An electrophysiological study of scene effects on object identification

The meaning of a visual scene influences the identification of visual objects embedded in it. We investigated the nature and time course of scene effects on object identification by recording event-related brain potentials (ERPs) and response times (RTs). In three experiments, participants identified objects within a scene that were either semantically congruous (e.g., a pot in a kitchen) or incongruous (e.g., a desk in a river). As expected, RTs were faster for congruous than incongruous objects. The earliest sign of reliable scene congruity effects in the ERPs (greater positivity for congruous pictures between 300 and 500 ms) was around 300 ms. Both the morphology and time course of the N390 scene congruity effect are reminiscent of the N400 sentence congruity effect typically observed in sentence context paradigms, suggesting a functional similarity of the neural processes involved. Overall, these results support theories postulating that visual scenes do not appreciably affect object identification processes before associated semantic information is activated. We speculate that the N390 scene congruity effect reflects the action of visual scene schemata stored in the anterior temporal lobe.