Emotional bias varies with stimulus type, arousal and task setting: Meta-analytic evidences.

Emotional bias, which describes human's asymmetric processing of emotional stimuli, consists of negativity bias (Increased response to negative over positive stimuli) and positivity offset (the reversed phenomenon). Previous studies suggest that stimulus arousal (high/low), stimulus type (scenic/verbal), cultural background (Eastern/Western), and task setting (explicit/implicit) may modulate emotional bias, but with inconclusive findings. To address how the profile of emotional bias varies with these factors, a meta-analysis of emotional P3 event-related potential amplitudes was performed. Forty-nine effect sizes from 38 studies involving 1263 subjects were calculated using Hedges'g. The results highlight significant moderators of arousal, stimulus type, and task setting. Specifically, high-arousal stimuli enhance negativity bias relative to low-arousal stimuli; scenic stimulus leads to a negativity bias while verbal stimulus is linked with a positivity offset; explicit emotion tasks lead to negativity bias, whereas implicit emotion tasks do not exhibit emotional bias. These results indicate that emotional bias is labile depending on stimulus arousal, stimulus type and task setting. The implication of these findings for emotion regulation is discussed.