Psychophysics of key-peck duration in the pigeon.
You can shape tiny response durations, but the starting form sets a hard limit on change.
01Research in Context
What this study did
Researchers worked with four pigeons in a small lab chamber. Each bird faced a lit key and earned grain by pecking it.
The team used differential reinforcement to shape how long each peck lasted. Short pecks paid off in one phase, long pecks in the next.
What they found
Peck length moved up or down with the new rule, but only so far. The birds' old 'natural' peck still pulled the final numbers.
Even when food favored 100-ms contacts, birds that started with 40-ms pecks never fully reached the goal.
How this fits with other research
Smith et al. (1975) saw no contrast in key-peck duration when they switched schedules. The 1980 study shows why: baseline topography locks the response, so contrast has little room to appear.
Parsons et al. (1981) tracked how long trace intervals weaken pecking. Both papers map time, but 1980 proves you can bend duration only if you fight the built-in motor pattern first.
Halpern et al. (1966) found that longer fixed-ratio schedules stretch the post-reinforcement pause. Together the studies show reinforcement can time both pauses and pecks, yet each response carries its own ceiling.
Why it matters
When you shape micro-behaviors like finger contact on an iPad or mouth stay on a straw, remember the client’s baseline form. Start closer to the natural duration, then stretch or shrink in baby steps. If progress stalls, check the original topography before you blame the reinforcer.
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02At a glance
03Original abstract
The duration of the pigeon's key peck was differentially reinforced in either a trials or a free-operant procedure. Mean emitted peck duration was a power function of the duration required for food delivery to occur. The exponents of the power function differed considerably from those observed in earlier research involving longer duration responses in pigeons and other species. The coefficients of variation also did not correspond with those of the earlier research on other responses, nor did consideration of the durations actually reinforced resolve the differences. Duration was neither a function of response rate nor of intermittency of reinforcement. Key-peck duration was changed in an orderly way by differential reinforcement. However, it appeared to be more strongly determined by its duration in the absence of differential reinforcement than were longer duration responses.
Journal of the experimental analysis of behavior, 1980 · doi:10.1901/jeab.1980.34-23