| There is a robust and seemingly compulsory need for humans to understand events in terms of their causal structure. This allows us to make sense of the world, and to predict and plan future actions. However, how we represent causality remains unknown. In two experiments, the underlying mental representation of simple collisions events was examined using event-related potentials (ERP). Participants viewed Michottean launching events in which the spatial and temporal parameters were systematically varied. Using an ERP oddball paradigm, we measured how participants differentiated these events. A long history of behavioral studies (e.g. Michotte, 1963; White, 1995) demonstrated that collision events are highly sensitive to changes in their spatiotemporal parameters. Participants were familiarized with launching events that, based on their spatiotemporal parameters, would be behaviorally categorized as causal. Oddballs differed in their temporal parameters: both oddballs were equally different from the standard, but one event was expected to be categorized as causal, whereas the other was expected to be categorized as noncausal. There was a significant difference in P3 to events that crossed these conceptual category boundaries, but not to within category events. However, when familiarized with a noncausal event, there was no difference in participants' electrophysiological responses to other noncausal events. This effect was robust to changes in the temporal parameters that maintained the same categorical boundaries but increased the difference in length of delay between causal and noncausal events. Based on this evidence, it appears that adults categorized events by their underlying causal structure, rather than their surface features. |
