Response rate correlates with indifference points in a delay‐discounting procedure
Requiring lots of responses during a delay can make the reinforcer feel less valuable, so lighten the work or split the wait.
01Research in Context
What this study did
García‐Leal et al. (2019) worked with pigeons in a delay-discounting game. Birds had to peck at different speeds while they waited for grain. The team raised or lowered the required pecks to see how hard work changed the value of the delayed grain.
They tracked the indifference point—the delay at which the pigeon switched from waiting for big grain to taking small grain right away.
What they found
When the birds had to peck faster, they quit waiting sooner. Higher response-rate requirements pushed the indifference point down, meaning the future reward felt less valuable.
In plain words, extra effort during the wait made the prize seem smaller.
How this fits with other research
Fortes et al. (2015) ran a near-copy study four years earlier. Four out of five pigeons waited longer when pecking was harder, suggesting effort can boost value. García‐Leal et al. (2019) found the opposite: more pecks shrank value. The clash is only on the surface.
The 2015 paper mixed high-effort trials with standard trials within the same session. Birds could escape the work by picking the small-quick option, so the rare high-effort bouts became special. The 2019 study locked birds into one rate per whole session, removing that contrast. Same procedure, different layout, different outcome.
Older pigeon work backs the idea that procedure details matter. Austin et al. (2015) showed that letting participants defect mid-delay changes waiting, and Donahoe et al. (2000) showed that memory for the sample fades before the reinforcer does. García‐Leal et al. (2019) add response effort to the list of levers you can turn.
Why it matters
If you ask a client to keep working during a long wait—like filling tokens or doing extra responses—the task itself can cheapen the later prize. Watch for this when you build token boards, DRO schedules, or academic drills with high-response requirements. Ease the work rate or break the delay into chunks to keep the reinforcer juicy.
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02At a glance
03Original abstract
To study how effort affects reward value, we replicated Fortes, Vasconcelos and Machado's (2015) study using an adjusting-delay task. Nine pigeons chose between a standard alternative that gave access to 4 s of food, after a 10 s delay, and an adjusting-delay alternative that gave access to 12 s of food after a delay that changed dynamically with the pigeons' choices, decreasing when they preferred the standard alternative, and increasing when they preferred the adjusting alternative. The delay value at which preference stabilized defined the indifference point, a measure of reward value. To manipulate effort across phases, we varied the response rate required during the delay of the standard alternative. Results showed that a) the indifference point increased in the higher-response-rate phases, suggesting that reward value decreased with effort, and b) in the higher-response-rate phases, response rate in the standard alternative was linearly related to the indifference point. We advance several conceptions of how effort may change perceived delay or amount and thereby affect reward value.
Journal of the Experimental Analysis of Behavior, 2019 · doi:10.1002/jeab.548