# Question
Title: Are there cognitive benefits to two hand typing versus one finger?
I've been reading an old popular psychology book by russian psychiatrist Vladimir Levi. One of the things that he has his depressed patients try is learn to juggle. He insists that such activity brings both halves of the brain together and that the brain "likes to juggle". His book was written in the 1980s, and there's little science presented in the book to back the claim.

Juggling involves coordinating both hands and is automatic, if I understand correctly. Touch typing involves coordinating 10 fingers together and is also automatic once learned.

In the 1990s and early 2000s, computer keyboards were the dominant way of inputting data into a computer. If one was **to type anything one used both hands together for extended periods of time** (most likely touch typing with both hands). But as of 2013, more and more people report using tablet PCs to surf the web and interact with friends online. Such typing most likely involves one finger pressing the letters on a virtual keyboard. It's a much slower process, as the keyboard is too small for both hands.

**Does touch-typing has any cognitive benefits?** Is the effect lost if one reverts to typing with a single finger?

# Answer
> 5 votes
**Benefits of touch typing on task performance**: I assume that when comparing skilled individuals, two handed touch typing on a traditional keyboard is faster, more reliable, and more automatic, than the other methods of text input that you mention (e.g., phone or tablet keyboards). These advantages are discussed here.

* Faster input means that ideas can be expressed more quickly.
* Visual attention does not need to be allocated to the keyboard which permits more attention to be placed on the content or the screen.
* The greater reliability and automaticity mean that less attention needs to be allocated to the task of typing than to other methods.
* A more consistent keyboard layout across devices further justifies the investment in learning touch typing.

For further discussion of the cognitive and performance benefits of skilled touch typing, check out Yechiam et al (2003). Discussing the benefits of touch typing over visual typing, they state:

> One main distinction of the touch-typing strategy appears to be the ability to look at the screen while typing and to devote a minimal level of visual search to the keyboard (Cooper, 1983). This ability is gained through the memorization of key positions and finger trajectories, which makes touch-typing a difficult skill to acquire. Other differences between touch-typing and visually guided typing include touch typists' (a) use of all fingers of both hands, as opposed to the use of one hand of only some of the fingers; (b) fixed assignment of fingers to keys; (c) reduced arm movements; and (d) fixed locations of the palms (Crooks, 1964).

**Broader cognitive benefits of touch typing**: While I have not read any specific research testing the idea, I think the benefits of touch typing relate to its superiority as a text entry method and not as some broader tool for brain integration. A large body of research on psychomotor and cognitive performance suggests that transfer across disparate domains tends to be minimal. The domains would need to have some overlapping elements.

More broadly, there is a strong link between unemployment and depression (e.g., Frese & Mohr, 1987). Engaging in meaningful or enjoyable activity might help improve mood in some cases (e.g., juggling, mastering some other new skill). However, I don't think the mechanism of that mood improvement would be hemispheric brain balancing.

### References

* Cooper, W. E. (1983). Introduction. In W. E. Cooper (Ed.), Cognitive aspects of skilled typewriting (pp. 1-38). New York: Springer-Verlag.
* Crooks, M. (1964). Touch typing for teachers. London: Pitman.
* Frese, M., & Mohr, G. (1987). Prolonged unemployment and depression in older workers: A longitudinal study of intervening variables. Social Science & Medicine, 25(2), 173-178. PDF
* Yechiam, E., Erev, I., Yehene, V., & Gopher, D. (2003). Melioration and the transition from touch-typing training to everyday use. Human Factors: The Journal of the Human Factors and Ergonomics Society, 45(4), 671-684.

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Tags: learning, performance, human-factors
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# Question
Title: What does hemispatial neglect vision look like?
I need to know more about hemispatial neglect, in order to compose a picture of what it would look like to someone who has this issue.

Is there any resources for finding more about their actual vision? I have seen the very popular picture on the internet of a patient who has the illness, and then draws a clock and a house:

But, I am trying to compose a real world image, as a person who has this illness, and I feel like just leaving half of the page empty is incorrect. I would think that they would see a full picture, it would just not include the left hand side.

# Answer
I think this is an interesting, but difficult question to answer.

Hemispatial neglect patients do not typically have problem with visual pathways *per se*. Wikipedia suggests that the disorder is most closely linked to damage of the temporo-parietal junction and posterior parietal cortex, areas associated with attention. Thus, the sensation (e.g. on the retina, and in early visual pathways) should be similar in patients and non-patients.

Let me make an analogy to the inattentional blindness literature. You may have seen a famous video by Daniel Simons and Christopher Charis. If you haven't, go watch it now before continuing... (I'll wait.)

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Now how would you paint a picture of how that video 'looks' to someone? Does that picture include a gorilla? It seems even normal perception has blindspots. In fact, much of our perception is not strictly bottom-up, but is a mixture between bottom-up and top-down processes.

I would argue comparing a hemispatial neglect patient to a control is (very loosely) like comparing someone watching the inattentional blindness video for the first time to someone who has seen it before.

One might argue that hemispatial neglect patients do not 'see' things any differently than us, only that they 'perceive' it differently. So you could possibly create a caricature of how these patients 'see' the world, but it would be just that: a caricature.

One thing for certain is that hemispatial neglect patients do not 'perceive' that half of their visual field is missing (e.g. leaving half the page blank). When prompted, these patients typically do not report that anything is out of the ordinary.

All that being said, this is not my area of expertise, so please feel free to post a better answer if you think this analogy is misleading...
> 5 votes

# Answer
I don't know much about this, but here are a few review articles (see here for more) that you could look at:
> 3 votes

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Tags: vision, neurology, attention
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# Question
Title: Is acrophobia connected to falling in dreams?
I'm interested in the link between phobias and related nightmares. Specifically, is acrophobia (i.e., irrational fear of heights) connected to falling in dreams?

# Answer
Dreams and nightmares often relate to thoughts, worries, and concerns that a person has during waking hours. Various theories both describe this phenomena and suggest reasons for this (e.g., activation of memories, memory consolidation, discarding information, working through issues). Thus, it seems plausible that someone with a particular phobia would be more likely to have dreams related to that phobia (i.e., fear of heights accompanied by dreams about falling).

Muris et al (2000) discuss some of the research on children looking at fears, worries, and scary dreams. They cite Amaya-Jackson and March (1995) as evidence for links between traumatic events and frightening dreams. They also mention research by Bauer (1976) which suggests that the contents of children's dreams and fears may change with age and that such changes co-occur both in daily fears and in scary dreams (e.g., fewer monsters and more fears about bodily injury/illness with age).

However, in addition to associating a phobia with dream content, you might also want to look at the baseline prevalence of any given type of dream. There is a sleep and dream database you can look at. In a survey of 2992 participants 48% reported having had a dream of falling (Bulkeley - database - Q9). Given the relatively high prevalence of dreams of falling, there may be other reasons, perhaps related to the nature of dreaming that induces them. For example, dreams of being unable to move can readily be explained by the paralysed state of body while dreaming. Perhaps a similar argument could be made about falling (e.g., a body sensation while dreaming is interpreted in a way that links with the fear of falling, thereby inducing the nightmare).

### References

* Bauer, D. H. (1976). An exploratory study of developmental changes in children's fears. Journal of Child Psychology and Psychiatry, 17(1), 69-74.
* March, J. S., Amaya-Jackson, L., Terry, R., & Costanzo, P. (1997). Posttraumatic symptomatology in children and adolescents after an industrial fire. Journal of the American Academy of Child & Adolescent Psychiatry, 36(8), 1080-1088.
* Muris, P., Merckelbach, H., Gadet, B., & Moulaert, V. (2000). Fears, worries, and scary dreams in 4-to 12-year-old children: Their content, developmental pattern, and origins. Journal of clinical child psychology, 29(1), 43-52. PDF
> 5 votes

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Tags: dreams, clinical-psychology
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# Question
Title: What positive writing exercises improve happiness?
Writing seems like a perfect medium for expressing ones problems but can it also be used to improve happiness somehow? Maybe through some sort of creative writing exercises that focus on positive thinking?

Are there any positive writing exercise that can improve happiness, if even temporarily?

# Answer
> 6 votes
### Writing therapy

There is quite a lot of research on writing therapy and expressive writing more generally. As you note, much of this research relates to writing about negative emotional experiences. There is some support for the positive mental health benefits in writing about traumatic events (e.g., see the meta-analysis by Smyth, 1998). While the interventions are focused on writing about negative events, the intervention

### Positive psychology and writing

I have read about a few specific positive psychology writing interventions, such as those mentioned here:

> * **Keep a gratitude diary**: Take the time each day to write down three things that went well and why. This causes psychological well-being levels to increase in a lasting way.
> * **Thank a mentor**: Write a letter of thanks to someone to whom you owe a debt of gratitude such as a teacher or grandparent. Then visit the person and read the letter to them. People who do this are measurably happier for more than a month.
> * **Learn to forgive**: Let go of anger and resentment by writing a letter of forgiveness to a person who has wronged you. Inability to forgive is associated with persistent rumination.

Toepfer and Walker (2009) discuss writing letters of gratitude. They cite several studies showing positive effect, stating that

> Expressive writing studies are plentiful and the once anemic domain of letter writing as a vehicle for improving health has seen a recent surge of interest (King, 2001; Sheldon & Lyubomirsky, 2006a; Seligman et al., 2005; Lyubomirsky, Dickerhoof, Boehm, & Sheldon, 2009). For example, VandeCreek, Janus, Pennebaker and Binau (2002) asked participants to pray and write letters to God and found that both prayer and the letters increased insight and positive emotion, more so than simple written descriptions, where a single letter to God had the most impact. The authors explained that the act of praying or explaining to another (in this case in a letter to God) was more conducive to personal insight and greater positive emotional formulations about life events. In other words, writing a letter to God was found to improve participant’s positive feelings about life events.
>
> Watkins, Woodward, Stone and Kolts (2003) conducted a study that examined mood changes as the result of various gratitude inductions, one of which was a letter writing condition. Their findings revealed that writing a gratitude based letter produced a positive affect increase compared to the other gratitude inductions (Watkins et al., 2003).

