Impact of facial ambiguity on prosocial behaviour and moderation effects of state-empathy

Generally, sad faces are approached while angry faces are avoided to help. However, ambiguous expressions, that is, morphs between sad and angry expressions, may induce approach-avoidance (AA) conflict. In this study, using a binary Dictator game, participants allocate points either prosocial (equal distribution) or non-prosocial (more to self) towards various facial expressions between themselves and the recipient over multiple trials. Considering prosocial behaviour as an approach response, we hypothesize that higher facial ambiguity between sad and angry expressions will lead to stronger AA-conflict, influencing prosocial behaviour and decision times. Additionally, we investigate whether state empathy moderates the relationship between AA-conflict (induced by facial ambiguity) and prosocial behaviour. We further explain the underlying cognitive mechanisms behind prosocial decision making by applying Drift Diffusion Modeling.