Unit price and choice in a token-reinforcement context.
Lower unit price and faster exchange create strong preference in token systems.
01Research in Context
What this study did
Researchers used pigeons to test how unit price guides token choices. Birds pecked for colored tokens on fixed-ratio schedules. They then traded tokens for food at two exchange counters that differed in cost or delay.
What they found
Pigeons almost always picked the counter with the lower unit price. When both counters cost the same, they chose the one that paid faster. The birds acted as if they weighed price plus immediacy.
How this fits with other research
Rutherford et al. (2003) ran a similar pigeon token task the year before. They showed that birds care about both how soon the token arrives and how soon the food follows. Burack et al. (2004) folded those two delays into one unit-price formula.
Matson et al. (2008) kept the same price rules but asked how many tokens birds would hoard. Higher production ratios cut hoarding, just as the unit-price model predicts.
Tan et al. (2015) and Andrade et al. (2017) kept the price idea but swapped in different backup reinforcers. Birds still followed price: they switched to cheaper or generalized tokens when the preferred ones got expensive.
Why it matters
Token economies obey simple cost rules, even with animals. Lower response cost and faster exchange drive near-exclusive preference. When you set up classroom or clinic token boards, keep the price low and the payoff quick. If you must raise the price, offer generalized back-ups so learners can still "shop" economically.
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02At a glance
03Original abstract
Pigeons were exposed to multiple and concurrent second-order schedules of token reinforcement, with stimulus lights serving as token reinforcers. Tokens were produced and exchanged for food according to various fixed-ratio schedules, yielding equal and unequal unit prices (responses per unit food delivery). On one schedule (termed the standard schedule), the unit price was held constant across conditions. On a second schedule (the alternative schedule), the unit price was either the same or different from the standard. Under conditions with unequal unit prices, near-exclusive preference for the lower unit price was obtained. Under conditions with equal unit prices, the direction and degree of preference depended on ratio size (number of responses per exchange period). When this ratio differed, strong preferences for the smaller ratio were observed. When this ratio was equal, preferences were nearer indifference. Response rates on the multiple schedule were generally consistent with the preference data in showing sensitivity to ratio size. Results are discussed in terms of a unit-price model that includes handling and reinforcer immediacy as additional costs. On the whole, results show that preferences were determined primarily by delay to the exchange period.
Journal of the experimental analysis of behavior, 2004 · doi:10.1901/jeab.2004.81-5