Burton and King found positive effects from getting participants to write about positive experiences. They also summarise some of the literature noting that

> research has begun to explore a variety of writing topics that might be associated with health beneﬁts that do not focus exclusively on negative experience. King and Miner (2000) found that writing only about the positive aspects of a traumatic experience was associated with the same health beneﬁts as writing about trauma. King (2001) found that individuals who wrote about their best possible future selves showed physical health beneﬁts as well as enhanced psychological well-being after writing.

Burton and King's instructions were:

> Think of the most wonderful experience or experiences in your life, happiest moments, ecstatic moments, moments of rapture, perhaps from being in love, or from listening to music, or suddenly ‘‘being hit’’ by a book or painting or from some great creative moment. Choose one such experience or moment. Try to imagine yourself at that moment, including all the feelings and emotions associated with the experience. Now write about the experience in as much detail as possible trying to include the feelings, thoughts, and emotions that were present at the time. Please try your best to re-experience the emotions involved.

As for a mechanism of operation, Wing et al present the following ideas:

> Writing about nontraumatic events likely shares some effects with writing about traumatic events. Writing about any meaningful aspect of life may promote cognitive processing, encouraging the examination, understanding, and assimilation of emotions that might otherwise be left unscrutinized (Pennebaker, 2002; Pennebaker, Mayne, & Francis, 1997; Pennebaker & Seagal, 1999). Writing about a meaningful topic may result in enhanced emotional regulation, related to perceptions of self-efficacy and control over emotional experiences (Greenberg, Wortman & Stone, 1996; King, 2001, 2002; Lepore et al., 2002). Writing may afford the writer the opportunity to gain a sense of mastery over his or her emotions and to clearly identify priorities, preferred outcomes, and goals (King, 2001).

### References

* Burton, C. M., & King, L. A. (2004). The health benefits of writing about intensely positive experiences. Journal of research in personality, 38(2), 150-163. PDF
* King, L. A. (2001). The health beneﬁts of writing about life goals. Personality and Social Psychology Bulletin, 27(7), 798–807.
* King, L. A., & Miner, K. N. (2000). Writing about the perceived beneﬁts of traumatic events: Implications for physical health. Personality and Social Psychology Bulletin, 26(2), 220–230.
* Wright, J. (2002). Online counselling: Learning from writing therapy. British Journal of Guidance and Counselling, 30(3), 285-298. PDF
* SMYTH, J.M.(1998).Written emotional expression: effect size, outcome types, and moderating variables. Journal of Consulting and Clinical Psychology, 66(1), 174±184. PDF
* Toepfer, S., & Walker, K. (2009). Letters of gratitude: Improving well-being through expressive writing. Journal of Writing Research, 1(3), 181-198. PDF
* Wing, J. F., Schutte, N. S., & Byrne, B. (2006). The effect of positive writing on emotional intelligence and life satisfaction. Journal of clinical psychology, 62(10), 1291-1302.

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Tags: cognitive-psychology, positive-psychology, positive-thinking
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# Question
Title: What is the longer term prognosis for women in their early 20's with Schizoaffective disorder?
I am asking as I have this condition and I am hoping to gather more data about my particular demographic, in order to give me a better idea as to what they are doing, as well to lead me to how those of us with this condition fare later in life.

**What is the long-term prognosis for schizoaffective disorder?**

# Answer
*Note, this is not my area, and not medical advice. If you need help with this you should consult an appropriately trained health practitioner.*

To consult the scientific literature, do a search like "schizoaffective disorder prognosis" on Google Scholar.

For example, Robinson et al (1999) provide some relevant empirical data. The sample was 50% female and had a mean age of 25.6 (SD=6.3) years. To quote their abstract:

> Background We examined relapse after response to a first episode of schizophrenia or schizoaffective disorder.
>
> Methods Patients with first-episode schizophrenia were assessed on measures of psychopathologic variables, cognition, social functioning, and biological variables and treated according to a standardized algorithm. The sample for the relapse analyses consisted of 104 patients who responded to treatment of their index episode and were at risk for relapse.
>
> Results Five years after initial recovery, the cumulative first relapse rate was 81.9% (95% confidence interval \[CI\], 70.6%-93.2%); the second relapse rate was 78.0% (95% CI, 46.5%-100.0%). By 4 years after recovery from a second relapse, the cumulative third relapse rate was 86.2% (95% CI, 61.5%-100.0%). Discontinuing antipsychotic drug therapy increased the risk of relapse by almost 5 times (hazard ratio for an initial relapse, 4.89 \[99% CI, 2.49-9.60\]; hazard ratio for a second relapse, 4.57 \[99% CI, 1.49-14.02\]). Subsequent analyses controlling for antipsychotic drug use showed that patients with poor premorbid adaptation to school and premorbid social withdrawal relapsed earlier. Sex, diagnosis, obstetric complications, duration of psychotic illness before treatment, baseline symptoms, neuroendocrine measures, methylphenidate hydrochloride challenge response, neuropsychologic and magnetic resonance imaging measures, time to response of the initial episode, adverse effects during treatment, and presence of residual symptoms after the initial episode were not significantly related to time to relapse.
>
> Conclusions **There is a high rate of relapse within 5 years of recovery from a first episode of schizophrenia and schizoaffective disorder. This risk is diminished by maintenance antipsychotic drug treatment**.

### References

* Robinson, D., Woerner, M. G., Alvir, J. M. J., Bilder, R., Goldman, R., Geisler, S., ... & Lieberman, J. A. (1999). Predictors of relapse following response from a first episode of schizophrenia or schizoaffective disorder. Archives of General Psychiatry, 56(3), 241. FULL TEXT
> 2 votes

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Tags: abnormal-psychology, schizophrenia
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# Question
Title: Teaching Problem Solving : Mastering bit by bit Vs Try it all by yourself?
**Background:**

I'm a teacher who *trains* hundreds of high school students in Math, Physics & Chemistry to crack probably toughest competitive exam in India.

I deal with the students who are hardworking and scored at least 70%+ in their 10th Grade. They are definitely in a position to figure out the variables and required formula and solve it, if the problem is direct. For rest of the post when I say problem solving, I'm referring to the problems of Math & Physics which are not as tough as 12th grade Olympiad problems but definitely a lot tougher than typical textbook level problems. You can see some of such problems here. Each paper shown in the link, needs to be solved in 3 hours and more than 70% must be secured.

**Typical way of training: \[Method1\] Try it all by yourself** Students are taught (it is ensured students *understood* the) concept. Solve 3-4 variety mid-level example problems, to illustrate application of concept to the problem and reinforce their understanding. Move on to the next concept. Do the same with all the concepts and finish the chapter. Then, students are given about 50-60 unsolved problems, no two of same model. Students spend *lot of time* solving these problems, they discuss with teachers and they discuss among themselves.

**Problem with above method:** The success percentage is very less. Its as low as 2-3%. I mean, only 2-3% of the students get through all the difficulties and finish those problems. Most of the other students find those problems too difficult to solve and are either losing motivation to solve such problems or think that they are not intelligent enough to solve the problems.

**Fixing the problem: \[Method2\] Master bit by bit** I've read few books like, Why Don't Students Like School, How to Solve It: A New Aspect of Mathematical Method and analyzed myself (how do I solve the problems?) and understood that we try to recollect the patterns of problems. By practicing problems we are learning the patterns of problems and when solving an unsolved problem trying to figure out our put the patterns that we already learned. So, I've broken down larger problems into smaller problems. I've arranged these problems in the increasing level of difficulty. For the patterns to be remembered properly, I've increased no. of simple problems. I'm ensuring that students are mastering problems concept by concept, level by level.

Result is, now my students are not demotivated, they feel problem solving is simple and they are doing problems well.

**Problem with my method:** I realized that my students are entering a dangerous zone. They are not willing to solve difficult problems and they are unable to solve unknown model problems. Did I overtrain them? I consulted my college professors regarding this and they were furious with my method. They said, that I am spoon feeding the students. They said that I *must* follow the method 1. That is what is going to help them in future in their higher studies and research.

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What exactly is happening? Why is method 2 failing? Why will method 1 work? Is it just about the psychological difference in feelings that method 1 guys feel more prepared for solving any kind of problem? Whats optimal way? Where can I learn more?

# Answer
There are two theoretical constructions that may be of use to you:

**Scaffolding**

> *"...what the child is able to do in collaboration today he will be able to do independently tomorrow" -Vygotsky*

You are right to graduate the level of difficulty of problems the students encounter. Intuitively, a student has before her a level of task which, although perhaps within her reach, nonetheless is difficult and, as such, allows students to develop their skills by doing tasks at this level.

Lev Vygotsky, a soviet psychologist who stressed the role of play in learning (a perspective which is particularly germane to problem solving skills, which rely on an organic schematisation of knowledge and approaches- relational understanding), codified this intuition in the formal notion of **The Zone Of Proximal Development**. In the ZPD, we have the tools to play with the problems we face, and will organically develop the skills to solve similar problems- and, as with our intuitive version, this is where the best learning takes place.

The crucial thing about the ZPD, however, as distinct from our intuitive construction, is that *tasks in the learner's ZPD are tasks that the student requires assistance to solve*. In this handy diagram from wikipedia, the ZPD is represented by the middle circle.

A psychologist named Jerome Bruner went on to analyse the kinds of "assistance" or **scaffolding** needed in the ZPD- support frameworks which aid the student in tackling the task on her own (*not, it must be noted, merely doing half the work*\- cf. BenCole's remark).

Quoting from Wiki's Promoting better learning: scaffolding:

> * Effective learning environments use instructional scaffolding to aid the student in his/her construction of new knowledge.
> * *Avoid* telling the learner exactly how to accomplish the task; do not solve the problem for the learner. This may help the learner immediately, but it hinders the learning process.
> * It is important to promote better learning by helping the learner achieve his/her learning goal through the use of instructional scaffolding. The use of scaffolding helps the learner to actively build and construct new knowledge.

To elucidate the whole Scaffolding theory in the abstract would take time, so I'll leave concrete recommendations for later and link the relevant wikipedia page, if you're curious.

