Short-Term Memory, Parsing, and the Primate Frontal Cortex

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Science  30 Jun 1967:
Vol. 156, Issue 3783, pp. 1765-1767
DOI: 10.1126/science.156.3783.1765


Removal of the frontal cortex of primates resulted earlier in a psychological deficit usually classified in terms of short-term memory. This classification is based on impairment in performance of delayed-response or alternation-type tasks. We report an experiment in which the classical 5-seconddelay right-left-right-left (R-L-R-L) altenation task was modified by placing a 15-seconid interval between each R-L couplet: R-L . . . R-L . . . R-L . . . . This mnodification made it possible for monkeys with frontal lesions, which had failed the classical task, to perform with very few errors. The result suggests that proper division, parsing of the stream of stimuli to which the organism is subjected, is a more important variable in the mechanism of short-term memory than is the maintenance of a neural trace per se.