How does verb aspect constrain event representations?

We investigated the relative contribution of perfective and imperfective aspectual cues on situation models. In Experiment 1, participants were more likely to choose pictures showing completed events than pictures showing ongoing events when they had read perfective sentences, but chose either picture after reading imperfective sentences. In Experiment 2, only one picture was presented and participants were faster to respond to completed pictures than to ongoing pictures when they had read perfective sentences, but showed no latency differences after reading the imperfective sentences. In Experiment 3, participants were faster to read perfective sentences after having seen completed pictures rather than intermediate pictures, but there was no difference for imperfective sentences. The consistent pattern of results demonstrates that readers construct mental representations of completed events when the perfective aspect is used to describe an event. The lack of effect on imperfective sentences and pictures suggests that each reader represents an in-progress event at varying stages of completion.