Effects of Discriminability and Choice-Figure Rotation on Visual Perception of Form

Abstract

The effects on form perception of two conditions of rotation (provided by rotated and nonrotated choice figures) were measured at different levels of discrimination difficulty. The stimuli were 6-by-6 constrained or “Redundancy-I” metric histoforms. Five levels of discriminability were provided by use of different degrees of similarity between target and choice figures. In each of the 5 difficulty conditions, 24 Ss responded in a paper-and-pencil figure-cancellation task in both conditions of choice-figure rotation, or, 120 Ss in all. Separate analyses of errors and response times indicated that perceptual performance with nonrotated choice figures was better than with rotated and that performance decreased as discrimination difficulty increased. In terms of the number of correct identifications per minute, performance was proportional to discrimination difficulty and the detrimental effect of choice-figure rotation was constant over the levels of difficulty employed.