**Metacognition**

> *"Students can learn to think better if schools concentrate on teaching them how to do so"- Presseisen*

Thinking about thinking has almost become a cliche in modern british education (and, I suspect, further afield!), but it is with good reason. The process of deliberating on strategies and approaches to to problems, including attitudes and emotional responses, called **metacognition** is invaluable both to problem solving and to learning in general.

It is what separates a boy who makes a mental list of all of his 'tools' and selects the best for the job, and the boy with the hammer ready to hand, to whom everything looks like a nail. It is what separates the girl for whom failure is a miasma to sulk in, and the girl who sees her own misery and changes tack. Incorporating metacognitive elements into pedagogy essential to develop students independent enough to solve problems.

Again, the theory in the abstract is enormous, so here's another wiki page:Metacognition.

Now for some concrete recommendations (these are just what springs to mind right now, I may add to it later):

* Incorporate metacognitive maxims into your pedagogy "You're stuck! Excellent- that means you're learning" "If you don't know what to do- make a list" "I like to take a while to plan my mode of attack!" and so on...
* Model your internal dialogue in approaching a problem- do this often, and *heavily* exaggerate every aspect of it
* The most effective model for scaffolding is interpersonal- find some TAs!
* If not TAs- getting them to work in groups or pairs can mimic this
* Getting students to make a list of the tools and equations at their disposal at the start of a given problem
* Forcing students to draw a neat, clear diagram
* Resources, such as mini whiteboards (students hold up their answers at the end of an allotted time) allow you to tailor your problems to their ZPDs
* Make problems manifest in different ways so they can incorporate their intuitions, approaches and playfulness from other spheres
* A flow chart or worksheet for approaches to general problems incorporating the above as well as socratic questions (make toolkit, draw picture, is there a general equation? what can we sub into it? etc) can be a real boon
* Most importantly, be creative (or at least appear to be so), and your students will show their own creativity- Vygotsky says learning is about play (and, as I've said, this model is certainly apposite to problem solving), you must put them in a playful place any way you can!
> 6 votes

# Answer
This is *not* intended an answer. I have a couple observations and I want actual formatting.

You say:

> So, I've broken down larger problems into smaller problems. I've arranged these problems in the increasing level of difficulty. For the patterns to be remembered properly, I've increased no. of simple problems.

and then:

> I'm ensuring that students are mastering problems concept by concept, level by level.

But if the first quote is correct, you aren't ensuring this.
*You* are breaking down the problem.
*You* are arranging these problems by difficulty.
*You* are increasing the number of 'simple' problems.

And you wonder why the students have difficulty with complex problems?

The students *NEED* to be the ones 1) breaking down the problem, 2) analyzing and ordering the problems according to difficulty, 3) working on increasingly complex problems *with simple problems thrown in to 'test' them*. Not every problem is complex, and if they expect it to be complex they will over-think. The opposite problem of what you have now, it would seem.

It seems like you're looking for a balance between holding your students' hands, and forcing them to figure out the problems for themselves. Perhaps try to blend the two methods, offering to break the problem down, but only if need be, or point out patterns in especially difficult problems.

But your colleagues are (partially) correct: the students *need* to be able to solve a complete, complex problem, from start to finish, without outside help. But *you have to guide them in developing this ability.*

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Again, *this is not an answer* because I am not an educator, nor do I have established research off of which to base my opinions or insight. So, take this with a brick of salt knowing that I don't know your situation.

Also, I will mention that this, as it stands, is a self-help question. While CogSci.SE usually jumps on self-help questions, the problem with most is not that they're self-help, but that they are either medical- or mental health-related, or they are extremely generic. Your question is neither; while you haven't received down-votes, you also haven't received up-votes. Just an explanation, if you were curious.
> 2 votes

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Tags: educational-psychology, problem-solving
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title: Does empathy extend to animals?

text:
# Question
Title: Does empathy extend to animals?
I've read that humans are able to empathize with other humans, to feel as another person does, through mirror neurons. I'm guessing that they're able to empathize with primates too, as they share similar brains, have similar limbs, faces, etc. So, when someone watches a monkey or child drink juice, they can empathize some of the joy of drinking juice.

But what about a human empathizing with less humanoid animals? Can a person who has developed a personal bond with say, a horse, 'feel' the same way as the horse does? Can one understand the joy of a cat eating its favorite food?

Do mirror neurons apply between humans and animals as well?

# Answer
> 7 votes
> But what about a human empathizing with less humanoid animals?

Empathic responding towards humans is generalized to other species. The greater the similarity of the species towards humans, the larger is the empathic response. The findings support the notion that there is a relationship between human empathy directed towards other humans and human empathy directed towards non-human animals. via

> Can one understand the joy of a cat eating its favorite food?

It depend on person. Problem is that we actually do not know how animals feel. And our empathy based on assumption that they feel like us. So it is one more proof of involving of mirror neurons in empathy.

> Empathy toward non conspecifics has different neural representation among individuals with different feeding habits, perhaps reflecting different motivational factors and beliefs. via

Also look at Anthrozoos: A Multidisciplinary Journal of The Interactions of People & Animals

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Tags: social-psychology, emotion, animal-cognition
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# Question
Title: How to adjust SSE or RMSE for the number of free parameters in the model?
How do I adjust SSE (sum of squared errors) or RMSE (root-mean-square errors) for the number of free parameters in the model?

Is there an "adjusted" RMSD metric similar to the adjusted r-squared metric?

# Answer
> 3 votes
There are at least 3 ways to discount SSE (or RMSE) by the number of free params:

$$ \text{adjusted RMSE} = \sqrt{\frac{SSE}{n - k}} $$

$$ AIC = n \times ln\left(\frac{SSE}{n}\right) - k \times ln(n) $$

$$ BIC = n \times ln\left(\frac{SSE}{n}\right) - 2 \times k $$

or in computer code style:

```
k = number of free params
n = number of DV's
SSE = sum of squared errors

adjusted RMSE = sqrt ( SSE / n - k )
AIC = n * ln(SSE/n) - k * ln(n)
BIC = n * ln(SSE/n) - 2 * k

```

# Answer
> 5 votes
To my knowledge, there is no adjusted RMSD.

RMSD, unlike $R^2$, isn't typically used to compare models across the literature. $R^2$ represents the proportion of variance explained by the model, a construct which translates well across different experimental designs. Adjusted $R^2$ distorts this by accounting for the number of parameters in your model, but is a better estimate of the proportion of variance in the *population* explained by your model.

RMSD is in whatever units you happen to be using. It should be interpreted against some benchmark for what you think a good model should be, or whatever has been deemed an "acceptable error rate". It's not clear to me that adjusting for the number of parameters in RMSD would provide a number that is inherently meaningful, but I'm not sure if this is true.

If you would like to select among several model candidates, you may want to compute AIC (Akaike Information Criterion) or BIC (Bayesian Information Criterion), both of which are attempts to maximize the likelihood of your model while minimizing the number of parameters. Both metrics are commonly used in cognitive modeling, and I think this may be what you are looking for.

While I think this question is on-topic here, you will likely get better answers on stats.stackexchange.com (as Jeromy points out) because your question is not really specific to *cognitive* modeling.

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Tags: cognitive-modeling, computational-modeling, statistics
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title: Do humans mentally discretize numbers?

text:
# Question
Title: Do humans mentally discretize numbers?
It seems reasonable to me that humans discretize numbers: this number is bigger than than number, or when faced with a series of numbers that range from 0 - 100, 50 is "middling", 10 is "low" and 90 is "high". It doesn't seem to me that the brain would place much value in the difference between 76 or 77.

I ask this in the context of scoring in games: many games present scores to players as numbers, but it seems to me the numbers themselves are meaningless, and actually translate to mental buckets where you can say "this is a good score" or "this is a bad score". Players don't actually perceive the numbers. This would indicate that games that use grading systems like A-F would be better communicators of player performance.

Is there any research to back up this theory? I'm coming up short, but I can't believe no-one has tried to answer this question.

# Answer
One common way of framing numerical cognition is in terms of a "mental number line". This mental number line is thought to have a logarithmic scale, so perceived differences are inversely proportional to their magnitude. For example, the difference between 6 and 7 is perceived as bigger than the difference between 76 and 77. This is just a variant of the Weber-Fechner Law, which applies in many perceptual domains (sound loudness, object weight, light brightness, etc.). So people don't exactly put numbers into discrete bins, but small differences begin to blur together for larger numbers.

In typical, educated adults there is also thought to be an explicit symbolic or linguistic representation of numbers that captures their exact value and allows us to do exact calculations.

For theories of numerical cognition, one good place to start is:

Feigenson, L., Dehaene, S., & Spelke, E. (2004). Core systems of number. *Trends in cognitive sciences*, 8(7), 307-314.
> 7 votes

# Answer
The ability to discretize numbers seems to depend on having words for discrete numbers. But humans seem to be able to estimate, regardless of linguistic constraints.

As a cool counterexample to "typical educated adults" as evidence for exact, symbolic representation of number, the Pirahã people of Brazil do not have words for numbers and do not seem to possess any numerical concepts beyond "few" or "many." So, it's not a given that humans universally represent number, but even the Pirahã seem to have ability to estimate, suggesting that your intuition may be correct and it's meaningful differences that are universally represented.

Gordon, P. (2004) Numerical Cognition Without Words: Evidence from Amazonia. *Science* (306), 496-499.
> 5 votes

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Tags: measurement, cognitive-modeling
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# Question
Title: How much information is lost when conveying an experience or emotion to another person?
Certain languages have words that do not literally translate into any another language. There is already a small loss of information in this sense.

Emotions are a personal experience and the gravity and meaning of them are dependent on the person who experiences them. The same goes for all conscious experiences.

So how much information is lost when one person is trying to convey these personal experiences with another person? Will actions carry more relevant data than words when explaining a personal experience?

Is there any way to quantify the loss in translation of experiences?

# Answer
Communication is always a lossy and inexact process. If I am trying to convey information to you - the times of trains, for example - I can use dates and times that I can be confident that you will interpret the same way I do. But you may not - I may say the train leaves at 8:40, and you assume I mean the morning, whereas I actually mean the evening. So while there is a consistent and standardised worldview that I share, I can have reasonably high confidence in this.

