Defining terms in behavior analysis: Reinforcer and discriminative stimulus.
The field still lacks a shared stopwatch for what counts as immediate reinforcement or a true SD.
01Research in Context
What this study did
The authors read every definition of "reinforcer" and "discriminative stimulus" they could find.
They noticed the books never agreed on how close in time the stimulus must follow the response.
They wrote a warning paper aimed at clinicians who work with talking clients.
What they found
No two sources used the same time window for calling something a reinforcer.
Some said 0.5 seconds, others said 30 seconds, and some gave no number at all.
The same fuzziness showed up when defining a discriminative stimulus.
How this fits with other research
Axe et al. (2021) is the direct sequel. Thirty years later, they showed that DTT manuals now misuse "SD" so often that the term has lost its meaning.
Corrigan et al. (1998) and Rose et al. (2000) both ran clean studies that assumed tight SD-reinforcer timing. Their data worked, which hints the field has been using workable rules even if the books disagree.
Duker et al. (1991) ran a lab study the same year. They found stimulus-choice delays hurt performance more than reinforcer delays. This supports the target paper’s warning: the two terms control behavior on different time scales.
Why it matters
When you write a program for a verbal client, spell out your time rule. Say "reinforcer delivered within 2 s" or "SD presented 1 s before response." This keeps your data clear and your team consistent.
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02At a glance
03Original abstract
Many definitions of reinforcer and discriminative stimulus found in behavioral texts include a requirement of temporal proximity between stimulus and response. However, this requirement is not consistently adopted. We present additional evidence from a questionnaire that was sent to members of the editorial boards of several behavioral journals showing that there is not universal agreement concerning the temporal parameters accepted in the definitions of reinforcer and discriminative stimulus. We suggest that the disagreement over the definitions of these essential terms ought to be at least addressed if not resolved. Because the discrepancy usually occurs when the behavior of verbal humans is at issue, we urge behavior analysts to be conservative when extending the terms reinforcer and discriminative stimulus from the behavior of nonhumans in the laboratory to human behavior where the effects of many stimuli may depend in part on sophisticated verbal repertoires.
The Analysis of verbal behavior, 1991 · doi:10.1007/BF03392869