Substitution effects in a generalized token economy with pigeons
Flexible tokens act as backup reinforcers when prized items get pricey, keeping the economy stable.
01Research in Context
What this study did
Andrade et al. (2017) worked with pigeons in a token economy. Birds earned two kinds of tokens. One type bought only food. The other type bought any backup item.
The team then raised the price of the food-only tokens. They watched to see if the birds would swap in the flexible tokens instead.
What they found
When food-only tokens cost more, the birds used more of the any-item tokens. The pigeons treated the flexible tokens as substitutes, just like shoppers switching brands when prices rise.
How this fits with other research
DeFulio et al. (2014) showed the same birds already liked flexible tokens more. The new study asks what happens next—when prices push them away from their favorite.
Tan et al. (2015) mapped the birds’ pecking order: food tokens first, flexible tokens second. The 2017 paper shows that order can flip if costs change.
Hart et al. (1974) doubled bus rides with tokens in a city, proving the idea works with people too. The lab and field studies together say token economies can bend without breaking.
Why it matters
Your client may lose interest if their favorite reinforcer gets hard to earn. Keep a few generalized tokens—stars that trade for any backup—in the mix. When Lego time now costs ten stars instead of five, the child can still buy screen time with the same flexible stars. You avoid meltdowns and keep the system running.
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02At a glance
03Original abstract
Pigeons made repeated choices between earning and exchanging reinforcer-specific tokens (green tokens exchangeable for food, red tokens exchangeable for water) and reinforcer-general tokens (white tokens exchangeable for food or water) in a closed token economy. Food and green food tokens could be earned on one panel; water and red water tokens could be earned on a second panel; white generalized tokens could be earned on either panel. Responses on one key produced tokens according to a fixed-ratio schedule, whereas responses on a second key produced exchange periods, during which all previously earned tokens could be exchanged for the appropriate commodity. Most conditions were conducted in a closed economy, and pigeons distributed their token allocation in ways that permitted food and water consumption. When the price of all tokens was equal and low, most pigeons preferred the generalized tokens. When token-production prices were manipulated, pigeons reduced production of the tokens that increased in price while increasing production of the generalized tokens that remained at a fixed price. The latter is consistent with a substitution effect: Generalized tokens increased and were exchanged for the more expensive reinforcer. When food and water were made freely available outside the session, token production and exchange was sharply reduced but was not eliminated, even in conditions when it no longer produced tokens. The results join with other recent data in showing sustained generalized functions of token reinforcers, and demonstrate the utility of token-economic methods for assessing demand for and substitution among multiple commodities in a laboratory context.
Journal of the Experimental Analysis of Behavior, 2017 · doi:10.1002/jeab.231