When it comes to emotions, these are, by definition, more subjective. The shared worldview is much smaller, and the chances of the words having the same meaning between us is significantly less. Because most words actually have emotional resonances, there is always this danger, but when the emotional resonance is the intention, this is an issue. I can only be sure of communicating the emotions to you if we share the same emotional language.

This language is build though our experiences, memories, make-up etc, so to share a language, we need to share all of this - effectively impossible. To measure the difference, we would need to do a substantial comparison of the relevant worldviews of the two communicants. Given that most people cannot even start to quantify their own dominant worldview, this does not seem likely.

* Just noted - you referred to experiences not emotions. However the same applies, because our experiences are communicated emotionally.
> 7 votes

# Answer
> So how much information is lost when one person is trying to convey these personal experiences with another person? Will actions carry more relevant data than words when explaining a personal experience?

I believe this really depends **completely** upon both *what specific words you use* to describe the experience / emotion as well as *the experiences and memories* of the person with whom you are speaking.

To convey an emotion well you must trigger a sense of empathy in the person you are speaking to. If you just say, "I feel happy", you're unlikely to convey nearly as much detail as if you describe that feeling in a way which triggers an emotional response in the listener.

As an example, compare the following two statements:

> I am sad.

This is quite broad and will likely trigger a wide range of emotions in the person reading / hearing it, if any emotions are triggered *at all*.

> O woe! O woeful, woeful, woeful day!
> Most lamentable day. Most woeful day That ever, ever I did yet behold!
> O day, O day, O day! O hateful day! Never was seen so black a day as this.
> O woeful day! O woeful day!"
> *\- William Shakespeare, Romeo and Juliet, 4.5*

This was just one quick example I could find. I'm sure if you peruse English Stack Exchange you could find much better examples, but my point is: the second paragraph conveys *a lot* more emotion than the first (contrived) statement. Therefore, to answer your question:

> Is there any way to quantify the loss in translation of experiences?

Not really, not that I can see anyway. *The way the experience translates just depends on far too many factors*. What words did you use? What did the person you were speaking with interpret those words as? What are your shared experiences? What are the other person's memories and experiences like? Are you evoking a sense of emotion for them? If so, what memories are you drawing on? These factors, and a lot more, will determine what they feel when they hear your words.
> 6 votes

# Answer
> Certain languages have words that do not literally translate into any another language. There is already a small loss of information in this sense.

Even though language is very influential for thinking (and read the The Newspeak appendix in 1984 for a thought provoking eye opener), even when you have a group with the same language level skills they will put different meanings to words.

As an experiment, try for instance to ask 10 persons to define the word `plan`. Even though there probably will be close to zero linguistic ambiguity about the word you will get potential very different answers; some people think a plan is an overall approximation while other think a plan is more a detailed step by step thing.

> Is there any way to quantify the loss in translation of experiences?

That would I think require a quantifiable method of measuring the difference in the individual meaning of words.
> 2 votes

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Tags: social-psychology, emotion, language, consciousness, philosophy-of-mind
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# Question
Title: How does knowledge about a subject aid in its recall?
I've experienced it many times with my students and also with myself. Let me illustrate with example:

When I'm teaching, I say something like this:

> Gastrointenstinal Track has following sections
>
> 1. Buccal Cavity
> 2. Pharynx
> 3. Esophagus
> 4. Stomach
> 5. Duodenum
> 6. Jejunum
> 7. Ileum
> 8. Caecum

To help them remember I repeat above thing multiple times. But still they don't remember much of the list.

Alternatively instead of just saying those things (even though that's all I need my students to remember), I spoke about each of the above item for few minutes. i.e. I gave more details of about each of those things. Result is that, now my students do not remember most of the details about each of those items, but they could remember the list. Which is exactly I want.

Whats happening here? Whats the science behind it? Is there more to what I'm describing?

# Answer
> 7 votes
The first method (repeat the terms over and over) is called **rote rehearsal**. It's not actually a very good way to learn, though it has the benefit that it always "works" because you can always repeat a list. You may be unable to perform certain other encoding tricks such as elaborative rehearsal due to the context of the items, like a list of random words. Consider it more of a fallback than a learning strategy.

The second method (talking about the item at length) is **elaborative rehearsal**, which, as Cheatboy2 points out, benefits from the levels of processing effect. The deeper you know something the more "connections" you can make, which has the advantage of making things easier to remember in general and easier to remember in the context of specific, related items.

Elaborative rehearsal has the benefit of creating *understanding* rather than simple *knowledge* of a term. Buccal Cavity is just a word until you realize what it means. Once you know what it means you can additionally draw connections between related words, which, in this case, is very helpful as all the words on the list to remember are in fact connected in various ways. If you don't elaborate on the connections between them in your own memory, you won't benefit from that effect.

I suggest giving both articles (in bold) a read to understand the deeper intricacies of both, but those are the general ideas behind why elaborative rehearsal is preferred. Note that a Mnemonic device may be a more effective method of teaching lists where the list is what's important, not a deeper understanding, or where there is little to elaborate on, such as ROYGBIV to remember the colors of the rainbow.

# Answer
> 2 votes
Probably because describing each element involve a deeper process of information for your students (they have to organize their knowledge to understand what is it and how it relate to the other parts).

Look at this: http://en.wikipedia.org/wiki/Levels-of-processing\_effect

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Tags: learning, memory, encoding
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title: Why are most people right handed?

text:
# Question
Title: Why are most people right handed?
How did right handedness win over left handedness in numbers?

Is it only a coincidence that there are more right handed people than left handed ones? Or, has some effect in nature explicitly made right handedness dominant?

# Answer
First of all, asymmetries in apparently symmetric creatures (of which most are) are actually quite typical. However, in most cases of hand dominance, there is no population-wide hand dominance. In other words, the population is split 50/50 between left and right handers. In humans, however, a lack of hand dominance is often associated with cognitive deficits.

In humans, population-wise, we are right-hand dominant (9:1). There are exceptions to a genetic influence, such as strict schools disciplining children into using their right hand, or an indirect consequence of developmental brain trauma or genetic diseases, but for the most part the right-hand dominance is thought to be a genetic outcome based on the emergent effects of several interacting genes. That is, there's no particular reason why nature "chose" right over left, just that having a dominant hand allows for more specialization with respect to tool-using which *could* possibly have given humans with this mutation a competitive edge over their ambidextrous competitors.

A single-gene theory (Corballis, 2009) proposes that there is a dextral and a chance allele of a particular gene and that people born with the dextral allele are likely to be right-handed while people born with the chance allele have equal chance of being left or right-handed.

<sub> Francks, C; DeLisi, LE; Fisher, SE; Laval, SH; Rue, JE; Stein, JF; Monaco, AP (2003). "Confirmatory evidence for linkage of relative hand skill to 2p12-q11". American journal of human genetics 72 (2): 499–502. (PDF)
Van Agtmael, T; Forrest, SM; Williamson, R (2002). "Parametric and non-parametric linkage analysis of several candidate regions for genes for human handedness". European journal of human genetics : EJHG 10 (10): 623–30.
Warren, Diane M.; Stern, Michael; Duggirala, Ravindranath; Dyer, Thomas D.; Almasy, Laura (2006). "Heritability and linkage analysis of hand, foot, and eye preference in Mexican Americans". Laterality: Asymmetries of Body, Brain and Cognition 11 (6): 508–524.
Scerri, T. S.; Brandler, W. M.; Paracchini, S.; Morris, A. P.; Ring, S. M.; Richardson, A. J.; Talcott, J. B.; Stein, J.; Monaco, A. P. (2010). "PCSK6 is associated with handedness in individuals with dyslexia". Human Molecular Genetics 20 (3): 608–614.
Michael C Corballis. (2009) The evolution and genetics of cerebral asymmetry. Phil. Trans. R. Soc. B 12, 364 (1519): 867-879 </sub>
> 7 votes

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Tags: evolution, behaviorism, genetics
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# Question
Title: Learning of new concepts being impeded by an error in previous work
*Note: I'm framing this question in terms of tutoring math since that's what I tutor most, though it applies to a wide range of subject matters.*

I do a decent amount of tutoring, and this is one phenomenon I see popping up constantly, and I occasionally catch myself doing the same thing, though less often since I've become aware of it

What happens is a student learns a new concept/formula/algorithm in class and then does practice or assignment questions. They will then come up to me and ask me to check their work because the answer they are getting doesn't make sense, or doesn't line up with a known answer. Sometimes, they will even have spent hours double or triple checking their work on this new formula.

I will look over their work and confirm its correctness. I have learned to ask "Can I see the work you did to get to this point?" They then show me this work, and most of the time, there is a simple arithmetic error or oversight (and if its a misunderstanding of previous material, then its a whole other issue).

What has happened is that the assignment question involves multiple steps, the student makes a simple error in an early step, and assumes the error to be in the later steps involving the newly taught equations, and wastes hours looking for an error there.

My related questions are:

* Does this phenomenon have a name, and if so what is it?
* What are the psychological processes behind this, i.e. why does the student not double check *all* of the work?
* Is there any way to mitigate this behaviour besides simply being aware of it?

# Answer
> 2 votes
There is a difference between being wrong and knowing you're wrong.

I like to think of this with the analogy of Wiley the Coyote from looney toons. He would usually try to catch the runner, and run off the cliff, but keep running for a while, and only fall when he realizes that he ran off a cliff.

The point in which your student is doing the assignments based on incorrect previous calculations is that point between coyote running off the cliff and realizing he has done so.

I'm not sure of the terminology about this phenomena, but here's my theory on why people tend to do this: Most of the students nowadays are conditioned to feel right about everything because **knowing, that you are wrong** feels bad, they feel like there is something wrong with them (rather then just being wrong), while the alternative, of being wrong and not knowing about it that feels exactly as being right.

This conditioning is introduced in our educational system very early and often results in not taking chances that could result in them being wrong, or (more related) in not even considering the possibility that they might be wrong at some point (when most of the time they are).

