Goldshmidt, J. N. , Lattal, K. M. , & Fantino, E. (1998).
Context effects on choice.
Journal of the Experimental Analysis of Behavior,
70, 301-320.
Four pigeons responded on a concurrent-chains
schedule in four experiments that examined whether the
effectiveness of a stimulus as a conditioned reinforcer is best
described by a global approach, as measured by the average
interreinforcement interval, or by a local contextual approach, as
measured by the onset of the stimulus preceding the conditioned
reinforcer. The interreinforcement interval was manipulated by
the inclusion of an intertrial interval, which increased the
overall time to reinforcement but did not change the local
contingencies on a given trial. A global analysis predicted
choice for the richer alternative to decrease with the inclusion
of an intertrial interval, whereas a local analysis predicted no
change in preference. Experiment 1 examined sensitivity to
intertrial intervals when each was signaled by the same houselight
that operated throughout the session. In Experiment 2, the
intertrial interval always was signaled by the stimulus correlated
with the richer terminal link. In Experiment 3, the intertrial
interval was signaled by the keylights correlated with the initial
links and two novel houselights. Experiment 4 provided free food
pseudorandomly during the intertrial interval. In all
experiments, subjects' preferences were consistent with a local
analysis of choice in concurrent chains. These results are
discussed in terms of delay-reduction theory, which traditionally
has failed to distinguish global and local contexts.
Key words: conditioned reinforcement, delay-
reduction theory, choice, intertrial interval, concurrent chains,
key peck, pigeons