Pigeons' wait-time responses to transitions in interfood-interval duration: Another look at cyclic schedule performance.
Pigeons time delays by averaging the last few intervals, so past schedules keep ghosting into the present.
01Research in Context
What this study did
Six pigeons pecked a key for grain on a repeating three-step cycle.
Each cycle delivered food after 15 s, then 45 s, then 15 s again.
Researchers measured how long the birds waited before the first peck after each food drop.
They wanted to see if the birds tracked the most recent interval or blended past ones.
What they found
Wait times grew when the interval switched from short to long.
They shrank when it switched from long to short.
After many cycles the birds still shifted, but the change got smaller.
The data fit a model that weights both how often and how recently each length appeared.
How this fits with other research
Martens et al. (1989) also saw pigeons average past events, but with light-and-tone cues instead of food gaps.
Martin et al. (1997) found two clear wait modes; this paper shows the modes are smeared when intervals keep flipping.
Lancioni et al. (2011) looked at time between trials, not food, yet both studies agree: pigeons lean on recent history more than rats do.
Together the set says timing is not a stopwatch—it is a running average that updates after every cycle.
Why it matters
Your client’s behavior works the same way. If you change the schedule, the old one still pulls for a while.
Fade reinforcement slowly or you will see resurgence.
Track the last few sessions, not just the last one, when you graph response rates.
Use this as a reminder: behavior remembers frequency, not just recency.
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02At a glance
03Original abstract
Recent developments reveal that animals can rapidly learn about intervals of time. We studied the nature of this fast-acting process in two experiments. In Experiment 1 pigeons were exposed to a modified fixed-time schedule, in which the time between food rewards (interfood interval) changed at an unpredictable point in each session, either decreasing from 15 to 5 s (step-down) or increasing from 15 to 45 s (step-up). The birds were able to track under both conditions by producing postreinforcement wait times proportional to the preceding interfood-interval duration. However, the time course of responding differed: Tracking was apparently more gradual in the step-up condition. Experiment 2 studied the effect of having both kinds of transitions within the same session by exposing pigeons to a repeating (cyclic) sequence of the interfood-interval values used in Experiment 1. Pigeons detected changes in the input sequence of interfood intervals, but only for a few sessions-discrimination worsened with further training. The dynamic effects we observed do not support a linear waiting process of time discrimination, but instead point to a timing mechanism based on the frequency and recency of prior interfood intervals and not the preceding interfood interval alone.
Journal of the experimental analysis of behavior, 1993 · doi:10.1901/jeab.1993.59-529