# Question
Title: What is the most effective maximum work duration per day?
A related question asks about the best work-break schedule for an effective eight hour work day.

This question presupposes that eight hours of work per day is a good duration and that all you need is to optimize your work-break schedule. But research seems to hint that alertness and productivity might increase if you **shorten your workday**: A survey (Bielenski, 1994) asking managers about their experiences with part time work in eight European countries found **a better quality of products or services**. Part time work here includes all different kinds of reduced weekly working hours. A German (Infratest Sozialforschung, 1985) and American (Beyer, 1986) study on flexible work time models (including part time and gliding time) found **an increase in production volume and quality, higher job satisfaction, and a decrease in lateness and absences**.

Research also shows that performance increases if you **increase your sleeping hours** (e.g. from eight to ten hours per night), and it is a banal truth that the the amount of sleep that you can or want to allow yourself is directly related to the amount of work: eight hours of work plus taking care of the rest of your life only leave you so many hours to rest. So maybe the question of breaks doesn't even arise anymore, when you awake relaxed and highly attentive after enough sleep, and when you work focussed for four hours without breaks, knowing that you'll be free to enjoy yourself for the rest of the day.

Assuming on the one hand that you do in fact need time to get things done and cannot speed up your work frequency and shorten working hours indefinitely; and assuming on the other hand that you will get tired and work less well after a certain time; then there should be a turning point somewhere, where working longer or shorter decreases your productivity.

Of course the exact location of this point (and the optimal per day work duration) will differ for different kinds of tasks, so there will not be one optimum for everything. If there is more research on this topic than you can or want to cover in your answer, please focus on "intellectual work" (like that of scientists or in administration).

Question:

**Is there research into how long you should work per day to be most effective?**

I'm looking for a comprehensive and definite answer on this, and therefore I am especially interested in recent meta-analyses and overview articles, some of which might be published in handbooks or encyclopedias of occupational psychology and not available on the web.

*No untested theories and no personal anecdotes, please.*

---

Sources:

* Beyer, H. T. (1986). *Betriebliche Arbeitszeitflexibilisierung*. München: Vahlen.
    + Bielenski, H. (ed.) (1994). *New Forms of Work and Activity. Survey of Experiences at Establishment Level in Eight European Countries*. Shankill: European Foundation for the Improvement of Living and Working Conditions.
    + Infratest Sozialforschung (1985). *Flexible Arbeitszeiten: Erfahrungen aus der Praxis*. Humanisierung des Arbeitslebens, vol. 68. Frankfurt am Main: Campus.

# Answer
This is a part-answer to your question and it doesn't come from occupational psychology, but from expertise research.

**Findings from Expertise Research**

In their seminal paper on the role of deliberate practice for the acquisition of expert performance, Ericsson et al. (1993) report a number of constraints that play a role in the acquisition of expert performance. One of these constraints is the *effort constraint*. What is meant by this is that, in order to improve one's skill, one has to engage in *deliberate practice*, which by definition is an effortful activity that requires full concentration. It is clear that such an activity cannot be kept up for very large amounts of time. Ericsson et al. cite works by Welford (1968) and Woodford & Schlosberg (1954) (which I haven't read) that compare the efficiency of practice durations ranging from 1-8 hr a day. These studies find that there is

> essentially no benefit from durations exceeding 4 hr per day and reduced benefit from practice exceeding 2 hr. (Ericsson et al., 1993, p.370)

The authors then report that studies on the aquisition of typing skill by Baddely & Longman (1978) and Dvorak et al. (1936), and studies on other perceptual motor skills (Henshaw & Holman, 1930) which

> indicate that the effective duration of deliberate practice is may be closer to 1 hr per day. (Ibid.)

Finally, they cite a study by Pirelli & J.R. Anderson (1985) that found

> no increased learning from doubling the number of training trials per session. (Ibid.)

Thereafter, Ericsson et al. (1993) turn to more intellectually demanding domains. They report on data from financially independent writers, who

> tend to write only 4 hr per day, leaving the rest of the day for rest and recuperation (Cowley, 1959; Plimpton, 1977). (Ibid., p.371)

In their own study 1, which investigated violinists at music college, the authors found that the best students practiced on average 3.5 hr per day.

**Maximum vs. Typical Performance**

From these findings it seems that the optimal duration lies somewhere between 1 and 4 hours. But it's important to note that this only holds for conditions of maximal effort and full concentration. Furthermore these studies investigate the acquisition, not the execution of a skill, which presumably is more important in the workplace. I would still argue that they can still be relevant in a work context.

In io-psychology there is the distinction between *maximum* and *typical performance*. Everything I have said so far obviously refers to maximum performance. The intellectual work of a scientist that you mention in your question might fall into this category. I can also imagine that a software developer needs full concentration. Probably, though, periods that require maximum performance and those that "only" require typical performance alternate. The time limit for typical performance may be much longer.

So my answer is only a part answer in at least two ways: First it only provides information about the time limit for maximum performance. Second, the studies that I cite have not actually been done within an occupational setting.

References:
<sub> Baddeley, A. D., & Longman, D. J. A. (1978). The influence of length and frequency of training session on the rate of learning to type. *Ergonomics, 21(8)*, 627-635.
Cowley, M.(Ed.). (1953). *Writers at work: The Paris review interviews, second series.* New York: Penguin Books.
Dvorak, A., Merrick, N. L., Dealey, W. L., & Ford, G. C. (1936). *Typewriting behavior.* New York: American Book Company.
Ericsson, K. A., Krampe, R. T., & Tesch-Römer, C. (1993). The role of deliberate practice in the acquisition of expert performance. *Psychological Review, 100(3)*, 363–406. doi:10.1037/0033-295X.100.3.363 PDF
Pirolli, P. L., & Anderson, J. R. (1985). The role of practice in fact retrieval. *Journal of experimental psychology: Learning, memory, and cognition, 11(1)*, 136.PDF
Plimpton, G. (Ed.). (1976). *Writers at work: The Paris review interviews.* New York: Viking Press.
Welford, A.T. (1968). *Fundamentals of skill.* London: Methuen.
Woodworth, R. S., & Schlosberg, H. (1954). *Experimental psychology.* New York: Holt, Rinehart & Winston.
</sub>
> 23 votes

# Answer
**It would appear that a 6 hour workday would obtain better results of productivity than a \>=8 hour day.**

In discussing the optimum length of a working day, I have taken a neurobiological approach and an occupational approach. As the individual is not an isolated organism; social and environmental demands, mean that in determining what is a most productive workday, needs to encompass the fact that the individual has other tasks to complete within a 24 hour cycle. The need for sleep, to maximise performance, also needs to be taken into consideration, within this context.

There are been much research showing the relationship between excessive work hours, resulting fatigue and decline in cognitive ability. The effect is also magnified as the working week progresses. Following this, there is evidence that a reduced working day (from 8 hour) increases productivity:

Working time and productivity International Labour Ofﬁce Geneva

The Effects of Working Time on Productivity and Firm Performance: a research synthesis paper; has examined this subject extensively:

> **a. Reduction in hours and worker productivity evidence**
> The potential theoretical and practical impact of a reduction in hours on productivity was assessed by the International Labour Organization (ILO) over twenty years ago (White, 1987). Improvements in the efficiency of labour utilization were evident from a century’s worth of research that found some productivity improvement following a reduction in hours, depending, of course, on the accompanying conditions and responses, in the medium if not the short term. Four types of reductions were distinguished, all of which remain relevant to today’s conditions. Each creates its own potential for productivity improvements that would offset much, if not all, of the initial costs associated with shorter working hours. The four types are: reductions in excessive hours, gradual reductions in standard hours, accelerated reductions in standard hours, and individualized options for reducing working hours. ...
>
> **a. Interactions between duration and employee-centered flexibility of work schedules**
> Importantly, the effect of working time flexibility often interacts with the duration of working hours. Greater discretion or control over the timing of their work helps workers to alleviate some of the negative effects of long hours on the incidence of work-related injuries, illnesses and time stress (Boden, 2005; Costa et al., 2006; Dembe et al., 2007; Hughes and Parkes, 2007). ...
> Reduced variability of hours has almost as much influence as higher flexibility on work/life satisfaction (Costa et al., 2006).

---

There has also been research into the best time of day to work. Research suggests that the peak times for alertness are mid to late morning (approx 11am), followed by another, lessor, peak in the late afternoon (approx 5.30pm).

**Circadian Rhythms.**

Human beings have natural Ultradian cycles, that govern our behaviour. I am focusing on the circadian rhythm, which is the natural 24 hour cycle that governs our physiology. It would be logical to propose that working within this cycle, as opposed to enforcing routines that are in conflict with this cycle, would be beneficial to finding an optimal working day structure.

