Melatonin in foods

17 Apr

The hormone melatonin is involved in the regulation of sleep, and sleep is known to help memory consolidation.

In this video, Dr. Gregger looks at the melatonin contents of different foods:


Social loafing and group learning

16 Apr

A paper published in Social Behavior and Personality looks at the phenomenon of social loafing, the tendency of some individuals to reduce effort when working in groups. This research has important implications for group and cooperative learning.

Here is the abstract:

“Social loafing has been defined as a phenomenon in which people exhibit a sizable decrease in individual effort when performing in groups as compared to when they perform alone, and has been regarded as a state variable. In this study, we instead conceptualized social loafing as a habitual response, given that many people have been found to be susceptible to social loafing in group tasks. We developed the self-reported Social Loafing Tendency Questionnaire (SLTQ) to measure individual variations in social loafing. In Study 1, the reliability and validity of the SLTQ were established in a sample of college students. In Study 2, SLTQ scores significantly negatively predicted individual performance in the group task condition, but not in the individual task condition. Social loafing can also be considered a trait variable, as it was found to modulate group dynamics when it was activated in a typical situation (i.e., being in a group).”

Group learning research often fails to consider the role of individual differences, as evidenced by this paper I published in The Journal of Instructional Psychology:

“Discussions of group and cooperative learning have often ignored individual difference as potential confounding variable. It is possible that some individuals may be disadvantaged by cooperative learning. The purpose of this study was to see if there was a relationship between preference for group learning (itself an individual difference variable) and self report GPA. University students (N = 66) completed the group learning and individual learning scales of the Perceptual Learning Style Preference Questionnaire and provides GPA information. Preference for group learning was negatively correlated with GPA (Spearman’s rho = -.31). Preference for individual learning was positively correlated with GPA (Spearman’s rho = .27).”

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Popular Mechanics’ oversimplification

15 Apr

Popular Mechanics posted a piece titled “6 Warning Signs That a Scientific Study is Bogus.” While I sympathize with the goal, there is a lot of bad research out there, and people should be empowered to judge the quality of research, this article is misleading on several fronts.

For example it asks:

“Does it Rely on Correlation?

Cigarette smoking has declined dramatically in the U.S. in the past few decades, and so has the national homicide rate. But just because two events occur at the same time doesn’t mean that one caused the other.”

It is certainly true that correlation is not causation, but it goes too far to say that a correlation study is bogus. Correlation is a often a prerequisite for causation ( a necessary but not sufficient condition). In fact, it was because scientists found a correlation between cigarette smoking and lung cancer that they thought it worthwhile to do experimental studies that confirmed the causal relationship.

A correlation design is a weakness of a study, but it does not make the study bogus.

The article also gives a grossly misleading summary of statistical analysis:

“A large number of test subjects makes a study more robust and reduces the likelihood that the results are random. In general, the more questions a paper asks, the greater its sample size should be. Most reliable papers contain something called a p-value, which measures the probability (p) that a study’s results occurred by random chance. In science a p-value of 0.05 suggests the study’s conclusions may be meaningful. Smaller p-values are better.”

Several things are wrong with this, first, a large sample size can also be misleading. The larger a sample size the greater the probability of finding statistical significant results, even if the effect is of no practical significance. Second, it ignores the importance of effect size, a measure that quantifies the strength of the relationship between the studied variables.

Popular Mechanics also cautions us to be suspicious of researchers who cite their own papers. If this is a vice, it is one that is widespread in the scientific literature and practiced by some of our best scientists.

A much better piece on can be found at Nature

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Anonymous blog comment suggests lack of confidentiality in peer review — and plays role in a new paper

15 Apr


Retraction Watch does a good job of explaining the controversy over a paper on human intelligence published in the journal Neuron.

Originally posted on Retraction Watch:

neuronA new paper in Intelligence is offering some, well, intel into the peer review process at one prestigious neuroscience journal.

The new paper is about another paper, a December 2012 study, “Fractionating Human Intelligence,” published in Neuron by Adam Hampshire and colleagues in December 2012. The Neuron study has been cited 16 times, according to Thomson Scientific’s Web of Knowledge.

Richard Haier and colleagues write in Intelligence that

View original 767 more words

Skepticism about twelve step programs

14 Apr

In the most recent issue of Pacific Standard, Maia Szalavitz reviews a number of recent books that critically examine Alcoholics Anonymous, and similar programs:

“some studies find that people mandated into AA do worse than those who are simply left alone. (If true, that would be no small problem. AA’s own surveys suggest that some 165,000 Americans and Canadians annually are court-mandated into the program—despite the fact that every court ruling on the issue has rejected such coercion as unconstitutional, given AA’s religious nature.)

Contrary to popular belief, most people recover from their addictions without any treatment—professional or self-help—regardless of whether the drug involved is alcohol, crack, methamphetamine, heroin, or cigarettes. One of the largest studies of recovery ever conducted found that, of those who had qualified for a diagnosis of alcoholism in the past year, only 25 percent still met the criteria for the disorder a year later. Despite this 75 percent recovery rate, only a quarter had gotten any type of help, including AA, and as many were now drinking in a low-risk manner as were abstinent.”


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Foreign Language Practice – Higher necessity means higher understanding and retention

14 Apr Featured Image -- 2075


Some interesting ideas on language practice.

Originally posted on Self Taught Japanese:

The effectiveness of foreign language practice depends on part on how pressing of a need there is to communicate and understand correctly.

When speaking with a native or fluent speaker of that language, there are all sorts of emotions that get engaged and one usually tries his or her hardest to comprehend and speak in a way that can be easily understood. Making mistakes can be embarrassing, or even lead to more serious repercussions depending on the context of the conversation.

For those who don’t have much contact with native speakers, you do may do like I do and try to consume all different sorts of content – novels, comic books, newspapers, videos, blogs, you name it. All of these can be excellent learning resources, but there typically is no strong motivation to understand each and every word, and any misunderstandings may go undiscovered, especially if the subject is fiction and…

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Sluggish cognitive tempo?

13 Apr

An article in yesterday’s New York Times announces a possible new disorder named sluggish cognitive tempo:

“some powerful figures in mental health are claiming to have identified a new disorder that could vastly expand the ranks of young people treated for attention problems. Called sluggish cognitive tempo, the condition is said to be characterized by lethargy, daydreaming and slow mental processing. By some researchers’ estimates, it is present in perhaps two million children.”

But many scientists express caution about this new construct:

“Yet some experts, including Dr. McBurnett and some members of the journal’s editorial board, say that there is no consensus on the new disorder’s specific symptoms, let alone scientific validity. They warn that the concept’s promotion without vastly more scientific rigor could expose children to unwarranted diagnoses and prescription medications”

A search of google scholar finds many papers on this topic. So, at this point, I reserve judgement until I am better informed.


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