Defining behavioral contrast for multiple schedules.
Pick the intraschedule baseline—equal reinforcement in both components—when you check for behavioral contrast.
01Research in Context
What this study did
Whalen et al. (1979) wrote a theory paper. They looked at two ways scientists define 'behavioral contrast.'
Both definitions try to explain why response rates jump when reinforcement changes in another part of a multiple schedule. The authors show which definition actually matches the data.
What they found
The team says: use the intraschedule definition. That means you compare the test phase to a baseline where both parts already give the same amount of reinforcement.
The other choice, the interschedule definition, mixes up the comparison and can hide real contrast or create fake contrast.
How this fits with other research
Bloomfield (1967) found pigeons gave more pecks on an FR schedule after reinforcement rose in the other key. Whalen et al. (1979) show that jump is only clear if you pick the intraschedule baseline.
Innis (1978) saw negative contrast but no positive contrast. The 1979 paper explains why: the intraschedule view makes those mixed results easier to see and test.
Lattal et al. (2024) later lump contrast with resurgence. They cite the old definitional muddle that K et al. already fixed, so their story now starts on cleaner ground.
Why it matters
When you run multiple-schedule interventions, always set an equal-reinforcement baseline first. Then compare any change to that line. This habit keeps your data honest and prevents you from chasing contrast effects that are really just baseline drift. The 1979 rule is still the quickest way to stay consistent with forty years of follow-up work.
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02At a glance
03Original abstract
Two different definitions of behavioral contrast have been used for multiple schedules. One, interschedule, definition identifies contrast as changes in the rates of responding which occur when subjects move from one multiple schedule to another. The other, intraschedule, definition emphasizes changes in the rates of responding which occur relative to a baseline rate of responding. The baseline is the rate of responding emitted during a multiple schedule that supplies equal rates of reinforcement in the two components. The distinction between these two definitions is important for empirical and theoretical reasons. For example, theoretical confusion has arisen when the interschedule definition has been used to test and reject theories which implicitly define contrast by the intraschedule definition.
Journal of the experimental analysis of behavior, 1979 · doi:10.1901/jeab.1979.32-457