Voluntary modulation of mental effort affects the attentional shift induced by angry faces in women

Facial expressions are biologically and socially relevant stimuli processed in an automatic way. The degree of attentional capture by emotional stimuli varies depending on contextual factors. We used fMRI to investigate whether voluntary modulation of invested effort in a target detection task can offset the automatic attentional shift induced by task-irrelevant angry and happy faces in a female-only sample. Participants had to respond to a target stimulus appearing perceptually closer either to the observer, or to the face stimulus. Crucially, they performed the task "with maximum exertion" (EXR) or "as relaxed as possible" (RLX). We found faster reaction times in the EXR condition, and a significant interaction effect between valence and target position in the RLX condition, suggesting that the engagement of maximum exertion was able to counteract the spatial attentional shifts induced by angry faces. fMRI data showed that brain regions involved in attentional, face, and salience processing were functionally modulated by the interaction of valence and target position. Notably, the fusiform face area was influenced not only by valence and target position, but also by mental effort, suggesting that the deployment of voluntary effort may modulate the activity induced by aversive facial expressions in this region.