I think that the only way of fixing this is deconditioning ourselves (or your students) in this case, that being wrong is something bad. Instead, indicating being wrong as a sign of progress. I think Einstein said:

```
A person who never made a mistake never tried anything new.

```

Encouraging your students questioning even things that might be established as truth by others is the key in my opinion.

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Tags: terminology, learning, educational-psychology
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# Question
Title: What is a test called that involves indicating whether a line has the same slope as a previous image?
I would like to know the name of the following test:

Participants were asked to memorize the slope of a line of a target image. Then different images (lines with varying slopes) were presented sequentially. Participants were asked to press one of two buttons to indicate whether the displayed image was the same or different to the target image.

* Is it a recognition memory test?
* Does this test have a specific name?

# Answer
The task sounds like a match-to-sample task which is indeed used in working memory studies. In this test participants are presented with a sample stimulus and have to judge whether or not following stimuli resemble this particular stimulus. Depending on the time span between the presentation of the sample stimulus and the following stimuli this task is sometimes also called a delayed match-to-sample task.
> 5 votes

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Tags: terminology, memory, test
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# Question
Title: In C. elegans, which neuron has the largest span, and why is it this large?
The model organism C. elegans is about 1 mm in length. This is quite small. In fact, some C. elegans neurons span \>25% of the length of its body (ref.).

This observation leads me to the following question: Which neuron in C. elegans has the largest span, and why is it this large?

# Answer
> 5 votes
I am a member of OpenWorm.org, an open-source project that aims to simulate a C. elegans cell-by-cell. I didn't know the answer to this myself off the top of my head, but I have access to a number of folks who have been working hard on C. elegans anatomy for the last couple of years so I went ahead and asked them this question on our discuss mailing list. Thanks to Chris Grove and Tim Busbice for providing the answer that I am reporting below:

*Chris Grove*:

> Finding the neuron with the largest span partly depends on your definition of "length" in this context. In terms of largest amount of total axon/dendrite length, this would most probably be the PVDL/PVDR sensory neurons. They produce a large number of branches of dendrites that act to perceive mechano and thermo-sensation. See the WormAtlas page here.

*Tim Busbice*:

> If by "length" one means, absolute longest extension from head to tail, that's a tougher call, as there are several that extend from the head to the tail. An example of these are the AVDL/AVDR command interneurons, that function as touch modulators for backward locomotion induced by head-touch, and also drive backward movement of the animal along with driver cell AVA neuron, AVE and A-type motor neurons.

You can find a lot of info on C. elegans anatomy on WormAtlas and on an OpenWorm data spreadsheet in which we are consolidating detailed anatomy data from different sources.

Also I would advise checking out the OpenWorm Browser \- a web-based 3D viewer that you can use to explore the C. elegans anatomy cell-by-cell (the 3D model was developed by Chris Grove, see VirtualWorm for details). For instance you can easily search for those "longest" neurons mentioned above! Screenshot of one of them selected (AVDL) below:

Hope this helped!

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Tags: neuroscience
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# Question
Title: Should fantasy distractors be avoided in multiple choice questions
Is there any reason not to include fantasy distractors (made-up wrong answers) in multiple choice tests.

**Examples:** What is the name of the compound HCl?

a) Hydrochloric acid

b) Chlorohydride acid

c) Chlorohydric acid etc

What is the term for a parasite that cannot complete its life cycle without its host?

a) Obligate parasite (correct)

b) Parasitic obligate (fantasy word)

c) Mandatory parasite (fantasy combination)

**Fantasy distractor definition:** Usually one chooses distractors that a student could confuse with the correct answer, based on knowledge of common cognitive models of the field. I call a fantasy distractor a distractor that is a made-up word - typically it would be used for testing/learning complex terms that consist of a combination of etymological roots by rearranging them or mixing them up.

**Potential concerns:** How high is the risk that students remember the fantasy distractor? What is the best practice on such fantasy items?

**Rationale for having fantasy items:** The reason for asking is that it seems having a greater number of distractors can make the test more of a retrieval test than a recognition test. Getting plausible non-fantasy distractors (eg in chemistry can be tough).

# Answer
> 2 votes
I would say no, there's no reason not to, and in fact it might be better, based on the following rather speculative reasoning.

In general, despite the general benefits of testing for learning, multiple choice testing can also lead to subsequent memory for incorrect responses, i.e. it can cause students to learn false responses.

> Marsh, Roediger, Bjork, & Bjork (2007) "The memorial consequences of multiple-choice testing." Psychonomic Bulletin & Review, 14(2) 194-199

This doesn't explicitly compare fantasy answers to other misleading answers, but intuitively, it seems that such "false learning" would be MORE likely to be reinforced in the future for plausible responses than for fantasy responses. The reason is that fantasy responses are unlikely to ever be encountered again, while plausible responses might be, leading to reinforcement of the false learning.

See also here regarding avoidance of false learning from multiple choice testing:

> Little and Bjork (2012) "The persisting benefits of using multiple-choice tests as learning." Proceedings of the 34th Annual Conference of the Cognitive Science Society.

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Tags: measurement, memory, test
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title: Is fear rational?

text:
# Question
Title: Is fear rational?
Let's suppose a big ugly monster thingy wants to eat you. While you're running away from it, you're feeling fear. Can this situation be considered one where fear would be rational?

# Answer
> 2 votes
Yes! Of course fear can be rational, especially when there is in fact a big scary monster and you are in danger.

There is an unfortunate meme in society that emotions and rationality are incompatible, but that's not the case. Emotions can only be irrational if you are mistaken to feel those emotions in that context.

Cases where fear is irrational include:

* Fear of cotton balls
* Fear of a non-existent monster
* Not fearing being chased by an actual monster/cheetah/grizzly bear

Now, it's largely up to you to decide what emotions are reasonable for each context, because otherwise the examples become a bit normative. For example, is it irrational to feel a lot of anxiety in social situations? That depends on the social situation, but I'll guess not.

The folks over at Less Wrong have given this sort of thing a lot of consideration. Here's their wiki link to the subject.

# Answer
> 3 votes
The answer depends on your definitions of "fear" and "rational".

If you simplify the complex English semantics, **rational** might mean either (1) "sensible; not foolish" or (2) "using the faculty of reasoning".

If you understand *rational* to mean "sensible", then fear can be rational or not, depending on the situation. Fear of mice is probably not very sensible, while fear of heights most probably is.

If you understand *rational* to refer to cognition (as opposed to affect), then the answer depends on your understanding of *fear*.

If you define **fear** as an emotion, then fear can, by definition, not be a cognition. An emotion can be caused by a cognition, it can be thought upon and suppressed by the faculty for rational thought, but it is not a cognition. In this sense fear would not be rational.

How could you define *fear* to make it meaningful to think of it as not an emotion?

If you define *fear* as, e.g., an attitude (the attitude of judging something to be dangerous or harmful), then fear would very likely have affective and cognitive components. I am not sure if any speaker of English would accept this definition (even the OED says that fear is an emotion), but you could certainly define fear in such a way -- which would lead to a lot of interesting but unnecessary confusion with your readers.

---

Psychologists would avoid the word "rational" here, because it is not a scientific term. It is a philosophical term. From this perspective, the opening question is not a question relating to cognitive sciences at all, but to everyday wisdom, and should be closed.

# Answer
> 1 votes
Why are you running away?

1) Are you running because of fear?
2) Are you running because the monster might harm you?
3) Are you running because you've had an encounter with a monster before and even though this one doesn't look like that one and that one had claws and this one doesn't but this one is still coming towards you, kinda fast?

Fear is a marker, like pain. Fear can be automatically activated by occurrences in one's environment in order to activate a response before the conscious mind could possibly have time to react.

LOOK OUT, DUCK! --- Yell this at someone sometime and watch them flinch, down and back. Almost every time.

The problem comes when we aren't paying full attention to our environment, and instead using cognitive shortcuts, such as stereotypes. In these cases, we're using past experiences to inform future expectations - when past experiences are traumatic, we will sometimes (unconsciously) assume negative future expectations, which is the fundamental basis of anxiety.

*Is fear rational?*

Let me turn that around:

*Is a dishwasher rational?*

Fear is a tool, baked into the human brain. A dishwasher is a tool. Both can malfunction, both can run improperly (long, short, etc). We can even, over time, reduce our exposure to both (meditation / washing the dishes by hand).

If we run a dishwasher once for each dish we have to wash, that would be irrational. If we feel fear at every occurrence, that would be irrational. If we run the dishwasher without soap, that would be irrational. Unless we have need for it.

It's all about context.

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Tags: cognitive-psychology, social-psychology, emotion, rationality
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# Question
Title: What effects does spending a lot of time in online communities have on interpersonal skills?
There are quite a few users who are pretty much addicted to the Stack Exchange network and spend over 3-4 hours per day here. Time spent here will result in lower amount of social interactions, and lesser time for other activities as well.

What are the effects that this has on the social skills of a person ?

In a way, we are all interacting with other individuals on this platform as well, but the communications are mostly textual and in a way, *buffered* (for lack of a better term). So, its safe to say that spending half an hour interacting with individuals here will be very different from interacting with individuals face-to-face. In such a scenario, what are expected and/or observed effects on communication abilities.

# Answer
> 2 votes
There seems to be a difference between social community users and non-users (e.g. http://dx.doi.org/10.1016/j.chb.2013.01.026), but these are only correlative data, not causative, but in a recent study "Facebook usage was found to interact with measures of psychological well-being, suggesting that it might be beneficial to students experiencing low self-esteem and low life satisfaction." (http://dx.doi.org/10.1080/0144929X.2010.550063)

This is just a quick hint and doesn't comprehensively answer your question, but maybe the articles contain references to other research.

*Follow the links to get to the original publications and a short abstract describing the study and results.*

---

More stuff I found through a Google Scholar search for "online communities effects":

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC411092/ http://repository.maestra.net/valutazione/MaterialeSarti/articoli/Johnson-Survey.pdf etc.

I don't know, if any of this is relevant, I just want to give you ideas to do your own research.

If you access Google Scholar through a university network, you'll get links to most of the articles, otherwise you'll still be able to read most of the abstracts.

