The impact of emotional stimuli in biasing attentional selection during visual search in natural scenes

Previous literature demonstrated that emotionally-arousing stimuli tend to capture automatically attentional resources. However, the impact of task-irrelevant emotionally-arousing stimuli in “grabbing” attention is still largely unexplored. The aim of the present study is to investigate at both behavioral and neural (fMRI) level the impact of emotional stimuli in biasing attention selection under different conditions of task-relevancy. We used a visual search task involving complex natural scenes (implying a high-level of competition among objects), in which positive and negative emotional items were in a task-relevant vs. irrelevant position (i.e., they were or they were not the current target to be searched for). When emotional items were task-irrelevant, subjects were asked to search for a neutral object in the scene. At a behavioural level we found faster detection of task-relevant emotional objects as compared to neutral objects (i.e., in the presence of task-irrelevant emotional distracters). fMRI analysis revealed that scenes including negative objects, irrespectively to their task-relevance, produced activation of insula, a well-known area involved with emotional processing. By contrast, task-irrelevant emotional distracters, irrespective of the valence, produced activation along the dorsal fronto-parietal (dFP) attention network. This indicates an effort in disengaging attention from emotional task-irrelevant objects and re-orienting attention to the rest of the scene. Overall, these findings suggest that emotional elements in complex scenes, irrespective of valence, capture attention and affect attentional selection by diverting processing resource from other – neutral – elements in the scene. Top-down attention control (i.e., highlighted by the activation of dFP network) needs to be engaged to overcome emotional distraction.