Token reinforcement, choice, and self-control in pigeons.
In token economies, the wait to exchange drives choice more than the wait to earn.
01Research in Context
What this study did
Kirkpatrick-Steger et al. (1996) worked with pigeons in a lab. The birds earned LED tokens first. Later they traded tokens for food. The team made the wait to trade longer or shorter. They watched which wait changed the birds' choices more.
The question: does the delay until you get the token matter most, or the delay until you can spend it?
What they found
The pigeons cared most about how long they had to wait to exchange tokens. When the exchange delay was the same, they switched their picks. The delay to earn the token had less pull on choice.
In short, the clock that starts after you earn the token is the one that guides self-control.
How this fits with other research
Grindle et al. (2012) later tested people and pigeons. With instant exchange, both species picked the sequence that paid first. Their data extend K et al.'s finding: once exchange is fast, early payoff wins.
Hamilton et al. (1978) showed that slowly fading in a long wait can push pigeons toward the bigger later reward. That seems to clash with K et al., but the methods differ. E et al. shaped delay tolerance step-by-step, while K et al. jumped straight to set delays. The takeaway: you can train patience, but abrupt long waits still hurt.
Cullinan et al. (2001) used the same token setup and varied how many responses were needed to trade. They found variable-ratio exchange kept birds working harder. Together the papers show both exchange delay and exchange effort steer choice.
Why it matters
For your token board, schedule the trade-in time carefully. A short, steady wait to cash in keeps learners sticking with the big goal. If you must stretch the delay, fade it in slowly—don't jump. And mix up the number of tokens needed; it beats a fixed count for steady work.
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02At a glance
03Original abstract
Pigeons were exposed to self-control procedures that involved illumination of light-emitting diodes (LEDs) as a form of token reinforcement. In a discrete-trials arrangement, subjects chose between one and three LEDs; each LED was exchangeable for 2-s access to food during distinct posttrial exchange periods. In Experiment 1, subjects generally preferred the immediate presentation of a single LED over the delayed presentation of three LEDs, but differences in the delay to the exchange period between the two options prevented a clear assessment of the relative influence of LED delay and exchange-period delay as determinants of choice. In Experiment 2, in which delays to the exchange period from either alternative were equal in most conditions, all subjects preferred the delayed three LEDs more often than in Experiment-1. In Experiment 3, subjects preferred the option that resulted in a greater amount of food more often if the choices also produced LEDs than if they did not. In Experiment 4, preference for the delayed three LEDs was obtained when delays to the exchange period were equal, but reversed in favor of an immediate single LED when the latter choice also resulted in quicker access to exchange periods. The overall pattern of results suggests that (a) delay to the exchange period is a more critical determinant of choice than is delay to token presentation; (b) tokens may function as conditioned reinforcers, although their discriminative properties may be responsible for the self-control that occurs under token reinforcer arrangements; and (c) previously reported differences in the self-control choices of humans and pigeons may have resulted at least in part from the procedural conventions of using token reinforcers with human subjects and food reinforcers with pigeon subjects.
Journal of the experimental analysis of behavior, 1996 · doi:10.1901/jeab.1996.66-29