Across-object relationships in perceived object orientation

An orientation discrimination paradigm was used to determine whether the perceived orientation of extended objects is based on the distribution of edge-orientations or on the response of mechanisms that encode relationships across the object; specifically we considered large, second-stage filters and cores (the perceived middle of the object) as encoders of the across-object relationship. The stimuli were ''rectangles'' with sinusoidally modulated long edges. Manipulating the frequency and relative phase of the edge modulation allowed us to assess the importance of the across-object relationships. Evidence was found for the importance of such relationships in determining perceived orientation. No evidence was found for direct use of the distribution of responding edge detectors. Published by Elsevier Science Ltd.