Browsing by Author "Van Honk, Jack"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Open Access
    Social and economic decision-making in Urbach-Wiethe Disease
    (2020) Fourie, Jorique; Van Honk, Jack; Stein, Dan J
    Background: Rodent and primate research have identified the basolateral amygdala as indispensable for social decision-making. This finding has not yet been translated to humans, and has even been partially contradicted by previous findings in patients with amygdala lesions that show generous economic investments in strangers. This thesis therefore aimed to determine whether selective basolateral amygdala damage in humans, caused by Urbach-Wiethe Disease, impairs instrumental non-social economic decision-making. Methods: Using an adapted reinforcement-learning task, the performance of basolateral amygdala damaged individuals (n=6) was compared with that of healthy controls (n=20) on social and economic decision-making during a probabilistic reinforcement task. The task required participants to make decisions for themselves and others based on learned probability of monetary reward or loss. A random effects Generalised Least Squares regression was conducted using Stata 15.1. to assess discrimination between Gain and Loss domains. A social-decision making task was also administered. Results: When making choices for themselves, Urbach-Wiethe Disease participants showed no difference in correct choices made between Gain and Loss domains. The Urbach-Wiethe disease participant's lack of discrimination between gains and losses for themselves was significantly different (p< 0.01) from that of controls, who made significantly more correct choices for themselves in the gain domain compared to the Loss domain. Social decision-making performance did not, however, differ significantly between Urbach-Wiethe Disease participants and controls. Conclusions: These findings regarding non-social decision-making support the important role of the basolateral amygdala as a salience detector, with lesions to this region resulting in reduced bias to the valence of potential economic outcomes, regardless of whether these pertain to costs or benefits. These findings are also consistent with prior work indicating that lesions to the basolateral amygdala can possibly produce loss-aversion due to a hypervigilance for fear and the lack of inhibition of the centromedial amygdala by the basolateral amygdala.
  • Thumbnail Image
    Item
    Open Access
    The effects of testosterone on embodiment: implications for social power
    (2018) Minné, Donné; Solms, Mark; Van Honk, Jack
    Following recent trends in the neurosciences in which the body is seen as a constituting factor in mental experience and behavior, this thesis examined the role of testosterone in mapping the state of the body. The general aim was thus to contribute to the literature on the embodied basis of power by asking whether a change in the neurochemistry associated with social power has any effect on embodiment? Accordingly, in a series of randomized, double-blind, placebocontrolled studies, this thesis assessed for the first time the effects of a 0.5mg dosage of testosterone on three important dimensions of embodiment in samples of women: 1) The perception of internal physiological signals (interoception), 2) Body ownership, and 3) The experience of sensory-motor agency. Psychological tests measuring emotion and personality were integrated into the design. Using a heartbeat tracking task, testosterone was shown to increase interoceptive accuracy at baseline, but this advantage was lost following ostracism in an online ball tossing game. In experiment two, it was found that testosterone compared to placebo prevented a decline in limb temperature during the Rubber Hand Illusion, a commonly used paradigm for manipulating experiences of body ownership and for measuring homeostatic changes related to disembodiment. In experiment three, testosterone was found to increase the implicit sense of agency as measured in terms of intentional binding, a task which exploits the tendency to perceive a contraction in time when one’s own actions are felt to be casually related to external effects. Results indicate that testosterone has the capacity to improve interoceptive accuracy, is able to help regulate homeostasis in response to erroneous top-down beliefs about the body, and to increase the feeling of sensorimotor control. While the limitations of this data are acknowledged, these main findings suggest that testosterone is able to modulate the experience and representation of the body and offer insight into some of the rudimentary embodied mechanisms via which the hormone might support the rise to power.
  • Thumbnail Image
    Item
    Open Access
    Trait dominance promotes reflexive staring at masked angry body postures
    (Public Library of Science, 2014) Hortensius, Ruud; Van Honk, Jack; De Gelder, Beatrice; Terburg, David
    It has been shown that dominant individuals sustain eye-contact when non-consciously confronted with angry faces, suggesting reflexive mechanisms underlying dominance behaviors. However, dominance and submission can be conveyed and provoked by means of not only facial but also bodily features. So far few studies have investigated the interplay of body postures with personality traits and behavior, despite the biological relevance and ecological validity of these postures. Here we investigate whether non-conscious exposure to bodily expressions of anger evokes reflex-like dominance behavior. In an interactive eye-tracking experiment thirty-two participants completed three social dominance tasks with angry, happy and neutral facial, bodily and face and body compound expressions that were masked from consciousness. We confirmed our predictions of slower gaze-aversion from both non-conscious bodily and compound expressions of anger compared to happiness in high dominant individuals. Results from a follow-up experiment suggest that the dominance behavior triggered by exposure to bodily anger occurs with basic detection of the category, but not recognition of the emotional content. Together these results suggest that dominant staring behavior is reflexively driven by non-conscious perception of the emotional content and triggered by not only facial but also bodily expression of anger.