SEPARABLE INTEGRAL CLASSIFICATION BY HYPERACTIVE AND NORMAL-CHILDREN

This research tested the hypothesis that information-processing defici ts associated with hyperactivity implicate a self-regulatory dysfuncti on. Hyperactive and control children were compared on nonspeeded class ification tasks. In Studies 1 and 2, children classified sets of eithe r three (triads) or four (tetrads) stimuli. The stimuli varied simulta neously on size and brightness or on length and density. They could be classified analytically (separably) on the basis of identical values for one dimension and holistically (integrally) on the basis of overal l similarity. Control children made an equal number of dimensional cla ssifications for triads and for tetrads. As predicted, however, hypera ctive children made fewer dimensional classifications for tetrads, sug gesting that they apparently resorted to less effortful holistic respo nding under the increased processing load. In an unexpected finding in Study 1, older hyperactive children appeared to behave like younger c ontrols, making more dimensional classifications when size, rather tha n brightness, was the shared dimension. Study 3 explored the possibili ty that hyperactive children lagged behind the controls in their respo nding to the shared dimensions. Three age groups of normal children (m ean ages: 5, 8, and 11 years) and adults were asked to classify stimul i that varied on size and brightness. Consistent with the lag hypothes is, normal preschoolers behaved like the young hyperactive children in Study 1, classifying equally on the basis of size and brightness. The discussion focuses on the contribution of processing load and stimulu s salience to the cognitive deficits of hyperactive children.