Midpoints, endpoints and the cognitive structure of events

Events unfold over time, i.e. they have a beginning and endpoint. Previous studies have illustrated the importance of endpoints for event perception and memory. However, this work has only discussed events with a self-evident endpoint, and the internal temporal structure of events has not received much attention. In this study, we hypothesise that event cognition computes boundedness, an abstract feature of the internal temporal structure of events. We further hypothesise that sensitivity to boundedness affects how individual temporal slices of events (such as event midpoints or endpoints) are processed and integrated into a coherent event representation. The results of three experiments confirm these hypotheses. In Experiment 1, viewers identified the class of bounded (non-homogeneous, culminating) and unbounded (homogeneous, non-culminating) events in a categorisation task. In Experiments 2 and 3, viewers reacted differently to temporal disruptions in bounded versus unbounded events. We conclude that boundedness shapes how events are temporally processed.