Competition between stimulus-reinforcer contingencies and anticipatory contrast.
New stimulus-reinforcer links can hide contrast effects, so test the contingency before you change the program.
01Research in Context
What this study did
The team set up a two-part schedule. In one part, food always followed a light. In the other part, food never followed the light.
They watched what happened to anticipatory contrast. That is the drop in responding when a rich schedule suddenly turns lean.
The question: will the new light-food relation wipe out the usual contrast effect?
What they found
Contrast shrank when the light always meant food. The animals still responded, but the dip was smaller.
When the light never meant food, contrast came back. The results were in-between when the relation was mixed.
Pavlovian cues can push contrast aside, but they do not always win completely.
How this fits with other research
Rincover et al. (1975) first showed strong positive and negative contrast in rats. The 1992 study adds a twist: those same contrast effects can be trimmed back if you glue a reliable signal to the reinforcer.
Rider et al. (1984) showed rats prefer short warning signals. Together with the target paper, this tells us signals do more than predict—they can override other dynamics like contrast.
Drifke et al. (2020) found that DRA keeps problem behavior low during FCT delays. Their contingency logic mirrors the target: giving the learner something clear to count on (a signal or a response) beats leaving them in a vacuum.
Why it matters
If you run multi-component schedules and contrast fades, do not assume the effect is gone. Check whether a new stimulus-reinforcer pair has slipped in and is competing for control.
Probe the contingency before you tweak the schedule. A quick test can tell you if contrast is still alive but masked.
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02At a glance
03Original abstract
Procedures used to study anticipatory contrast are conceptually similar to those used to study autoshaping, in that two target stimuli signal either higher or lower rates of reinforcement in the following components of the schedule. Despite this signal contingency, anticipatory contrast entails response rates that are higher to the target stimulus followed by the lower rate of reinforcement. To determine the relation between such effects and autoshaping, different variations of the procedure were used in which the signal contingency was presented in the absence of reinforcement in the target components themselves and in which the reinforcement schedules in the different following components were signaled by the same stimulus. Autoshaping effects of this signal contingency were demonstrated when no reinforcement was available during the target-component signals themselves. Intermediate patterns of behavior occurred when reinforcement was available during the target-component signals and when their different following schedules were correlated with the same stimulus. Attempts to isolate these signal and contrast effects functionally by using the signal-key procedure were unsuccessful. The results demonstrate that Pavlovian stimulus contingencies are in competition with the dynamics of anticipatory contrast, thus reducing its occurrence under some circumstances.
Journal of the experimental analysis of behavior, 1992 · doi:10.1901/jeab.1992.58-287