Effects of a concurrent memory task on hemispheric asymmetries in categorization

Recent research on the division of processing between the two cerebral hemispheres has often employed two concurrent tasks to investigate the dynamic nature of hemispheric asymmetries. The experiment reported here explored the effects of two concurrent high-level cognitive tasks (memory retention and semantic categorization) on the direction and magnitude of hemispheric differences in the processing of words and pictures. Subjects were required to categorize words and pictures presented to either the left visual field-right hemisphere (LVF-RH) or the right visual field-left hemisphere (RVF-LH). The categorization could be performed while holding either verbal material in memory (digit span), pictorial material in memory (serial nonsense figure recognition), or with no concurrent memory task. The effects produced hemisphere-specific, material-nonspecific interference. The verbal task removed a RVF-LH advantage at word categorization and enhanced a LVF-RH advantage on picture categorization; the pictorial task interfered with picture categorization in the LVF-RH, while enhancing a RVF-LH advantage at word categorization. The results are discussed in terms of multiple resource models of hemisphere function, capacity limitations, and the functional locus of processing required to produce various dynamic hemispheric effects.     

Current issues in theory construction: A commentary on Waters and Sroufe

The view of competence proposed by Waters and Sroufe remains faithful to a kind of theorizing about human personality which emphasizes its unitary and universal properties. Developments in other areas of inquiry, however, are redirecting theoretical efforts toward a more pluralistic and contextualistic view of human nature and development. Implications for future theories of development are discussed.     

Identifying the relevant aspects of a problem text

Forty-nine subjects judged the relevancy of sentence parts of a word problem (the Allsports problem). Patterns of subjects' judgments suggest three problem-solving heuristics: a SETS heuristic, a TIME heuristic, and a QUESTION heuristic. Presentation of the question before the problem tends to suppress SETS and TIME heuristics. A computer program (ATTEND) is presented to simulate subjects' behavior on the Allsports problem. The program is context-sensitive in that it can change a relevance judgment upon the acquisition of further information. Averaged subject judgments and ATTEND judgments agree for 87% of the items.     

Stages-of-learning analysis of developmental interactions in memory,with illustrations from developmental interactions in picture-word effects

Although Age × Treatment interactions have been widely viewed as key results in theories of memory development, most examples of such results (e.g., Age × Treatment interactions in the effects of item concreteness, item elaboration, and organizational context) have been identified in list-learning experiments where children of different ages receive a small, fixed number of study-test cycles on the target list. A stages-of-learning analysis reveals that such designs confound a treatment's potential interactions with age and its potential interactions with stage of learning. The analysis also reveals specific situations in which such designs will produce converging, diverging, and crossover Age × Treatment interactions even though the treatment does not interact with age in any way. A series of experiments is reported in which a mathematical model that incorporates stages-of-learning distinctions is applied to the well-known interaction between age and item concreteness (pictures versus words) in cued recall. Although a diverging Age × Treatment interaction has been observed in previous research, it was found that there are at least four different interactions between the picture-word manipulation and age; (a) a diverging interaction at storage that operates throughout elementary school; (b) a diverging interaction localized within retrieval learning and operating during the first half of the elementary school; (c) a converging interaction localized within retrieval learning and operating during the second half of elementary school; and (d) a diverging interaction localized within retrieval performance and operating throughout elementary school.     

Dementia in Parkinson disease: A neuropsychological analysis

An extensive set of neuropsychological measures was administered to 60 Parkinson's disease patients and age-, sex-, and education-matched controls in order to investigate the nature and prevalence of the cognitive deficit in the disease. Parkinsonian patients performed significantly poorer on all measures with the exception of tests for apraxia and object recognition, and on a test of vocabulary knowledge. Discriminant analysis of the test data revealed that over 93% of patients are impaired relative to matched controls, but that assigning a prevalence rate for dementia in the disease may be difficult due to the continuous distribution of cognitive deficits.