Choice As A Function Of Reinforcement Ratios In Delayed Matching-to-sample.
Short delays lock in sample control; longer delays let reinforcement ratio drive the bus.
01Research in Context
What this study did
The team worked with pigeons in a delayed matching-to-sample task. Birds saw a color sample, waited 0–6 s, then picked the matching color from two side keys.
The researchers changed two things across trials: how often each choice paid off and how long the delay lasted. They logged every peck to see which factor steered the birds’ choices.
What they found
When the delay was short, pigeons almost always pecked the correct color no matter the payoff odds. As the delay grew, accuracy slid and the birds’ choices slid toward whichever side had the richer payoff overall.
The data fit a simple equation: stimulus control faded hyperbolically with time, while reinforcement ratio pulled stronger as the delay lengthened.
How this fits with other research
Rider et al. (1984) saw the same hyperbolic loss of stimulus control in a signal-detection task, but they kept payoff rates even; the new study shows the loss opens the door for reinforcement ratio to take over.
Bird et al. (2011) later added reinforcer-size cues mid-delay and reversed accuracy instantly. Together the three papers paint one story: delay weakens sample control, then any available payoff cue—ratio or magnitude—grabs the steering wheel.
Campbell (2003) pushed ratios to the extreme and found position bias; our target paper shows the shift begins as soon as the sample signal fades, not only at extreme ratios.
Why it matters
When you run matching-to-sample programs with learners who have short memory spans, keep delays tight to protect stimulus control. If you must lengthen the delay, expect choices to drift toward the richer payoff side and adjust your reinforcement schedule accordingly. Track accuracy separately for short- and long-delay trials so you can spot when teaching is shifting from sample control to payoff control.
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02At a glance
03Original abstract
Pigeons were studied in two experiments using a delayed matching‐to‐sample task. In Experiment 1, 4 subjects were exposed to a task in which the proportion of reinforcement associated with matching and nonmatching, and the overall proportion of reinforcement associated with selecting each choice, regardless of the sample stimulus, were varied. Choice was sensitive to both proportions. A least squares regression analysis showed that Wixted's (1989) proportions of reinforcement model closely fit the data from Experiment 1; however, the model failed to make accurate qualitative predictions for some test conditions. In Experiment 2, 4 subjects were exposed to a delayed matching‐to‐sample task in which the retention intervals and the reduction in delay to reinforcement signaled by the onset of the sample stimulus were independently varied. When the retention interval was short and when the delay‐reduction value of the sample stimulus was high, the sample exerted greater control over choice; the control by the overall proportion of reinforcements for selecting each choice stimulus was correspondingly low. Conversely, when the retention interval was long and the delay‐reduction value of the sample stimulus was low, the sample exerted relatively less control over choice; control by the overall proportion of reinforcements obtained for selecting each choice stimulus was correspondingly high. A signal detection analysis found that sensitivity to reinforcement varied directly with retention interval. Data were also consistent with misallocation models. No evidence was found to suggest that pigeons ignore the rate at which selecting individual choice stimuli is reinforced, as has been reported in studies with human subjects.
Journal of the experimental analysis of behavior, 1996 · doi:10.1901/jeab.1996.66-11