Implications of the Right Shift Theory of Handedness for Individual Differences in Hemisphere Specialisation
Two main approaches to problems of individual differences in hemisphere specialisation are to be found in the literature. The first is avoidance: subjects are restricted to fully right-handed males, with no known left-handed relatives. It is assumed that such subjects are likely to be homogeneous for the typical pattern of cerebral specialisation. The second approach is to compare subjects for personal hand preference, or for the presence of left-handed relatives, usually taking care to treat the sexes separately, in the expectation that these variables will be associated with differing patterns of cerebral specialisation. The right shift (RS) theory of handedness (Annett, 1972) suggests that the homogeneity of subjects in the first approach, and the discriminating power of variables in the second approach, are overestimated. Some of the challenges of the RS theory were evident from its initial formulation, and others have been discovered in subsequent explorations of it’s implications. A brief review of the development of the theory was given by Annett (1981) and a full review by Annett (1985). This paper summarises implications of the theory for individual differences, giving first an overview, and then a selective review of evidence for the main assumptions.
KeywordsLeft Handedness Lawson Peaked
Unable to display preview. Download preview PDF.
- Annett, M. (1978). “A Single Gene Explanation of Right and Left Handedness and Brainedness”. Lanchester Polytechnic, Coventry.Google Scholar
- Annett, M. (1985). “Left, Right, Hand and Brain: The Right Shift Theory”, Lawrence Erlbaum, London.Google Scholar
- Annett, M. and Kilshaw, D. (1984). Lateral preference and skill in dyslexics: Implications of the right shift theory. Journal of Child Psychology and Psychiatry, 25, 357–377.Google Scholar
- Carter-Saltzman, L. (1980). Biological and sociocultural effects on handedness: Comparison between biological and adoptive families. Science, 209, 1263–1265.Google Scholar
- Gloning, K. and Quatember, R. (1966). Statistical evidence of neuropsychological syndromes in left handed and ambidextrous patients. Cortex, 2, 484–488.Google Scholar
- Hecaen, H. and Ajuriaguerra, J. (1964). “Left handedness: Manual Superiority and Cerebral Dominance”. Grune and Stratton, New York.Google Scholar
- Netley, D. and Rovet, J. (1983). Relationships among brain organization, maturation rate and the development of verbal and nonverbal ability. In: “Language Functions and Brain Organization”. S.J. Segalowitz, ed., Academic Press, New York. 245–266.Google Scholar
- Sherman, J.A. (1978). “Sex-related Cognitive Differences: An Essay on Theory and Evidence”. Charles C. Thomas, Springfield, Illinois. Waber, D.P. (1976). Sex differences in cognition: A function of maturation rates. Science, 192, 572–574.Google Scholar