Learning disabilities, distinctive encoding, and hemispheric resources

The purpose of this study was to isolate possible sources of learning ability differences in distinctive encoding of item-specific and relational information. Two mechanisms postulated as underlying ability group differences were attentional capacity (as inferred from the magnitude and direction of correlations between primary and secondary recall) and resource monitoring strategies (as reflected in measures of selective attention and laterality). In Experiment 1, learning disabled and nondisabled childrens' word recall was compared on dichotic listening recall tasks that included nonorienting instructions, and orienting instructions that directed children's attention toward semantic, phonemic, or structural word features. Disabled children showed lower recall and more diffuse selective attention to word features than nondisabled children. Reciprocity (negative correlations) between targeted and background words within and between ability groups was comparable, except when targeted word features were phonemically organized. Experiment 2 indicated that disabled childrens' cued recall was inferior to that of nondisabled children, even though both ability groups produced comparable symmetrical recall patterns related to ear presentations. Taken together, the results suggest that the locus of disabled childrens' distinctive encoding deficiencies is related to resource monitoring strategies during interhemispheric processing.