Williams, B. A. (1999).
Value transmission in discrimination learning involving stimulus chains.
Journal of the Experimental Analysis of Behavior,
72, 177-185.
Rats learned a series of reversals of a positional discrimination
in which responses to one lever led to delayed food and responses
to a second lever led to no food. Interpolated within the delays
leading to the different outcomes were two-link stimulus chains.
The pairing of each stimulus element with the delayed outcome of
food or no food varied across reversals. Either stimulus element
could have the same correlation with outcome as occurred on the
preceding reversal or the opposite correlation as on the
preceding reversal. New reversals were acquired more quickly when
both stimulus elements had the same status as during the
preceding reversal, and were acquired most slowly when both
stimulus elements had the opposite status as that of the
preceding reversal. The rate of learning was intermediate when
only one of the stimulus elements had the same status as that
during the preceding reversal. All of the data are compatible
with an interpretation in terms of backward chaining of stimulus
value.
Key words: chain schedules, conditioned reinforcement, delay of
reinforcement, discrimination learning, lever press, rats