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Tags: social-psychology, communication, internet
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# Question
Title: Is there a metric of the overall excitation of the brain or nervous system?
I'm thinking of a way to describe what's happening to a single channel EEG/MEG sensor output. I've noticed that there is significant difference in the readings from a quiet observations, versus a person who's engaged in a conversation. I'm looking for some way to quantify the two distinct states, so a computer algorithm may have a chance of distinguishing the two. Potentially, in the future I would like to compare readings from one individual to the next, or compare the arousal of two individuals engaged in a conversation.

**It would be helpful to know what are the names of metrics that may be used to measure the overall arousal/excitation of a person**, that person's nervous system or brain. I can think of Actigraphy (the study of human motion) as one, its units are arbitrary activity count, or m/s^3. These are scored as "zero point crossings", or "area under the curve" of an accelerometer graph. But are there any other metrics or units of human activity/excitation? Maybe some of them are related to an EEG/EMG readings? Like an obscure algorithm named after some scientist?

# Answer
> 3 votes
MEGs using SQUIDs can detect magnetic flux density measured in teslas. Away from sleep studies and epileptic brain activity, this should be a useful indicator of relative brain arousal. Readings from two different people on this scale should be comparable based on the orders of magnitude for the unit measurement. As for comparative measurements of brain arousal, I don't think Actigraphy would be useful, nor any other method of measuring somatic motion. These can certainly determine weather a person is sleeping, sedentary, or exercising, but discriminating between different sedentary behaviors would be difficult and determining relative brain activity for those behaviors would be reliant on more traditional methods (EEG,MEG, etc). MRI methods might be useful, as the total change in blood oxygen volume from a base state or inactive state can be distinguished from a more active state.

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Tags: measurement, performance, eeg, arousal
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# Question
Title: What factors influence a person's perceived expertise?
For example, some people believe they are excellent human lie detectors. But, research shows that the average person is only able to detect deception about 54% of the time. What techniques could be used to influence perceived expertise?

# Answer
> 4 votes
**Expertise** – defined by Hovland, Janis and Kelley (1953) as "the extent to which a communicator is percieved to be the source of valid assertions" – is the second dimension of source credibility besides trustworthiness and attractiveness in their source-credibility model. The perceived expertise is, of course, not independent of these other dimensions: attractive people are considered more knowledgeable, and trustworthiness has a similar effect.

Leaving aside obvious objective cues for expertise (e.g. proven success with identical problems, the university degree of a medical doctor, or years of practical experience in a relevant field) I want to focus on irrelevant and subjective cues.

What constitutes expertise would most certainly depend on the field and the expertise of the person judging the expertise of another. For example, Golbeck and Fleischmann (2010) found that in online Q&A sites such as cogsci.stackexchange.com, photo cues such as smiles or showing the person egaged in a relevant activity only improve trust in a poster's knowledgeability among non-experts. And while the expertise of a person producing tangible goods can be easily discerned even by a layman user ("Do these shoes fit?"), intangible services such as child care or a physician's diagnosis and the relevant expertise are very difficult to measure, sometimes even for experts. (Zeithaml, 1981)

In a study on the social communication of political expertise, Huckfeldt (2001) found the most important factors to influence perceived political knowledge to be interest (influencing perceived expertise with a probability of .74), objectively defined knowledge (.36), agreement of discussion partner (.31), agreement between discussion partners (.29), partisan extremity (.14) and education (.11).

As you can see, apart from objective knowledge, perceived expertise is in part influenced by wether other people agree with a speaker, how strongly he favors one standpoint (neutrality and scepticism, both signs of healthy scientific reasoning, seem to substract from apparent expertise), and how educated he appears in general (i.e. a well-groomed person with a PhD will appear more of an expert, no matter if he indeed has any knowledge of the field he expands about or not).

Following a dual processing model such as the elaboration likelihood model, source factors such as expertise, likability, attractiveness and consensus serve as heuristic cues when recipients lack the ability or motivation to scrutinize a message effortfully. But not all recipients use the same cues. Low self-monitors (whose attitudes are based on values) elaborate an expert source's message more effortfully than the same message delivered by an attractive source, while high self-monitors (whose attitudes are based on sochial adjustment concerns) process messages from an attractive source more effortfully. (Ziegler, von Schwichow & Diehl, 2005)

In other words: When a message is unambiguous, strong arguments lead to more agreement than weak arguments (not source characteristics such as expertise). But when the message is ambiguous, it leads to more favorable reactions (aggreement, attitude change) when it is delivered by a source whose characteristics match the personality of the message's recipient.

I am sure there is more, but this is what I can come up with at the moment. If you want to find more, look at research on persuasion.

References:

* Goldbeck, J., & Fleischmann, K. R. (2010). Trust in social Q&A: The impact of text and photo cues of expertise. In Proceedings of the 73rd ASIS&T Annual Meeting on Navigating Stream in an Information Ecosystem (vol. 47). Silver Springs, MD: American Society for Information Science. http://delivery.acm.org/10.1145/1930000/1920442/a77-golbeck.pdf
* Hovland, C. I., Irving, K. J., & Kelley, H. H. (1953). Communication and Persuasion. New Haven, CT: Yale University Press. http://xa.yimg.com/kq/groups/24018828/1542385145/name/4188769.pdf
* Huckfeldt, R. (2001). The social communication of political experts. Amercian Journal of Political Science, 45, 425-438. http://www.jstor.org/stable/2669350
* Zeithaml, V. A. (1981). How consumer evaluation processes differ between goods and services. In J. Donnelly & W. George (eds.), Marketing of Services (pp. 186-190). Chicago: American Marketing.
* Ziegler, R., von Schwichow, A., & Diehl, M. (2005). Matching the message source to attitude functions: Implications for biased processing. Journal of Experimental Social Psychology, 41, 645–653. http://dx.doi.org/10.1016/j.jesp.2004.12.002

---

A note on lie detectors:

In a study on "Police officers' ability to detect suspects' lies" (Mann, Vrij & Bull, 2004), the ability to detect lies strongly correlated with (self-)percieved experience in interviewing suspects. Participants where UK police officers of differing ages (22 to 52), length of service (1 to 30 years) and work areas (e.g. criminal investigation, trainers, traffic officers etc.) Average self-reported experience in interviewing suspects was 3.75 (on a scale from 1 = totally inexperienced to 5 = highly experienced).

For the whole sample accuracy in detecting lies was 66%, which is significantly higher than the level of chance. Experience was somewhat correlated (around .20), while length of service was uncorrelated (-.07) to accuracy.

* Mann, S., Vrij, A., & Bull, R. (2004). Detecting true lies: Police officers' ability to detect suspects' lies. Journal of Applied Psychology, 89, 137-149.

# Answer
> 1 votes
It seems like your question is tapping into a number of different questions. First, you might ask about what causes people to perceive expertise in others verus what causes people to perceive expertise in themselves. Second, there is the question of when are expertise perceptions inflated and if so what individuals are prone to this and what tasks are more likely to induce this.

### What makes someone be perceived as an expert?

I imagine the question can be answered somewhat by casual observation. Having appropriate qualifications, having a known track record of behaviour indicative of expertise, dressing and behaving like other experts, presenting ideas and acting with confidence, an so on are presumably related to perceptions of expertise. Of course, some people exploit these signs to demonstrate expertise that they don't possess (e.g., using technical jargon to intimidate; exaggerating stories of past successes).

### What tasks lead to inflated sense of expertise?

You use the example of detecting deception. This suggests you are interested in why people would think that they are "experts" at detecting deception, even when they are actually relatively poor at the task.

There are many similar tasks which are renowned for involving inflated perceptions of expertise. These include driving a car, speculating on the stock market, lie detection, evaluating employees from job interviews, and so on. For many of these tasks, there is a literature on why people tend to have an inflated opinion of their own expertise (e.g., see this previous question on self-perceptions of driving ability.

As for causes of inflated expertise, you might look at as interaction between task and person features.

Task features include:

* lack of objective feedback on absolute and comparative performance (e.g., we don't usually find out when someone has lied to us; we don't find out how well the employee we did not hire would have performed)
* outcomes are inherently relatively unrelated to behaviour (e.g., stock market speculation)

Person features:

There are wide range of psychological processes that can lead people to have inflated perceptions of their own expertise (for instance see this list). Take two examples, first self-serving bias reflects one general bias. People may wish to see themselves as experts and thus they may rationalise their experience so as to justify inflated self perception. Second, people often don't know what they don't know.

### Concluding thoughts

A lot more could be said about all this, but I imagine more interesting answers could be provided by a more focused question. If interest lies in a particular domain of inflated expertise such as lie detection, then there is a dedicated literature on that. Or if interest is focused on the most effective way to demonstrate expertise in some context such as leadership or advertising or ongoing relationships, there will also be a specific literature on that.

---
Tags: perception, expertise
---


# Question
Title: Is StackExchange.com Addiction Dangerous?
I recently looked at the meta.math.stackexchange.com and found the second anniversary was celebrated. As in the last year's Happy-Birthday post (linked therein) , some people declared the addiction to the site.

My question is: What kind of addiction is this?

Certainly some kind of internet addiction, combined with a good portion of gamification, represented by reputation, badges, ... But in this case, I think there is also some kind of altruistic helper-syndrome.

Does this make math addiction a good one? Are there examples of helpful, let's say in a social sense, addictions?

# Answer
> 3 votes
For something to be considered a mental disorder worthy of it's own definition, it needs to have some really strong effects that are consistently different from others definitions and are not explained by co-morbidity of others.

ADHD, OCD, and Tourettes all exhibit co-morbidity and common brain regions, but since the symptoms and treatment differ so radically, we treat them as distinct from each other.

In short, you are asking the wrong question : ) I'm sure there is plenty of good lit out there on helping people to the point of harming oneself. Usually, however, this type of "addiction" is a better understood as a generalized form of something else and you would be hard pressed to come up with symptoms and treatments that would generalize only to help addicts of sites like stack exchange.

It's like talking about "breast cancer" instead of categorizing it according to cell types, treatment, etc. Sure, you will get more money for breast cancer than a-morphic-sciency-sounding cancer, but that doesn't help one predict what could kill it.

