Income maximizing on concurrent ratio-interval schedules of reinforcement.
Short sessions or tiny reinforcers push learners toward ratio schedules—use this to boost response rates when time is tight.
01Research in Context
What this study did
Barnes et al. (1990) let six pigeons pick between two keys. One key needed a set number of pecks (VR). The other key paid off after a set time (VI).
The team then cut the session length or shrank the grain size. They watched how the birds’ choices moved.
What they found
When sessions were short or grain was small, birds pecked the VR key more. They chased the richer payoff to get the most food per minute.
When sessions were long or grain was big, they eased back and split time more evenly.
How this fits with other research
Iwata et al. (1990) ran the same VR-RI comparison with toddlers. The kids also pressed faster on the ratio side, showing the rule crosses species.
HERRNSTEISLOANE (1964) showed pigeons like variable schedules. D’s work adds that the liking grows stronger when food is scarce or time is short.
Clark et al. (1970) found pigeons sometimes pick the leaner periodic schedule. D’s molar view explains why: birds look at total income, not just local rate.
Why it matters
Your client may work harder on a token board (ratio) than on a timer (interval) if session time is tight or if tokens buy only tiny treats. Try shortening the work period or using smaller bites, then watch preference shift toward the ratio task.
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02At a glance
03Original abstract
Three experiments examined the effect of food availability on pigeons' choice behavior under concurrent schedules of reinforcement. In Experiment 1, 3 pigeons earned their daily food ration by choosing, in 30-min sessions, between concurrent variable-ratio 30 variable-interval 40-s schedules. Food presentations during both schedules lasted 2 or 12 s, depending upon the condition. Relative variable-ratio response rate was inversely related to hopper duration. In Experiment 2, 4 pigeons received their daily feeding by responding on the same schedule pair as in Experiment 1 (with 4-s food presentations) in sessions that varied in length from 10 to 30 min, depending on the condition. The length of a vertical slit projected on a response key increased with time so that "passage of time" might be more easily discriminable. As session duration decreased, relative variable-ratio response rate increased. In Experiment 3, 4 pigeons chose between two variable-interval 40-s schedules. One schedule operated without regard to the schedule selected, whereas the other operated only when the subject responded in its presence (dependent). Although these schedules had the same feedback function, preference for the dependent variable interval increased as session duration decreased from 30 to 10 min. The preference changes in these studies reveal the operation of an income-maximizing process in choice.
Journal of the experimental analysis of behavior, 1990 · doi:10.1901/jeab.1990.53-273