Configural biases and reversible figures: evidence of multilevel grouping effects

Four experiments sought to identify the processes underlying 2 classes of grouping effects that are readily produced with a hierarchical figure type known as ambiguous triangles. Previous work has shown that aligning small equilateral triangles in particular configurations can both facilitate and interfere with observers' ability to report the pointing direction of the individual triangles. We determined that selectively adapting the observer to low-frequency gratings of the same orientation as the aligned triangles markedly altered the interfering and facilitative effects of the global configuration only when an accuracy measure of performance was used. When a response latency measure was used, no effect of the same adaptation condition was found. Results are discussed in terms of multiple levels of grouping effects in the visual system and the differential sensitivity of these levels to basic neural adaptation.