Abstract
It as been argued that an adaptation paradigm can be used to establish links between neural activity and perception. The purpose of the present study was to determine if three adaptation patterns influence the shape perception of distorted squares. The adaptation stimuli were circular and contained radial (circular), angular, or plaid (2 sine waves) spatial frequencies. The target stimuli were squares with contours varying in amplitude. The adaptation stimulus was presented for 5 seconds followed by the target for 500ms. Thresholds were obtained with a forced choice paradigm where the subject had to indicate whether the stimulus was curved inward or outward. Results show that the adaptation patterns influenced the responses in different ways. Radial adaptation patterns caused a significant threshold increase while the other adaptation patterns had no influence. This suggests that mechanisms involved in processing circular patterns share common neural pathways with those that process distorted squares.