat mech?

As for your **nature vs. nurture** distinction, if we accept mutliple realizability then we can use the above ideas to try to formalize the terminology. We can think of *nature features* as ones that are best described at the level of the specific implementation of the human brain, and *nurture features* as ones that are best described on a macro-level that would apply to any reasonable implementation. I don't know if this idea has been deeply studied or if it has any interesting bearing on the nature vs. nurture debate.

# Answer
> 2 votes
This is my own conjecture:

I would think a **Nature**/neurobiological/genetic disorder would be classified as some sort of "Structural Disorder." Maybe the **Nurture** side would be something like "Processing Disorder"? (this is assuming we're talking maladaptive effects)

Is our science even to a point where we can differentiate between a neurobiological disorder and a severe psychological disorder though? Maybe some neurobiological disorders start as unchecked psychological disorders. Or maybe our metacognitive capabilities are such that we can self-regulate ourselves (most likely with professional help) out of a neurobiological condition. Maybe it's all somewhere in between.

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Tags: neuroscience, terminology, nature-nurture, genetics
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# Question
Title: Why do participants prefer to give input values that are "round numbers"?
### Background

I have just been analysing some data where participants attempt to control a dynamic system with integer numeric inputs between 0 and 100. I've noticed that there is a general tendency for participants to give responses that are divisible by 10 (e.g., 0, 10, 20, 30, etc.). After that participants' second favourite input values are those divisible by 5 but not by 10 ( e.g., 5, 15, 25, 35, etc.). After that excluding some general patterns in the data, all the other input numbers appear about equally common (e.g., 1, 2, 3, 4, 6, 7, 8, 9, 11, 12, etc.).

Perhaps in a related way, I can also remember from market research that when you ask people how often they do certain things, as the number gets larger, they will often show a similar tendency to approximate and use numbers divisible by 10 or 100 and so on. I also seem to remember reading research where people report number of sexual partners, where a similar tendency was observed.

Thus, this tendency is consistent with a preference for what are informally referred to as "round numbers", where as in Wikipedia it is argued that "a number ending in 5 might be considered in a way more "round" than one ending in neither 0 nor 5. "

### Question

* What explains people's general tendency to prefer certain input values when trying to control a system (e.g., numbers divisible by 10 or 5)?
* Is there any specific research that has quantified this effect in another system control task?
* Does a similar mechanism underlie the popularity of such numbers in a system control task as does in a frequency estimation task?

# Answer
> 8 votes
The effect you are referring to is called **heaping**. Unfortunately, I am not aware of a source discussing the psychological aspect of this phenomenon, but I found an article about a statistical approach to heaped data.

> **Roberts JM, Brewer DD. (2001) Measures and tests of heaping in discrete quantitative distributions. Journal of Applied Statistics 28(7), 887-896.** http://www.tandfonline.com/doi/abs/10.1080/02664760120074960
>
> **Abstract** Heaping is often found in discrete quantitative data based on subject responses to open-ended interview questions or observer assessments. Heaping occurs when subjects or observers prefer some set of numbers as responses (e.g. multiples of 5) simply because of the features of this set. Although heaping represents a common type of measurement error, apparently no prior general measure of heaping exists. We present simple measures and tests of heaping in discrete quantitative data, illustrate them with data from an epidemiologic study, and evaluate the bias of these statistics. These techniques permit formal measurement of heaping and facilitate comparisons of the degree of heaping in data from different samples, substantive domains, and data collection methods.

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Tags: cognitive-psychology
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# Question
Title: Is this optical illusion the visual equivalent of binaural beats?
The optical motional illusion shown below, makes your brain see some motion, where there is none.

In my opinion it's fascinating, although after a while you get a headache. It reminds me of binaural beats, where the brain simulates the difference tone, which is obviously not there. The way that these illusions work is obviously quite different than how binaural beats work, as stated in the comments.

