Friday, October 12, 2018

Mice: Performance in behavioral tasks did not correlate strongly with number of neurons; whereas neuronal number is a good predictor of cognitive skills across species, it is not a predictor of cognitive across individuals within a species

Lack of correlation between number of neurons and behavioral performance in Swiss mice. Kleber Neves, Gerson D. Guercio, Yuri Anjos-Travassos, Stella Costa, Ananda Perozzo, Karine Montezuma, Suzana Herculano-Houzel, Rogerio Panizzutti
bioRxiv 428607; doi:

Abstract: Neuronal number varies by several orders of magnitude across species, and has been proposed to predict cognitive capability across species. Remarkably, numbers of neurons vary across individual mice by a factor of 2 or more. We directly addressed the question of whether there is a relationship between performance in behavioral tests and the number of neurons in functionally relevant structures in the mouse brain. Naive Swiss mice went through a battery of behavioral tasks designed to measure cognitive, motor and olfactory skills. We estimated the number of neurons in different brain regions (cerebral cortex, hippocampus, olfactory bulb, cerebellum and remaining areas) and crossed the two datasets to test the a priori hypothesis of correlation between cognitive abilities and numbers of neurons. As previous evidence indicates that environmental enrichment may increase neurogenesis and improve neuronal survival, we added a control group that did not undergo cognitive testing to rule out the possibility that our test battery could alter the neuronal number. We found that behavioral testing did not change numbers of neurons in the cerebral cortex and in the hippocampus. Surprisingly, performance in the behavioral tasks did not correlate strongly with number of neurons in any of the brain regions studied. Our results show that whereas neuronal number is a good predictor of cognitive skills across species, it is not a predictor of cognitive, sensory or motor ability across individuals within a species, which suggests that other factors are more relevant for explaining cognitive differences between individuals of the same species.

Industrial Revolution: Some psychological traits –lower level of time discounting, higher level of optimism, decreased materialistic orientation, & higher level of trust in others– are likely to increase the rate of innovation

Psychological Origins of the Industrial Revolution. Nicolas Baumard. Behavioral and Brain Sciences (forthcoming),

Since the Industrial Revolution, human societies have experienced high and sustained rates of economic growth. Recent explanations of this sudden and massive change in economic history have held that modern growth results from an acceleration of innovation. But it is unclear why the rate of innovation drastically accelerated in England in the 18th century. An important factor might be the alteration of individual preferences with regard to innovation due to the unprecedented living standards of the English during that period, for two reasons. First, recent developments in economic history challenge the standard Malthusian view according to which living standards were stagnant until the Industrial Revolution. Pre-industrial England enjoyed a level of affluence that was unprecedented in history. Second, Life History Theory, a branch of evolutionary biology, has demonstrated that the human brain is designed to respond adaptively to variations in resources in the local environment. In particular, a more favorable environment (high resources, low mortality) triggers the expression of future-oriented preferences. In this paper, I argue that some of these psychological traits –a lower level of time discounting, a higher level of optimism, decreased materialistic orientation, and a higher level of trust in others– are likely to increase the rate of innovation. I review the evidence regarding the impact of affluence on preferences in contemporary as well as past populations, and conclude that the impact of affluence on neuro-cognitive systems may partly explain the modern acceleration of technological innovations and the associated economic growth.

Rolf Degen summarizing: If competition is framed as competition with oneself, rather than with other people, women are more competitive than men

Gender differences in interpersonal and intrapersonal competitive behavior. Jeffrey Carpenter, Rachel Frank, Emiliano Huet-Vaughn. Journal of Behavioral and Experimental Economics,

•    We ask if gender affects an individual’s willingness to compete against oneself
•    Our lab experiment randomly sorts subjects to compete against others or themselves
•    Women select intrapersonal competition more than interpersonal competition
•    Women select intrapersonal competition comparatively more than men
•    Perseverance or ”grit” does not predict competitive behavior
•    Men are more risk-seeking and this has some effect on the inclination to compete

Abstract: Gender differences in competitive behavior continue to be documented by econo-mists and other social scientists; however, the bulk of the research addresses competition with others and excludes other economically relevant contests. In this paper, we ask: how does gender affect how individuals react to competing against themselves? In a laboratory experiment in which some subjects compete against others and some compete against themselves, we find women select into intrapersonal competition at significantly higher rates than interpersonal competition and comparatively more than men. In addition, we find that while perseverance or “grit” does not explain the gender difference in behavior, risk attitudes have some explanatory power.

Schadenfreude is higher in real-life situations compared to psychologists' experiments in the lab

Schadenfreude is higher in real-life situations compared to hypothetical scenarios. Maria Luz Gonzalez-Gadea, Agustin Ibanez, Mariano Sigman. PLOS, October 11, 2018,

Abstract: Schadenfreude (i.e., the pleasure derived from another’s misfortune) has been widely studied by having participants imagine how they would feel in hypothetical scenarios describing another person’s pain or misfortune. However, research on affective forecasting shows that self-judgments of emotions are inaccurate in hypothetical situations. Here we show a study in which we first presented a hypothetical schadenfreude situation and few months later, due to an exceptional circumstance, the situation turned out to happen in reality. This fortuitous circumstance allowed us to compare people’s imagined emotional reactions with their actual feelings. Results showed that schadenfreude was higher in the real situation than in the hypothetical one. More importantly, participants used different proxies to predict their emotional reaction: while out-group dislike served as a proxy of schadenfreude in both types of scenario, the degree of in-group identification also increased schadenfreude in those who had experienced the real event, arguably a mechanism to promote positive self-evaluation. These results highlight the importance of assessing schadenfreude in the heat of the moment.