Sample-duration effects on pigeons' delayed matching as a function of predictability of duration.
More exposure time only helps if the learner can predict what that time means.
01Research in Context
What this study did
Webb et al. (1999) worked with pigeons in a lab.
The birds had to match colors after a short delay.
Sometimes the color stayed on for a long time, sometimes short.
The twist: on some days the length told the bird which color would be correct; on other days it gave no clue.
What they found
When duration was random, longer samples gave better accuracy.
When duration predicted the answer, short samples worked just as well or better.
Predictability flipped the usual “more time is better” rule.
How this fits with other research
Green et al. (1987) also ran pigeon delay tasks.
They showed that adding position cues sped learning.
Together the two studies say: extra cues, whether position or duration rules, reshape how time affects memory.
Parmenter (1999) wrote a theory paper the same year.
It argued that many “memory loss” errors are really stimulus ambiguity.
J et al.’s predictability effect supports that idea: control drops when the signal is unclear, not when memory fades.
Tranberg et al. (1980) found that simply turning the lights off during the delay hurt accuracy.
Pair that with J et al. and you see: any change that muddles the context, whether darkness or unpredictable length, can weaken performance.
Why it matters
For BCBAs the message is clear: stimulus control depends on what the learner can predict.
If you give extra time, make sure the length itself signals something useful.
Otherwise you may get no gain, or even worse performance.
Check your cues; if they’re ambiguous, tighten the contingency before assuming memory is the problem.
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Join Free →Before your next matching session, decide if the length of the sample stimulus will signal the correct choice; if not, keep samples brief to avoid ambiguity.
02At a glance
03Original abstract
Three experiments assessed the impact of sample duration on pigeons' delayed matching as a function of whether or not the samples themselves signaled how long they would remain on. When duration was uncorrelated with the sample appearing on each matching trial, the typical effect of duration was observed: Choice accuracy was higher with long (15-s) than with short (5-s) durations. By contrast, this difference either disappeared or reversed when the 5- and 15-s durations were correlated with the sample stimuli. Sample duration itself cued comparison choice by some birds in the latter (predictable) condition when duration was also correlated with the reinforced choice alternatives. However, even when duration could not provide a cue for choice, pigeons matched predictably short-duration samples as accurately as, or more accurately than, predictably long-duration samples. Moreover, this result was observed independently of whether the contextual conditions of the retention interval were the same as, or different from, those of the intertrial interval. These results strongly support the view that conditional stimulus control by the samples is partly a function of their conditioned reinforcing properties, as determined by the relative reduction in overall delay to reinforcement that they signal.
Journal of the experimental analysis of behavior, 1999 · doi:10.1901/jeab.1999.72-279