The Weight of Emotions in Decision-Making: How Fearful and Happy Facial Stimuli Modulate Action Readiness of Goal-Directed Actions

Abstract

Modern theories of behavioral control converge with the idea that goal-directed/voluntary behaviors are intimately tied to the evaluation of resources. Of key relevance in the decision-making processes that underlie action selection are those stimuli that bear emotional content. However, even though it is acknowledged that emotional information affects behavioral control, the exact way in which emotions impact on action planning is largely unknown. To clarify this issue, I gave an emotional version of a go/no-go task to healthy participants, in which they had to perform the same arm reaching movement when pictures of fearful or happy faces were presented, and to withhold it when pictures of faces with neutral expressions were presented. This task allows for the investigation of the effects of emotional stimuli when they are task-relevant without conflating movement planning with target detection and task switching. It was found that both the reaction times (RTs) and the percentages of errors increased when the go-signal was the image of a fearful looking face, as opposed to when the go-signal was a happy looking face. Importantly, to control for the role of the features of the stimuli, I ran a control task in which the same pictures were shown; however, participants had to move/withhold the commanded movement according to gender, disregarding the emotional valence. In this context, the differences between RTs and error percentages between the fearful and happy faces disappeared. On the one hand, these results suggest that fearful facial stimuli are likely to capture and hold attention more strongly than faces that express happiness, which could serve to increase vigilance for detecting a potential threat in an observer's environment. On the other hand, they also suggest that the influence of fearful facial stimuli is not automatic, but it depends on the task requirements.

Keywords: decision making; emotion; go/no-go task; motor control; reaching arm movements.

FIGURE 1

(A) Emotion-discrimination-task. The trial started with the presentation of a red circle at the center of the touchscreen. Subjects had to touch and hold it for a variable delay. Then a peripheral target appeared, followed by a picture depicting one of three expressions. Participants were instructed to reach and hold the peripheral target when the face expressed an emotion (fear or happiness) and to refrain from moving if the face had a neutral expression. All experimental conditions were randomized; (B) Gender-discrimination-task. The course of the events was the same described for the previous task; however, in this instance, participants were required to move when they saw a woman and not to move when they saw a man or vice versa. The order of administration of the two tasks was counterbalanced across subjects.

FIGURE 2

(A) Effect of emotional facial expression on reaction times (RTs). Mean RTs to fearful and happy emotional faces in the emotion-discrimination-task (on the left) and in gender-discrimination-task (on the right). Results were split according to the gender of the participants. Overall females were faster than males and, more importantly, participants were slower when the go-signal was a fearful face than when it was a happy face just during the emotion-discrimination-task (see text for the statistics). In each box plot, the boundary of the box closest to zero indicates the first quartile, a red line within the box marks the median, and the boundary of the box farthest from zero indicates the third quartile. Whiskers indicate values 1.5 times the interquartile range below the first quartile and above the third quartile. (B) Effect of emotional facial expression on the percentage of errors. Mean percentage of errors to fearful and happy faces in the emotion-discrimination-task (on the left) and in gender-discrimination-task (on the right). Participants made a larger amount of mistakes in the emotion-discrimination-task than in the gender-discrimination-task. No differences were found between males and females (see text for the statistics).