Functional and postural lateral preferences in humans: interrelations and life-span age differences.

This study aimed to provide data on lateral preferences among older subjects, to analyze age differences, and to determine interrelations between lateral preferences. Four functional preferences (handedness, footedness, eyedness, earedness) and three postural lateral preferences (hand-clasping, arm-folding, leg-crossing) were assessed in 628 Germans (252 men, 376 women) aged between 19 and 90 years. Sex differences, age differences, and associations between lateralities were analyzed applying chi-square tests. Logistic regression analyses considering age, sex, and interactions between variables were applied to analyze combined effects on laterality measures. Right-sided preference for handedness, footedness, eyedness, earedness, and leg-crossing characterized 86.8%, 77.1%, 70.9%, 67.8%, and 56.6%, respectively, of subjects, while a left-sided preference for hand-clasping and arm-folding characterized 56.4% and 60.2%, respectively, of all participants. Results are within the range of other populations. Only footedness differed between the sexes: there were more left-footed men. Older cohorts showed a rightward shift in handedness, eyedness, earedness, and leg-crossing, the opposite for arm-folding. No age-related differences exist in footedness or hand-clasping. Logistic regression models indicate no interaction between age and sex for each laterality measure. The four functional lateralities are significantly interrelated. All also are positively associated with leg-crossing. Conversely, the postural lateralities generally are not correlated, although leg-crossing and arm-folding are, inversely. The observed relationships among lateralities support the hypothesis that handedness, footedness, leg-crossing, and earedness might be aspects of a larger phenotype that is independent of hand-clasping and arm-folding.