Despite that, it's said that the beats stimulate your brain, so my questions are

1. What is the name of this optical illusion?
> Akiyoshi Kitaoka studied these kind of optimized Fraser-Wilcox illusions.
2. Does it affect the brain in a similar way to binaural beats? I mean the overall effect, not the specific way how Fraser-Wilcox illusions or binaural beats enter your mind.

For those who liked the previous picture, here it is:

# Answer
Binaural beats result from a difference between the stimulus presented to each ear. The brain tries to integrate them and the perceived low-frequency beat is an artifact of that processing. There are optical illusions that involve presenting distinct, isolated inputs to each eye, and I'd consider those the closest equivalent to binaural beats.

The apparent motion in the image doesn't rely on binocular vision; you can see that easily by looking at it with one eye closed (in fact, I think that makes it stronger). I'd guess it's probably based on edge detection or lateral inhibition, which don't (I think) have a particularly close analog in sound perception.
> 5 votes

# Answer
I've tried looking at this image in greyscale and I still get the illusion. So it doesn't seem like the illusion relies on chromatic information. The effect is definitely weaker however, so it might be the case that the illusion relies on common properties of the colour and non-colour visual pathways (e.g., parvocellular and magnocellular), however we would need an isoilluminant chromatic version of the stimuli to be sure.

Maybe the following article will provide the answer.

Cropper, S. J. & Wuerger, S. M. (2005). The detection of motion in chromatic stimuli: A critical review. Behavioural and Cognitive Science Reviews, (Invited for publication).
> 4 votes

# Answer
Akiyoshi's website answers the first of your questions. He calls it the **peripheral drift illusion**.

The *Rotating Snakes* illusion is the culmination of a long series of modifications that Akiyoshi made to enhance the peripheral drift effect, that was discovered by Fraser and Wilcox. In 2003 he wrote a paper describing his work, but admitted that all he had was rules to enhance the effect, but not an explanation for it:

> Although this study only reveals phenomenological or design rules to obtain the peripheral drift illusion with large illusion magnitude, we are seeking an explanation on the basis of motion detector models.

His publications page shows a new (2012) paper which offers a more comprehensive explanation based of fMRI studies of the primary visual cortex, V1. If you have Elsevier access you can read it here. Yet another reason why publicly funded research should have public access.
> 4 votes

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Tags: terminology, perception
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title: Can mental exhaustion be measured?

text:
# Question
Title: Can mental exhaustion be measured?
I asked this question a long while ago, but I never got an answer to whether mental exhaustion can be measured. If mental exhaustion could be measured, it would mean that I would have a way of knowing the performance I can get out of my brain in a day. I would be able to know what is best for refilling my brain with energy (maybe TV is your best option after all...;) ) As far as I understand, different parts of the brain gets used for different purposes, so they should get exhausted at different times, so the measuring would have to be on specific regions of the brain or performance of the brain in various fields.

# Answer
> 5 votes
A sleep study by Van Dongen et al (2003) uses three metrics to measure the effects of fatigue due to sleep loss. The first is cognitive throughput:

> A serial addition/subtraction task was included in the assessment battery to measure cognitive throughput. The serial addition/subtraction task is a subject-paced task requiring the completion of 50 mental arithmetic trials. The average number of correct responses per min was used as a neurobehavioral assay of cognitive throughput performance.

Second, alertness / vigilance (response time to stimuli):

> The neurobehavioral assessment battery included a psychomotor vigilance task to measure behavioral alertness. The psychomotor vigilance task (PVT) is a sustained-attention reaction time task with a random inter-stimulus interval of 2–10 s. Lapses (reaction times greater than 500 ms) were counted per 10 min test bout as a measure of performance.

Third, memory:

> The neurobehavioral assessment battery also included a computerized digit symbol substitution task to measure working memory. This subject-paced task involves the matching of digits (0–9) to symbols (circle, triangle, etc.). The number of correct responses in 1.5 min was counted to measure working memory performance.

