How to teach a pigeon to maximize overall reinforcement rate.
A bright cue plus fast shaping steps lets pigeons ditch matching and go for the richest schedule.
01Research in Context
What this study did
Davison et al. (1995) worked with pigeons in a lab. The birds pecked two keys that gave food on different schedules.
The team added a bright light that turned on when the birds picked the key that paid better overall. They slowly shaped the birds to pick that key more and more.
What they found
With the light cue, the pigeons learned to ignore the usual matching rule. They kept picking the key that earned the most food, even when the local pay rate was lower.
The shaping plus stimulus let them maximize total reinforcement for as long as the session ran.
How this fits with other research
Hopkins et al. (1977) showed pigeons already like stimuli that signal upcoming food. M et al. used that liking to pull choice away from strict matching.
Bacon-Prue et al. (1980) proved big fast shaping steps work fine. M et al. followed the same brisk pace while shifting choice, not peck location.
Evenhuis (1996), published next year, added that stimulus difference between keys also guides choice. Together the two papers say both added cues and key contrast help pigeons maximize payoff.
Why it matters
You can break the matching law if you pair the better long-term option with a clear signal and shape the shift in big steps. Try adding a colored card, beep, or word when the client picks the activity that earns more tokens. Shape the move in large hops, not baby steps. The cue plus quick jumps can lock in the maximizing response.
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02At a glance
03Original abstract
In two experiments deviations from matching earned higher overall reinforcement rates than did matching. In Experiment 1 response proportions were calculated over a 360-response moving average, updated with each response. Response proportions that differed from the nominal reinforcement proportions, by a criterion that was gradually increased, were eligible for reinforcement. Response proportions that did not differ from matching were not eligible for reinforcement. When the deviation requirement was relatively small, the contingency proved to be effective. However, there was a limit as to how far response proportions could be pushed from matching. Consequently, when the deviation requirement was large, overall reinforcement rate decreased and pecking was eventually extinguished. In Experiment 2 a discriminative stimulus was added to the procedure. The houselight was correlated with the relationship between response proportions and the nominal (programmed) reinforcement proportions. When the difference between response and reinforcement proportions met the deviation requirement, the light was white and responses were eligible for reinforcement. When the difference between response and reinforcement proportions failed to exceed the deviation requirement, the light was blue and responses were not eligible for reinforcement. With the addition of the light, it proved to be possible to shape deviations from matching without any apparent limit. Thus, in Experiment 2 overall reinforcement rate predicted choice proportions and relative reinforcement rate did not. In contrast, in previous experiments on the relationship between matching and overall reinforcement maximization, relative reinforcement rate was usually the better predictor of responding. The results show that whether overall or relative reinforcement rate better predicts choice proportions may in part be determined by stimulus conditions.
Journal of the experimental analysis of behavior, 1995 · doi:10.1901/jeab.1995.64-277