---
Tags: social-psychology, gamification, addiction
---


title: How rare is synesthesia?

text:
# Question
Title: How rare is synesthesia?
I visited a neuropsychologist recently who told me I have Synesthesia. I never really knew what it was, but it's fascinating and I can't believe it isn't the norm among people. For me, certain numbers just have had personalities.

For some reason, the more difficulty I had with the number, the more complex personality it had. For instance, I had a lot of trouble with odd numbers, and larger numbers. Therefore, 1 and 2 do not have personalities. On the contrary, 7 and 9 are the most developed personalities.

How rare is this condition?

# Answer
From Hubbard & Ramachandran (2005):

> \[...\] the estimated prevalence of synesthesia has varied dramatically, between as many as 1 in 20 (Galton, 1883) and as few as 1 in 25,000 (Cytowic, 1989). The most widely cited study to date suggests that synesthesia occurs in at least 1 in 2000 people (Baron-Cohen et al., 1996), although this is now generally regarded as an underestimate. Our own informal samples have suggested that the prevalence of grapheme-color synesthesia might be between 1 in 200 (Ramachandran and Hubbard, 2001b) and 1 in 100 (Mulvenna et al., 2004). **Subsequent large-scale studies have suggested that the prevalence of synesthesia might be as high as 1 in 20 across all forms and 1 in 100 for grapheme-color synesthesia** (J. Simner, personal communication). This high prevalence argues against the notion that synesthesia is merely a “benign cognitive variant” (see Ward and Mattingley, 2005) and instead suggests that it is a widespread phenomenon that may provide novel insights into the neural basis of the mind (Ramachandran and Hubbard, 2001b).

**References**

> Hubbard, E. M., & Ramachandran, V. S. (2005). Neurocognitive mechanisms of synesthesia. Neuron, 48(3), 509.
> 11 votes

# Answer
The wikipedia Article on Synesthesia cites some prevalence studies

> Random population studies ... determined that 1 in 23 individuals have some kind of synesthesia, while 1 in 90 have colored graphemes (Simmer et al 2006). Colored days of the week and colored graphemes are the most common types(Simmer et al 2006; Campen, 1999).

### References

* Simner J, Mulvenna C, Sagiv N, et al. (2006). "Synaesthesia: the prevalence of atypical cross-modal experiences". Perception 35 (8): 1024–33. doi:10.1068/p5469. PMID 17076063.
* Campen C (1999). "Artistic and psychological experiments with synesthesia". Leonardo 32 (1): 9–14. doi:10.1162/002409499552948.
> 6 votes

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Tags: perception, synesthesia
---


# Question
Title: How to compute Chi-square value and degrees of freedom in Excel?
I am trying to understand the statistical test of the chi-square in Excel. I already made the test but I still don't know how to compute the χ² value and what it means, how to compute the degrees of freedom and how to write a propper APA approved result section. Can anyone help me and explain this in a simple way?

I have a population of n=76. 'Left' = 25 and 'Right' = 51. The hypothesis is you would expect a normal distribution ('Left' =38 and 'Right' = 38). So the question is 'is this distribution a coincidence?' The p \< .029. By seeing this outcome I thought there is that is no coincidence that there isn't a normal distribution and it must be due to a variable.

Is it true in this case the degress of freedom is just n-1?

# Answer
> 2 votes
*This is really more of a statistical question (except perhaps the bit about APA style). As such it probably belongs on stats.stackexchange.com .*

A binary variable does not have a "normal distribution". A normal distribution is bell shaped and is relevant to continuous data.

Your null hypothesis is that the population proportions for left and right handers are equal. Thus, if your chi-square value is sufficiently large, then you might reject the null hypothesis and conclude that the population proportions are unequal.

If $k$ is the number of categories (you have two categories), then degrees of freedom for the one sample chi-square test is $k-1$ (i.e., $2-1 = 1$).

To calculate chi-square check out the example here.

The following formula in Excel should give you a p-value. For example if your chi-square value was 22, and your degrees of freedom was 3:

```
 =1-CHISQ.DIST(22, 3,TRUE)

```
* the first argument is the chi-square value
* The second argument is the degrees of freedom
* The third argument indicates that a cumulative distribution (CDF) is desired
* Thus by taking 1 minus the value of the CDF you get the probability of getting a chi-square value as large or larger than the observed value.

You can check your formula by looking at existing calculated tables. http://home.comcast.net/~sharov/PopEcol/tables/chisq.html

---
Tags: methodology, statistics
---


# Question
Title: How to explain emoticons to an autistic person?
I am currently chatting in an IRC and there is one girl (i think she's about 18 years old) and she has Asperger syndrome and therefore is unable to understand countenance and feelings. She told me that she only knows of happiness, sadness and rage but doesn't really understand what each means.

Furthermore the other people use emoticons like `:)`, `:(`, `>:[`, `^^`, ... and she really has problems to follow the discussion because she is really confused about all of this and when I tell her what each emoticon means five minutes later she will not be able to distinguish between these.

**Do you have any suggestions on what to do to reassure her and maybe help her a bit so that she could enjoy the chat like everyone else, more or less?** *(Although I know she won't understand everything...)*

# Answer
> 13 votes
First question, how deep is your knowledge about autism and Asperger Syndrome? Do you understand how autistic people think? Do you understand, what this girl have meant, when she have written, she *doesn't really understand what each means*?

For neurotypical person, a typical use-case for *I understand you* phrase is *I know what you feel*. But autistic people by *understand* mean in the first line *to know the cause-and-effect*. So your friend saying she don't understand what really each emotion means, could as good mean: *I don't know how particular emotions are affecting the meaning of words the given person use*.

If you want to explain emoticons to her, you should IMHO in first line explain, how particular emoticon in modifying the meaning of the sentence. So, think of emiticons not as the way to communicate emotions (which is of low importance to autistic people) but as the modifiers that change the meaning of the sentence or of the particular words.

# Answer
> 6 votes
I'd like to expand on volkerjaan's answer. I am Asperger myself. I know what `:-)`, `;-)` and `;-(` mean (though I know `^^` only as *see above*). I don't necessarily understand when people are using them. I *do* understand their origins, and I suspect that is what the question boils down to.

To explain what they *mean*:

* `:-)` — person feels happy
* `:-(` — person feels sad
* `;-)` — person is joking

To follow the conversation, it is not needed to understand the meaning. It is enough to *know* the meaning. In my interpretation, understanding is related to *why*. As an Asperger, the ability for abstraction is often different from those in neurotypicals. So I would explain it as follows.

## Emoticon explanation for Asperger

When we draw a face, we like to simplify things. For example, sometimes we draw only a circle with dots for the eyes, and a line for the mouth. For example, from the Wikipedia article on smiley:

This represents a *face* in an abstract way. The face is happy, because the edges of the mouth are turned *upward*. Of course, a real face looks very different. However, this is an abstract representation of a happy face. For an unhappy face, the edges of the mouth would go down.

When we are on IRC, or in another text-only medium, we do not use pictures. Therefore, we need to make drawings in a different way. One way to make drawings on IRC is by using characters normally used for other things. This is what we do when we use emoticons.

A *emoticon* is a sideways drawing of a face. To see it in the correct orientation, turn your head to the left, so that you see the `:` or the `;` on top, the `-` in the middle and the `)` or `(` at the bottom.

* In `:-)`, when turned side-ways, we see three parts: first the `:`, then the `-`, and finally the `)`.

+ The `:` represents the *eyes*. They are two black dots (depending on your viewer) like in the picture of the smiley below.
    + The `-` represents the *nose*. The nose is not shown in the smiley before. Sometimes, it is not shown in emoticons either, and people write `:)` instead of `:-)`. People are lazy~
    + Finally, the `)` represents the *mouth*. Like in the smiley above, the edges of the mouth are turned upward. This means *happy*.
* For `:-(`, the first two parts are the same: `:` are the eyes and `-` is the nose. The third character is different:

+ The `(` in this smiley represents again the mouth, but now the edges of the mouth are turned *downward*. This is a representation of being *sad*.
* The third emoticon is `;-)`. It is again similar to the first one, `:-)`, but now the first character is different.

+ Remember how `:` represented the eyes. In this case, `;` represents the eyes, but with a wink. The `;` consists of something that looks like `.` and something that looks like `,`. The `.` is the open eye and the `,` represents the closed eye. This is strange: *why is the closed eye larger than the open eye?* **It should be the other way around!** Yes, it should. Even if it is **wrong**, people use `;` when they mean: *two eyes, one of the two is closed*. When one of the two eyes is closed, it is a wink.

People use the wink when they mean *I am joking*.

There are many other emoticons, but those are the most used ones. There is a list on Wikipedia. This lists the meanings, but it does not explain any of them. I don't know if there is a website anywhere with explanations. Sometimes, you just need to accept what it means, without understanding them. But I hope that my description above explains the most common ones.

# Answer
> 1 votes
The most succint way to explain emoticons is that they are an expression of informal rating on a person's recent comments.

:) represents, as Omoe said, a informal expression of pleasure at something which has just been expressed.

:( a contextual informal 'unhappiness'.

Emoticons are just 'up-votes' and 'down-votes'. They have nothing to do with real emotions. There is a good reason that people prior to the advent of Internet 'talk' and 'chat' wrote real sentences.. their words cost something to put on paper. They were meaningful.

# Answer
> 0 votes
### `:)` (also spelled `:-)`)

A modifier meaning that someone is happy or want to relieve.

E.g.:

> I was a really nice day :).
>
> Don't worry, you will pass the exam :).

### `:(` (also spelled: `:-(`)

A modifier that someone is sad or wants to say sorry.

E.g.:

> ...and then I spilt all milk :(.
>
> I couldn't do it for you :(.

## `;)` (also spelled: `;-)`)

A modifier saying that someone is joking or laughing, or to not take something serious.

Warning: sometimes it can mean that someone makes an ironic comment.

E.g.:

> And then she sit on the chair with a pin... ;)
>
> Which pages do you need for the assignment? 105-121... or wait, not - you need to read the whole book! ;)

### ^^

(I'm not sure if I get it right, since it's less common) - excited, surprised, astonished, flirting.

