Dienstag, 29. Juli 2014

Intelligence moderates neural responses to monetary reward and punishment

Intelligence moderates neural responses to monetary reward and punishment
D.R. Hawes , C.G. DeYoung, J.R. Gray, A. Rustichini (2014)


Abstract

The relation between intelligence (IQ) and neural responses to monetary gains and losses were investigated in a simple decision task. In 94 healthy adults, typical responses of striatal BOLD signal after monetary reward and punishment were weaker for subjects with higher IQ. IQ-moderated differential responses to gains and losses were also found for regions in the medial prefrontal cortex, posterior cingulate cortex, and left inferior frontal cortex. These regions have previously been identified with the subjective utility of monetary outcomes. Analysis of subjects’ behavior revealed a correlation between IQ and the extent to which choices were related to experienced decision outcomes in preceding trials. Specifically, higher IQ predicted behavior to be more strongly correlated with an extended period of previously experienced decision outcomes, whereas lower IQ predicted behavior to be correlated exclusively to the most recent decision outcomes. We link these behavioral and imaging findings to a theoretical model capable of describing a role for intelligence during the evaluation of rewards generated by unknown probabilistic processes. Our results demonstrate neural differences in how people of different intelligence respond to experienced monetary rewards and punishments. Our theoretical discussion offers a functional description for how these individual differences may be linked to choice behavior. Together, our results and model support the hypothesis that observed correlations between intelligence and preferences may be rooted in the way decision outcomes are experienced ex post, rather than deriving exclusively from how choices are evaluated ex-ante.

Relationship between Smiling and Laughter in Humans (Homo sapiens): Testing the Power Asymmetry Hypothesis

Relationship between Smiling and Laughter in Humans (Homo sapiens): Testing the Power Asymmetry Hypothesis
Marc Mehu & Robin I.M. Dunbar (2008)


Abstract

The power asymmetry hypothesis claims that individuals should have distinct signals of appeasement/affiliation and play when status difference is high, whereas these signals should overlap in egalitarian interactions. Naturalistic observations were conducted on humans interacting in groups that differed in terms of age composition (and presumably social status). Three affiliative behaviours were recorded by focal sampling: spontaneous smiles, deliberate smiles and laughter. Interestingly, young men showed significantly higher proportions of deliberate smiles in comparison to laughter when interacting with people of a different age class than when interacting in same-age groups. The pattern of affiliative behaviours in women remained unaffected by the age composition of groups. This partly supports the power asymmetry hypothesis and suggests that in men, deliberate smiles could play a role in the regulation of hierarchical relationships.

A Winning Smile? Smile Intensity, Physical Dominance, and Fighter Performance

A Winning Smile? Smile Intensity, Physical Dominance, and Fighter Performance
Michael W. Kraus & Teh-Way David Chen (Jan 2013)


Abstract

The smile is perhaps the most widely studied facial expression of emotion, and in this article we examine its status as a sign of physical dominance. We reason, on the basis of prior research, that prior to a physical confrontation, smiles are a nonverbal sign of reduced hostility and aggression, and thereby unintentionally communicate reduced physical dominance. Two studies provide evidence in support of this prediction: Study 1 found that professional fighters who smiled more in a prefight photograph taken facing their opponent performed more poorly during the fight in relation to their less intensely smiling counterparts. In Study 2, untrained observers judged a fighter as less hostile and aggressive, and thereby less physically dominant when the fighters’ facial expression was manipulated to show a smiling expression in relation to the same fighter displaying a neutral expression. Discussion focused on the reasons why smiles are associated with decreased physical dominance.

Rushton - Suzuki Debate (February 1989)

https://www.youtube.com/watch?v=i9FGHtfnYWY&feature=youtu.be&t=8m19s

Montag, 28. Juli 2014

Cultural differences in indecisiveness: The role of naïve dialecticism

Cultural differences in indecisiveness: The role of naïve dialecticism
Andy H. Ng and Michaela Hynie (November 2014)
Personality and Individual Differences



Highlights

o East Asian Canadians (EAC) are more indecisive than European Canadians (EC).

o East Asian Canadians (EAC) are more indecisive than South Asian Canadians (SAC).

o EAC (vs. EC and SAC) exhibit lower need for cognition (NFC).

o EAC (vs. EC and SAC) exhibit higher naïve dialecticism (ND).

o NFC and ND mediate the relationship between culture and indecisiveness.



Abstract

East Asians exhibit naïve dialecticism, a set of worldviews that tolerates contradictions. As influenced by naïve dialecticism, East Asians are more likely to hold and less likely to change ambivalent attitudes, compared with European North Americans. If East Asians have a heightened tendency to see both positive and negative aspects of an object or issue, but a lesser inclination to resolve these inconsistencies, East Asians (vs. European North Americans) may experience more difficulty in committing to an action, and thus be more indecisive. Consistent with this hypothesis, we found that East Asian Canadians scored higher on a measure of chronic indecisiveness than did European Canadians and South Asian Canadians, and that naïve dialecticism and need for cognition mediated the relationship between culture and indecisiveness. These results add to the extant literature on indecisiveness, demonstrating cultural variations in indecisiveness and an underlying cultural factor that is responsible for these cultural differences.

Human Conversational Behavior

Human Conversational Behavior
R.I.M. Dunbar, A. Marriott, N.D.C. Duncan (1997)


Abstract

Observational studies of human conversations in relaxed social settings suggest that these consist predominantly of exchanges of social information (mostly concerning personal relationships and experiences). Most of these exchanges involve information about the speaker or third parties, and very few involve critical comments or the soliciting or giving of advice. Although a policing function may still be important (e.g., for controlling social cheats), it seems that this does not often involve overt criticism of other individuals' behavior. The few significant differences between the sexes in the proportion of conversation time devoted to particular topics are interpreted as reflecting females' concerns with networking and males' concerns with self-display in what amount to a conventional mating lek.

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>Comparisons within and between the three samples suggest that a number of important sex differences exist. One is a tendency for males to devote more conversation time to intellectual or work-related topics. A second is for this pattern to become exaggerated when females are present. A third is for male conversations to change more dramatically with age than those of females, ...<

Sonntag, 27. Juli 2014

The social role of touch in humans and primates: Behavioural function and neurobiological mechanisms

The social role of touch in humans and primates: Behavioural function and neurobiological mechanisms
R.I.M. Dunbar (2010)


Abstract

Grooming is a widespread activity throughout the animal kingdom, but in primates (including humans) social grooming, or allo-grooming (the grooming of others), plays a particularly important role in social bonding which, in turn, has a major impact on an individual’s lifetime reproductive fitness. New evidence from comparative brain analyses suggests that primates have social relationships of a qualitatively different kind to those found in other animal species, and I suggest that, in primates, social grooming has acquired a new function of supporting these. I review the evidence for a neuropeptide basis for social bonding, and draw attention to the fact that the neuroendrocrine pathways involved are quite unresolved. Despite recent claims for the central importance of oxytocin, there is equally good, but invariably ignored, evidence for a role for endorphins. I suggest that these two neuropeptide families may play different roles in the processes of social bonding in primates and non-primates, and that more experimental work will be needed to tease them apart.