Understanding and anticipating the behavior and associated mental/emotional states of mind of others is crucial for successful social interactions. Typically developed (TD) humans rely on the processing and integration of social cues that accompany other’s actions to make, either implicitly or explicitly, inferences about others’ mental states. Interestingly, the attribution of affective or mental states to the agent can in turn (top down) induce distortions in the visual perception of those actions (Hudson, Liu, & Jellema, 2009; Hudson & Jellema, 2011; Jellema, Pecchinenda, Palumbo, & Tan, 2011). The aim of this thesis was to investigate bottom-up and top-down influences on distortions in the perception of dynamic facial expressions and to explore the role those biases may play in action/emotion understanding.