Reduction and elimination of the Poggendorff misalignment effect by minor changes at intersections: implications for the perceptual-compromise explanation.

Abstract

Recent experiments (Day & Kasperczyk, 1985 a) showed that the Morinaga misalignment effect is greatly reduced or eliminated by slight changes to the aligned features, which do not alter the essential form of the configuration. The purpose of the three experiments described here was to find out whether similar slight changes to the aligned oblique of the Poggendorff figure have the same effect. It was shown that a short (5 mm) right-angle line at the intersection end of the oblique reduced its apparent misalignment with a dot by about half (Experiment 1). A circular spot or gap centred on the intersection had the same effect (Experiment 2). The component of the gap primarily involved proved to be that between oblique and parallel, not gaps in the parallel itself (Experiment 3). These outcomes, which are paradoxical when considered with those from earlier experiments, are discussed from the standpoint of the recently proposed perceptual-compromise explanation of apparent misalignment, and a resolution of the paradox is suggested.