Side-bias in alcohol and heroin addicts.

Alcoholics, heroin addicts and normal controls were asked for their degree of preference for the two lateral (left, right) sides during their performance of unilateral activities involving one of the four paired organs, hand, foot, eye and ear. Side-bias was assessed by a questionnaire, with 22 items for hand preference, and five items each for foot, eye and ear preference. Group difference was assessed with a mixed-factorial design (Group x Side) for each form of side-bias. Unlike heroin addicts and normal controls, alcoholics exhibited a significant reduction in right side-bias for all four measures, which suggests an anomalous pattern of lateralization.