Reactivity and Behavioral Inhibition as Personality Traits in Nonhuman Primates

Abstract

While the history of the study of personality dates back to the early 1900s, most animal research, particularly on nonhuman primates, is much more recent. That personality in animals reflects our common evolutionary history is not surprising, and given our close genetic relatedness, should be expected. The personality trait that has received the most research in nonhuman primates is what we have called elsewhere, reactivity (others have referred to it as fearfulness, timidity, shyness, etc.). While several methods have been used to study it (including personality rating scales), generally, reactivity in nonhuman primates is most often measured using behavior codings. Two paradigms have received the most research: social separations and the human intruder paradigm. Individual differences in reactivity are stable across time and situations. Reactivity can also predict multiple behavioral outcomes, including enduring anxiety, low social dominance rank and submissiveness, high alcohol intake, and other forms of affective psychopathology. One major advantage of using nonhuman primates to model personality is that the underlying physiology and central nervous system foundations can be more readily studied than in humans. These studies show the importance of the amygdala and frontal cortex, as well as the HPA Axis, central norepinephrine, and serotonin in regulating reactivity. Studies also show the importance of early parental influence and genes on reactivity. Recent studies using molecular genetics show that the serotonin transporter and corticotrophin releasing hormone genes probably play important roles in its etiology but interact with early rearing history and situations to modulate reactivity. (PsycINFO Database Record (c) 2015 APA, all rights reserved). (chapter)