Information, certainty, and learning.
Tighter SD-to-reinforcer intervals cut acquisition time in a predictable curve that works across species.
01Research in Context
What this study did
Researchers trained rats on simple conditioning tasks. They varied how soon the food pellet followed the cue light. Then they counted how many trials each rat needed to learn the link.
The team also tracked how fast the rats pressed the lever once learning was complete.
What they found
Learning speed followed a clean curve. When the cue-to-food interval was short, rats mastered the task in fewer trials. When the interval grew, trials-to-criterion grew in a fixed ratio.
The final lever-pressing speed fit the same curve, showing one rule governs both acquisition and steady performance.
How this fits with other research
DByiers et al. (2025) saw the same timing logic in mice. They found reinforcement rate controls behavior during the cue, while probability shapes what happens after. JKaplan-Kahn et al. (2026) now add that the cue-to-reinforcer ratio also decides how fast the whole association forms.
Rand (1977) showed pigeons shift time between keys instead of changing speed. The rat data agree: the scalar rule predicts trials to mastery, not peck rate itself.
Eckerman (1969) reported higher reinforcement probability speeds up stimulus control. The 2026 curve refines that idea into a single formula you can plug minutes into.
Why it matters
You now have a ruler for program design. If you want faster discrimination, tighten the delay between SD and reinforcement. For example, deliver praise within one second rather than three. The same curve estimates how many extra trials a looser schedule will cost you. Check your data against the ratio; if a learner is slower than the line, look for attention or motivation blocks instead of adding more trials.
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02At a glance
03Original abstract
More than four decades ago, Gibbon and Balsam (1981) showed that the acquisition of Pavlovian conditioning in pigeons is directly related to the informativeness of the conditioning stimulus (CS) about the unconditioned stimulus (US), where informativeness is defined as the ratio of the US-US interval (<i>C</i>) to the CS-US interval (<i>T</i>). However, the evidence for this relationship in other species has been equivocal. Here, we describe an experiment that measured the acquisition of appetitive Pavlovian conditioning in 14 groups of rats trained with different <i>C</i>/<i>T</i> ratios (ranging from 1.5 to 300) to establish how learning is related to informativeness. We show that the number of trials required for rats to start responding to the CS is determined by the <i>C</i>/<i>T</i> ratio, and the specific scalar relationship between the rate of learning and informativeness is similar to that previously obtained with pigeons. We also found that the response rate after extended conditioning is strongly related to <i>T</i>, with the terminal CS response rate being a scalar function of the CS reinforcement rate (1 <i>/T</i>). Moreover, this same scalar relationship extended to the rats' response rates during the inter-trial interval, which was directly proportional to the overall rate of reinforcement in the context (1 <i>/C</i>). The findings establish that animals encode rates of reinforcement, and that conditioning is directly related to how much information the CS provides about the US. The consistency of these observations across species, captured by a simple regression function, suggests a universal model of conditioning.
, 2026 · doi:10.7554/elife.102155