> Wakefulness
> The longer the brain has been awake, the greater the spontaneous firing rates of cerebral cortex neurons with this increase being reversed by sleep. Another effect of wakefulness (which may or may not be related to this) is that it lowers the small stores of glycogen held in the astrocytes that can supply energy to the brain's neurons—one of the functions of sleep, it has been proposed, is to create the opportunity for them to be replenished.
>
> Sleepiness The longer the time spent awake, the greater the drive for sleep. ..... The second factor is circadian, which varies with a 24 hour periodicity and is independent of the amount of preceding sleep or wakefulness. .... Together, the homeostatic and circadian factors modulate the need for sleep and influence the balance between alertness and sleepiness. ....*Neurobiology of sleep and wakefulness Robert W. McCarley and Christopher M Sinton (2008) doi:10.4249/scholarpedia.3313*

The following charts provide a good visual representation of the bodies 24 hour cycle:

*The pink line is the predicted alertness<br>The blue dots are recall data*

chart taken from the followup to "Polyphasic Sleep: Facts and Myths" Dr Piotr Wozniak

image courtesy of File:Biological clock human.svg

---

* I disagree with rethinking the smaller 90 minute work and break cycles. My explanation for this is given clearly in this answer. There is evidence, even within a shorter workday, that the 90 minute cycle exists and breaks enhance performance. I am going to focus on the optimal total hours of a working day.
* There are various physical, emotional, mental, financial and environmental factors (eg job stability) that would cause a variation in what an optimal working day would be; so for the purposes of this question I am assuming we are discussing individuals, within the norms for these factors (ie not unwell in these areas or experiencing undue stress).
* I am assuming that you want the focus of this answer to be on work, rather than sleep. So, without going into discussion about optimal sleep patterns; it follows, logically, that a regular, extended working day of, for example: 16 hours, would prohibit the individual from getting optimal sleep, which in turn affects performance. So, for the sake of this discussion, I am assuming that an optimal work day, takes into account the need to optimize sleep, and that the individual is doing so.
* I'm not addressing shift work here; as the scope becomes too large.
* The relationship between optimizing such activity as for example: playing the violin, needs to take into account the effect on the fingers; whereas in office work, there is less propensity for such risk of repetitive strain or injury.
* There has been research regarding compressed working weeks, the benefits of completely 5 days work on 4 days.

---

**Full-time vs Part-Time work:**

The following provides evidence for and against job performance and comparisons between full-time and part-time work hours. It is interesting to note that the difference in these findings could be related to the reward system of the job. The differences in performance, could (and probably are) be linked to the capacity to increase earnings with improved performance vs a fixed wage rate.

Looking at this alone, it would suggest that shorter working hours promote better performance when financial rewards are offered for higher productivity. Which supports the notion of a shorter working day being more optimal for productivity.

**Argument for Part-time over Full-time work:**
*(full-time work is classified as a 40 hour working week)*

> Part-time workers tend to be more productive, hour for hour, than full-time workers because it is easier to work at peak efficiency for short periods.

An interesting, if not obvious point, made by Berkley University HR. Flexible Work Arrangements: Part-Time Work

> A comparison of part-time vs. full-time salespeople from four U.S. direct selling companies that part-timers had greater job satisfaction and less propensity to quit. Part-timers were also better performers as measured by earnings per hour worked.

*Another interesting finding in this study, opens a whole avenue for analysis, between having options and motivation upon performance.*

> When these same respondents were analyzed in terms of other jobs held simultaneously with their direct selling job, some evidence indicated that job satisfaction was lower while earnings per hour and propensity to quit were greater as the extent of other outside employment increased.

Full-time vs. part-time salespeople: A comparison on job satisfaction, performance, and turnover in direct selling Thomas R. Wotruba doi.org/10.1016/0167-8116(90)90014-E

**Argument for Full-time over Part-time work:**

A interesting note with regard to the differences of work outcomes between full-time and part-time workers; the only notable difference is regard to job, the implication being that full-time workers are more likely to have a more responsible attitude towards their jobs. If the overall working week were to change, this difference would need to be re-examined.

> Employees who work fewer hours per week tend to assign less importance to the work outcomes measured in this study.

Differences in the importance of work outcomes between full-time and part-time hospital employees Douglas S. Wakefield1, James P. Curry1, Charles W. Mueller2, James L. Price2 DOI: 10.1002/job.403008010

In studies on employee attitude, their was no difference between full-time and part-time workers.

> A meta-analysis was conducted (k =38, N =51,231) to examine the size of the difference between full- and part-time employees on job attitudes. Results indicated that there was little difference between full-time (FT) and part-time (PT) employees on job satisfaction, organizational commitment, intentions to leave and facets of job satisfaction.Full-time employees were found to be more involved with their jobs than PT employees.

Job attitudes of part-time vs. full-time workers: A meta-analytic review Todd J. Thorsteinson DOI: 10.1348/0963179037659136

In terms of performing tasks beyond immediate job criteria, the results sway towards full-time employees rating better, but this is also not clearly defined. This could be linked towards employment attitude.

> There are two types of performance: in-role and extra-role work performance or OCB ... Marchese and Ryan (2001) found significant differences between full-time and part-time workers in job performance. Full-time employees had a higher level of performance. Another study showed no significant difference between full-time and part-time workers in terms of performance (Wotruba, 1990)

A Comparison Between Full and Part-Time Lodging Employees on Job Satisfaction, Organizational Commitment, and Job Performance Abdullah Al Omar, Jet al

---

**Shorter workdays:**

There is clear evidence that a reduction of workday to 6 hours benefits work performance. This could be due to many complex, pyscho-social factors.

> There are some company-based interventions that have studied the effects of a reduction in workhours from 7 or more to 6 hours. In an intervention study among female health care workers, a decrease in workhours (to a 6-hour workday) resulted in improvements in the social life of the workers and in moderate improvements in well-being when the group was compared with a reference group with no changes in workhours. In another study, a shift to 6-hour workdays was followed by a reduction of neck-shoulder and back pain in three separate organizations when fulltime payment of the workers was retained. According to Anttila, the benefits of shorter workhours were the most apparent in regard to social life, but they also introduced some positive effects on the perceived stress of the workers ...

Scand J Work Environ Health 2006;32(6, special issue):502-514 Workhours in relation to work stress, recovery and health by Mikko Harma, MD

**Physical effect of shorter workday:**

> The shortening of regular workdays from \>7 hours to 6 hours may considerably reduce the prevalence of neck-shoulder pain among persons with physically demanding care work. The potential health benefits should encourage intervention studies also in other occupations with increased risk of work-related musculoskeletal disorders.

A shorter workday as a means of reducing the occurrence of musculoskeletal disorders by Ebba L Wergeland, PhD, et al Scand J Work Environ Health 2003;29(1):27-34

As @Jens noted in Ericsson's study.

> best students practiced on average 3.5 hr per day

This, along with the evidence about attention and circadian rhythms, perhaps, suggests that this is an optimal time for mental acuity. (not taking into consideration the physical restraints of finger strain on violinists).

The double peak of alertness within the circadian cycle gives credence to the notion of a "siesta" of prolonged, daily work break, to boost productivity, but this argument is not as straightforward as it may seem on the surface.

---

**Studies which may be helpful:**

This study 15 Indus. & Lab. Rel. Rev. 307 (1961-1962) Shorter Hours - In Theory and Practice; Dankert, Clyde E. gives detailed analysis, where output optimum is examined and optimum working day and optimum working week evaluated.

Orthostatic symptoms, blood pressure and working postures of factory and service workers over an observed workday Suzy Ngomoa, et al doi.org/10.1016/j.apergo.2007.11.004

*I do not have access to these articles*

---

Associated References:

A META-ANALYSIS OF WORK DEMAND STRESSORS AND JOB PERFORMANCE: EXAMINING MAIN AND MODERATING EFFECTS SIMONA GILBOA1, ARIE SHIROM1, YITZHAK FRIED2, CARY COOPER3 DOI: 10.1111/j.1744-6570.2008.00113.x

Extended workdays: Effects on performance and ratings offatigue and alertness ROGER R. ROSA DANIEL D. WHEELER and JOEL S. WARM MICHAEL J. COLLIGAN

CIRCADIAN RHYTHMS OF PERFORMANCE: NEW TRENDS 2000, Vol. 17, No. 6 , Pages 719-732 Julie Carrier1,2 and Timothy H. Monk3 doi/abs/10.1081/CBI-100102108

Carrier, J., & Monk, T. H. (2000). Circadian rhythms of performance: New trends. Chronobiology International, 17, 719–732. doi:10.1081/CBI-100102108.

Schmidt, C., Collette, C., Cajochen, C., & Peigneux, P. (2007). A time to think: Circadian rhythms in human cognition.Cognitive Neuropsychology,24, 755–789.doi:10.1080/ 02643290701754158

Health effects of shift work and extended hours of work J M Harrington

Adverse changes in mood and cognitive performance of house officers after night duty. D. I. Orton and J. H. Gruzelier

Extended workdays: Effects of 8-hour and 12-hour rotating shift schedules on performance, subjective alertness, sleep patterns, and psychosocial variables DOI:10.1080/02678378908256877 Roger R. Rosaa, Michael J. Colligana & Paul Lewisb

Professor Cary Cooper CBE publications

Changes in Electromyographic Activity Associated with Occupational Stress and Poor Performance in the Workplace Frank E. Gomer Behavioral Science Applications, Yellow Springs, Ohio Louis D. Silverstein Sperry Corporation, Phoenix, Arizona W. Keith Berg University of Florida, Gainesville, Florida Donald L. Lassiter Georgia Institute of Technology, Atlanta, Georgia

Job content and working time: the scope for joint change DOI:10.1080/00140139108967349 KAZUTAKA KOGIa

IS PART-TIME EMPLOYMENT BENEFICIAL FOR FIRM PRODUCTIVITY? Annemarie Nelen, Andries De Gripa, Didier Fouarge

---

**Note:**

*There is much anecdotal evidence of professional working 4 or 5 hour days to maximise their performance; one example being an author writing a book.*
> 13 votes

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Tags: performance, io-psychology
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# Question
Title: What causes seizures to develop years after a childhood brain injury?
A friend of mine told me that her daughter was in an accident prior to the age of 12 which resulted in head trauma and brain damage. The child went through an extensive recovery process (relearning how to walk, speak, etc) and made a nearly full recovery, the only symptoms which remained were frequent headaches.

The doctors said at the time of the accident that when the child reached her late teens / early 20s, she might develop seizures. Sure enough, shortly after she turned 18 the seizures began.

What causes seizures to develop years after a childhood brain injury? What is it about the developing brain which can cause years to pass before such seizures begin?

