Anomalous cerebral dominance can have multiple manifestations, e.g., l
eft-eye preference or left-foot preference in the absence of left hand
edness per re. The 1987 estimate of prevalence of anomalous dominance
in the population by Geschwind and Behan approaches 30%, three times t
he estimate obtained by using handedness alone as the sorting criterio
n. Accordingly, substantial numbers of subjects assigned to ''dextral'
' groups may actually display other legitimate indicators of anomalous
dominance. As such there is a tendency to commit Type II errors in st
udies in which handedness alone is used to represent the Variance attr
ibuted to cerebral dominance. Accordingly, null hypotheses assessing t
he relations of cerebral dominance with dependent variables are accept
ed even though they may, in fact, be false.