The metrics ought to be effective for measuring mental performance due to fatigue whatever the cause of fatigue might be.

### References

* Van Dongen, H.P.A., Maislin, G., Mullington, J.M., Dinges, D.F. & others (2003). The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. SLEEP-NEW YORK THEN WESTCHESTER-, 26, 117-129.

# Answer
> 4 votes
There are a several perspectives of mental fatigue. Here are a few starting points:

* There is a huge literature on **burnout** (see wikipedia article for a review, and Maslach et al, 2001, PDF) for their annual review of psychology article. Burnout refers to a rather chronic form of emotional and mental exhaustion. Burnout is often assessed in research using questionnaires, but obviously it could be clinically assessed. Of course, your question seems more concerned with short term fatigue rather than longer term fatigue, and cognitive fatigue rather than emotional fatigue.
* There are a lot of studies looking at **fatigue and work hours** (see this google scholar search). Such studies are often conducted within the context of human factors, occupational health, and work stress perspectives. You might like this one by Folkard et al (2003, PDF) on shift work, safety and productivity, it has some graphs relating time of day and time since break to productivity (i.e., not exactly answering your question, but marginally relevant).
* You could look at the literature on **vigilance** that discusses the general deterioration of vigilance skills over time (see this wikipedia discussion).

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Tags: mental-exhaustion
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# Question
Title: Are there colors women find attractive on men?
I have heard that men find women dressed in red more attractive (I can confirm this from personal experience as well).

What color or colors do women prefer on men, if any?

# Answer
The initial report of men finding women more attractive in red or even with a red background on a photo did receive a lot of press. However, the study has since been done in reverse. Women tend to find red more attractive on men as well... or even with a red background on their photo.

> Red, rank, and romance in women viewing men. Elliot, Andrew J.; Niesta Kayser, Daniela; Greitemeyer, Tobias; Lichtenfeld, Stephanie; Gramzow, Richard H.; Maier, Markus A.; Liu, Huijun Journal of Experimental Psychology: General, Vol 139(3), Aug 2010, 399-417. doi: 10.1037/a0019689
> 5 votes

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Tags: sensation, physical-attraction, sex-differences, attraction
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# Question
Title: Where is the visual "image" that we "see" finally assembled?
David Hubel's online book, Eye, Brain and Vision describes in great detail our early visual system. The image that we are conscious of when we open our eyes goes through a complex path:

The final seamless, stereoscopic (2.5D) "image" that we "see" can only be assembled after V1, the primary visual cortex. Unfortunately, V1 is as far as Hubel's book goes, and as far as I can tell its a mystery to Google too, **exactly where the final "image" we "see" is assembled.** Does any one have better info than *the Google* regarding this?

# Answer
I think you are succumbing to the **homunculus argument**, the fallacy that there is some sort of image in the brain for someone to view. There is no magical theater in your head where what is incident on your retina is projected. All you have in your brain is complicated patterns of neural activity, there are no images and nothing to view. However, these patterns of activity give rise to your phenomenological experience. To fully understand this you should ask:

What are current neuronal explanations and models of 'consciousness'?

But lets try to clear up some of the conceptual difficulties with vision in particular. Your experience of the visual world is effected by two types of inputs: (1) the data from your retina, and (2) data from the rest of your senses, including memory. Why is obvious that not everything comes from (1)? Consider one the following:

* You experience a whole visual scene, there isn't a certain nothing-ness somewhere. Yet on your retina, there is a blind-spot, something fills in that part of your experience for you.
* You have an experience of certain far away buildings being further then nearby buildings. Yet your eyes are too close together for the difference in angle of the two images to be measurable at the fidelity of your retina. How does your mind know the buildings are further? Parallax and memories of how big certain objects typically are and how this scales with distance.