# Answer
> 3 votes
there is a lot of info confirming Post Traumatic Epilepsy (PTE), but little on the exact causation, due to the mysterious nature of the causation of epilepsy.

There is much research supporting the link between brain injury and subsequent seizures, Post-traumatic epilepsy , including the onset of delayed seizures:

> Traumatic brain injury (TBI) has been recognized as a cause of epilepsy since antiquity, and it remains one of the most common and important causes of acquired epilepsy today. Epidemiologic studies have demonstrated a clear relationship between the severity of injury and the likelihood of developing epilepsy, with the risk approaching 50% in TBI cases associated with direct injury to brain parenchyma. Importantly, many TBI victims develop epilepsy months or years following the initial injury, ...

Epilepsy after head injury: an overview. Lowenstein DH. doi: 10.1111/j.1528-1167.2008.02004.x.

> Posttraumatic seizures may not appear for as long as 20 years after an accident.

Stanford Epilepsy Center Robert S. Fisher, M.D., Ph.D.

Increased incidence and impact of nonconvulsive and convulsive seizures after traumatic brain injury as detected by continuous electroencephalographic monitoring Paul M. Vespa, M.D., et al

The risks of epilepsy after traumatic brain injury ☆ John F Annegers2, Sharon Pasternak Coan The University of Texas Health Science Center at Houston, School of Public Health, USA

A Population-Based Study of Seizures after Traumatic Brain Injuries John F. Annegers, Ph.D., et al N Engl J Med 1998; 338:20-24January 1, 1998DOI: 10.1056/NEJM199801013380104

---

As to the causal relationship:

The cause of epilepsy is largely unkown.

> **What causes epilepsy?**
> There are many causes of epilepsy, which vary with the age at which seizures begin and the nature of the seizures. However 50% of cases, the cause is unknown. ...
> A brain injury, which results in scar tissue, predisposes individuals to developing epilepsy, although there can be a long period, often years, between the damage occurring and the seizures commencing. ...
>
> **What is a seizure?**
> A seizure occurs when the brains nerve cells misfire and generate sudden, uncontrolled burst of electrical activity in the brain. ...

It has been shown that the nature of the head injury influences the likelihood of developing seizures.

> **Nature of trauma**
> Intracranial hematomas, in which blood accumulates inside the skull, are one of the most important risk factors for PTE.\[23\] Subdural hematoma confers a higher risk of PTE than does epidural hematoma, possibly because it causes more damage to brain tissue.\[7\] Repeated intracranial surgery confers a high risk for late PTE, possibly because people who need more surgery are more likely to have factors associated with worse brain trauma such as large hematomas or cerebral swelling.\[7\] In addition, the chances of developing PTE differ by the location of the brain lesion: brain contusion that occurs on in one or the other of the frontal lobes has been found to carry a 20% PTE risk, while a contusion in one of the parietal lobes carries a 19% risk and one in a temporal lobe carries a 16% chance.\[21\] When contusions occur in both hemispheres, the risk is 26% for the frontal lobes, 66% for the parietal, and 31% for the temporal.\[21\]

It is not clearly understood how traumatic brain injury causes seizures.

> Epilepsy is a common outcome of traumatic brain injury (TBI), but the mechanisms of posttraumatic epileptogenesis are poorly understood. One clue is the occurrence of selective hippocampal cell death after fluid-percussion TBI in rats, consistent with the reported reduction of hippocampal volume bilaterally in humans after TBI and resembling hippocampal sclerosis, a hallmark of temporal-lobe epilepsy. Other features of temporal-lobe epilepsy, such as long-term seizure susceptibility, persistent hyperexcitability in the dentate gyrus (DG), and mossy fiber synaptic reorganization, however, have not been examined after TBI. To determine whether TBI induces these changes, we used a well studied model of TBI by weight drop on somatosensory cortex in adult rats. First, we confirmed an early and selective cell loss in the hilus of the DG and area CA3 of hippocampus, ipsilateral to the impact. Second, we found persistently enhanced susceptibility to pentylenetetrazole-induced convulsions 15 weeks after TBI. Third, by applying GABAA antagonists during field-potential and optical recordings in hippocampal slices 3 and 15 weeks after TBI, we unmasked a persistent, abnormal APV-sensitive hyperexcitability that was bilateral and localized to the granule cell and molecular layers of the DG. Finally, using Timm histochemistry, we detected progressive sprouting of mossy fibers into the inner molecular layers of the DG bilaterally 2–27 weeks after TBI. These findings are consistent with the development of posttraumatic epilepsy in an animal model of impact head injury, showing a striking similarity to the enduring behavioral, functional, and structural alterations associated with temporal-lobe epilepsy.

Physiological and Structural Evidence for Hippocampal Involvement in Persistent Seizure Susceptibility after Traumatic Brain Injury Golijeh Golarai1,2,

Increase in extracellular glutamate caused by reduced cerebral perfusion pressure and seizures after human traumatic brain injury: a microdialysis study Paul Vespa, M.D., et al

Brain injury induces c-fos protein(s) in nerve and glial-like cells in adult mammalian brain M. DragunowCorresponding author contact information, 1, H.A. Robertson2

---

It would seem that seizure at the time of the injury, increase the chance of having late onset epilepsy.

> TBI is a relatively rare cause of epilepsy in childhood, although immediate seizures are associated with an increased risk of developing post-traumatic epilepsy

doi: 10.1080/02699050902973913. Occurrence of epilepsy during the first 10 years after traumatic brain injury acquired in childhood up to the age of 18 years in the south western Swedish population-based series. Emanuelson I, Uvebrant P.

> Posttraumatic seizures may occur almost simultaneously with head injury or be delayed for several years.
> • Once posttraumatic epilepsy has developed, it remits less often than previously reported.
> • Patients with posttraumatic epilepsy appear to have a higher mortality rate than patients with traumatic brain injury without epilepsy.
> • Posttraumatic epilepsy appears in many cases as temporal lobe epilepsy that possibly originates from the hippocampus.
>
> ... 40% to 50% of new cases of posttraumatic seizures occur within 6 months, 70% within 1 year, and 80% within 2 years after head injury ... ... Seizures occurring within 5 minutes of traumatic injury to the head are called "immediate" posttraumatic seizures (Majkowski 1991). Such seizures do not represent epilepsy, per se, and should be viewed as an acute response to the head injury.

Posttraumatic epilepsy
Contributors Ravindra Kumar Garg MD, author. Dr. Garg of King George's Medical University in Lucknow, India, has no relevant financial relationships to disclose.
C P Panayiotopoulos MD PhD, editor. Dr. Panayiotopoulos of St. Thomas' Hospital received a publication grant and salary from UCB Pharma S.A.

J Neurol Neurosurg Psychiatry 2002;73:i8-i16 doi:10.1136/jnnp.73.suppl\_1.i8 HEAD INJURY FOR NEUROLOGISTS Richard Greenwood

---

Given the swelling can expand over time, and there can be delayed hemorrhaging; this could account for some delayed onset seizures.

> • A contusion consists of blood intermixed with brain tissue.
> • Data have shown that traumatic intracerebral hemorrhages often expand over time.
> • Delayed posttraumatic hemorrhages may sometimes result from coalesced blood within contusions.

Traumatic intracerebral hemorrhage Contributors Ravindra Kumar Garg MD, author. Steven R Levine MD, editor.

---

My own thoughts would be, that if a brain injury occurs during childhood; given the degree of growth and change from childhood through to adulthood; and given the the predictive likelihood (that if epilepsy will develop) that it will do so before the ages of 18-21; I suspect that the growth and disruption to scar tissue and possible delay in disruption of existing contusions could account for the delay in onset of PTE.

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Tags: brain-injury, brain-development
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# Question
Title: The relationship between working memory and emotion
I stumbled up on this article about working memory.

Within a table of indicators of good or poor working memory, it listed the following for adult working memory:

> **Indicators that a working memory needs exercise**
>
> * Frequently late to work
> * Often underestimates time required for a task
> * Has problems breaking a project into manageable steps
> * Often loses temper with children and spouse

It is the last point:

> * ***Often loses temper with children and spouse***

This brings me to the question:

**Are there studies examining the relationship between working memory and emotion?<br>If so what are the results?**

# Answer
Working memory and other aspects of executive function (attention, for instance) are linked. There is evidence that improving self control improves emotional outbursts (see article below). So, improving working memory should improve self control, which should prevent emotional outbursts.

See: Denson, T. F., Capper, M. M., Oaten, M., Friese, M., & Schofield, T. P. (2011). Self-control training decreases aggression in response to provocation in aggressive individuals. Journal of Research in Personality, 45(2), 252–256. doi:10.1016/j.jrp.2011.02.001
> 5 votes

# Answer
My husband and I have Traumatic Brain Injury and Cognitive difficulties. All of the points above describe us. The most difficult obstacle is the last, loosing temper with spouse. The statistics state "that in a marriage where one partner receives TBI 80% of them fail. When both are involved it is said they physically hurt or kill each other. Six years into the TBI we still struggle. Emotions and memory are both disturbed when the Frontal lobe is damaged. Therefore both working memory and emotions are related by their location. If a person has a deficit in working memory they are easily agitated and therefor emotional. Assuming you are only considering the loss of temper emotion that would be disrupted by lack of memory. You also only point out children and spouse which are most often the target of a familiar relationship and therefor spend much time in each others presence. A reminder of the retirement syndrome, where age creates memory difficulties and stresses a relationship due to 24/7 time on hands and usually spent with those mentioned. Fact is I can blame my memory difficulties on age. Emotions are generated by unhappiness and memory,or loss of,creates unhappiness. Executive functions are stored closely and related by area and therefor improving one of either would improve the other by definition of the area stored and malfunction in either or that area. There are other characteristics like retention for instance that may cause some of the points noted and time management or staying on task also apathy which may case " who gives a care" at the moment. This is my hypothesis.
> 0 votes

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Tags: cognitive-psychology, emotion, working-memory
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# Question
Title: What neural mechanism explains the tendency to visually attend to the whole scene before attending to details?
I have the intuition that human vision first attends to large-scale objects and then small-scale details. Is there any mechanism in the visual cortex that will explain this phenomenon? Is there a resolution refinement process when we look at scenes?

