STIMULUS SIMILARITY AND ORDER AS FACTORS IN VISUAL SHORT-TERM-MEMORY IN NONHUMAN-PRIMATES

Assessed the short-term retention of 3 male rhesus monkeys and 1 male stumptailed macaque for a single sample or for 2 successively presented samples in 4 delayed matching-to-sample experiments with delays of .03, 4, 8, 16, and 32 sec. The single sample tasks included 1 (Exp I) or 2 (Exp IV) distractor stimuli in the choice set (matching test). In the 2 successive samples tasks, the Ss matched (reconstructed) the order of presentation of 2 samples with (Exp III) and without (Exp II) a distractor stimulus. Also, the possible combinations of 8 stimuli (4 colors and 4 shapes) were arranged to test the effects of sample set and choice set similarity. Analyses of the errors indicated that both sample and choice set similarity were significant sources of confusions in delayed matching. Order errors occurred independently of similarity but were a source of forgetting primarily at the longest delays. Two exceptions to the similarity effect (2nd response errors in Exp III and errors of an inexperienced group in Exp IV) were observed. (28 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1979 American Psychological Association.