Operant acceleration during a pre-reward stimulus.
An 80-second stimulus that always ends with food can make rats press faster even though the lever-food rule never changes.
01Research in Context
What this study did
Henton et al. (1970) worked with lab rats pressing a lever for food.
An 80-second tone always ended with a pellet. The researchers flipped the rule on and off to see what happened to the pressing rate.
They used an ABAB design: first food followed the tone, then it didn’t, then it did again.
What they found
When the tone surely ended with food, the rats pressed faster and took less time between presses.
When that link was removed, the speed-up vanished. Restoring the link brought the speed-up right back.
How this fits with other research
Kendall (1974) extends the same idea. Short pre-food cues also boost rates, but long ones can slow already-fast responding. The 80-second window in W et al. sits in the middle, still on the helpful side.
Edwards et al. (1970) seems to contradict: extra food slowed fixed-ratio pecking. The key difference is signaling. W’s rats knew the food was coming because the tone told them; D’s birds got unsignaled free food, which disrupted the ratio.
Nevin (1969) is a direct predecessor. It first showed that brief stimuli right before food quicken fixed-interval responding. W stretched that stimulus to over a minute and still saw the same kick.
Why it matters
A simple cue that reliably ends with reinforcement can energize the very behavior already on pay. You can use this during thin schedules or long work stretches: flash a card, ring a chime, or start a timer that always ends with the reinforcer. Keep the cue under two minutes and watch response pace rise without touching the contingency itself.
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02At a glance
03Original abstract
Stimuli of 20, 40, and 80 sec duration terminated with five non-response-contingent food pellets were superimposed upon lever pressing reinforced with single pellets on a DRL 30-sec schedule. Two rhesus monkeys served as subjects. No change in response frequency was observed during the 20- and 40-sec stimuli. During the 80-sec pre-food stimulus, overall response frequency increased to approximately 150% and 220% of pre-stimulus levels, and the temporal distributions of interresponse times shifted toward the shorter intervals. When the 80-sec stimulus was no longer terminated with food, the response frequency decreased and the temporal distributions of interresponse times gradually approached pre-stimulus levels. An increased frequency of short interresponse times and an increase in response rate was again observed when the pellet termination procedure was reinstituted with the 80-sec stimulus. No change in response frequency or interresponse times was observed in the absence of the conditioning stimulus, and performance efficiency, as reflected in the ratio of responses to reinforcements during non-stimulus periods, remained stable throughout the experiment.
Journal of the experimental analysis of behavior, 1970 · doi:10.1901/jeab.1970.13-205