(Un)intentionality bias in action observation revisited

When observing individuals in action, we often infer their goals and intentions. Yet, in situations where actions are ambiguous and could be either intentionally generated or not, there is a tendency to perceive these actions as internally driven. This intentionality bias is influenced by individual differences in schizotypal cognitive style. In this study, we examined how healthy individuals distinguish between intentional and unintentional actions when perceiving actions of a finger attached to a pulling device. Participants reported to use different strategies to infer intentionality (e.g., action onset, perceived movement speed, hand and finger posture) and tended to attribute more intentionality to actions where the posture of the finger aligned with the final goal of the action (i.e., a bent finger pushing a button was perceived more intentional than a straight finger doing the same action). Moreover, the perceived action intentionality varied depending on the individual schizotypal cognitive style. The tendency to perceive the action as intentional when it was done with a bent finger rather than a straight finger decreased as the participants' schizotypal scores increased. These findings suggest that intentionality attribution is not based on processes that automatically infer intentions as the primary cause of human actions. Rather than being an intentional bias, we believe that attributing and denying intentions requires the coherent integration of high- and low-level cognitive processes modulated by individual differences.