# Answer
First, it is not only your intuition - there are many experimental results showing that we first perceive the gist of scenes (for example, is it outdoors or indoors?), then the major parts of it (was there an animal, or a human figure in it?) then more and more details (is that figure male or female? what is her expression?) \[1\] \[2\]. Note, however, that it is not exactly related to the size of the object, but more to its perceived importance or relevance. (See also this great video about change blindness, that exemplifies that)

**Reverse Hierarchy Theory** \[3\] proposes a mechanism for that - the activation in the network flows mostly "bottom up", but conscious perception starts at higher level, and then actively (through attention) accesses "lower level" details as they are needed. or in their words:

> Classically, the visual system was seen as a hierarchy of cortical areas and cell types. Neurons of low-level areas (V1, V2) receive visual input and represent simple features such as lines or edges of specific orientation and location. Their outputs are integrated and processed by successive cortical levels (V3, V4, medial-temporal area MT), which gradually generalize over spatial parameters and specialize to represent global features. Finally, further levels (inferotemporal area IT, prefrontal area PF, etc.) integrate their outputs to represent abstract forms, objects, and categories. The function of feedback connections was unknown. Reverse Hierarchy Theory proposes that the above forward hierarchy acts implicitly, with explicit perception beginning at high-level cortex, representing the gist of the scene on the basis of a first-order approximate integration of low-level input. Later, explicit perception returns to lower areas via the feedback connections, to integrate into conscious vision with scrutiny the detailed information available there. Thus, initial perception is based on spread attention (large receptive fields), guessing at details, and making binding or conjunction errors. Later vision incorporates details, overcoming such blindnesses

---

\[1\] Potter, M. C. (1976). Short-term conceptual memory for pictures. Journal of Experimental Psychology: Human Learning and Memory; Journal of Experimental Psychology: Human Learning and Memory, 2(5), 509. link

\[2\] Rensink, R. A., O'Regan, J. K., & Clark, J. J. (1997). To see or not to see: The need for attention to perceive changes in scenes. Psychological Science, 8(5), 368-373. link

\[3\] Hochstein, S., & Ahissar, M. (2002). View from the top-hierarchies and reverse hierarchies in the visual system. Neuron, 36(5), 791-804. link
> 13 votes

# Answer
The phenomenon you describe is called the global precedence effect, and was first studied extensively by David Navon (1977). One way to measure this effect is to create conflict between global and local features. For example, Navon presented observes with letter stimuli that were globally organised into different letters, such as;

Observers were instructed to indicate either a) when the smaller letters were E vs H or b) when the larger letters formed an E vs H. Navon found that reaction times were generally faster when the global and local features were congruent. However, the conflict caused by the global form impaired reaction times in a) much more than the conflict caused by the smaller letters in b). Greater interference from the global structure was interpreted as showing that the global form is processed before the local details.

This effect was studied in greater detail by Aude Oliva and Phillipe Schyns. Oliva presented hybrid images of natural scenes. These images were composed of the high spatial frequency information from one scene, and the low spatial frequency information from another scene. For example in the images below the low spatial frequency information of a highway has been combined with the high spatial frequency information of a picture of skyscrapers (top image) and vice versa in the bottom image. They showed that the low spatial frequency information is more useful, particularly in cases where the scenes were viewed only briefly, or when participants had to make a very fast judgement.

What is interesting about the study conducted by Schyns and Oliva is that it provides a evidence for a neural explanation for why global features dominate over details. This explanation is based on two cell types that exist in the retina the send axons to the thalamus in the brain. These cell types are roughly divided into two types: the larger magnocellular neuron, and the smaller parvocellular neuron. These cell types have different spatial preferences and temporal characteristics. Mangocellular neurons prefer low spatial frequency inputs and show a rapid, transient response. Parvocellular neurons on the other hand prefer colourful, high spatial frequency input and show a slow, sustained response. So the idea is that the magnocellular pathway rapidly carries coarse, low spatial frequency information to the brain to form an initial interpretation of the world. This interpretation is then compared to the more detailed information carried by the parvocellular pathway as it arrives in the cortex.

References Navon, D. (1977). Forest before trees: The precedence of global features in visual perception, Cognitive Psychology, Vol 9(3), 353-383.

Schyns, P. G., & Oliva, A. (1994). From blobs to boundary edges: Evidence for time-and spatial-scale-dependent scene recognition. Psychological Science, 5(4), 195-200.
> 4 votes

# Answer
Human vision is more accustomed to first see things that move. So, considering both large scale objects and small scale objects are present in the vision field, the object will shows the first sign of movement will be first attended by the visual cortex. I believe this is because of the evolutionary process where human were hunters and mind evolved to detect any animal movement in the periphery.
> -3 votes

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Tags: cognitive-psychology, neuroscience, vision, attention
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# Question
Title: Why do people make rants on Meta Stack Exchange sites?
Meta stackexchange sites are often the venue for immature rants authored by disgruntled members of the site. The Math stackexchange and meta stackoverflow includes a lot of this behavior. During a recent instance of this, one site member pointed out the unconstructive nature of ranting on meta and the ranter (after calming down) responded a joke that why we do this would be a question for the Psych SE.

* What do people engage in rants on meta stack exchange site?
* Is there something about math/computing people that causes this behavior?
* What psychological theories are relevant?

# Answer
> 2 votes
> **rant, *n.* 1. a.** An extravagant, bombastic, or declamatory speech or utterance; (now *esp.*) a long, angry, or impassioned speech; a tirade. (OED)

`Why do people make rants on Meta SE?` translates to `What makes people get emotionally upset in a social situation and then express their emotions?`

I'm not going to go into this, because the answer is at the same time banal and overwhelmingly complex.

The only aspect that differs between social life online and away-from-keyboard is the higher level of anonymity online. Otherwise it is a common fallacy to think of the internet as being somehow not like "real life".

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Tags: social-psychology, internet, communication
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# Question
Title: Retrieving information: how can we know so fast that we don't know something?
If someone asks us something that we don't know, how can we know so fast that that's the case? Shouldn't we spend a considerable amount of time scanning our memories until we realize the information is unknown?

# Answer
"There are known knowns; there are things we know that we know. There are known unknowns; that is to say, there are things that we now know we don't know. But there are also unknown unknowns – there are things we do not know we don't know."

Donald Rumsfeld

This question is difficult to answer because researchers are rarely interested in how it is we know we don't know. Typically, memory researchers are either interested in how we remember, why we forget, and how we confabulate or form false memories. How it is that we can quickly decide "no entry found" is less of a pertinent question. There may be some research out there on the issue but I'm sure it will be very difficult to find. Broadly, however we can think of a potential answer by dividing the problem into two questions; how do we retrieve information, and how do we make judgements about our thoughts (meta-cognition)?

How do we retrieve information? Retrieval is thought to occur when there is a sufficient match between the current input pattern, and a previously encountered input pattern (Tulving, 1983). Sometimes however, the input pattern is merely a partial cue, and successful recognition entails activation of information that is associated with the cue. Activation of semantically related information is thought to occur due to spreading activation throughout a semantic network (Collins & Loftus, 1975). For example, someone asks "Where was JFK killed?" Presumably the partial cue 'JFK' activates related information such as 'John F Kennedy', 'President of USA','Cuba Missile Crisis','Assassinated', 'Texas'.

One property of the encoding-match hypothesis of memory retrieval is that more input information increases the chances that associated information will be activated. This property of memories is that we can use meta-cognitive strategies to facilitate activation of all related information. We do this by attempting think about particular cues, for example we might focus on the details that JFK was shot in an open car, Lee Harvey Oswald shot JFK from a book repository, in the hope that the city name will be activated.

At a certain stage however, we must make the meta-cognitive judgement that activation is not possible. In recognition tasks the standard assumption is that we simply adopt a meta-cognitive strategy of "wait X seconds, if recognition has not occurred, then the information is not present." There is a lot of controversy surrounding this assumption and what it means in memory tasks.

Although this is not a complete answer, I hope it at least sheds light on why we can know that we don't know so quickly. If retrieval is just the reactivation of a previous perceptual state, then recognition should occur at the speed of perception. However, if the cue is only partial, and activation of the target information relies on spreading activation, then recognition will take longer.

References

Tulving, E. (1983). Elements of episodic memory (p. 123). Oxford: Clarendon Press.

Collins, A. M., & Loftus, E. F. (1975). A spreading-activation theory of semantic processing. Psychological review, 82(6), 407.
> 1 votes

# Answer
I am not an expert but I think this is because the brain would find existing memories instead of looking for memories that might not be there.

For example:

Say you have a good knowledge in C# but don't have that good of a knowledge in C++, but you know the extent of your knowledge.

You'd immediately know you cannot answer a question when asked about a concept in C++ you have not heard of / are not up to yet.

Another example:

When asked where you last saw someone, you can remember quickly or you can't.

For example, you have a friend that went missing unexpectedly but when you last saw her the confrontation was so casual you can't even remember it.. except that you can.. just slightly.

If you see your friend and give them a quick wave, but are in an area you aren't familiar with (Say a shopping district you've never went to), you'd have a difficult time recalling the PLACE where you found them. This is especially true if you're just acquaintances who just say "Hi" and "Bye!"

