Effects of signaled versus unsignaled delay of reinforcement on choice.
A cue only helps choice if it uniquely marks the better, shorter delay.
01Research in Context
What this study did
Researchers used pigeons in a two-key setup. Birds could pick a side that led to food after 5 s or a side that led to food after 15 s.
Some trials gave the bird a short light that only happened before the 5-s wait. Other trials gave the same light before both waits. The team watched which side the bird chose.
What they found
Birds stuck with the short 5-s delay when the light was tied only to that side. When the light showed up before both waits, the birds cared less about the short delay and picked it less often.
A signal that means something keeps preference strong. A signal that means nothing weakens it.
How this fits with other research
Grosch et al. (1981) first showed pigeons like any signaled delay over an unsignaled one. Cullinan et al. (2001) adds the twist: the signal must tell which delay is coming, or the boost fades.
Lattal (1984) found that signaled delays keep response rates high. The new study moves from rate to choice, showing the same rule: meaning matters.
Kuroda et al. (2014) later moved the idea to discrimination tasks. Full, clear signals kept accuracy high, matching the choice pattern seen here.
Why it matters
When you use a token, timer, or praise before a reinforcer, make the signal match the wait time the learner picked. A one-size-fits-all cue blunts the power of the shorter wait. Save your shared cues for other uses; keep the differential ones for delays you want chosen.
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02At a glance
03Original abstract
Pigeons chose between 5-s and 15-s delay-of-reinforcement alternatives. The first key peck to satisfy the choice schedule began a delay timer, and food was delivered at the end of the interval. Key pecks during the delay interval were measured, but had no scheduled effect. In Experiment 1, signal conditions and choice schedules were varied across conditions. During unsignaled conditions, no stimulus change signaled the beginning of a delay interval. During differential and nondifferential signal conditions, offset of the choice stimuli and onset of a delay stimulus signaled the beginning of a delay interval. During differential signal conditions, different stimuli were correlated with the 5-s and 15-s delays, whereas the same stimulus appeared during both delay durations during nondifferential signal conditions. Pigeons showed similar, extreme levels of preference for the 5-s delay alternative during unsignaled and differentially signaled conditions. Preference levels were reliably lower with nondifferential signals. Experiment 2 assessed preference with two pairs of unsignaled delays in which the ratio of delays was held constant but the absolute duration was increased fourfold. No effect of absolute duration was found. The results highlight the importance of delayed primary reinforcement effects and challenge models of choice that focus solely on conditioned reinforcement.
Journal of the experimental analysis of behavior, 2001 · doi:10.1901/jeab.2001.75-165