Delayed matching-to-sample performance: Effects of relative reinforcer frequency and of signaled versus unsignaled reinforcer magnitudes.
Signaling reinforcer magnitude can hurt discrimination performance—keep magnitude cues neutral in conditional-discrimination tasks.
01Research in Context
What this study did
Sayers et al. (1995) taught pigeons a delayed matching-to-sample task. Birds saw a color sample, waited a few seconds, then picked the matching color from two choices.
The team changed two things: how often each choice paid off and whether the birds saw a cue that told them the upcoming food amount.
What they found
Longer wait times hurt accuracy. Telling the birds how much food was coming hurt accuracy even more.
When the food cue was present, the birds paid less attention to the actual colors they were supposed to match.
How this fits with other research
Bird et al. (2011) later showed the same food cue can suddenly flip accuracy mid-delay. This confirms the 1995 finding and adds that the cue works like a switch, not just a slow drag.
Burgio et al. (1986) already showed that any delay hurts matching. The 1995 study narrows the problem: it is not just the wait, but what the bird thinks it will get at the end.
Clark et al. (1970) proved that a tiny orange flash linked to food can wreck matching. The 1995 paper extends this idea: even a gentle hint about bigger food can do the same damage.
Why it matters
If you run conditional-discrimination tasks, keep food size cues neutral. Hide the upcoming reward size or keep it the same every trial. This simple move can protect the stimulus control you worked hard to build.
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02At a glance
03Original abstract
Six pigeons were trained on a delayed red-green matching-to-sample task that arranged four delays within sessions. Matching responses intermittently produced either 1.5-s access to food or 4.5-s access to food, and nonmatching responses produced either 1.5-s or 4.5-s blackout. Two phases were conducted: a signaled phase in which the reinforcer magnitudes (small and large) were signaled by houselights (positioned either on the left or right of the chamber), and an unsignaled phase in which there was no correlation between reinforcer magnitude and houselight position. In both phases, the relative frequency with which red and green matching responses produced food was varied across five values. Both matching accuracy and the sensitivity of performance to the distribution of reinforcers for matching responses decreased with increasing delays in both phases. In addition, accuracy and reinforcer sensitivity were significantly lower on signaled small-reinforcer trials compared with accuracy and sensitivity values on signaled large-reinforcer trials and on both types of unsignaled trials. These results are discussed in the context of research on both nonhuman animal and human memory.
Journal of the experimental analysis of behavior, 1995 · doi:10.1901/jeab.1995.63-33