Browsing by Subject "Personality psychology"

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Individual differences and universal condition-dependent mechanisms
(2013-05) Lewis, David Michael; Buss, David M.
This study investigated the hypothesis that universal psychological adaptations produce personality variation when individuals differentially face adaptive problems that shifted the cost-benefit tradeoffs of alternative personality strategies in ancestral environments. The current research tested the hypothesis that psychological adaptations calibrate individual differences in neuroticism as a functional response to social exclusion. If psychological adaptations produce neuroticism in response to social exclusion, and heritable components of individuals' social partner value influence their likelihood of being excluded, then individual differences in social partner value should yield heritable differences in neuroticism. Three conceptually distinct sub-studies tested hypotheses derived from this conceptual framework. Sub-study 1 tested the relationship between individuals' mate value, social exclusion, and neuroticism. Individuals' mate value exhibited both a direct effect on neuroticism and an indirect effect through the experience of social exclusion. Sub-study 2 investigated sexual jealousy as a specialized class of neuroticism in response to infidelity. As predicted, individuals' mate value predicted the likelihood of their partners' infidelity and their own mate guarding behavior. Sub-study 3 manipulated the threat of infidelity to test for functional shifts in neuroticism in response to relationship exclusion. Participants read vignettes describing their mates' certain fidelity, uncertain fidelity, and certain infidelity, and wrote what they would think, feel, say, and do in response to each scenario. An independent sample assessed participants' personalities based on these cognitive, affective, and behavioral responses. As predicted, participants' neuroticism tracked relationship exclusion; participants' neuroticism levels increased with infidelity threat. These findings are consistent with the hypothesis that a universal psychological mechanism adaptively calibrates neuroticism levels in response to relationship exclusion; the certain absence or presence of the adaptive problem of relationship exclusion should deactivate or activate anti-exclusion mechanisms in all individuals. Above this situational effect, under conditions of uncertain infidelity -- in which the threat of infidelity would have ancestrally varied with men's (but not women's) mate value -- men's mate value predicted their neuroticism. Together, these findings support the hypothesis that humans possess psychological adaptations that functionally calibrate neuroticism levels. More broadly, they highlight the heuristic value of an evolutionary adaptationist framework for the study of personality and individual differences.
Scale development and construct validation of a chimpanzee rating scale
(2010-08) Freeman, Hani; Gosling, Sam; Josephs, Robert A.; Beevers, Christopher G.; Lewis, Rebecca J.; Nehete, Pramod
The last two decades have seen a surge in published research on primate personality. This surge contrasts with the paucity of research over the preceding century. People interested in primate personality research come from a broad range of fields, but they are all interested in measuring primate personality in a way that is reliable, valid, and practical. This dissertation aims to describe the development and evaluation of the construct validity of a new rating scale in chimpanzees. The scale is based on a bottom-up approach to scale development and was developed using steps from both Uher (2008a,b) and Gosling (1998). As described in Chapter 3, the scale was evaluated by using it to rate 143 chimpanzees at the University of Texas MD Anderson Cancer Center Facility in Bastrop, TX. Twenty-one people who have worked with the chimpanzees between 6 months to 20 years rated the chimpanzees. Chapter 4 describes how inter-class correlation coefficients (ICCs) were used to calculate the reliability of the items on the scale. There was only one item (predictable) that turned out to not be reliable. The other 40 items were included in subsequent analyses. An exploratory factor analysis, as described in Chapter 5, was performed in order to determine the structure underlying the scale. Five methods were used to determine that a six-factor solution fit the data best. The six factors were labeled Reactivity, Dominance, Openness, Extroversion Agreeableness, and Conscientiousness based on the degree to that they correlated with other previous chimpanzees scales that used those labels. The convergent and discriminant validity of the factors was evaluated, as described in Chapter 6, by looking at the predicted relationships between each of the six factors and the variables of sex, age, rearing history, behavior in reaction to a novel stimulus, general behavior, injuries, illnesses, blood chemistry, and cortisol. The results indicate that there is a lack of evidence for convergent validity, but some evidence for discriminant validity of the new chimpanzee rating scale. The discussion in Chapter 7 focuses on the findings from the study as well as strengths and limitations of the new chimpanzee rating scale.