The linkage between decision-making and bodily states: an investigation using an emotional startle reflex paradigm and the Iowa Gambling task

Theories such as the somatic marker hypothesis posit that emotions and feedback from bodily states support higher cognition and decision-making. This study investigated the connection between decision-making and activity of the startle reflex, a defense reflex that is sensitive to emotional states. Decision-making was assessed using the Iowa Gambling Task (IGT), which simulates real-life decision-making with respect to complexity and uncertainty. The startle reflex was quantified, via electromyography, as the eyeblink following intense noise stimulation during the viewing of pleasant, neutral, and unpleasant emotional pictures. Forty-two healthy participants were classified according to their performance on the IGT using the median-split method. Overall, the startle amplitude was lower during pleasant and higher during unpleasant pictures than during neutral pictures. Participants with high IGT performance exhibited smaller response amplitudes than those with low IGT performance, independent of picture valence. Furthermore, inverse linear associations were seen between IGT performance and response amplitudes. The association between decision-making and startle reflex activity may be mediated by individual differences in emotional state. According to previous studies, a positive emotional state, as opposed to a negative emotional state, relates to smaller startle amplitudes and a preference for decision-making strategies based on intuition and body-related information (i.e., somatic markers), which are beneficial in situations involving complex and uncertain decisions. Moreover, an impact of individual differences in prefrontal cortex function on decision-making and startle reflex activity is feasible. The startle paradigm may be a useful tool to investigate interactions between bodily states and higher-order cognitive processing in future research.