But if you are in a grey area, say you've been to a certain place before and saw your friend/acquaintance there, you may not remember or you will remember, that is just subjective. You'd be likely to remember quicker if it was a large event between you two. (Like a wedding!)

**All in all, usually when asked that type of question images will flash by while you're saying "Hmm.. umm.. well I think I last saw (him/her) at this place." or you can be unsure and blank out.**

Sorry for my inexperience, I am just giving an example to explain what I cannot really formally write.
> 1 votes

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Tags: memory
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title: Diet for brain stimuli

text:
# Question
Title: Diet for brain stimuli
I want to ask which foods or supplements enhance brain function and how,like for example protein is good after a muscle workout what is the equivalent for the evolving of the brain,antioxidants are said to be good, but why.

Also,do you have in mind any constructive book or article from which I can elaborate myself.Furthermore do exist diet for brain stimulation?Thanks in advance.

# Answer
> 5 votes
Assuming a diet is not deficient; this is a brief overview of some of the dietary needs for optimal brain function.

1. Maintaining glucose levels is necessary to maintain healthy brain function.
2. There is substantial research on the positive effects of omega 3 fatty acids on brain function.
3. Vitamin and mineral deficiencies can cause disruption to brain function (note so can excesses).

**Glucose:**

This article gives some good detail about how to maintain healthy glucose levels; with discussion of glycaemic index and maintaining a steady release of glucose from the breakdown of complex carbohydrates.

Nourish - Carbohydrates Fuel Your Brain

> Glucose, Learning and Memory - Study
>
> Psychology professor Paul E. Gold has researched the stability of glucose levels in the brain. Working with Ewan C. McNay , they found that as rats went through a maze, concentrations of glucose declined in the animals' hippocampus , a key brain area involved in learning and memory – even more dramatically so in older brains.
>
> Except under conditions of starvation, it was thought that the brain always had an ample supply of glucose. "While this is the case in terms of consciousness, the new findings suggest that glucose is not always present in ample amounts to optimally support learning and memory functions," said Gold, who is director of the Medical Scholars Program in the University of Illinois College of Medicine.
>
> "The brain runs on glucose. Young rats can do a pretty good job of supplying all the glucose that a particular area of the brain needs until the task becomes difficult," explained McNay, a postdoctoral researcher in psychology at Yale University. "For an old rat given the same task, the brain glucose supply vanishes out the window. This correlates with a big deficit in performance. A lack of fuel affects the ability to think and remember."

Brain Energy Metabolism
An Integrated Cellular Perspective
Pierre J. Magistretti, Luc Pellerin, and Jean-Luc Martin

> Glucose is the obligatory energy substrate for brain and it is almost entirely oxidized to CO2 and H2O.

Role of glucose in regulating the brain and cognition.
P E Gold

> Extensive evidence indicates that relatively modest increases in circulating glucose concentrations enhance learning and memory processes in rodents and humans.\

**Omega 3 fatty acids:**

> Lipids (fats)\- some fats are essential for proper brain function. Two lipids especially critical to the brain are the n-6 and n-3 fatty acids. Low levels of n-3 cause visual problems by badly affecting the retina. Studies in rats have shown that diets without n-3 fatty acids cause learning and motor disabilities and may damage systems that use the neurotransmitters dopamine and serotonin in the frontal cortex. The n-6 fatty acids affect neurotransmitter release and contribute to the ability of neurons to use glucose for energy.

Brain foods: the effects of nutrients on brain function
Fernando Gómez-Pinilla doi: 10.1038/nrn2421

> ... a diet that is rich in omega-3 fatty acids is garnering appreciation for supporting cognitive processes in humans and upregulating genes that are important for maintaining synaptic function and plasticity in rodents. In turn, diets that are high in saturated fat are becoming notorious for reducing molecular substrates that support cognitive processing and increasing the risk of neurological dysfunction in both humans and animals.

**Vitamins:**

From:
B vitamins and the aging brain.
Selhub J, Troen A, Rosenberg IH. doi: 10.1111/j.1753-4887.2010.00346.x.

> Deficiencies of the vitamins folate, B(12) , and B(6) are associated with neurological and psychological dysfunction and with congenital defects. In the elderly, cognitive impairment and incident dementia may be related to the high prevalence of inadequate B vitamin status and to elevations of plasma homocysteine

The Vitamin You Need for a Sharp Brain as You Age
Dr. Mercola

> Accordingto the latest research, people with high levels of markers for vitamin B12 deficiency were more likely to score lower on cognitive tests, as well as have a smaller total brain volume, which suggests a lack of the vitamin may lead to brain shrinkage

Vitamin B12, cognition, and brain MRI measures: a cross-sectional examination.
Tangney CC, et al doi: 10.1212/WNL.0b013e3182315a33.

> Concentrations of all vitamin B12-related markers, but not serum vitamin B12 itself, were associated with global cognitive function and with total brain volume.

Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease.
Eyles DW, Burne TH, McGrath JJ. doi: 10.1016/j.yfrne.2012.07.001

> Increasingly vitamin D deficiency is being associated with a number of psychiatric conditions. In particular for disorders with a developmental basis, such as autistic spectrum disorder and schizophrenia the neurobiological plausibility of this association is strengthened by the preclinical data indicating vitamin D deficiency in early life affects neuronal differentiation, axonal connectivity, dopamine ontogeny and brain structure and function. More recently epidemiological associations have been made between low vitamin D and psychiatric disorders not typically associated with abnormalities in brain development such as depression and Alzheimer's disease

The following link gives a good overview of vitamin deficiencies and toxicities.

Fat-Soluble Vitamins: A, D, E, and K
by L. Bellows and R. Moore

> Fat-soluble vitamins: A, D, E, and K — are stored in the body for long periods of time, and pose a greater risk for toxicity than water-soluble vitamins. Fat-soluble vitamins are only needed in small amounts.

Note: that, within all scientific research,there can be research that is "conclusive", but it is also important to be mindful, that not all findings are conclusive.

Vitamin D and cognitive performance in adults: a systematic review. Annweiler C, et al doi: 10.1111/j.1468-1331.2009.02755.x.

> . Three studies showed four significant positive associations between serum 25OHD concentrations and global cognitive functions, whereas three other studies exploring specific aspects of cognition showed 11 non-significant associations. This systematic review shows that the association between serum 25OHD concentrations and cognitive performance is not yet clearly established. The inconclusive results of the reviewed studies could be due to methodology, types of the cognitive tasks used and/or the cellular mechanisms of vitamin D.

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Tags: brain-training, feeding
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# Question
Title: Dreams and sleep phases, and duration of dreams
Supposedly, people mainly dream during REM sleep, and dreams last up to 20 minutes (see for example the first paragraphs of the Wikipedia article on Dreams).

My subjective experience differs:

* No matter at what time I awake, I always awake from a dream.
*And since I often awake not on my own (during phases of light sleep) but because I'm disturbed by outside noises (the crying baby of our neighbors, car doors slamming), and often feel groggy and disoriented upon awakening, I probably often awake from deep phases of non-REM sleep. Still, I always awake from a dream.*
* When I wake up I often remember an unbroken storyline from the last thoughts before I fell asleep until the moment of awakening.
*So obviously my dreams must have continued for hours – either in an unbroken stream or by taking up after a break where the story was "paused" before it.*

**Are there recent theories or research findings that explain this subjective experience?**

# Answer
I don't think what you're describing is that unusual. I read about dreams and dreaming in Jaak Panksepp's "Affective Neuroscience" some years ago, and here is what I remember:

First, it is not entirely accurate to say that dreams happen only during REM sleep. What is unique to REM dreams is visual imagery. NREM sleep, also called slow wave sleep, also contains dreams, but they are just a series of thoughts - not very different from when you think about things while awake.

Second, even if you are describing visual dreams: REM sleep is more shallow than slow wave sleep, i.e. outside noises will wake you up more easily than during the other sleep stages.

Third, it's very standard to dream about things that are currently going on in your life.

Fourth, dreams are extremely fragile, they evaporate from memory very quickly unless you actively do something mental with them, and it is easy confabulate some new details into them while trying to keep them from slipping away. It could be that you are reconstructing the content or duration of your dreams a little bit while you are trying to compare them to your thoughts before sleep.
> 6 votes

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Tags: dreams
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# Question
Title: Is it possible for non-BDSM relationships to learn anything from slave-master relationships?
I am interested in research on slave-master relationships within the BDSM spectrum. This questions concerns people who do not just engage in BDSM recreationally, but rater define their relationship by this type of relationship.

Master-slave relationships is one of reciprocated devotion and requires much forethought in planning activities. This includes both psychological and physical punishments, play and games. Many people take their roles in their relationship very seriously. There are clearly defined rules and boundaries that must be respected. This is held in high regard amongst the community.

**Is it possible for non-BDSM relationships to learn anything from slave-master relationships?**

# Answer
BDSM relationships are generally very clear on the respective roles of the individuals. Thus, they provide a refuge from the "war of the sexes" that is being fought in most non-BDSM relationships.

In non-BDSM relationships today, men and women are usually extremely confused about their roles. Men and women both have difficulties accepting women as (co)providers; both partners are expected to partake in child-rearing and household chores, which does not relieve one partner from the tedium of the job, but double the stress by leading to conflicts and an unclear diffusion of responsibility; sex is a minefield where men are afraid to "use" their women, and women can no longer "let go"; etc.

BDSM relationships are reactionary in that they return to the clarity and emotional safety of pre-feminist relationships, only without the patriarchal roles. As both Skippy (user3267) in her question and MingYue in his answer have described, BDSM relationships are often less about specific forms of sexuality, but about a specific from of relationship: one with clearly defined roles, and both partners being able to relax and be themselves in the secure knowledge of what is expected of them, how to behave, and where the limits of their agreement lie – because every relationship is a contract, only non-BDSM relationships make the mistake of tabooing this fact and clogging the free flow of an honest exchange with a thick layer of romantic spirituality.

