Interval Timing

All recurring events occur on some schedule. Using schedules of reinforcement in relatively simplified and constrained laboratory conditions makes it possible to separate signal from noise and evaluate behavior-environment relations. Here is some of our work using schedules of reinforcement to study interval timing.

HUMANS

Human temporal learning with mixed signals

People learn to time 2-s and 4-s intervals in a multiple and mixed peak procedure.

When the same signal was associated with two intervals...
  • Some participants covered both bases by responding at both times
  • Others used an either/or strategy; they only responded at the short OR long interval

These experiments demonstrated that informative signals not only help people learn what to do, but also when to do it.

Subramaniam & Kyonka, 2022, licensed under CC BY 4.0

PIGEONS

Response requirements alter interval timing.

Picture
Liz Kyonka, (c) 2014.
Time markers are events that predict when other events will occur. Sometimes time markers are events generated by the subject (i.e., responses), such as pressing a button at a crosswalk. Other time markers are events that aren’t under the subject’s control, like most traffic lights.

We investigated whether the type of time marker would affect temporal discrimination: Pigeons were exposed to fixed-interval schedules in which the onset of the interval was signaled by the illumination of a key light or initiated by a peck to a lighted key. Food was delivered following the first response after the interval elapsed. In Experiment 2, on occasional trials food was not delivered (i.e. “no-food” or “peak trials”).

A yoking procedure equated reinforcement rates between the schedule types in both experiments. Absolute response rates early in the intervals were higher in the response-initiated schedules, but patterns of responding between interval onset and food delivery were similar for intervals initiated by responses and stimulus changes. However, during peak trials in Experiment 2 the duration of responding at a high rate was longer for response-initiated schedules than stimulus-initiated schedules. This suggests that timing precision was reduced in the response-initiated schedules and that relative “distinctiveness” of a time marker may determine its efficacy.

Fox & Kyonka, 2015

QAB Laboratory
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