Repeated measurements of reinforcement effects on gradients of stimulus control.
Use FI, VI, or VR when you need sharp, lasting stimulus discrimination; FR and DRL weaken it.
01Research in Context
What this study did
Zeiler (1969) ran pigeons on five different reinforcement schedules. The birds pecked a key under FI, VI, VR, FR, or DRL. After steady responding, the team tested how sharply each bird discriminated colors near the trained hue. They repeated the color tests many times to see if the gradient held up.
What they found
FI, VI, and VR kept the steepest, most stable color gradients. FR and DRL flattened the curve and the birds' choices wobbled more across tests. In plain words, the first three schedules locked stimulus control tight; the last two did not.
How this fits with other research
Crossman et al. (1973) extends the story. They ended sessions with one big reinforcer after a long, stretching interval. That trick beat even the best schedules here, keeping gradients crisp through many extinction probes.
Selekman (1973) adds a twist. He showed that strong stimulus control (like the kind FI/VI give) shields behavior from resurgence when food later stops. The two papers dovetail: pick FI or VI and you get both a sharp gradient and safer extinction.
Hayes et al. (1975) seem to clash at first. They got clean color peaks with response-independent food, no peck required. But their peaks took longer to form. The lesson: pairing response with reinforcer (as in D's FI/VI) speeds up tight stimulus control.
Why it matters
When you want a client to tell two cues apart, run the task on FI or VI first. These schedules build steep, durable stimulus control that survives later changes. Save FR or DRL for other goals; they soften discrimination. End sessions with an occasional large reinforcer, K-style, if you must probe in extinction later.
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02At a glance
03Original abstract
Two experiments studied the effects of reinforcement schedules on generalization gradients. In Exp. 1, after pigeons' responding to a vertical line was reinforced, the pigeons were tested with 10 lines differing in orientation. Reconditioning and the redetermination of generalization gradients were repeated from 8 to 11 times with the schedule of reinforcement varied in the reconditioning phase. Stable gradients could not be observed because the successive reconditionings and tests steepened the gradients and reduced responding. Experiment 2 over-came these effects by first training the birds to respond to all of the stimuli. Then, brief periods of reinforced responding to the stimulus correlated with reinforcement alternated with the presentation of the 10 lines in extinction. The development of stimulus control was studied eight times with each bird, twice with each of four schedules of reinforcement. Gradients were similar each time a schedule was imposed; the degree of control by the stimulus correlated with reinforcement varied with particular schedules. Behavioral contrast occurred when periods of reinforcement and extinction alternated and was more durable with fixed-interval, variable-interval, and variable-ratio schedules than with fixed-ratio or differential-reinforcement-of-low-rate schedules.
Journal of the experimental analysis of behavior, 1969 · doi:10.1901/jeab.1969.12-451