Contextual effects of surprised expressions on the encoding and recognition of emotional target faces: An event-related potential (ERP) study.

Several studies reported that the encoding and recognition of emotional target faces are modulated by negative contextual expressions. However, it is unknown whether other contextual expressions, such as emotionally ambiguous expressions, affect the encoding and recognition of target faces. To this end, electroencephalography (EEG) was recorded during the presentation of angry or happy target faces after a random sequence of surprised or neutral contextual faces that did not differ in normative valence ratings. Subsequently, participants were asked to perform an unexpected old/new recognition task in which target faces were shown in either the encoded or a non-encoded expression. During the encoding phase, event-related potential (ERP) results showed that surprised as compared to neutral contextual faces led to smaller late positive potentials (LPP) for happy but not for angry target faces. Similar effects were also observed in the N170, even though the interaction of context and target expression failed to reach statistical significance. In the later recognition phase, recognition rates were lower for encoded happy faces when they had been encountered in surprised as compared to neutral context, regardless of whether the target face showed the encoded or a non-encoded expression. However, this context effect was not observed for angry-encoded faces. Taken together, the present study indicates that ambiguous contextual expressions, e.g., surprised faces, affect structural and cognitive encoding and later recognition of happy target faces to a larger extent than neutral contextual faces; whereas angry faces are more resistant to context effects.