What non-BDSM relationships can learn from BDSM relationships is to communicate clearly, to define the roles of each partner, and to stop feeling guilty about not loving in a politically correct way. Equal rights don't apply inside the bedroom.

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Since there has been some debate concerning the dangers and pathology of sadism, I would like to append a paraphrase of a section in a textbook on sexual deviance (Fiedler, 2004, p. 267f.):

> Research has shown that an inclination to sexual sadism is a mostly safe and harmless preference. Practices of sexual sadism are usally performed with the utmost caution and care, so that injury or trauma is extremely rare (Scott, 1983; Weinberg & Kamel, 1983).
>
> Studies with persons egaging in sadistic practices with their partners have repeatedly found that these persons are socially well integrated, valued by their friends and neighbors and successful (Spengler, 1977; 1979; Scott, 1983; Moser & Levitt, 1987; Baumeister & Butler, 1997). Some authors attest that the social adjustment and psychic health of individuals engaging in sadistic practices with their partners are *above average*.
>
> Since an inclination towards sexual masochism is about four times as common as an inclination towards sexual sadism (Baumeister & Butler, 1992), we may conclude that some persons practicing sadism in their relationships are not sadistic at all but rather complying with the needs of their loved ones.
>
> In sum, a majority of persons performing sadism in their relationships have no psychological disorder.

Sources:

* Baumeister, R. F., & Butler, J. L. (1997). Sexual masochism: Deviance without pathology. In D. R. Laws & W. T. O'Donohue (Eds.), *Sexual Deviance: Theory, Assessment, and Treatment* (pp. 225-239). New York: Guilford.
* Fiedler, P. (2004). *Sexuelle Orientierung und sexuelle Abweichung* \[Sexual Orientation and Sexual Deviance\]. Weinheim: Beltz.
* Moser, C., & Levitt, E. E. (1987). An exploratory-descriptive study of a sadomasochistically oriented sample. *Journal of Sex Research, 23*, 322-337.
* Scott, G. G. (1983). *Erotic power: An exploraton of dominance and submission*. Secausus, NJ: Citadel.
* Spengler, A. (1977). Manifest sadomasochism of males: Results of an empirical study. *Archives of Sexual Behavior, 6*, 441-456.
* Spengler, A. (1979). *Sadomasochisten und ihre Subkulturen*. Frankfurt: Campus.
* Weinberg, T. S., & Kamel, W. L. (Eds.) (1983). *S and M: Studies in sadomasochism*. Buffalo, NY: Prometheus.
> 9 votes

# Answer
I do not think so is the short answer. I belong to a minority of men who are submissives to a female Master. She does not treat me as a slave and does not expect me to do anything I am uncomfortable with. I do all the housecleaning, her laundry, cook her meals and generally serve her in whatever fashion that gives her pleasure. I do so out of love of her. She is mentally tougher and more like a man in business thinking and dealing but very much a woman. It took her awhile to accept that she was the much stronger personality and that anyone could want to devote their life to her and serve her. I consider her my Master and refer to her as Master. She considers herself Master and has a name she has given me that we use privately. I also consider myself to be her property for her use and for her pleasure. At no time however does she treat me like a slave or administer punishment etc. It is nothing like what I have read about Master-Slave relationships in BDSM.
> 2 votes

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Tags: social-psychology, sexuality
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# Question
Title: Can the brain work better in stressful conditions?
I was watching a documentary about the brain the other day, BBC's Human Body - Brain Power. It said that the perception power of the brain increases when you are in a tense situation. For example; if you know that you are about to die because your house is on fire, the brain will perceive everything more quickly than normal. In other words, the brain works better when you are under stress or tensed a lot (because brain wants you to survive; this is only in life or death situations of course)

I was wondering if the same thing happens to a student during an exam. Is it good for a student to be tensed a bit while taking an exam? I mean if you are solving a question at home, you usually make a lot of mistakes, but the frequency of those mistakes decreases during an exam.

Is my observation correct? Or does a student need to be completely calm during an exam?

# Answer
> 6 votes
A little stress is good, as it leads to greater psychological arousal, but lots of stress will decrease performance. This is known as the Yerkes–Dodson law, from the famous experiment by Yerkes and Dodson (1908) which related strength of motivational electric shocks to performance; performance increased up to a point and then plummeted.

One more comment about something you said:

> For example; if you know that you are about to die because your house is on fire, the brain will perceive everything more quickly than normal.

People do report subjective time dilation for scary events but quantitative attempts have found no evidence for such, see Stetson et. al. (2007).

**References**

Stetson, Chess, Matthew P. Fiesta, and David M. Eagleman. "Does time really slow down during a frightening event?." PLoS One 2.12 (2007): e1295.

Yerkes RM, Dodson JD (1908). "The relation of strength of stimulus to rapidity of habit-formation". Journal of Comparative Neurology and Psychology 18: 459–482.

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Tags: perception, stress
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# Question
Title: Does individual work performance follow a Paretian distribution?
O'Boyle and Aguinis (2012) wrote a paper arguing that individual job performance follows a Paretian distribution rather than a normal distribution (put simply, a very long tail to the right, rather than a bell-shape). The abstract was as follows:

> We revisit a long-held assumption in human resource management, organizational behavior, and industrial and organizational psychology that individual performance follows a Gaussian (normal) distribution. We conducted 5 studies involving 198 samples including 633,263 researchers, entertainers, politicians, and amateur and professional athletes. Results are remarkably consistent across industries, types of jobs, types of performance measures, and time frames and indicate that individual performance is not normally distributed—instead, it follows a Paretian (power law) distribution. Assuming normality of individual performance can lead to misspecified theories and misleading practices. Thus, our results have implications for all theories and applications that directly or indirectly address the performance of individual workers including performance measurement and management, utility analysis in preemployment testing and training and development, personnel selec- tion, leadership, and the prediction of performance, among others.

### Question

* Are they correct in claiming that most researchers assume that individual job performance is normally distributed?
* Are they correct in claiming that the Paretian distribution provides a better fit to individual job performance than the normal distribution?

### Reference

* ERNEST O’BOYLE JR. HERMAN AGUINIS (2012). THE BEST AND THE REST: REVISITING THE NORM OF NORMALITY OF INDIVIDUAL PERFORMANCE. Personnel Psychology Volume 65, Issue 1, pages 79–119, Spring 2012 PUBLISHER SITE; also see UNIVERSITY PRESS RELEASE

# Answer
An alert of a follow up paper ON THE DISTRIBUTION OF JOB PERFORMANCE: THE ROLE OF MEASUREMENT CHARACTERISTICS IN OBSERVED DEPARTURES FROM NORMALITY and subsequent search brought me to this discussion. I don't have full access to these articles unfortunately.

Of the two questions that posed, no, I wouldn't expect to find a normal distribution and no, I wouldn't expect to find a pareto distribution. As was mentioned in the G+ discussion that Artem linked to, what we tend to see is some skewed distribution such as a log-normal.

A good tool for exploring these types of situations, especially in a dynamic / systems-based situation is to use simulation. This is what I did in a 2010 blog post on 'forced ranking' which at it's heart frequently assumes normally distributed performance.

The post shows selection of any sort quickly produces a skewed population. This selection can be either on entry level selection or during a performance review cycle. What I didn't explore in that simple model, but again supports the outcome, is self-selection - i.e. the likelihood of an employee leaving is to some degree based on their assessment of fit.

I also explore what happens if we use a probability distribution not only for the individual, but also a distribution for the likely measurement error (because only in rare situations can be objectively measure performance.) For me this is the sort of instance where a Bayesian Hierarchical model makes sense.

In my day job working with senior HR people to help them understand their workforces I find simulation a powerful tool. We can make a few simple assumptions and show that over time unexpected results will occur. Many times it will show that normal distributions don't logically hold over time.
> 6 votes

# Answer
I like that O'Boyle and Aguinis (2012) highlight the importance of discussing the distribution of job performance. Their results clearly demonstrate that for some performance metrics a normal distribution is a very poor representation. They also present a persuasive argument for why this has practical implications for managing human resources. That said I think there are a couple of issues regarding the generalisation of their results.

### Issue of what is the natural metric of performance

It is possible to transform a variable to change its distribution. For example, it is common to apply a log or square root transformation to skewed variables in order to make the resulting variable approximately normal. Thus, in order to speak about **the** distribution of performance one is confronted with the issue of what is the **appropriate** metric of performance for a given variable.

To take one concrete example measures of time to perform a task are often positively skewed. In some instances it is modelled with an Inverse Gaussian distribution (e.g., Baayen & Milin, 2010). However, instead of using time to perform a task, you could measure productivity as the amount of times a task is performed in a unit time. This will be a multiple of the inverse of time to perform the task (i.e., $c \times 1/y$ where $y$ is time to produce one unit and $c$ is the amount of time given to perform the task repeatedly). In addition to reversing the scale it will also substantially transform the distribution.

The example demonstrates that not only can any given performance measure take on a variety of distributions, but that often there is more than one **natural** metric of performance.

### How might distribution vary across tasks and performance metrics?

The following summarises the performance measures used in the article which results showed were better fit by a Paretian than a normal distribution.