If we concentrate only on method (1), then all the information is there from the retina on-wards and only degrades (as part of the signal is thrown away, compressed, or undergoes noise) on its way to V1 and on-wards. However, its encoding changes to become more compatible with integration with other sensory and memory information. By the time the data has reached V1 and V2, it is in an encoding that we understand well enough to reconstruct videos of what people are seeing/experiencing. As the Gallant Lab that ran the linked study summarizes:

> The human visual system consists of several dozen distinct cortical visual areas and sub-cortical nuclei, arranged in a network that is both hierarchical and parallel. Visual information comes into the eye and is there transduced into nerve impulses. These are sent on to the lateral geniculate nucleus and then to primary visual cortex (area V1). Area V1 is the largest single processing module in the human brain. Its function is to represent visual information in a very general form by decomposing visual stimuli into spatially localized elements. Signals leaving V1 are distributed to other visual areas, such as V2 and V3. Although the function of these higher visual areas is not fully understood, it is believed that they extract relatively more complicated information about a scene. For example, area V2 is thought to represent moderately complex features such as angles and curvature, while high-level areas are thought to represent very complex patterns such as faces. The encoding model used in our experiment was designed to describe the function of early visual areas such as V1 and V2, but was not meant to describe higher visual areas. As one might expect, the model does a good job of decoding information in early visual areas but it does not perform as well in higher areas.

Remember, there is no video in those areas. It is just firing of neurons that the scientists have figured out how to decode and interpret. As the quote mentions, the higher visual areas are not well understood right now, but presumably that is where a lot of the type (2) feedback is happening. Even inside the mildly understood visual areas, a lot of processing is distributed. For instance, take a look at the question about face-blindness:

Does the fusiform face area in patients with Prosopagnosia (face blindness) show lower activity under an fMRI?

By damaging one part of the brain (the fusiform face area) you are able to continue to 'see' tables and chairs perfectly fine, and yet you can't properly identify or recognize faces.

Hopefully this convinces you that it doesn't make sense to look for 'the image' in the brain. Together the mind and the eye are able to shape what you perceive and give it meaning, but it is a pseudo-question to ask where that image is finally assembled. It is not assembled, there is no image, there is only encoding of retina activity into higher level firing patterns that produces in us the experience of vision and meaning.
> 16 votes

# Answer
The nervous system, especially the cortex, is a distributed system. Asking "where" is not always a sensible question. In reality, different properties of the visual scene are assembled in different areas of cortex. There is no one area where everything is reassembled. All the information we know about a scene is stored all over the visual system. In inferotemporal, we might represent complex objects. In mediotemporal, we might represent movement within the visual scene. These properties are somewhere integrated into an understanding of the scene as a whole (we can see an object moving and also know *what* it is), likely in the posterior parietal lobe, or the superior temporal gyrus. But it would be a mistake to say that the PPL/STG is where we "see" the world. It's merely assembling other groups of neurons into a representation of the overall visual scene.

Think of it like this. Different areas of the cortex come to represent different properties of the visual scene. These representations can be used by other areas to form more complicated representations. And so on. There is no point of convergence in the cortex, only an availability of increasingly complex representations.
> 8 votes

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Tags: neuroscience, vision, philosophy-of-mind
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# Question
Title: What are the minimal requirements for successful gamification?
I am very interested in the concept of Gamification, the idea (used here on Stack Exchange) that by making mundane tasks into a game, you can elicit desired behavior from users of software. (For example, by giving people arbitrary reputation points, you encourage them to help the best answers rise to the top...)

Wikipedia says that some of the techniques used for gamification include:

> * achievement "badges"
> * achievement levels
> * "leader boards"
> * a progress bar or other visual meter to indicate how close people are to completing a task a company is trying to encourage, such as completing a social networking profile or earning a frequent shopper loyalty award.\[7\]
> * virtual currency
> * systems for awarding, redeeming, trading, gifting, and otherwise exchanging points
> * challenges between users embedding small casual games within other activities.\[2\]

I'd like to see what studies actually say about gamification. If I wanted to start a new website which used gamificiation to entice users to participate, which techniques are the most efficient? Do some techniques work better than others? Do you need multiple rewards (E.G. reputation and badges)?

