Individual differences in bodily freezing predict emotional biases in decision making

Abstract

Instrumental decision making has long been argued to be vulnerable to emotional responses. Literature on multiple decision making systems suggests that this emotional biasing might reflect effects of a system that regulates innately specified, evolutionarily preprogrammed responses. To test this hypothesis directly, we investigated whether effects of emotional faces on instrumental action can be predicted by effects of emotional faces on bodily freezing, an innately specified response to aversive relative to appetitive cues. We tested 43 women using a novel emotional decision making task combined with posturography, which involves a force platform to detect small oscillations of the body to accurately quantify postural control in upright stance. On the platform, participants learned whole body approach-avoidance actions based on monetary feedback, while being primed by emotional faces (angry/happy). Our data evidence an emotional biasing of instrumental action. Thus, angry relative to happy faces slowed instrumental approach relative to avoidance responses. Critically, individual differences in this emotional biasing effect were predicted by individual differences in bodily freezing. This result suggests that emotional biasing of instrumental action involves interaction with a system that controls innately specified responses. Furthermore, our findings help bridge (animal and human) decision making and emotion research to advance our mechanistic understanding of decision making anomalies in daily encounters as well as in a wide range of psychopathology.

Keywords: approach-avoidance; decision making; emotion; freezing; learning.

Figure 1

Top panel: emotional decision making task. Trial events from the (A) approach block and (B) avoidance block. After face-prime offset (3000 ms), the instrumental target appeared, to which subjects were required to make a go- or nogo-response within 2500 ms. Response feedback (500 ms) was provided before the monetary outcome (1000 ms). In these examples a go-response had been recorded as indicated by the orange-colored squares during the response feedback phase. The duration of the intertrial interval was 3000 ms on average. Bottom panel: Balance board apparatus (left) and examples of a go-response (right) in (A) the approach block and (B) the avoidance block. Approach-go: sideway step on the balance board towards the side of the instrumental target (A). Avoidance-go: sideway step on the balance board away from the side of the instrumental target (B). Approach-/avoidance- nogo-responses involved remaining stationary at the center of the balance board.

Figure 2

Left: Center of pressure (COP) displacement of a representative leftward step. Right: Velocity profile of the step shown in the left panel. Arrow indicates the moment that was defined as the reaction time.

Figure 3

Left: Emotional bias effect on instrumental approach-avoidance. Slower approach (vs. avoidance) after angry (vs. happy) faces, showing an action-specific effect of emotional primes. Error bars represent standard error of the mean. Right: Correlation between bodily freezing and the emotional bias effect. Angry (vs. happy) induced freezing corresponds to sway (mm/s) during happy minus angry (x-axis). Emotional bias effect corresponds to angry (vs. happy) induced slowing of approach (vs. avoidance) (y-axis).