Reinforcement: food signals the time and location of future food.
Food reinforcement works mainly as a signal of future food, not as a strengthener of the response that produced it.
01Research in Context
What this study did
Cowie et al. (2011) worked with pigeons in a lab. The birds pecked keys for food.
Each food delivery also told the bird when and where the next food would come. The team watched if the birds’ key pecks got stronger.
What they found
Food worked like a traffic light, not like a power-up. The birds quickly switched to the key that signaled more food.
The key that had just paid off did not get many more pecks. The signal mattered more than the past reward.
How this fits with other research
Attwood et al. (1988) saw the same thing earlier. Pigeons worked harder for stimuli that predicted food delivery than for ones that only told response rules.
Eisenmajer et al. (1998) looked at unsignaled 3-second delays. Those delays crushed both preference and response rates. Together the papers show timing and signaling drive behavior, not the food itself.
Clark et al. (1977) kept squirrel monkeys pressing levers under food-postponement. Their data match the new view: food delivery controls behavior by setting up the next food moment, not by feeding the last response.
Why it matters
For your clients, deliver the reinforcer right away or give a clear signal if you must wait. Make the stimulus that predicts good things easy to see. Do not assume the item alone will strengthen the response; the learner is tracking what comes next. Try pairing a brief cue with delayed edibles or praise so the cue carries the predictive power.
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02At a glance
03Original abstract
It has long been understood that food deliveries may act as signals of future food location, and not only as strengtheners of prefood responding as the law of effect suggests. Recent research has taken this idea further--the main effect of food deliveries, or other "reinforcers", may be signaling rather than strengthening. The present experiment investigated the ability of food deliveries to signal food contingencies across time after food. In Phase 1, the next food delivery was always equally likely to be arranged for a left- or a right-key response. Conditions were arranged such that the next food delivery was likely to occur either sooner on the left (or right) key, or sooner on the just-productive (or not-just-productive) key. In Phase 2, similar contingencies were arranged, but the last-food location was signaled by a red keylight. Preference, measured in 2-s bins across interfood intervals, was jointly controlled by the likely time and location of the next food delivery. In Phase 1, when any food delivery signaled a likely sooner next food delivery on a particular key, postfood preference was strongly toward that key, and moved toward the other key across the interreinforcer interval. In other conditions in which food delivery on the two keys signaled different subsequent contingencies, postfood preference was less extreme, and quickly moved toward indifference. In Phase 2, in all three conditions, initial preference was strongly toward the likely-sooner food key, and moved to the other key across the interfood interval. In both phases, at a more extended level of analysis, sequences of same-key food deliveries caused a small increase in preference for the just-productive key, suggesting the presence of a "reinforcement effect", albeit one that was very small.
Journal of the experimental analysis of behavior, 2011 · doi:10.1901/jeab.2011.96-63