Discovery of simple binary sequences in brain damaged patients

1. Administered a temporal rules induction test to 59 normal controls and to 113 right and 162 left brain-damaged patients. 76 Ss with left hemispheric lesions were considered as aphasics. Ss were shown 2 tokens of different colors following 3 established sequences. They were informed that presentation of the tokens followed a rule, so that if they concentrated on the temporal order in which the stimuli were presented, they could get the correct sequence. The hypothesis that left brain-damaged Ss would perform worse than Ss with lesions in the right hemisphere, since left brain-damaged Ss may be impaired in tasks requiring analysis of temporally ordered information, was not supported. No relationship was found between severity of aphasia and scores on the temporal rules induction test, but within the aphasic group the worst scores were obtained by Ss with semantic-lexical impairment (despite the absence of any obvious link between sequencing processes and operations of lexical choice). Results are at variance with the hypothesis that temporal sequencing ability may be a basic endowment of the left hemisphere, more fundamental than (and accounting for) the left hemisphere dominance for language. (33 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)