Effects of predictors of hemispheric specialization on individual differences in hemispheric activation

In two studies predictors of variation in hemispheric specialization--handedness, sex, familial history of sinistrality, writing posture and sighting dominance--were found not to be independent of individual differences in characteristic activation asymmetry. Predominant direction of conjugate lateral eye movements was used to assess activation asymmetry. The lack of independence between these two dimensions of individual difference, predictors of variation in hemispheric specialization and in activation asymmetry, suggests caution in interpreting the results of studies in which one dimension is examined and the other is uncontrolled.