Choice and rate of reinforcement.
Choice follows expected wait time, not just reinforcement rate—schedule extremes break the match.
01Research in Context
What this study did
Fantino (1969) ran pigeons on two side-by-side VI schedules. The birds could hop between keys at any time. The team varied how often each side paid off. They watched where the birds spent their time and how often they pecked.
The goal was to see if choice followed the pay rate or something else.
What they found
When the two sides paid at middle-of-the-road rates, the birds' time and pecks lined up almost perfectly with the payoff odds. This is the classic matching result.
But when one side became extreme—very rich or very lean—the match fell apart. The birds acted as if they were picking the option that cut the wait for food, not just the one that paid more often.
How this fits with other research
Glynn (1970) ran a near-copy study the next year. He kept the payoff rate × duration product the same across keys. The birds still matched, showing that 'rate' and 'time' can trade off while choice stays steady. This backs E's idea that time, not raw rate, is the key variable.
Emmelkamp et al. (1986) repeated the setup with costs equalized. Birds still matched instead of maximizing. That tells us matching is not just a side effect of effort—it's a core feature of choice.
Reid et al. (1983) reviewed dozens of similar tests. They folded Fantino (1969) into a broader story called the Equalizing Principle: local reinforcement rates even out across alternatives when long change-over delays are used. The review turns the single study into a rule you can bank on.
Avellaneda et al. (2025) now lets the sensitivity parameter in the matching law shift with overall payoff rate. This tweak fixes the very breakdowns E first saw under extreme schedules, giving us a modern equation set you can plug into your concurrent-schedule designs.
Why it matters
When you set up concurrent programs—whether for leisure skills, compliance tasks, or token boards—remember clients allocate their time to cut delay, not just to chase more rewards. If one option pays 75% of the time but the other pays instantly after a long wait, the leaner, faster side can still win. Keep payoff rates moderate and delays similar on both alternatives to get clean matching and stable responding.
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02At a glance
03Original abstract
Pigeons' responses in the presence of two concurrently available (initial-link) stimuli produced one of two different (terminal-link) stimuli. The rate of reinforcement in the presence of one terminal-link stimulus was three times that of the other. Three different pairs of identical but independent variable-interval schedules controlled entry into the terminal links. When the intermediate pair was in effect, the pigeons distributed their (choice) responses in the presence of the concurrently available stimuli of the initial links in the same proportion as reinforcements were distributed in the mutually exclusive terminal links. This finding was consistent with those of earlier studies. When either the pair of larger or smaller variable-interval schedules was in effect, however, proportions of choice responses did not match proportions of reinforcements. In addition, matching was not obtained when entry into the terminal links was controlled by unequal variable-interval schedules. A formulation consistent with extant data states that choice behavior is dependent upon the amount of reduction in the expected time to primary reinforcement, as signified by entry into one terminal link, relative to the amount of reduction in expected time to reinforcement signified by entry into the other terminal link.
Journal of the experimental analysis of behavior, 1969 · doi:10.1901/jeab.1969.12-723