In search of closure: Subjective contour illusions, gestalt completion tests, and implications

This study investigates the construct validity of perceptual closure tests (CTs), and isolates a common processing demand from the right-hemisphere. Sixty-seven patients with focal unilateral lesions (34 right side, 33 left side), and 80 control subjects participated. Multivariate analyses indicated that (1) there was substantial age-related variance in all CTs, while sex was variably significant; (2) CTs are not uniform in their discriminating ability, and hence factorially complex; and (3) their specifically right hemisphere-sensitive dimension was subjective contour illusions, and interestingly unrelated to facial discrimination ability. The methodological and theoretical implications are discussed.