What do studies show are the minimum requirements for successful gamification?

# Answer
In short, I'd say the minimum requirement is to understand which behaviours you are influencing and why.

Before you consider which game techniques to use, consider the 'story' of the product/service.

Each story includes:

* Actor/s. Who are your targets?
* These actors are motivated by something. This is what your game should leverage.
* There is a goal. What are you/the actor trying to achieve. Help them progress towards the goal. Motivational factors / game techniques should encourage behaviours that move towards this goal and discourage behaviours that move away from it.
* The actor begins in a context. Understanding the context gives you clues to opportunities and constraints.
* The actor progresses through a journey (or arc). Mapping this journey helps you know when to employ certain techniques.
* An outcome is achieved. This is the most critical part of course.

Draw this out in a path. Include the diversions, obstacles etc. Identify the main path as well as the little loops of activity that contribute.

Tip: If this isn't clear consider well known kid's stories. They are all shaped by this familiar pattern.

The techniques you list above and ones you will see elsewhere are valid. However by considering the story you will understand when to use certain techniques and how they should be approached.
> 2 votes

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Tags: io-psychology, educational-psychology, gamification
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# Question
Title: Measuring changes in hemispheric dominance over time
I've recently started using my trackball left-handed after being right-handed my whole life. The motivation is partly to balance out wrist strain, and partly to see how much my brain rejects the idea.

Since I am at the computer for a good portion of the day, this is a fundamental change. I started to wonder whether it might actually have some measurable impact on hemispheric dominance, and found (unsurprisingly) that Google had some links which posed the same question. To this point I have only my own admitted ignorance combined with unsubstantiated claims on the Internet.

**Is there a reasonably reliable and convenient way to measure changes in hemispheric dominance over time?**

**Edit**: As I mentioned, I did some Googling around about the potential connection between dominant mouse hand and hemispheric dominance. The only tools I discovered along the way were simple questionnaires. I took 3-4 of them in the absence of any better ideas, and will repeat them over the next few months. I suspect that using Brain Age-style games or Lumosity might be more useful than a questionnaire, but wonder if results would change more due to practice than anything else. I was hoping that I overlooked something that more directly targets hemispheric dominance.

# Answer
> 7 votes
I would first like to discuss the concept of lateralization and clear up a common misconception about hemispheric dominance.

> "A brain is considered to be asymmetrical (or lateralized) if one side (hemisphere or other brain region) is **structurally different** from the other **and/or performs a different set of functions**." (Bisazza et al., 1998).

A good example is the lateralization of language which relates to handedness. It has been widely accepted that a majority of people are left dominant for language, although right dominance increases with the degree of left handedness (Knecht et al., 2000).

Lateralization and behavioural asymmetries are neither restricted to language or humans (Bisazza et al., 1998). In the scientific community, hemispheric dominance is usually discussed in the context of a specific function. However, there is a **common misconception** by those who have an incomplete understanding of brain lateralization, particularly worsened by the spread of popular science articles and pseudoscientific tests (such as the one linked to in the comments) that **wrongly assumes there is an overall dominance of one side of the brain** (with left corresponding to logical and analytical thinking and right corresponding to emotional and creative thinking), that determines your personality trends. This is an incorrect oversimplification that is explained in a good article by RationalWiki.

