Abstract shape representation in human visual perception.

The ability to form shape representations from visual input is crucial to perception, thought, and action. Perceived shape is abstract, as evidenced when we can see a contour specified only by discrete dots, when a cloud appears to resemble a fish, or when we match shapes across transformations of scale and orientation. Surprisingly little is known about the formation of abstract shape representations in biological vision. We report experiments that demonstrate the existence of abstract shape representations in visual perception and identify the time course of their formation. In Experiment 1, we varied stimulus exposure time in a task that required abstract shape and found that it emerges about 100 ms after stimulus onset. The results also showed that abstract shape representations are invariant across certain transformations and that they can be recovered from spatially separated dots. Experiment 2 found that encoding of basic visual features, such as dot locations, occurs during the first 30 ms after stimulus onset, indicating that shape representations require processing time beyond that needed to extract spatial features. Experiment 3 used a convergent method to confirm the timing and importance of abstract shape representations. Given sufficient time, shape representations form automatically and obligatorily, affecting performance even in a task in which neither instructions nor accurate responding involved shape. These results provide evidence for the existence, emergence, and functional importance of abstract shape representations in visual perception. We contrast these results with "deep learning" systems and with proposals that deny the importance of abstract representations in human perception and cognition. (PsycINFO Database Record