Lionello-DeNolf, K. M., & Urcuioli, P. J. (2003).
A procedure for generating differential sample responding without different exteroceptive stimuli.
Journal of the Experimental Analysis of Behavior,
79, 21-35.
Sidman (1994, 2000) suggested that responses as well as stimuli
can join equivalence classes, a hypothesis difficult to test
because differential responding typically requires different
stimuli. The present experiments describe a procedure with
pigeons that avoids this potential confounding effect. In
Experiment 1, spacing two responses 3 s apart (a
differential-reinforcement-of-low-rate [DRL] schedule) to a white
stimulus on some trials produced food or the comparison stimuli
in a matching task, whereas pecking 10 or more times with no
temporal restrictions (a fixed-ratio [FR] schedule) produced the
same effect on other trials. Completing the alternative
(unscheduled) requirement terminated the white stimulus and
repeated the trial. Following such errors, pigeons learned to
switch to the alternative response pattern on the repeat trials.
In addition, the correct response pattern functioned as a
conditional cue for comparison choice. In Experiment 2, mixed
DRL-FR training was preceded by two-sample/two-alternative
matching to sample with DRL and FR sample-response requirements.
In a subsequent transfer test in which the correct response
pattern to white served as the sample, pigeons preferentially
chose the comparison previously reinforced following that pattern
in the baseline task. This unsignaled response procedure may be
useful for assessing whether differential responses can be
members of acquired equivalence classes.
Key words: stimulus equivalence, unsignaled response,
fixed-ratio, differential-reinforcement-of-low-rate, key peck, pigeons