Dienstag, 11. Juli 2017

Brain volume and intelligence: The moderating role of intelligence measurement quality

Brain volume and intelligence: The moderating role of intelligence measurement quality
Gilles E. Gignac, Timothy C. Bates (2017)


Correlation between brain volume and IQ in healthy adults is r ≈ .40.
The importance of correcting correlations for range restriction is demonstrated.
Intelligence measurement quality was a moderator of the brain volume/IQ effect.
Fair, good, and excellent measures of IQ yielded correlations of .23, .32, and .39.
p-Curve analysis indicated the significant results in the area likely not due to p-hacking.


A substantial amount of empirical research has estimated the association between brain volume and intelligence. The most recent meta-analysis (Pietschnig, Penke, Wicherts, Zeiler, & Voracek, 2015) reported a correlation of .24 between brain volume and intelligence – notably lower than previous meta-analytic estimates. This headline meta-analytic result was based on a mixture of samples (healthy and clinical) and sample correlations not corrected for range restriction. Additionally, the role of IQ assessment quality was not considered. Finally, evidential value of the literature was not formally evaluated. Based on the results of our meta-analysis of the Pietschnig et al.'s sample data, the corrected correlation between brain volume and intelligence in healthy adult samples was r = .31 (k = 32; N = 1758). Furthermore, the quality of intelligence measurement was found to moderate the effect between brain volume and intelligence (b = .08, p = .028). Investigations that used ‘fair’, ‘good’, and ‘excellent’ measures of intelligence yielded corrected brain volume and intelligence correlations of .23 (k = 9; N = 547), .32 (k = 10; N = 646), and .39 (k = 13; N = 565), respectively. The Henmi/Copas adjusted confidence intervals, the p-uniform results, and the p-curve results failed to suggest evidence of publication bias and/or p-hacking. The results were interpreted to suggest that the association between in vivo brain volume and intelligence is arguably best characterised as r ≈ .40. Researchers are encouraged to consider intelligence measurement quality in future meta-analyses, based on the guidelines provided in this investigation.

Sonntag, 9. Juli 2017

>In English, the words "explore" and "exploit" come loaded with completely opposite connotations. But to a computer scientist, these words have much more specific and neutral meanings. Simply put, exploration is gathering information, and exploitation is using the information you have to get a known good result.<

B. Christian & T. Griffiths

[Also see ...]

Creativity and Genius:

"Creativity and genius are unrelated to g except that a person’s level of g acts as a threshold variable below which socially significant forms of creativity are highly improbable. This g threshold is probably at least one standard deviation above the mean level of g in the general population. Besides the traits that Galton thought necessary for “ eminence” (viz., high ability, zeal, and persist­ence), genius implies outstanding creativity as well. Though such exceptional creativity is conspicuously lacking in the vast majority of people who have a high IQ, it is probably impossible to find any creative geniuses with low IQs. In other words, high ability is a necessary but not sufficient condition for the emergence of socially significant creativity. Genius itself should not be confused with merely high IQ, which is what we generally mean by the term “ gifted” (which also applies to special talents, such as music and art). True creativity involves more than just high ability. It is still uncertain what this is ..."

The g factor (1998)
Arthur R. Jensen 

Why are there so many explanations for primate brain evolution?

Why are there so many explanations for primate brain evolution?
R. I. M. Dunbar, Susanne Shultz (2017)


The question as to why primates have evolved unusually large brains has received much attention, with many alternative proposals all supported by evidence. We review the main hypotheses, the assumptions they make and the evidence for and against them. Taking as our starting point the fact that every hypothesis has sound empirical evidence to support it, we argue that the hypotheses are best interpreted in terms of a framework of evolutionary causes (selection factors), consequences (evolutionary windows of opportunity) and constraints (usually physiological limitations requiring resolution if large brains are to evolve). Explanations for brain evolution in birds and mammals generally, and primates in particular, have to be seen against the backdrop of the challenges involved with the evolution of coordinated, cohesive, bonded social groups that require novel social behaviours for their resolution, together with the specialized cognition and neural substrates that underpin this. A crucial, but frequently overlooked, issue is that fact that the evolution of large brains required energetic, physiological and time budget constraints to be overcome. In some cases, this was reflected in the evolution of ‘smart foraging’ and technical intelligence, but in many cases required the evolution of behavioural competences (such as coalition formation) that required novel cognitive skills. These may all have been supported by a domain-general form of cognition that can be used in many different contexts.
"If you memorize a thousand jokes, that doesn't make you a person with a sense of humor. Sense of humor is more subtle. A good sense of humor is about timing, the ability to say the funny thing at the right time and to the right people."

"While most humor research concerns jokes (with distinct “set-up lines” and “punch lines”), only about 10% to 15% of laughter in natural social contexts occurs in response to classically-structured jokes that would seem funny when repeated out of context (Provine, 2000). Rather, most laughter occurs in response to short utterances or nonverbal micro-performances during informal conversation. These might seem funny in the immediate social context, but would often seem fairly mundane or stupid if repeated later."


Samstag, 8. Juli 2017

"Thinking about Death and Pain Makes People Funnier"

"is it possible that the greatest comedians of all time are the ones that have the most painful thoughts [?]"

"Perhaps humor is rooted in tragedy, pain and struggle in ways we cannot imagine or fully understand yet."

Gil Greengross