The impact of stimulus format and presentation order on social working memory updating.

Emotional faces and words have been extensively employed to examine cognitive emotional processing including social working memory, which plays a pivotal role in social interactions. However, it remains unclear which exact role these two stimulus formats play in updating specific emotional content, such as positive or negative information. Therefore, the current study examined the differences in working memory updating (WMU) of negative, neutral, and positive faces (Experiment 1) and words (Experiment 2), using a classic two-back paradigm with an event-related potential technique. In both experiments, emotional stimuli were presented in the same or different-valence order to further determine whether presentation order can also influence the WMU of specific emotional content. Our results showed that both stimulus format and presentation order play a role: (a) while faces showed an affective bias [larger P2 and late positive potential (LPP) for negative and positive faces than for neutral faces], words showed a negativity bias (larger LPP for negative words than both neutral and positive words); (b) While faces showed better performance with same-valence order, words showed better performance with different-valence order. Taken together, our findings indicate that, even if faces and words can contain the same emotional information, they impact social WMU differently.