Only irrelevant sad but not happy faces are inhibited under high perceptual load.

Perceptual load plays a critical role in identification and awareness of stimuli. Given the differences in emotion-attention interactions, we investigated the perception of distractor emotional faces in two different load conditions under divided attention with a task based on the inattentional blindness paradigm. Participants performed a low- or high-load task with a string of letters presented against a happy, sad or neutral face (in a circular form) as the background. Participants were asked to identify the face that appeared in the critical trial. Results indicate an interaction between emotion and load. First, identification of faces with happy expression was better than chance and unaffected by load. Second, performance was worse than chance for faces with sad expression in the high-load condition, indicating inhibition of unattended sad distractor faces in the critical trial. This indicates that inhibitory processes during a difficult attentional task under divided attention influence subsequent perception of distractor stimuli especially sad faces. The results have implications for the theories of selective attention as well as the role of emotions in conscious perception.