The influence of contextual uncertainty on facial expression processing: Evidence from behavior and ERPs

The brain helps individuals build expectations based on emotional prediction, facilitating the processing of faces in social interactions. Due to the intricacy of the environment, accurately predicting emotions remains a formidable task. Contextual uncertainty represents a state characterized by the inability to predict when, how, and why events occur. It leads to intensified sentiments and triggers adverse emotions like anxiety. Therefore, comprehending the influences of contextual uncertainty carries importance. The present study utilized event-related potentials (ERPs) technology to investigate contextual uncertainty's influence on facial expression processing. We employed a novel S1-S2 paradigm, using scene images as S1 and faces as S2. From the learning phase into the testing phase, the certain to uncertain group (CER to UNC) experienced more unpredictability (increased uncertainty), whereas the uncertain to certain group (UNC to CER) experienced more predictability (decreased uncertainty). This allowed for manipulating dynamic alterations in predictive relationships. The behavioral results showed that the valence ratings of neutral facial expressions were more negative in the CER to UNC group with increased contextual uncertainty. The ERP results showed that the more negative SPN (stimulus preceding negativity) amplitudes and positive LPP (late positive potential) amplitudes were observed in the UNC to CER group with decreased contextual uncertainty, compared to the CER to UNC group with increased contextual uncertainty. These findings have indicated that contextual uncertainty affects facial expression processing. In summary, these results contributed to comprehending the contextual uncertainty.