Abstract
One of the most remarkable features of human perception is its ability to represent causation. Here we demonstrate that causal perception is sensitive to certain physical regularities in collision events that result from Newtonian mechanics. Consider two balls, A and B, with A moving towards B at 1 m/s and B at rest. When A is with B, A stops moving and B begins moving in the same direction. According to Newtonian mechanics of collisions, B cannot move faster than 2 m/s in this example, no matter the difference in masses between A and B. It is well established that if B moves at any speed less than 2 m/s, people will perceive this collision as a causal "launching" event (Michotte 1946/1963). When participants observe collision events that violate this principle, e.g. if B moves at 3 m/s, they still perceive a causal relationship, but report that the event seems unnatural. Building on these reports, the current project asks whether causal perception is sensitive to these regularities in Newtonian mechanics. We employ a novel visual search task in which participants are required to locate a single collision event with an unequal speed ratio between A and B (1:3 or 3:1) in the presence of two 1:1 launching events. We find that people are robustly faster at detecting collision events that violate these regularities (1:3 speed ratio) than collision events with the inverse speed ratio (3:1), which are seen as launching. However, there is no such difference in minimally different events that do not involve the perception of causality (e.g., events with a temporal or spatial gap) (Fig. 1). These results suggest that causal perception is sensitive to principles of Newtonian mechanics.
Meeting abstract presented at VSS 2014