* Academic: Number of publications in top journals over 9.5 year period
* Creative: Number of award nominations; number of top 500 songs, etc.
* Political: Number of appearances in the legislature; time in office
* Sports: Home run count; number of wins; goals scored;

There are several common elements that describe these performance domains:

* Higher scores on these metrics are achieved by being close to the best in the domain. In most sporting contests prizes are not distributed evenly. Salaries and prizes are much higher for those at the top. Similar arguments can be made about political success.
* Higher performance often yields additional support which reinforces performance. If you are a successful writer, then you are likely to get more support from publishers in terms of promotion and production support.
* The tasks lack natural performance constraints and are often non-standardised. I imagine that the distribution on more standardised tasks would be more normal. For example, number of calls successfully handled in a call centre or number of widgets made on a production line amongst reasonably trained employees would vary but would be a lot more normally distributed.

In an article by Theodore Micceri (1989) he reviewed the distribution of test scores in a wide range of psychometric tests and found substantial variation in the degree to which normality was obtained. While Micceri (1989) is used as a critique of the ubiquity of the normal distribution, it also highlights that distributions can vary substantially across contexts and domains, some being normal, some not being so.

O'Boyle and Aguinis state in their discussion that

> Our central finding is that the distribution of individual performance does not follow a Gaussian distribution but a Paretian distribution.

This is helpful in encouraging those wanting to pursue further research on the distribution of performance. Nonetheless, the distribution of performance will vary as a function of the task and the metric of performance used. All the datasets used in O'Boyle and Aguinis share certain characteristics and leave out a large proportion of the performance space.

Thus, I think the question properly phrased should be: "Under what conditions is the distribution of task performance characterised by a Paretian distribution?" or to be more inclusive of the range of possible performance distributions, "what causes the distribution of performance to vary?"

My initial hypothesis is that performance distributions are related to issues of task standardisation, inherent performance constraints, and the degree to which the winner-takes-all. That said, I'd like to see a more comprehensive review of performance measures that systematically examined a wider range of tasks.

### References

* Micceri, T. (1989). The unicorn, the normal curve, and other improbable creatures. *Psychological Bulletin, 105*, 156. PDF
* Baayen, R. H. & Milin, P. (2010). Analyzing reaction times. *International Journal of Psychological Research, 3*, 12-28. PDF
> 3 votes

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Tags: performance, io-psychology
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# Question
Title: What is the psychology of notification colour?
After reading the question What is the impact of showing the amount of unattended notifications to the user, it occurred to me that many notifications (certainly not all) are red, two examples being inbox messages here (SE) and any notification on Facebook. Whereas, some notifications on StackExchange are in light blue (eg for badges and edits). Green is often associated with check-mark notifications (such as on my AVG virus scan and as the accepted answer here).

(*Anecdotal side note: I sometimes get the feeling "oh what have I done this time" when the red notification shows here and a "oh goody!" when the blue shows up*).

There are many examples of different colours being used for different types of notifications. What is the psychological basis of these notification colours?

# Answer
> 1 votes
It is all about attention and reaction time: Information are coded in visual, aural and tactile channel. Here you have primer of visual coding. Visual coding could be signs or text.

You have shorter time of reaction to primary colors (red yellow blue) and there is some kind of international standard which determine meaning of colors ( red-stop, green - walk... etc...) That is the reason why red.

I recomend you that you read some text in visual sensory perception, measuring time reaction, and some book of ergonomics psychology.

EDIT: Literature: http://hfs.sagepub.com/content/17/6/542.short

http://www.who.int/fctc/guidelines/ArtElevenWogalterNine.pdf

EDIT2: Here are lot about reaction time: http://biae.clemson.edu/bpc/bp/lab/110/reaction.htm

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Tags: social-psychology, perception, reference-request, hci
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# Question
Title: Why does being in a natural environment induce some kind of "peace" state while mecha/tech ones induce the opposite?
Usually, natural environments (being out in "nature") tend to induce a happy and peaceful state, while mechanical and technological ones tend to induce stress and sadness.

Why does this happen? Are we born with this notion, or do we just build up that in our minds over time? and even so, why?

# Answer
> 12 votes
Maybe we should ask a vietnam vet if he feels less stress in nature than inside a building.

I think the reason we feel tense inside is because we've been conditioned to expect stressful situations to happen while inside, so we're on guard for it (ie tense). Nothing bad has ever happened to us while sitting on a park bench listening to the birds chirp. Now, if tigers start leaping out at us on a consistent basis while at the park, this feeling may change. We might decide the sounds of clicking keyboards and tapping shoes to be more relaxing.

Another point to consider is that the sounds of birds chirping means "things are ok". Bird have a high viewpoint compared to terrestrial animals and when birds are singing, there probably isn't a tiger stalking us. Also, if you notice, birds sing after storms pass. I know when I hear the birds singing, I can go back outside and get back to work... the storm is over. Its possible this knowledge is instinctual.

The same could be said of crickets and frogs. When you hear crickets and frogs, things are ok. When the crickets and frogs suddenly stop, that when you grab the flashlight and see what's lurking in the woods.

An odd one is the sound of water. If you're a prey animal, which humans would be in the wild, you'd have a large chance of being ambushed while getting a drink. All predators gather around the watering hole and stalk victims. So this raises the question... why are water sounds relaxing? This is evidence against instinct. Water sounds would be relaxing as a result of association rather than instinct. When I take a drink of water, I feel better. When I go fishing, I don't have to worry about anything but fishing. Water has always been good to me, so when I hear it, I feel better. Also, the sounds of water tends to drown-out other sounds. That's why spies on tv tend to have their conversations near moving water. There is something about the randomness of water sounds that won't allow pattern recognition in other sounds. When we hear water, its hard to be disturbed by other sounds, therefore, easier to be at peace.

# Answer
> 7 votes
In this article, the authors note that natural sounds promote faster stress recovery than artificial sounds. One of the main reasons is because the natural sounds are more familiar than the artificial sounds. According to Eleanor Ratcliffe, natural sounds (such as bird song) may evoke memories of different seasons. This in turn, produces positive affect.

You might be interested in this TED talk about the ways sounds affect us. It seems that many nature sounds are at the 12 Hz frequency (alpha waves and the natural breathing rhythm) according to Julian Treasure.

**Source**

Stress Recovery during Exposure to Nature Sound and Environmental Noise by Jesper J. Alvarsson et al. Int. J. Environ. Res. Public Health 2010, 7(3), 1036-1046; doi:10.3390/ijerph7031036

# Answer
> 5 votes
I'm surprised nobody brought this up yet. Maybe that fact is a sign of you all having gotten used to it:

**Artificial environments usually are filled with noise.** You only notice how much noise there is, when you take a hike in the wilderness, and there are no more far away car sounds, no radios and televisions, no human multitude talking, no computer fans – only the wind and the birds.

Noise induces stress and this basic level of stress never leaves us civilized people, because the sounds of civilization never leave us, not even at night. We may no longer consciously hear it – once I moved away from the flat beside the highway I was at first unable to sleep because of the unfamiliar quiet – but our brains process it and it affects our physiology.

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Tags: well-being, physiology, stress
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# Question
Title: Articles about model of eye movements and trajectories
I need to work with data from an eye tracker. I have raw data about eye coordinates. I need to reconstruct trajectories of eye movements. Since I know modern science has several methods for this task, I already googled for them, but I don't know which ones are serious and authority works.

# Answer
> 2 votes
I am not sure what you may have looked up previously, but here are a couple of referenced articles that may be of help to you: "Identifying Fixations and Saccades in Eye-Tracking Protocols" (Salvucci and Goldberg, 2000), from their abstract:

> In this paper we propose a taxonomy of fixation identification algorithms that classifies algorithms in terms of how they utilize spatial and temporal information in eye-tracking protocols.

In terms of Human-computer interaction:

"Commentary on Section 4. Eye tracking in human-computer interaction and usability research: Ready to deliver the promises." (Jacob and Karn), this article makes reference to several more specific references.

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Tags: reference-request, eye-movement
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# Question
Title: What is actually going on in your brain during a night terror?
I used to have really bad night terrors back in the day, where I would think I was floating and I would wake up and actually my vision would be very fuzzy - so I just want to know..

What is actually going on in your brain during a night terror? Is there any evidence that the type of bed one sleeps on makes any difference in lowering the incidence of night terrors?

# Answer
> 5 votes
Night terrors, a type of parasomnia has been the subject of considerable study.

According to "Insights from studying human sleep disorders" (Mahowald and Schenck, 2005), parasomnias are in two categories:

> The common parasomnias are another example of ‘dissociated sleep states’, representing the simultaneous admixture of wakefulness and either NREM sleep (disorders of arousal such as sleepwalking or sleep terrors) or wakefulness and REM sleep (REM sleep behaviour disorder). Parasomnias may result in striking clinical phenomena, which appear as the brain becomes reorganized across states, and are therefore apt to occur during the transition from one state to another.

Sleep terrors are an example of NREM sleep disorder and are usually the result of febrile illness, sleep deprivation, physical activity, emotional stress and medications - so the question about the bed can relate, particularly if the bed is causing lack of sleep.

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Tags: sleep, dreams
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# Question
Title: Research software for conducting a task between card sorting and sketch map drawing
I'm doing research in Spatial Cognition and am looking for software which will allow me to conduct the following task:

Participants will walk around a space and sit down to a computer task afterwards. There'd be a 2d architectural layout of the space visited by participants presented in the centre of the screen. On the side of the screen, the participants will see randomly scattered image stimuli, representing objects they have seen inside the space. I want them to be able to either drag&drop the images to their assumed locations in the architectural layout, or to click/select an image and click on the place inside the layout where they think they saw a given object. I want to record the final location and the sequence of operations.

I looked at card sorting tools from HCI, but these seem to be too restrictive (won't allow to change background image for example), so I thought someone in this group could hear of psychological software capable of running this sort of task.

# Answer
> 1 votes
This is a Mac related answer - I'm sure there are equivalent applications on other platforms.

When I'm doing usability testing on prototypes we use a combination of OmniGraffle or Keynote and Silverback. Silverback records all the interactions on the screen (will highlight when they click etc.) and will also use the built-in iSight camera to record a video of the user. You can 'mark' interesting points in the recording for easy view later.

