Experimental Studies of a Perceptual Anomaly

Abstract

This is the fourth of a series of articles reporting an investigation into the Block Design Rotation Effect. This effect was first observed in some patients while they were doing the Goldstein Block Design Test, in which the subject has to reproduce patterns with the aid of coloured cubes. Some patients, while completing the designs correctly, would leave the completed pattern in a rotated position without apparently being aware of this (2). Such rotation frequently reached 45° (Illustration 1) but rarely exceeded this amount.