Emotional facial expressions affect inhibitory control only when they are task-relevant

The ability to integrate emotional information with ongoing cognitive processes is critical to generate appropriate behaviors, especially in social contexts. In particular, facial emotional expressions are highly relevant for social interactions, as they could trigger either defensive or approaching responses. These reactions are modulated by inhibitory control, which plays the crucial role of preventing the execution of impulsive and inappropriate responses. Although there is a consensus around the fact that emotional information affects motor behavior, the study of the impact of facial emotional expressions on inhibition leads to contrasting findings. In our view, a crucial confounding factor that can explain such inconsistencies is the task-relevance of the emotional content of the stimuli. To clarify this issue, we compared the effect on inhibitory control of the same set of facial expressions in two different experimental versions of a Go/No-go task. Forty subjects were recruited for the study. In one version of the task (Emotional Go/No-go task), they had to execute a reaching movement whenever a neutral face was shown and refrain from moving in the presence of an emotional facial expression (fear or happiness). In the other version of the task (Gender Go/No-go task), participants were instructed to withhold their movements when pictures of a given gender were presented, thus, irrespectively of the faces' emotional expression. In Emotional Go/No-go task, data show that the capability of refraining from actions is significantly more impaired after the presentation of happy faces than after the presentation of fearful faces. Conversely, in the Gender Go/No-go task this effect disappears. In this study, for the first time, we tested the impact of task-relevance of the same stimuli on the inhibitory control of the same type of movements net of other confounding factors (e.g., differences in arousal, conflating motor responses with emotional valence of the stimuli). We found a clear-cut result: inhibitory control is affected only when emotional expressions are task-relevant. Therefore, facial emotions do not influence behavioral responses automatically. Instead, they would do so only when they are intrinsically relevant for ongoing goals