The assessment and analysis of handedness: The Edinburgh inventory

The need for a simply applied quantitative assessment of handedness is discussed and some previous forms reviewed. An inventory of 20 items with a set of instructions and response- and computational-conventions is proposed and the results obtained from a young adult population numbering some 1100 individuals are reported. The separate items are examined from the point of view of sex, cultural and socio-economic factors which might appertain to them and also of their inter-relationship to each other and to the measure com- puted from them all. Criteria derived from these considerations are then applied to eliminate 10 of the original 20 items and the results recomputed to provide frequency-distribution and cumulative frequency functions and a revised item-analysis. The difference of incidence of handedness between the sexes is discussed.

The assessment and analysis of handedness

An association analysis was made of the responses of young adults to a hand-preference questionnaire. Many patterns of preference were distinguished and there were no marked differences between adjacent classes. These findings are believed to demonstrate that hand preference is distributed continuously and not discretely. When it is necessary to classify handedness, the preference continuum can be divided at several levels of discrimination. A second study of hand preference and manual speed showed that it is possible to order the main preference groups for asymmetry of manual skill. Some of the problems of studies of laterality are examined as possible consequences of the treatment of a continuous distribution as if it were discrete.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.2044-8295.1970.tb01248.x

A classification of hand preference by association analysis.

Part two of this three-part series commences with anomalous dominance and special talents. Part one appears in a previous issue of theArchives. 1 ANOMALOUS DOMINANCE AND SPECIAL TALENTS According to our hypothesis, slowed growth within certain zones of the left hemisphere is likely to result in enlargement of other cortical regions, in particular, the homologous contralateral area, but also adjacent unfaffected regions. The influences that favor anomalous dominance may thus favor talents associated with superior development of certain regions either in the right hemisphere or in adjacent parts of the left hemisphere. Even with excessive retardation of growth and the resultant migration abnormalities and learning disorders (LD), high talents may exist as a result of compensatory enlargement of other cortical regions. Several types of data are in concordance with these conclusions. Several studies have claimed that the average level of spatial talents is higher in male subiects. 2 Hier

https://jamanetwork.com/journals/jamaneurology/articlepdf/584161/archneur_42_5_008.pdf

Cerebral lateralization. Biological mechanisms, associations, and pathology: II. A hypothesis and a program for research.

This article presents a tentative theoretical framework for the study of asymmetry in the context of human bimanual action. It is emphasized that in man most skilled manual activities involve two hands playing different roles, a fact that has been often overlooked in the experimental study of human manual lateralization. As an alternative to the current concepts of manual preference and manual superiority-whose relevance is limited to the particular case of unimanual actions-the more general concept of lateral preference is proposed to denote preference for one of the two possible ways of assigning two roles to two hands. A simple model describing man's favored intermanual division of labor in the model are the following. 1) The two hands represent two motors, that is, decomplexity is ignored in the suggested approach. 2) In man, the two manual motors cooperate with one another as if they were assembled in series, thereby forming a kinematic chain: In a right-hander allowed to follow his or her lateral preferences, motion produced by the right hand tends to articulate with motion produced by the left. It is suggested that the kinematic chain model may help in understanding the adaptive advantage of human manual specialization.

Asymmetric division of labor in human skilled bimanual action: the kinematic chain as a model.

An inquiry by means of a questionnaire which included a ‘handedness inventory’ was made into the prevalence of left-handedness among musicians, and the difficulties, if any, which lefthanders experienced in acquiring executant skills. It was found that left-handedness is neither less nor more common in the group of musicians studied than in a population of psychology undergraduates, and that left-handedness did not in general occasion any special difficulty. The left-handers adapted successfully to the ‘right-handedness’ of their instruments, the only substantial connexion in which left-handed practices were retained being in conducting. It is suggested on the basis of these findings that ‘right-handedness’ is less a matter of superior inherent ‘dexterity’ or the capacity for agility, precision and speed in the right hand than of closer, more immediate, availability of the right hand as the instrument of the individual's conceptions and intentions. It is further suggested that the especial function of the dominant cerebral hemisphere is to mediate between the executive intentions of the individual and his physical means of expressing them, whether through manual or vocal channels.

R. C. Oldfield

Papers

Handedness in musicians