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Abstract

In Chapter 8 we observed that groups suffering from brain and neurological damage, mental retardation, affective disorders, or psychopathy exhibit distributions of lateral preference behaviors that differ from those observed in the general population. Most of the empirical evidence suggests that these clinical groups display a higher incidence of left-sidedness, greater degrees of inconsistent sidedness, and higher incidences of crossed preference patterns. In our discussion of these findings, we encountered a number of theoretical positions that attempted to link such distributions of lateral preference, which differ from the norm, with observed or inferred pathological factors. These theoretical positions ranged from a rather mechanism-free statistical argument through notions of maturational lags, environmental factors, or disruptions of the patterns of hemispheric specialization. Although we cannot establish the most valid theoretical position, the data reviewed indicate that there is an association between certain classes of affective and cognitive abnormalities and the incidence of certain patterns of lateral preference. A number of investigators have posed the obvious reciprocal question and have explored whether or not specific patterns of lateral preference can be used to indicate some form of cognitive deficit.