Temporal reproduction.
Pigeons copy durations with errors that grow in lock-step with the target length, so BCBAs should tighten reinforcement criteria as required times get longer.
01Research in Context
What this study did
Researchers asked pigeons to copy a light that stayed on for 1, 2, or 4 seconds.
The birds had to peck a second key for the same length of time to earn food.
Each session gave dozens of trials so the team could map how close the copies were.
What they found
The birds were rarely perfect, but their errors followed a clear rule.
Short times were copied with small errors; long times with bigger errors.
The spread grew in step with the target length, exactly as Weber’s law predicts.
How this fits with other research
Blackman (1970) first showed pigeons can stretch or shrink pauses to meet time limits. The new study proves the same scalar rule holds when birds must reproduce a remembered duration.
Sherwell et al. (2014) added brief flashes to mark when reinforcers would flip. Those extra cues sharpened timing, showing the scalar clock can be nudged with salient signals.
Flory et al. (1974) timed pigeons under DRL schedules and also saw errors widen with longer targets. Both papers fit the same power-function line, giving the scalar rule a 15-year track record.
Why it matters
If your learner is asked to wait 10 s before touching a token, expect twice as much drift as at 5 s. Build in prompts or visual timers to tighten the spread, just as Sarah’s flashes did. When shaping duration-based responses, reinforce closer approximations on longer targets to offset the natural Weber creep.
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02At a glance
03Original abstract
A signal appeared for a certain time period. After the period elapsed, pigeons had to begin and complete a sequence of 15 responses in a time window ranging from the signal duration to 50% longer. Sessions involved as many as 10 different signal durations occurring in a random sequence. The times produced by pigeons often were in the same ranges as those that have been found with adult human subjects. The average times were described equally well as linear or power functions of signal duration. However, instead of the overestimation of durations usually found when animals have timed the duration of antecedent stimuli, the linear functions suggested that the pigeons underestimated the durations of their own behavior. The birds showing the strongest control when the conditions involved eight or 10 different duration requirements revealed the constant coefficients of variation that support Weber's law and scalar timing theory. Scalar timing in temporal differentiation appears to depend on non-ambiguous information about the duration required for reinforcement and on a high degree of sensitivity to the duration requirement.
Journal of the experimental analysis of behavior, 1989 · doi:10.1901/jeab.1989.52-81