Perceptual Grouping and High-Order Cognitive Ability

High-order cognitive functions require the integration of information across functionally related modules. This relationship suggests that cognitive ability is related to the efficiency and processing speed of basic integrative function. In order to examine individual differences for this relationship, we compared standardized tests of intelligence to visual perceptual grouping abilities, which represents a basic process of integration. Sixty participants discriminated perceived grouping of dot patterns based upon similarity in luminance. Psychophysical measurements were made of the functional limits and processing speed of grouping. We assessed cognitive abilities with the Wechsler Abbreviated Scale of Intelligence (WASI) and found that measures of grouping efficiency as well as speed varied considerably across subjects, indicating substantial individual differences at this relatively early level of visual processing. Faster grouping speed was associated with higher scores on all WASI subtests, whereas grouping ability, when not restricted by time, was associated only with the performance IQ components. These results demonstrate an association between a basic integrative function, in which cognitive and motoric factors were minimized, with measures of high-order cognition, which include both verbal and spatial cognitive components.