Thus, your question is misguided in focusing on changes in hemispheric dominance. Even if you focused on change of lateralization for a specific function, this is unlikely as it requires substantial reorganization of the brain that is really only observed during development and to a much smaller extent following brain injury. However it is still good to question what changes there may be due to using a non-dominant hand more often! In fact (Teixeira and Teixeira, 2007) looks at how **practice with the non-preferred hand alters manual preference for a specific task**, and suggests this generalizes to other related motor tasks (Teixeira and Okazaki, 2007). **The task used in their 2007 study involves sequentially touching the thumb with (in order) the ring, middle, little, and index fingers. The goal is to complete 5 cycles without interruption in the shortest time possible.** They assess this before, after, and 30 days following practice, observing a noticeable shift in those that are allowed to practice compared to controls. You can choose a similar task and/or something different (for example, score in a quick video game that requires pointing with the trackball) and measure how you improve in comparison to a friend who doesn't practice with the left hand.

Ironically, they discuss how the **left premotor cortex is dominant for learning sequential tasks** (whether performed with right or left hand) and so might limit the observable shifts. For this reason it might be good to try their task to compare with that study and also your own task for personal interest. **If you are really interested in how performance and practice (especially long term) can affect the brain, there is lots of existing literature and imaging studies on the differences in brains of musicians** compared to non-musicians or amateurs. Due to years of practice, professional musicians often have differences in and sometimes larger motor areas (Schlaug, 2006), increased cerebellar volume (Hutchinson et al., 2003), increased auditory cortical representation (Pantev et al., 1998) and increased assymetries such as in the planum temporale (Schlaug et al., 1995).

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Tags: neuroscience, measurement, experimental-psychology
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# Question
Title: Research suggesting conscious control over brain region activation?
Has there been any research proving, disproving, or exploring the concept of conscious activation of specific brain regions?

To elaborate on this:

I've read that performing processing tasks causes the brain to reinforce that type/kind of processing or thinking. For example, visualizing performing a task fires the same neurons as actually performing the task.

Thus, **has there been research into the idea that mental models and biofeedback mechanisms can result in conscious control over the activation of particular brain regions?**

For example, with biofeedback and practice, can I consciously, measurably, and significantly increase activity (blood flow, electrical activity, etc) in the frontal lobe?

# Answer
> 17 votes
Yes! Recent work using fMRI has shown that subjects can indeed control localized brain regions through practice \[1\]. Some regions that have been tested include the rostal ACC \[2\] responsible for pain perception, PPA responsible for representing locations, and FFA responsible for representing faces. Repeated experiments seem to suggest the phenomenon is robust, and that the technique may not be particular to regulating any specific brain region but could work on many brain regions given the proper experimental design.

Typically, these experiments work by utilizing real-time fMRI, a technique that allows real-time biofeedback of brain activation to be presented to a subject in an fMRI scanner. In these experiments, a subject may specifically be instructed to "up-regulate" or "down-regulate" activation in a brain region by performing a specific task. For instance, a subject can "up-regulate" activation in the fusiform face area (FFA) by mentally picturing faces. Consequently, feedback is presented to the subject (e.g., as a 'thermometer') indicating level of activation of the FFA.

Interestingly, subjects become better at up-regulating or down-regulating activation in specific brain regions by attending to feedback-- even moreso than subjects who do not receive biofeedback. This is reflected both in the fMRI images and subjective reports from the subjects. This technique has potential implications for rehabilitation, e.g. giving chronic pain patients another tool to cope with their disorder.

The technique has even been used to up-regulate abstract, distributed patterns across the brain. For instance, Stephen LaConte and colleagues have used a machine learning technique called support-vector machines to classify abstract patterns such as 'craving' or 'not craving', represented as a distributed pattern of brain activity. Using real-time fMRI, smokers have been able to learn to control their cravings through instruction and biofeedback.

I believe similar findings have been shown using EEG as well, though I am not as familiar with the literature. However, there is evidence that subjects using an EEG brain-computer interface to control an on-screen keyboard become better with practice, which suggests that they are able to manipulate their brain patterns in order to perform the task.

