Louis Costa

Hemisphere differences in the acquisition and use of descriptive systems

Abstract Differences in neuroanatomical organization of the cerebral hemispheres may account for two fundamental distinctions in processing: the right hemisphere has a greater ability to perform intermodal integration and to process novel stimuli; the left hemisphere is more capable of unimodal and motor processing as well as the storage of compact codes. In the process of acquisition of a new descriptive system, the right hemisphere plays a critical role in initial stages of acquisition, whereas the left hemisphere is superior at utilizing well-routinized codes. This leads to a right-to-left shift of hemisphere superiority as a function of increased competence with respect to a particular type of processing. This process is discussed in reference to various descriptive systems which are operative in normal cognition.

Clinical neuropsychology: Prospects and problems

Abstract The relationships between test performance, cognitive constructs, and underlying neurological status are examined. It is concluded that, while there are many tests that are sensitive to dysfunction in a given cortical area few are specific to such dysfunction. This is particularly true in the case of behavioral functions mediated by the frontal lobes. Modern clinical neuropsychology represents a fusion of experimental and correlational approaches in both research and practice. A serious time lag exists in the execution of seminal research and its application in clinical practice. The use of small collaborative data banks in reducing this time lag is discussed.

Clinical neuropsychology: a discipline in evolution.

The future of neuropsychology is considered first in terms of the potential impact of events occurring in clinical medicine, neuroscience research, basic behavioral science and applied psychology, and related disciplines. The focus is then turned inward on clinical neuropsychology itself and a series of suggestions are made concerning how this specialty can evolve to best meet the challenges it will face.

Ear asymmetries in dichotic listening tasks which increase in difficulty

Accuracy and laterality of ear preference in repeating 2, 3 and 4 word pairs (WP) of dichotic stimuli in English and French were determined in 80 right-handed subjects (anglophone/francophone, male/female), who were tested in both their native language (L1) and nonnative language (L2). Relative performance accuracy decreased as a function of word pairs per trial (from 2 to 4) as well as language (from L1 to L2). Right-lateral preference in turn increased as a function of WP (from 2 to 4) as well as language (L1 to L2). Right-ear advantage (REA) in L2 decreased as a function of language proficiency (low to high). REA was observed in over 90% of subjects. A rationale for greater lateralization of L2 performance is offered.