The importance of eye movements in the analysis of simple patterns.

How important are eye movements to visual pattern analysis? Previous findings indicate that at least one visual task (counting) is seriously impaired without them. We asked whether a comparable limitation applies to pattern recognition. Subjects were presented with pairs of randomly generated arrays composed of black and white pixels. The subjects indicated whether the arrays were identical or differed by one pixel. In one experiment, they were instructed to use normal eye movements, in another they were required to fixate on a point between the arrays. When eye movements were permitted, subjects' performance showed evidence for a search in which the discrepant pixel was eventually found, given adequate inspection time. When fixation was required, search was less efficient and the discrepant pixel was sometimes not found, despite prolonged inspection time. These results were independent of target size over a wide range. Our findings indicate that eye movements play a crucial role in pattern analysis that is not related to resolution.