E.g.

> I met this cute guy ^^.
>
> They announced the winners and, guess what, they read my name ^^.

---
Tags: autism, communication, aspergers
---


title: Most common cognitive biases?

text:
# Question
Title: Most common cognitive biases?
I'm an amateur student of cognitive biases and psychological traps and have been reading some of the work of Kahneman, Tversky, Gilovich et al. along with more popular books like Cialdini's "Influence." Has any work has been done on which of the cognitive biases/shortcomings are the most prevalent and widespread?

In layman's terms, I'm trying to answer the question: which behavioral traps are the most common? I'm aware that this is a loaded question in that different sociocultural influences can have a huge impact on what is "common". Any pointers much appreciated! Thanks.

# Answer
This question is not answerable without having a measure of what the most common day-to-day scenarios are. However, I can try a guess: since most people interact in a public, anonymous setting on a daily basis, I would think the fundamental attribution error is most probable. This is especially true while driving -- "did that idiot just cut me off?!"

However, my estimation of fundamental attribution error as the most common cognitive bias may itself be an instance of availability heuristic.
> 2 votes

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Tags: cognitive-psychology, bias
---


# Question
Title: Which branch of psychology deals with decision making under stress?
Our decisions are usually based on a system of perspectives, which in turn are based on one's own set of values. However there are traumatizing situations where this system of perspectives is turned completely upside down forcing us to make decisions that may look irrational (or that are really irrational due to emotional and other mental factors eg. panic).

Which branch of psychology deals with the subject of how different unexpected inputs affect our decision making process?

# Answer
Decision-making or decision theory is its own subdiscipline under cognitive science (also often studied by statisticians, philosophers, economists, and faculty in business schools). Within this discipline, understanding how stress affects your behavior is very important and not understudied area. For a recent survey with a neurobiological focus, see:

Starcke, K., & Brand, M. (2012). Decision making under stress: A selective review. Neuroscience & Biobehavioral Reviews, 36(4), 1228-1248.

Of course, stress and decision making is not restricted to humans. It is also studied in a purely biological setting. For a survey focusing on predation, see:

Lima, S. L. (1998). Stress and decision making under the risk of predation: recent developments from behavioral, reproductive, and ecological perspectives. Advances in the Study of Behavior, 27, 215-290.
> 5 votes

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Tags: decision-making, rationality, stress
---


# Question
Title: What is the standard error of measurement for teacher made multiple choice tests?
Assume a teacher constructs a four-choice multiple choice test. Each item has only one correct response. The test is scored from 0 to 100 representing the percentage of items answered correctly.

I want to have some rules of thumb that could be informative regarding how many items are required to achieve a given standard error of measurement. For example, it would be nice to be able to advice teachers who write their own multiple choice exams "if you have 100 items that are reasonably well worded, you can expect a standard error of measurement of 2.5".

The standard error of measurement is often defined as:

$$s\_e=s\_x \sqrt{1-r\_{xx}}$$

where $s\_x$ is the standard deviation and $r\_{xx}$ is the reliability.

Furthermore internal consistency reliability can be calculated from the number of items $k$ and the mean inter-item correlation $\bar{r}\_{ij}$ (i.e., average correlation between item $i$ and item $j$ for all $k$ items where $i\neq j$):

$$r\_{xx}=\frac{k(\bar{r}\_{ij})} {1 + (k -1) \bar{r}\_{ij}}$$

However, I'm wanting to translate the above information into meaningful recommendations for teachers. Thus, this assumes that I have some empirical estimate of typical values of $\bar{r}\_{ij}$ and that I have an estimate of $s\_x$. It then requires application of the formulas to calculate standard errors of measurement for likely numbers of items $k$. In particular, I was thinking about numbers of items equal to: 10, 20, 50, 80, 100, 120, 150, and 200.

Thus, I was wondering whether there are any published estimates of the standard error of measurement teacher constructed multiple choice tests.

# Answer
> 3 votes
Harvill mentions an estimate by Lord (1959). Lord (1959) presents some data for the standard error of measurement for some moderately difficult cognitive measures. While there are many caveats (e.g., the estimate of the standard error is most accurate for scores around 50% and the estimates are based on tests that are neither particularly easy or particularly difficult with means in the .35 to .75 range), Lord provides a simple formula that can be used as a rule of thumb for predicting standard error of measurement in his sample of cognitive measures which performed quite well.

$$\hat{s}\_e = .432 \sqrt{k}$$

where $k$ is the number of items. Alternatively, if you are interested in the mean correct on a 0 to 100 scale rather than the total correct, you can divide by $k$ and multiply by 100.

$$\hat{s}\_e = \frac{.432 \sqrt{k}}{k} \times 100$$

When I plugged this into R for some sample values I obtained:

```
> lord_approximation <- function(k) 0.432 * sqrt(k) /k * 100
> k <- c(10, 20, 50, 80, 100, 120, 150, 200)
> cbind(k, sem=round(lord_approximation(k), 2))
       k   sem
[1,]  10 13.66
[2,]  20  9.66
[3,]  50  6.11
[4,]  80  4.83
[5,] 100  4.32
[6,] 120  3.94
[7,] 150  3.53
[8,] 200  3.05

```

Of course, not all of this reduction in standard error of measurement is due to greater accuracy. Some of it comes from the smaller standard deviation in true scores that occurs when you take the mean of more items. Furthermore, these estimates are based on relatively well designed cognitive measures. Teacher designed tests may have slightly lower reliability and thus larger SEM.

### References

* Harvill, L. M. (1991). Standard error of measurement. Educational Measurement: Issues and Practice, 10(2), 33-41. PDF
* Lord, F. M. (1959). Tests of the same length do have the same standard error of measurement. Educational and Psychological Measurement, 19, 233-239.

# Answer
> 2 votes
To me the most natural solution is to just use item response theory (IRT). IRT has been around for a few decades, so it is well established, implemented in a variety of software packages and provides a sensible, extensible framework for this type of problem.

Essentially, one assumes an underlying latent construct of interest, values of which should drive responses on the test. For multiple choice where the answer is "right" or "wrong", you can use a series of logit (canonically) or probit models. Then for each student, you can estimate the score on the underlying latent variable and that will naturally come with some estimate of its quality/variability.

Issues that are automatically handled:

* If everyone (or nearly everyone) gets an answer correct, it contributes very little information
* Corollary to #1, if almost no one gets an answer correct and someone does, it should be weighted more heavily. Essentially, item difficulty is automatically handled.
* Inter-dependence among items is accounted for. Asking the same item 10 times in a row will not artificially decrease your measurement error.

If you take a Bayesian view, for each student, you could use the model and their test responses to calculate a posterior distribution for the latent construct of interest, which would allow both a point estimate (e.g., posterior mean, median, or mode), as well as estimates of variability (e.g., standard deviation; 95% high posterior density region).

This sort of thing is essentially what big nation wide tests and testing services do. It is actually not too hard to do, but probably enough effort most teachers who already feel overworked do not adopt them.

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Tags: measurement, test, educational-psychology, reliability
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# Question
Title: Is there a name for the tendency to use proper nouns often in conversation?
I think it may happen with people who have lack of confidence, for example shy people. So in conversation they often add proper nouns (eg. names of persons or countries) to give "evidence" and weight of their sayings.
In fact, I am interested either such a phenomenon exists, not necessarily having a name for it.

Example:

> -Do you like cheese?
> -Yes, but not the types they have here, like the commercial Mozarrela. Now, if you were in a Mediterranean country, that's other story. Like in Spain or Italy. I remember the tasty cheeses from my trip in Sicilia.
> -Hey, that place has a bad reputation...
> -Ha, I felt like Michael Corleone

# Answer
The behavior to lend credibility or importance to one's statements is called "name dropping".

Name dropping is a typical **ingratiation tactic**. Other ingratiation tactics are: other-enhancement, opinion conformity, self-enhancement, self-depreciation, instrumental dependency, and a variety of situation specific behaviors. While ingratiating behavior is strongest towards superiors across all people, there are people who show more or less ingratiating behavior across all situations and relationships (Bohra & Pandey, 1984).

Besides this function of name dropping "to position oneself in a status hierarchy", where people "may claim connections to celebrities or other high-status people to raise their own status" and impress their listeners, "\[n\]ame display is also used to **discover whether there is a common bond** between new acquaintances. People who lived in the same city or attended the same school may go through long lists of names seeking common ground." (Donath & Boyd, 2004)

This function of "seeking common ground" can not only be achieved by dropping personal names of possible common acquaintances, but also by naming authors, movies or products that you enjoy: if your partner knows and likes Mozzarella or Michael Corleone, too, these **common interests** form a basis for a new friendship that would have otherwise been difficult to build.

In short: you have to be careful and porperly analyze the person and situation to understand the causes and aims of name dropping.

References:

* Bohra, K. A., & Pandey, J. (1984). Ingratiation toward strangers, friends, and bosses. Journal of Social Psychology, 122(2), 217-222. doi:10.1080/00224545.1984.9713483
* Donath, J., & Boyd, D. (2004). Public Displays of Connection. BT Technology Journal, 22(4), 71-82. doi:10.1023/B:BTTJ.0000047585.06264.cc
> 6 votes

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Tags: terminology
---


# Question
Title: What was the experiment where a person is given something and then has to share it with another person
Bob is given a bar of chocolate by the experimenter. Then he is to propose how he will share the chocolate with Emilly. If Emilly agrees with Bob's proposal, the kids will each get their share. If Emilly disagrees, nobody gets anything.

The experiment demonstrates that Emilly will refuse a profitable share (anything more than no chocolate is profitable for her), if the split Bob proposed would be "unfair".

# Answer
> 6 votes
The experiment you are referring to is usually called the ultimatum game, and was first experimentally tested by Güth, Schmittberger, and Schwarze in 1982 <sup>\[1\]</sup>.

---

\[1\] Güth, Werner, Rolf Schmittberger, and Bernd Schwarze. "An experimental analysis of ultimatum bargaining." Journal of Economic Behavior & Organization 3.4 (1982): 367-388. PDF

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Tags: experimental-psychology, decision-making, economics
---