Running and responding reinforced by the opportunity to run: effect of reinforcer duration.
Longer turns on the wheel made rats press less, so keep activity reinforcers brief.
01Research in Context
What this study did
Researchers let rats press a lever to earn time on a running wheel. They tested three durations: 30, 60, or 240 seconds of wheel access.
The team tracked how fast the rats pressed and how fast they ran once the wheel opened.
What they found
Longer running time back-fired. Rats pressed less and ran slower when the reward lasted four minutes instead of half a minute.
The result flips the usual rule that bigger rewards make behavior stronger.
How this fits with other research
Reed et al. (1988) showed the opposite with food: bigger food pellets made rats press faster. The difference is the reinforcer type—food versus running—not a mistake.
Staddon (1970) saw the same drop in speed when longer food delivery stretched the pause after reinforcement. The 1997 study proves the pattern holds even when the reward is an activity, not food.
Pilowsky et al. (1998) moved the setup to fixed-interval schedules and still found longer wheel access cut pressing rates. Together the two papers warn: more running time can suppress the very response you want.
Why it matters
If you use activity reinforcers—extra playground time, a scooter lap, dance break—keep the access short. A long turn can satiate the learner and drop responding just like the rats. Start with brief intervals and watch the data; if rates fall, shrink the reward duration before you blame the program.
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02At a glance
03Original abstract
The present study investigated the effect of reinforcer duration on running and on responding reinforced by the opportunity to run. Eleven male Wistar rats responded on levers for the opportunity to run in a running wheel. Opportunities to run were programmed to occur on a tandem fixed-ratio 1 variable-interval 30-s reinforcement schedule. Reinforcer duration varied across conditions from 30 to 120 s. As reinforcer duration increased, the rates of running and lever pressing declined, and latency to lever press increased. The increase in latency to respond was consistent with findings that unconditioned inhibitory aftereffects of reinforcement increase with reinforcer magnitude. The decrease in local lever-pressing rates, however, was inconsistent with the view that response strength increases with the duration of the reinforcer. Response rate varied inversely, not directly, with reinforcer duration. Furthermore, within-session data challenge satiation, fatigue, and response deprivation as determinants of the observed changes in running and responding. In sum, the results point to the need for further research with nonappetitive forms of reinforcement.
Journal of the experimental analysis of behavior, 1997 · doi:10.1901/jeab.1997.67-337