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Right hemisphere contributions to lexical semantics
Neuropsychologw Vol. 27, No. 10. p. 1311. 1989 Pergamon Press ptc Printed in Great Bntain.
BOOK REVIEW Right Hemisphere Contributions to Lexical Semantics. Edited by C. ISBN: 3-540-19247-6 and O-387-19247-6 (U.S.)
CHIARELLO.
Springer,
Berlin, 1988. X + 100~~.
THE SPEAKERS
at the symposium on “Defining the Right Hemisphere’s Contribution to Lexical Semantics”, held in Veldhoven during the ninth I.N.S. European Meeting in 1986, agreed to provide a revised version of their communications in writing. Two additional papers were also solicited. As a result, the book, edited hy Christine Chiarello, presents seven chapters from established scientists. The object is not to review the literature. but to offer specific and personal insights into the semantic processes involving right hemisphere activity. The problem can be approached with different experimental procedures for different populations. Joanette and Goulet focus on category naming by right hemisphere damaged subjects. They summarize three of their studies and show a specificity of a naming impairment that cannot be interpreted as a genera1 deficit, such as a lack of initiative. Brownell also analyzes performances of right hemisphere damaged subjects in a sentence-to-picture matching task and in similarity judgements. Possible disturbances in appreciation of the metaphoric and connotative meaning of words are discussed. The next two chapters take another perspective by describing reading behaviour of left hemisphere damaged aphasic subjects. In this context, Landis and Regard examine the hypothesis that in the processing of linguistic materials by normal subjects, lateral differences result from an inhibition of the actual right hemisphere competence by the intact left hemisphere. Weniger er al., also deal with interhemispheric interactions in the identification of written words. In cases ofsevere aphasia, no lateral difference after unilateral tachistoscopic stimulation is observed, so a right hemisphere contribution to single-word processing is assumed. After bilateral stimulation, however, these right hemisphere resources are mobilized and a left hemisphere advantage emerges. The fifth and sixth chapters present divided visual field experiments with normal subjects performing lexical or semantic decision tasks. Chiarello convincingly argues for similar priming effects after stimulation in the right and left visual field when facilitation results from automatic spreading of activation. Inhibition due to controlled semantic selectivity, however, would only occur after right visual field stimulation. Eran Zaidel et al., oppose two interpretations of observed performances after left visual field stimulation: an effect of callosal transfer to the left hemisphere or direct access to right hemisphere processing resources. Some support is found for each hypothesis, depending on task demands and stimulus characteristics. Finally, in his concluding remarks, Milberg discusses the preceeding papers and distinguishes between the representation of knowledge and control processes: the cerebral hemispheres might differ in the way they store information and/or in their access to these representations. These studies clearly belong to a second generation of research. Well beyond the first attempts to replace a rough verbal/nonverbal dichotomy as the basis of cerebra1 asymmetry and to demonstrate some right hemisphere linguistic capacities, the effort is devoted to a better specification of the processes underlying overt behaviour. Yet, more problems than solutions are encountered. Obviously, we are still far from a detailed account of the operations by which the brain codes lexical meaning. Several questions remain unanswered. Is there a unique contribution of the right hemisphere to lexical semantics or only conjugated operations with the left hemisphere? How do words capture semantic features extracted from the visual world? Might the semantic system fractionate in relation to input modality or knowledge domains? Nevertheless, this book shows that a refined understanding of lexical semantic processes may be gained by analyzing lateral differences with the kind of subtle methods cognitive neuropsychology proposes. PIERRE FEYEREISEN
1311
BOOK REVIEW Right Hemisphere Contributions to Lexical Semantics. Edited by C. ISBN: 3-540-19247-6 and O-387-19247-6 (U.S.)
CHIARELLO.
Springer,
Berlin, 1988. X + 100~~.
THE SPEAKERS
at the symposium on “Defining the Right Hemisphere’s Contribution to Lexical Semantics”, held in Veldhoven during the ninth I.N.S. European Meeting in 1986, agreed to provide a revised version of their communications in writing. Two additional papers were also solicited. As a result, the book, edited hy Christine Chiarello, presents seven chapters from established scientists. The object is not to review the literature. but to offer specific and personal insights into the semantic processes involving right hemisphere activity. The problem can be approached with different experimental procedures for different populations. Joanette and Goulet focus on category naming by right hemisphere damaged subjects. They summarize three of their studies and show a specificity of a naming impairment that cannot be interpreted as a genera1 deficit, such as a lack of initiative. Brownell also analyzes performances of right hemisphere damaged subjects in a sentence-to-picture matching task and in similarity judgements. Possible disturbances in appreciation of the metaphoric and connotative meaning of words are discussed. The next two chapters take another perspective by describing reading behaviour of left hemisphere damaged aphasic subjects. In this context, Landis and Regard examine the hypothesis that in the processing of linguistic materials by normal subjects, lateral differences result from an inhibition of the actual right hemisphere competence by the intact left hemisphere. Weniger er al., also deal with interhemispheric interactions in the identification of written words. In cases ofsevere aphasia, no lateral difference after unilateral tachistoscopic stimulation is observed, so a right hemisphere contribution to single-word processing is assumed. After bilateral stimulation, however, these right hemisphere resources are mobilized and a left hemisphere advantage emerges. The fifth and sixth chapters present divided visual field experiments with normal subjects performing lexical or semantic decision tasks. Chiarello convincingly argues for similar priming effects after stimulation in the right and left visual field when facilitation results from automatic spreading of activation. Inhibition due to controlled semantic selectivity, however, would only occur after right visual field stimulation. Eran Zaidel et al., oppose two interpretations of observed performances after left visual field stimulation: an effect of callosal transfer to the left hemisphere or direct access to right hemisphere processing resources. Some support is found for each hypothesis, depending on task demands and stimulus characteristics. Finally, in his concluding remarks, Milberg discusses the preceeding papers and distinguishes between the representation of knowledge and control processes: the cerebral hemispheres might differ in the way they store information and/or in their access to these representations. These studies clearly belong to a second generation of research. Well beyond the first attempts to replace a rough verbal/nonverbal dichotomy as the basis of cerebra1 asymmetry and to demonstrate some right hemisphere linguistic capacities, the effort is devoted to a better specification of the processes underlying overt behaviour. Yet, more problems than solutions are encountered. Obviously, we are still far from a detailed account of the operations by which the brain codes lexical meaning. Several questions remain unanswered. Is there a unique contribution of the right hemisphere to lexical semantics or only conjugated operations with the left hemisphere? How do words capture semantic features extracted from the visual world? Might the semantic system fractionate in relation to input modality or knowledge domains? Nevertheless, this book shows that a refined understanding of lexical semantic processes may be gained by analyzing lateral differences with the kind of subtle methods cognitive neuropsychology proposes. PIERRE FEYEREISEN
1311