Laterality of hand, foot, eye, and ear was measured in a sample of 1964 subjects, ranging in age from 8 to 100 years. Age trends were found, with hand, foot, and eye preference becoming more right-sided and ear preference becoming more left-sided with increasing age. Sex differences emerged in foot, eye, and ear preference but these did not systematically interact with the age variable. Several causal mechanisms are proposed but none can fully explain either the direction or the magnitude of the observed age changes. Thus, these data are most consistent with the view that the study of sidedness in humans should proceed with a consideration of a complex of underlying factors and individual difference variables.

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Most humans display lateral asymmetries in the use of the paired limbs and sensory organs. Four types of lateral preference (handedness, footedness, eyedness, and earedness) were measured in a sample of 962 individuals, ranging in age from 10 to 75 years. Factor analytic techniques were used to assess whether these aspects of laterality are manifestations of a common process or whether they should be viewed as a multidimensional complex. Three independent factors, representing limb, eye and ear preference were obtained. This dimensional structure remained invariant across the separate sex and age subgroups within the sample. These results suggest that human laterality is a multidimensional process, and that laterality of limbs and sense organs may result from different mechanisms.

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