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Effects of differential reinforcement expectancies on successful matching-to-sample performance in pigeons
Journal article   Peer reviewed

Effects of differential reinforcement expectancies on successful matching-to-sample performance in pigeons

Robert E DeLong and Edward A Wasserman
Journal of experimental psychology. Animal behavior processes, Vol.7(4), pp.394-412
10/1981
DOI: 10.1037/0097-7403.7.4.394

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Abstract

Employed a symbolic variant of J. A. Konorski's (1959) delayed successive matching-to-sample task to determine whether differential reinforcement expectancies affect discriminative responding. One of 2 sample stimuli was followed, after a delay (0, 5, or 10 sec), by 1 of 2 test stimuli. Ss' keypecking during test periods could produce food only on positive trials; nonreinforcement invariably occurred on negative trials. Differential reinforcement was scheduled by following the 2 positive trial sequences with different probabilities of reinforcement; nondifferential reinforcement was scheduled by following the 2 positive trial sequences with a single, intermediate probability of reinforcement. Ss given differential reinforcement acquired the conditional discrimination more rapidly and reached higher terminal levels of performance than nondifferential controls (Exp I, 16 Ss). Moreover, the magnitude of these differences increased as the delay between sample and test stimuli was lengthened. Reversing the probabilities of reinforcement in the differential problem produced a substantial and durable disruption of conditional discrimination performance (Exp II, same Ss). The same pattern of results was obtained when differential sample keypecking was eliminated (Exp III, 8 Ss). Results can be interpreted parsimoniously by postulating the existence of learned reinforcement expectancies, and they detract from the merits of trace theory as a complete account of animal memory. (37 ref)

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