Quantification of rats' behavior during reinforcement periods.
Reinforcement periods hide a tiny scallop—response speed dips early and bumps up late—and the size of the dip tells you if your ratio is on track.
01Research in Context
What this study did
Rider (1983) watched rats press a bar during reinforcement periods. The rats first worked on a fixed-ratio schedule, then got steady food for a short time.
The team counted every press and mapped how the speed changed second-by-second inside each reinforcement period.
What they found
Response speed dropped fast in the first 15–20 seconds of food access. A tiny scallop appeared: presses sped up again just before the period ended.
Bigger fixed ratios made both the early drop and the late bump stronger.
How this fits with other research
Critchfield et al. (2003) extends the same scallop shape to U.S. Congress. Year after year, bill writing slows after a recess and surges before the next one, proving the pattern survives outside the lab.
Pisacreta (1982) warns that real-world "scallops" are messy. The rat data give the clean baseline that R says is rarely seen with people.
Lovitt et al. (1970) shows response rate can act like a social signal. Taken together, rate is both an output we shape and a cue that can shape others.
Why it matters
You now know that even brief reinforcement periods hold a mini-pattern. Watch your client’s response speed in the first 20 seconds of praise or token delivery. If you see the early drop and late surge, your schedule is working like the lab model. Use this micro-check to fine-tune ratio size or praise timing in real time.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Count responses in the first and last 20 seconds of praise time; if speed stays flat, try a slightly larger ratio.
02At a glance
03Original abstract
What is treated as a single unit of reinforcement often involves what could be called a reinforcement period during which two or more acts of ingestion may occur, and each of these may have associated with it a series of responses, some reflexive, some learned, that lead up to ingestion. Food-tray presentation to a pigeon is an example of such a "reinforcement period." In order to quantify this behavior, a continuous-reinforcement schedule was used as the reinforcement period and was chained to a fixed-ratio schedule. Both fixed-ratio size and reinforcement-period duration were manipulated. Rats were used as subjects, food as reinforcement, and a lever press as the operant. Major findings included (a) a rapid decline in response rates during the first 15 to 20 seconds of the reinforcement periods, and (b) a strong positive relationship between these response rates and the size of the fixed ratio. Also revealed was a short scallop not normally found in fixed-ratio response patterns, whose length was a function of fixed-ratio size and reinforcement-period duration. It is suggested that rapidly fluctuating excitatory processes can account for many of these findings and that such processes are functionally significant in terms of behavioral compensation.
Journal of the experimental analysis of behavior, 1983 · doi:10.1901/jeab.1983.39-457