Timing multimodal events in pigeons.
Pigeons time a weighted average of compound cues, not just the last one.
01Research in Context
What this study did
Researchers ran pigeons on a peak procedure with compound signals. A light came on, then a tone, then food. The birds had to learn when to expect food.
They tested whether the birds timed only the last cue or the whole chain. They tracked response rates across trials to see where the pigeons peaked.
What they found
The pigeons did not time just the final tone. Their response curves fit a weighted average of all three signals. The first light still pulled the peak earlier.
The birds blended the whole sequence into one internal clock. The model calls this flexible criterion averaging.
How this fits with other research
Szempruch et al. (1993) saw pigeons adjust wait times when food intervals changed. Like K et al., the birds used recent and frequent cues, not just the last one. Both studies show memory for multiple time stamps.
Martin et al. (1997) found two residence modes: short checks and long stays. Each mode tracked different timing variables. K et al. add that pigeons can fuse those variables into one blended clock.
Meyer et al. (1987) showed humans and pigeons commit early when reward chance is low. Their data look like a single sharp rule. K et al. reveal the rule is actually a weighted average behind the scenes.
Why it matters
If your learner hears a warning, then a prompt, then praise, do not assume they time only the final cue. They may be averaging the whole chain. Try spacing early signals closer to the reinforcer to pull the perceived time forward. Check response curves; a shifted peak tells you which parts of the sequence still weigh heaviest.
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02At a glance
03Original abstract
The peak procedure was used in two experiments to study pigeons' ability to time multimodal events. In the first experiment, birds were trained to time a single event consisting of a 9-s tone or light followed by a 21-s fixed interval associated with a signal of light or tone (signal of the other modality). On occasional empty trials, different lengths of the first signal were followed by a long period of the second signal. Peak response times as a function of the duration of the first signal were linear and had a slope of close to one in all birds. This indicates that the birds were timing only the second signal. In a second experiment, two complex events were used in training. One consisted of a 9-s tone or light followed by a 21-s fixed interval associated with a light or tone. The other consisted of a 21-s tone or light followed by a 9-s fixed interval associated with a light or tone. Different durations of the first signal were again used on empty trials. Peak response times as a function of the duration of the first signal were again linear in all birds. The slope of the function was less than one but greater than zero for 3 birds. This indicates that these birds were partly timing the entire complex event of 30-s duration and partly timing only the second signal of the event. A model is proposed in which the bird takes as a criterion for timing a weighted average of different target criteria. Comparisons with the performance of rats are made.
Journal of the experimental analysis of behavior, 1989 · doi:10.1901/jeab.1989.52-363