### References

1. de Charms et al. (2004). Learned regulation of spatially localized brain activation using real-time fMRI. NeuroImage, 21, 436-443. Retrieved from http://www.christofflab.ca/pdfs/deCharms\_2004\_Neuroimage.pdf
2. de Charms et al. (2005). Control over brain activation and pain learned by using real-time functional MRI. PNAS, 102, 18626–18631. Retrieved from http://www.stanford.edu/~fumiko/publications.files/Hoeft(Maeda)\_2005PNASdeCharms.pdf

# Answer
> 9 votes
Not only can brain activation be controlled though consciousness (which is expected under most reductionist accounts of the mind-brain problem) and measured in the lab (as @Jeff's answer showed) but it can actually be used as an interface!

Erik Ramsey is locked-in syndrome patient and is incapable of movement apart from his eyes. However, he has control of his brain enough to be distinguished by electrodes implanted into his cerebral cortex (Guenther, 2009). Although the sensors were implanted in the motor-area responsible for speech (which you would expect typical inviduals to have control over, since they can speak), the understanding of how to decode this is not full. Thus, the patient had to train in order to adapt to the system:

> Accuracy of the volunteer's vowel productions with the synthesizer improved quickly with practice, with a 25% improvement in average hit rate (from 45% to 70%) and 46% decrease in average endpoint error from the first to the last block of a three-vowel task.

In a much more dramatic experiment, Adrian Owen has used brain imaging techniques as means of communicating with vegetative-state patients. It is known that visualizing playing-tennis and walking around the house produce very distinct (to an fMRI) activation in the brain. So owed used that capability to allow a vegetative-state patient to answer yes-or-no questions. He asked the patient to imagine playing tennis for yes, navigating the house for no (Monti et al., 2010).

Of course, this is not an answer to the exact question you asked, but by thinking about these activities the patient is effective the blood flow in his brain significantly enough to be measured by fMRI and used as a form of communication. Of course, some do raise concerns over the philosophical questions related to consciousness in these patients, to better understand consciousness in general, take a look at:

What are current neuronal explanations and models of 'consciousness'?

### References

Guenther, F.H., Brumberg, J.S., Wright, E.J., Nieto-Castanon, A., Tourville, J.A., Panko, M., Law, R., Siebert, S.A., Bartels, J.L., Andreasen, D.S., Ehirim, P., Mao, H., & Kennedy, P.R. (2009). A wireless brain-machine interface for real-time speech synthesis. PLoS ONE, 4(12)

Monti MM, Vanhaudenhuyse A, Coleman MR, Boly M, Pickard JD, Tshibanda L, Owen AM, & Laureys S. (2010). Willful modulation of brain activity in disorders of consciousness. New England Journal of Medicine, 362(7):579-89.

# Answer
> 8 votes
A minor addition to Jeff:

There are ongoing researchs on controlling brain's response (e.g amygdala) to negative situations and using this techniques for psychiatric interventions (e.g. for anxiety disorders, depression). \[1\]

There are different possibilities for learning adaptive coping strategies with simple, stuctured biofeedback training setups. But scaling/portability issues about equipments using for brain response/training studies have not yet solved.

**Reference**

1. Stanford study suggests girls can 'rewire' brains to ward off depression http://news.stanford.edu/news/2012/february/depression-brain-imaging-020912.html

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Tags: neuroscience, consciousness, neuroimaging, health-psychology
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# Question
Title: What is the correlation between feeling superior and well-being?
I have noticed in myself and others, when people perceive themselves as "better off" than the majority of others (e.g., smarter, better looking, higher social status, better brain function, more insight, more capable, etc.) they tend to feel greater well-being, peace, and self-assurance.

* Are there any studies on this?
* Is it just primal parts of the brain being activated?
* If so, how can we activate that without the external circumstance?

**EDIT**
For example, just found this one: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2430590/

# Answer
Diener et al's (1999) review in *Psychological Bulletin* provides an excellent entry point into the well-being literature. It reviews the literature with regards to the many causes and correlates of well-being.