On OmniGraffle set the room as a background layer that can't be edited and the objects on another layer.

An alternative is to use something like GoTo meeting and 'broadcast' the session to another room where the team can watch. What you won't get as easily here is highlighting of clicks etc.

Only thing this setup won't do is move on click rather than dragging.

Steve Krug's book "Rocket surgery made easy" is a great getting-started guide to this sort of thing.

# Answer
> 2 votes
I think a good option would be to use a general purpose language. For example, I once used Visual Basic to program a task that allowed for dragging elements around a display. The IDE for Visual Studio makes it easier to create GUIs. You could readily include a background image and so forth. You could also record location of visual elements and each action that a user takes.

# Answer
> 2 votes
At our institute (at a university), all experiments are custom programmed, mostly in Python, often using PsychoPy, or in MATLAB. We have staff, from post-docs to student assistants, that do nothing but write code (such as packages for R). If you plan to do more than one experiment in your life, I would strongly recommend to learn programming them. You'd be very unhappy with the limitations that any pre-made solutions would impose on your research.

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Tags: methodology, experimental-psychology, test, software
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# Question
Title: Have there been any mechanisms proposed for normalization in probabilistic population codes?
I heard a talk yesterday by Dora Angelaki about multi-sensory integration. Part of the talk was about bayesian inference with multiple noisy sources of information. I know that there has been a lot of theoretical work done on bayesian inference and population coding, but I was wondering if there have been any biological mechanisms proposed for the population activity normalization necessary for these computations?

# Answer
It depends what you mean by a biological mechanism. If you mean that there should be a protein cascade that implements normalization, that doesn't seem plausible, in my opinion. Normalization in probabilistic population codes is just one of many computations that can be performed in a neural system.

If you're okay with the notion that there's nothing biologically unique about normalization, then Normalization for probabilistic inference with neurons (a paper written by my supervisor, Chris Eliasmith) proposes a spiking neural network performs normalization on probability density functions.
> 2 votes

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Tags: neuroscience, theoretical-neuroscience, bayesian
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# Question
Title: Research on "probabilistic thinking" in non-human animals?
We all seem to have a "probabilistic sense", which manifests itself in certain types of expectations (e.g. even if one has never used a bow to shoot an arrow, one expects that hitting a small target will be more difficult than hitting a large target, all other things being equal), and also in certain characteristic responses when events do not match those expectations (these responses consist primarily of surprise, but also include suspicion, and in extreme cases maybe even awe or fear).

For me at least, this probabilistic sense feels subjectively very fundamental, in the same way that physical pain, hunger, thirst, etc., "feel fundamental". In other words, I could not describe them to someone in simpler terms. (I may be able to explain to someone the mechanics of shooting an arrow with a bow, but I would not know how to explain to someone how to feel the immediate intuition that hitting a small target would be harder than hitting a large one.)

**Motivated by the kind of questions that follow, I'm looking for a review of research on "probabilistic thinking" by non-human animals.**

How analogous is this "probabilistic sense" to the more traditional ("classical") senses like vision and touch?
In particular, how much does it depends on human culture?

I've searched for these keywords online, but I have not come up with anything. Maybe I'm not using the right keywords. Also, since probabilistic methods as standard tools in research (and hence, the research literature is awash in terms like "probability", "expectation", "Bayesian", "statistical", etc.), it is very difficult to craft searches that are selective for the research I'm looking for. Some *specific* pointers (i.e., to specific papers, or books, or at least specific researchers) would be appreciated.

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FWIW, the clearest example I can come up with to illustrate what I mean by "probabilistic thinking" is this thought experiment. Imagine presenting a human subject the opportunity to participate in a raffle for some prize that the subject finds desirable, and suppose the subject is just told that he/she has the choice of having (A) one, or (B) two tickets for the raffle (at no cost in either case). We would expect, of course, that every "normal" subject would prefer (B) over (A). (In fact we would question the sanity (or at least the seriousness and sincerity) of any subject who fully understood the situation, and still preferred (A) over (B).)

What makes the universal preference for (B) an example of "probabilistic thinking" is the simultaneous recognition on the subject's part that choice (B) is *unequivocally* better, and that still it could fail to lead to the prize, even if the raffle had only three tickets.

I'm not sure how one would go about setting such an experiment with non-human animals, but I've been impressed before by the ingenuity of the experiments that researchers devise to test animal cognition, so I remain hopeful that something like the "probabilistic thinking" I illustrate above has been investigated.

That said, I realize that it would be rather difficulty is to distinguish between pure "probabilistic thinking" (as a distinct, independent faculty) and conditioning. In fact, it can be (and has been) argued that what I'm calling "probabilistic thinking" is nothing more than a special case of conditioning. (After all, conditioning may be thought of as the nurturing of certain expectations, and preferring two tickets over one could be simply a manifestation of one such expectation.) Ironically enough, when it comes to humans, I can't think of any ethical experiment that would be able to establish "probabilistic thinking" as a faculty that would be present even in the absence of any conditioning. With animal subjects, however, it may be possible to set up experiments that minimize the possible confounding by conditioning.

# Answer
Try an internet search on animal learning probability. Although that might not be what you want because it sounds like you specifically want insight as opposed to learning in general.

Your particular example is problematic because you're inferring far too much on the subjects part. They might prefer B because they just want more of anything offered. The experiments need to be much more careful than that in order to attribute effects to probabilistic thinking. What kind of response will occur doesn't just depend on the probability of events but what kind of reward contingencies are associated. Both people and animals do dumb things with simple probabilities and rewards. But they do the same thing. Does that justify an argument that they have a probabilistic sense?

Deriving a distinction between insight and conditioning is sometimes problematic (for example food aversion in rats) and insight is usually only accepted when it can pass the interocular impact test. While I can show you lots of papers on probability learning I'm unaware of any that tap insight about probabilities.

Consider the problem for the researcher. In order to establish insight into probabilities the subject has to experience the events repeatedly in a relevant way so that they become learnable. Given this takes a degree of exposure in the first place it would be very hard to dissociate conditioning from insight based learning.

Also consider that people sometimes can learn probabilities but don't always do intelligent things with them. For example, when there are two possible events and one happens 75% of the time people tend to select the frequent event 75% of the time. This is rather boneheaded because selecting the frequent event all of the time will give you the most accurate performance. Animals actually learn to do the latter. So maybe animals have a stronger probability sense? Regardless, they clearly they learn probabilities.
> 5 votes

# Answer
This type of research is fairly new in the animal domain, so I guess it would be difficult to find a review unless you use keywords for specific cognitive functions and a species (e.g. "decision making" AND "rat").

This link is probably of interest:

Rats match humans in decision making that involves combining different sensory cues

Also note that rats are perhaps more intricate in their "culture" than previously believed:

Empathy and pro-social behavior in rats
> 3 votes

# Answer
I believe these two beautiful articles target just what you are looking for:

Niv, Y., Joel, D., Meilijson, I., & Ruppin, E. (2008). Adaptive Behavior Evolution of Reinforcement Learning in Uncertain Environments : A Simple Explanation for Complex... doi:10.1177/10597123020101001

Shafir, Reich, Tsur, Erev & Lotem, 2008: Perceptual accuracy and conflicting effects of certainty on risk-taking behaviour

You might want to have a close look at the work of Arnon Lotem, who is a zoologist who collaborated intensively with decision making researchers to find out more about the decision making behavior of animals. I assume it includes what you refer to as "probabilistic thinking", as assessing the probability is a part of making judgement and decision.
> 3 votes

# Answer
There's a great 2012 paper by A. Kheifets and Randy Gallistel showing a "probability sense" in animals. I love the paper's title: 'mice take calculated risks'. It's well worth reading.

> **abstract**: Animals successfully navigate the world despite having only incomplete information about behaviorally important contingencies. It is an open question to what degree this behavior is driven by estimates of stochastic parameters (brain-constructed models of the experienced world) and to what degree it is directed by reinforcement-driven processes that optimize behavior in the limit without estimating stochastic parameters (model-free adaptation processes, such as associative learning). We find that mice adjust their behavior in response to a change in probability more quickly and abruptly than can be explained by differential reinforcement. Our results imply that mice represent probabilities and perform calculations over them to optimize their behavior, even when the optimization produces negligible material gain.
> 1 votes

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Tags: decision-making, animal-cognition, conditioning
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# Question
Title: Waking around the same time without an alarm
*Anecdotal background*

I find that regardless of what time I go to bed, or how exhausted I am, I always wake up the next morning between 5 and 6am. This is despite my alarm being consistently set for 6:15am. I used to work in an industry, over 15 years ago, where earlier morning starts were part of the job (started work at 6am then), but none quite as drastic since then. I do not take naps, either.

This happens irrespective of the conditions (temperature, etc).

So, I do not have a fixed time of sleep and it is not necessarily easy to get of bed at that time (some mornings here are very cold).

*The question*

**What are the neurological triggers that cause someone to continually wake up at a set time in the morning, regardless of time of sleep and conditions?**

Note - this **not** a self help question. I have read the questions and answers for "What defines the easiest time to get out of bed in the morning for humans?" and "How are people able to wake themselves up after a pre-specified amount of time?" and they did not quite have the answers I am after.

# Answer
> Ever wondered why you wake up in the morning—even when the alarm clock isn't making jarring noises? Wonder no more. Researchers at the Salk Institute for Biological Studies have identified a new component of the biological clock, a gene responsible for starting the clock from its restful state every morning.

http://www.salk.edu/news/pressrelease\_details.php?press\_id=521
> 5 votes

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Tags: sleep
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