Within-session Response Patterns On Conjoint Variable-interval Variable-time Schedules.
Free reinforcers delivered on a timer still sculpt the little hills and valleys you see inside a session—satiation beats fatigue as the driver.
01Research in Context
What this study did
The team ran a single-case lab study with neurotypical adults. They mixed two schedules in every session: a regular VI schedule that paid only after a response, plus a VT schedule that paid no matter what the person did.
The goal was to see how this free extra money changed the little ups and downs in responding that happen inside one session.
What they found
When the extra VT money stayed below about two payments a minute, the response pattern looked just like a plain VI session. Once the free money topped 120 per hour, the pattern broke away.
The shape change supports a satiation or habituation story, not a tired-muscles story.
How this fits with other research
Spanoudis et al. (2011) ran the same kind of mix, only with FI plus FT in a vocational task. They also saw that free reinforcers altered but did not kill responding, a direct replication of the 1996 pattern.
Thompson et al. (1971) had earlier shown that dense non-contingent money first lifts, then drops, response rate within a session. Cameron et al. (1996) extend that idea by pinning the drop on satiation, not fatigue.
Storch et al. (2012) added stimulus variety to the mix. They found that rotating moderately preferred items can re-energize responding mid-session, showing that both satiation and stimulus change shape the same within-session curves.
Why it matters
If you run dense non-contingent reinforcement to reduce problem behavior, watch for a mid-session slump in the alternative responses you still want. The slump is probably satiation, not laziness. Briefly pause the free reinforcers or swap in a fresher item to bring responding back up.
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Join Free →If client responding dips mid-session during dense NCR, pause the timer for two minutes or switch to a fresh reinforcer, then resume.
02At a glance
03Original abstract
Operant responding often changes within sessions, even when factors such as rate of reinforcement remain constant. The present study was designed to determine whether within‐session response patterns are determined by the total number of reinforcers delivered during the session or only by the reinforcers earned by the operant response. Four rats pressed a lever and 3 pigeons pecked a key for food reinforcers delivered by a conjoint variable‐interval variable‐time schedule. The overall rate of reinforcement of the conjoint schedule varied across conditions from 15 to 480 reinforcers per hour. When fewer than 120 reinforcers were delivered per hour, the within‐session patterns of responding on conjoint schedules were similar to those previously observed when subjects received the same total number of reinforcers by responding on simple variable‐interval schedules. Response patterns were less similar to those observed on simple variable‐interval schedules when the overall rate of reinforcement exceeded 120 reinforcers per hour. These results suggest that response‐independent reinforcers can affect the within‐session pattern of responding on a response‐dependent schedule. The results are incompatible with a response‐based explanation of within‐session changes in responding (e.g., fatigue), but are consistent with both reinforcer‐based (e.g., satiation) and stimulus‐based (e.g., habituation) explanations.
Journal of the experimental analysis of behavior, 1996 · doi:10.1901/jeab.1996.66-205