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Brent Strickland, Brian J. Scholl; Representations of “Event Types” in Visual Cognition: The Case of Containment vs. Occlusion. Journal of Vision 2010;10(7):183. doi: 10.1167/10.7.183.
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© ARVO (1962-2015); The Authors (2016-present)
The visual system segments dynamic visual input into discrete event representations, but these are typically considered to be token representations, wherein particular events are picked out by universal segmentation routines. In contrast, recent infant cognition research by Renee Baillargeon and others suggests that our core knowledge of the world involves “event type” representations: during perception, the mind automatically categorizes dynamic events into types such as occlusion, containment, support, etc. This categorization then automatically guides attention to different properties of events based on their category. For example, an object's width is particularly relevant to containment events (wherein one object is lowered inside another), because that variable specifies whether the event is possible (i.e. whether it will ‘fit’). However, this is not true for the variable of height. This framework has been supported by looking-time experiments from Baillargeon's group: when viewing containment events, infants encode objects' widths at a younger age than they encode their heights – but no such difference in age is observed for similar occlusion events. Here we tested the possibility that this type of ‘core knowledge’ can also be observed in mid-level object-based visual cognition in adults. Participants viewed dynamic 2D displays that each included several repeating events wherein rectangles either moved into or behind containers. Occasionally, the moving rectangles would change either their height or width while out of sight, and observers pressed a key when they detected such changes. Change detection performance mirrored the developmental results: detection was significantly better for width changes than for height changes in containment events, but no such difference was found for occlusion events. This was true even though many observers did not report noticing the subtle difference between occlusion and containment. These results suggest that event-type representations are a part of the underlying currency of adult visual cognition.
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