Choice of Handedness Measures in Studies of Hemispheric Specialization

Abstract

Left-and right-handers have been reported to differ in lateral hemispheric specialization for cognition. We compared different methods of dividing subjects into handedness groups : preference (a 12-item questionnaire), performance (speed, strength, dexterity), and preference plus performance, and determined which method of handedness classification indicated the greatest group differences on EEG and dichotic measures of lateral specialization. All handedness measures were significantly intercorrelated. These handedness measures were significantly correlated with the dichotic test over the whole population but were significantly correlated with EEG asymmetry only in females. Scoring degree of handedness showed significant relationships to lateral specialization which were not seen when subjects were classified into discrete handedness groups. Ambidextrous subjects performed as well as right-or left-handers on unimanual tasks despite a lack of hand preference. The hand used for writing was shown to be too limited to be used as the sole index of handedness in studies related to cognition.Int J Neurosci Downloaded from informahealthcare.com by University of Newcastle on 12/27/14For personal use only.

Handedness and speech: A critical reappraisal of the role of genetic and environmental factors in the cerebral lateralization of function.

“…This task specificity for proficiency differences between hands has also been reported by other investigators (e.g., Barnsley & Rabinovitch, 1970; Buxton, 1937; Johnstone, Galin, & Herron, 1979; Rigal, 1992) and is not only compatible with the nonhuman lateral preference data reported earlier, but it is also in keeping with more general evidence on the specificity of human motor skills as demonstrated in laboratory tests of manual ability (see, e.g., Fleishman & Ellison, 1962; Fleishman & Hempel, 1954) and activities relating to sport and athletics (see, e.g., Fleishman, 1964; Hempel & Fleishman, 1955). Buxton and Humphreys (1935) have also provided evidence to show that intercorrelations between task performances decrease with practice, suggesting that an increasing proficiency on each task leads to an increasing specificity of the action patterns underlying each skill (for a more comprehensive consideration of the evidence on motor learning and the specificity of skill, see Provins, in press).…”

Development of Motor Co‐ordination by Normal Left‐handed Children

“…greater equality between left and right, among left-handers when they are compared with right-handers on non-motor tasks or on a visually guided motor task such as the Purdue Pegboard (Broman and Gardner 1979). Left-handed children between the ages of five and 10, like lefthanded adults (Johnstone et al 1979), perform better with their preferred hand. In this study this was true on three out of four tasks.…”

Hand skill and hand preference in blind and sighted children

“…The Crawford dexterity task used in three studies (Benton, 1962;Johnstone, Galin, & Herron, 1979;Satz, Achenbach, & Fennel, 1967) found a fairly high relationship between preference and skill. Even hand strength as measured by a dynometer (Woo & Pearson, 1927) favoured the right hand in most males and showed little misclassification between preference and skill.…”