Exteroceptive control of fixed-interval responding.
A visible timer can hijack timing behavior—use it when you want calm, predictable waits.
01Research in Context
What this study did
Pigeons pecked a key for food on a fixed-interval schedule.
A visual clock turned on with each interval and stayed on until food arrived.
The team asked: does the clock alone steer the birds’ timing?
What they found
The clock grabbed almost total control.
Birds waited, then sped up exactly with the clock, even when the real food time stayed the same.
A new clock-linked pattern appeared, showing the outside light ruled the birds’ inner timer.
How this fits with other research
Greene et al. (1978) later gave college students the same clock-FI setup. People also scalloped only when the digital clock was in view; take it away and they switched to break-and-run.
Dews (1966) did the opposite: he turned the lights off and sometimes skipped food. Pigeons still timed the interval, proving an inner clock can work without outside cues.
Frame et al. (1984) moved the idea to variable-interval schedules in rats. Stimulus length still stretched pauses, showing the clock rule travels across species and schedules.
Why it matters
Your clients, like pigeons and students, often watch clocks, phones, or timers. If you want smooth waiting or scalloped work bursts, put a clear visual timer in view. If you need break-and-run speed, hide the timer and let the natural interval do the work. One small display flip can reshape entire response patterns.
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02At a glance
03Original abstract
Two pigeons were exposed to several fixed-interval schedules of food reinforcement. In some cases, exteroceptive stimuli associated with the passage of time were present. Such visual "clock" stimuli were found to gain almost complete control over the behavior, although at the longest fixed interval studied, the superposition of a new temporal discrimination upon the visual discrimination was observed. Where clock stimuli were made contingent upon the birds' behavior, a new form of responding was generated. This behavior was discussed in terms of positive and negative response-tendencies resulting from several stimulus factors: Some of these functioned as S(Delta)'s and secondary negative reinforcers; some functioned as S(D)'s and secondary positive reinforcers; and some were ambiguous with respect to reinforcement conditions. A "pure temporal" discrimination was superimposed upon these factors, but its exact nature was indeterminate from the present data.
Journal of the experimental analysis of behavior, 1962 · doi:10.1901/jeab.1962.5-49