Reaction time in brain disease: some reflections.

Two factors associated with measurements of RT, viz., the role of task complexity and the relationship of RT to locus and size of lesion, are considered. Analysis of the literature suggests that the two factors are interrelated. There appears to be a trend for the complexity gradient to be steeper in patients with widespread brain damage than in those with focal lesions. Although simple RT is generally reported to be slower in patients with right hemisphere lesions, there are indications that complex RT may be slower in patients with left hemisphere lesions. The multiplicity of procedures utilized in different studies is probably responsible for some of the inconsistent findings in the literature. Explicit definition of these procedures and the employment of combinations of them should resolve these inconsistent findings and help to elucidate the relationship between RT and cerebral status.