Time limits for completing fixed ratios. III. Stimulus variables.
A visible or audible timer turns hidden deadlines into clear rules that animals and people can follow.
01Research in Context
What this study did
Researchers set time limits on fixed-ratio tasks for pigeons. The birds had to finish pecking a set number of times before a deadline.
Sometimes a light or sound told the birds how much time was left. Other times the clock ran silently. The team watched how long each bird took to finish the ratio.
What they found
When the stimulus was on, the birds hit the deadline almost every time. Their pecking speed lined up with the time limit.
Without the stimulus, accuracy fell apart as the deadline got longer. The birds could not feel the passing time on their own.
How this fits with other research
Blackman (1970) showed the basic effect: pigeons can learn to meet FR deadlines. Périkel et al. (1974) adds the key detail — a signal makes the skill reliable.
Frame et al. (1984) moved the same signal idea to variable-interval schedules with rats. The stimulus-duration rule works across species and schedule types.
Keller et al. (1978) seems to disagree. Their pigeons did not blend durations when new tones were played. The difference is the task: V shaped new response speeds, while J only asked birds to repeat a known deadline. Categorical control still holds; the 1974 study simply used an already-learned cutoff.
Why it matters
If you give a learner a time-bound task, add a clear cue that marks the passage of time. A timer beep, fading color, or spoken prompt can replace the hidden clock. The learner then adjusts pace early instead of running out of time.
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02At a glance
03Original abstract
Pigeons received food only if they took longer than a specified time to begin and complete a fixed ratio. In Experiment 1, ratios with shorter durations had no stimulus consequence; in Experiment 2, these ratios ended with a stimulus change. In both studies, the mean time to complete the ratio exceeded requirements of less than 30 sec, approximately matched requirements of 30 sec, and fell progressively short of matching thereafter. Variability increased together with the means. The various effects resembled those of temporal differentiation experiments involving single responses. Although both number of ratios and time separating successive food presentations increased along with ratio duration, control experiments showed that differential reinforcement of duration, rather than either form or reinforcer intermittency, accounted for the performance. Experiment 2 also studied the effects of adding a stimulus that signalled when the required time had elapsed. The stimulus produced durations that matched even the most stringent requirements. This precision was not maintained when the stimulus was removed. Temporal differentiation schedules seem to have similar effects regardless of the response class and temporal property involved.
Journal of the experimental analysis of behavior, 1974 · doi:10.1901/jeab.1974.22-285