### Individual Differences

First, individual differences explain a lot of variance in well-being. This is often seen in terms of personality traits such as neuroticism and extraversion (e.g., see the huge meta-analysis of DeNeve and Cooper, 1998). People with low neuroticism and high extraversion tend to experience more well-being. In relation to social comparison, it may be that these personality traits influence lenses of social comparisons both in terms of the standards that are set and how circumstances are appraised relative to those circumstances.

### Discrepancy theories and social comparison

I recommend reading page 282 and 283 of Diener et al (1999) where the authors review discrepancy and social comparison theories in relation to subjective well-being. First the authors mention an early discrepancy theory by Michalos:

> According to Michalos's theory, individuals compare themselves to multiple standards including other people, past conditions, aspirations and ideal levels of satisfaction, and needs or goals. Satisfaction judgments are then based on discrepancies between current conditions and these standards. A discrepancy that involves an upward comparison (i.e., where the comparison standard is higher) will result in decreased satisfaction, whereas a downward comparison will result in increased satisfaction.

The authors then discuss how subsequent research has shown the situation to be more complex than originally conceptualised: e.g.,

* There is a degree of flexibility in which social comparisons we adopt.
* Adopting high expectations and thereby creating a discrepancy does not necessarily induce lower well-being, especially if people feel like they are making progress towards theirs goals.
* Comparisons are not just social, but can come from a variety of sources.
* There's a difference between short-term and more enduring effects on well-being.

### Superiority versus positive social comparison

It is also worth making a distinction between a positive social comparison and superiority. We might see a positive social comparison as an evaluation of life circumstances as better than some comparison group. In contrast superiority can be quite close to arrogance. Taken to its extreme we can see superiority as an element in narcissism (e.g., "Has a grandiose sense of self-importance (e.g., exaggerates achievements and talents, expects to be recognized as superior without commensurate achievements" DSM IV-TR). When the basis of such positive self-evaluations is fragile, I believe this can be related to lower or more volatile self-esteem.

### Various factors

Although you mention that it is perception, there is research on various measures that you mention. To take a couple:

* intelligence: Several meta-analyses suggest the relationship is fairly minimal (e.g., Sigelman, 1981; Wilson, 1967)
* social status - income: Diener et al discuss how the relationship between income and well-being is modest at best.

### Primal Factors and Brains

I'm not sure how necessary it is to think of the process in terms of brains. Certainly the process of well-being at some level must be explained in terms of biological processes, but I'm not sure if such a level of explanation is required to understand the relationship between social comparison and well-being.

You might want to read about evolutionary perspectives to well-being. For example, Grinde (2002) discusses this perspective (See reference and PDF below).

### Activating without external circumstances

There is a lot of research in positive psychology on how to attain happiness. A starting point could be to look at Seligman's ideas around three paths to happiness. Perhaps check out this TED talk by Martin Seligman

### References

* DeNeve, K.M. & Cooper, H. (1998). The happy personality: a meta-analysis of 137 personality traits and subjective well-being.. Psychological bulletin, 124, 197. PDF
* Diener, E., Suh, E.M., Lucas, R.E. & Smith, H.L. (1999). Subjective well-being: Three decades of progress.. Psychological bulletin, 125, 276. PDF
* Grinde, B. (2002). Happiness in the perspective of evolutionary psychology. Journal of Happiness Studies, 3, 331-354. PDF
* Michalos, A. C. (1985). Multiple discrepancies theory (MDT) Social Indicators Research, 16, 347-413.
* Sigelman, L. (1981). Is ignorance bliss? A reconsideration of the folk wisdom. Human Relations, 34, 965-974.
* Wilson, W. (1967). Correlates of avowed happiness. Psychological Bulletin, 67, 294-306.
> 6 votes

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Tags: social-psychology, well-being, health-psychology, positive-thinking, correlation
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