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The experiment reported herein was conducted to determine
whether interresponse-time (IRT) shaping can produce different
response rates in 2 components of a multiple schedule that are
equated with respect to reinforcement rate. To this end, pigeons'
key pecks were reinforced with food, if they terminated IRTs that
were more extreme (shorter in 1 component and longer in the
other) than 20 of the most recent 24 IRTs, and an average of 30
s had elapsed since the previous reinforcement. Large
intercomponent differences in response rate occurred in all of the
subjects, even though the intercomponent differences in
reinforcement rate were negligible. The relevance of the present
findings to prior research on IRT shaping is discussed.