Identifying and explaining apparent universal sex differences in cognition and behavior

Identifying and explaining apparent universal sex differences in cognition and behavior
Lee Ellis; October 2011
Personality and Individual Differences


Abstract

With growing recognition that there are universal sex differences in cognition and behavior, four theories have been proposed to account for these differences: the founder effect theory, the social structuralist theory, the evolutionary theory, and the evolutionary neuroandrogenic (ENA) theory. The latter of these theories is described in considerable detail as offering an explanation for most of 65 recently identifiedapparent universal sex differences (AUSDs) in cognition and behavior. Regarding “ultimate causes” (why), ENA theory asserts that (a) evolutionary-genetic factors incline females to bias their mate choices toward males who are loyal and competent provisioners of resources and (b) males are merely a genetic variant on the female sex selected for responding to female mating biases. In terms of “proximate causes” (how), the theory maintains that high exposure to androgens has evolved to alter the male brain functioning in two specific ways relative to most female brains: (a) suboptimal arousal and (b) a rightward shift in neocortical functioning. These two functional patterns are described and hypothesized to incline males and females to learn differently in many respects. The most fundamental differences involve males learning ways of either complying with or circumventing female mate preferences. Numerous universal sex differences in cognition and behavior are hypothesized to result from these evolved neurohormonal factors, including most of the 65 AUSDs herein summarized in seven categorical tables.

Neurobehavioral Evidence for Changes in Dopamine System Activity During Adolescence

Neurobehavioral Evidence for Changes in Dopamine System Activity During Adolescence
Dustin Wahlstrom et al., 2010
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2845533/


Abstract

Human adolescence has been characterized by increases in risk-taking, emotional lability, and deficient patterns of behavioral regulation. These behaviors have often been attributed to changes in brain structure that occur during this developmental period, notably alterations in gray and white matter that impact synaptic architecture in frontal, limbic, and striatal regions. In this review, we provide a rationale for considering that these behaviors may be due to changes in dopamine system activity, particularly overactivity, during adolescence relative to either childhood or adulthood. This rationale relies on animal data due to limitations in assessing neurochemical activity more directly in juveniles. Accordingly, we also present a strategy that incorporates molecular genetic techniques to infer the status of the underlying tone of the dopamine system across developmental groups. Implications for the understanding of adolescent behavioral development are discussed.

Social power and approach-related neural activity

Social power and approach-related neural activity
Maarten A S Boksem et al.; 2008


Abstract

It has been argued that power activates a general tendency to approach whereas powerlessness activates a tendency to inhibit. The assumption is that elevated power involves reward-rich environments, freedom and, as a consequence, triggers an approach-related motivational orientation and attention to rewards. In contrast, reduced power is associated with increased threat, punishment and social constraint and thereby activates inhibition-related motivation. Moreover, approach motivation has been found to be associated with increased relative left-sided frontal brain activity, while withdrawal motivation has been associated with increased right sided activations. We measured EEG activity while subjects engaged in a task priming either high or low social power. Results show that high social power is indeed associated with greater left-frontal brain activity compared to low social power, providing the first neural evidence for the theory that high power is associated with approach-related motivation. We propose a framework accounting for differences in both approach motivation and goal-directed behaviour associated with different levels of power.

Non-verbal behavior as courtship signals: the role of control and choice in selecting partners

Non-verbal behavior as courtship signals: the role of control and choice in selecting partners

Karl Grammer et al., 2000

http://evolution.anthro.univie.ac.at/institutes/urbanethology/resources/articles/articles/publications/grammerfink.pdf

Abstract

In this work, we provide evidence based on direct observation of behavior in encounters of opposite-sexed strangers, that women initiate and "control" the outcome. In the first minute of these videotaped 10-min interactions, neither female "solicitation" behavior nor "negative" behavior is strongly related to professed interest in the man, while female "affirmative" behavior at this stage modulates male verbal output in later stages (4 ± 10 min). Although the rate of female courtship-like behavior is significantly higher in the first minute, it is only in the fourth to tenth minute that the rate of female courtship-like behavior is correlated with professed female interest. We hypothesize that this serves as a strategic dynamic reflecting sexual asymmetry in parental investment and the potential cost of male deception to women. Ambiguous protean behavioral strategies veil individuals' intentions and make their future actions unpredictable. These behavioral strategies may result in men's overestimation of female sexual interest.

Attention-deficit/hyperactivity disorder: is it time to reappraise the role of sugar consumption?

Attention-deficit/hyperactivity disorder: is it time to reappraise the role of sugar consumption?
Johnson R J et al., 2011


Abstract

Attention-deficit/hyperactivity disorder (ADHD) affects nearly 10% of children in the United States, and the prevalence of this disorder has increased steadily over the past decades. The cause of ADHD is unknown, although recent studies suggest that it may be associated with a disruption in dopamine signaling whereby dopamine D2 receptors are reduced in reward-related brain regions. This same pattern of reduced dopamine-mediated signaling is observed in various reward-deficiency syndromes associated with food or drug addiction, as well as in obesity. While genetic mechanisms are likely contributory to cases of ADHD, the marked frequency of the disorder suggests that other factors are involved in the etiology. In this article, we revisit the hypothesis that excessive sugar intake may have an underlying role in ADHD. We review preclinical and clinical data suggesting overlaps among ADHD, sugar and drug addiction, and obesity. Further, we present the hypothesis that the chronic effects of excessive sugar intake may lead to alterations in mesolimbic dopamine signaling, which could contribute to the symptoms associated with ADHD. We recommend further studies to investigate the possible relationship between chronic sugar intake and ADHD.