Choice, changeover, and travel: A quantitative model.
Travel time during choice acts like subtractive punishment—lost reinforcers predict the shift away from longer changeover delays.
01Research in Context
What this study did
The team used two levers that delivered food on variable-interval schedules. Pigeons switched between the levers, but each switch started a fixed-time lockout called a changeover delay.
They slowly raised the lockout from 0 to 20 seconds across conditions. The goal was to see how extra 'travel time' changed the birds' preference for the richer side.
What they found
Going from 0 to 10 seconds made the birds' choices almost perfectly match the real payoff ratios. Pushing the delay to 20 seconds gave no extra benefit.
The data fit a subtractive-punishment model: the lockout simply removed reinforcers, so the birds acted as if those missing rewards had never existed.
How this fits with other research
Martens et al. (1989) showed the same matching law works for a girl's disruptive and on-task behavior in class. Both studies keep the math but swap pigeons for people.
Jason et al. (1985) and VanHouten et al. (2022) changed real-world contingencies—traffic-light timing and city-wide yielding—and saw big jumps in driver compliance. Their reversals echo the lab reversal here, proving schedule tweaks scale beyond cages.
Robinson et al. (2019) found that letting tokens accumulate, not frequent small payouts, boosted work for students with ADHD. That lines up with the current view: delays that block or bunch reinforcers shift behavior in predictable, quantifiable ways.
Why it matters
You can now treat transition time as lost reinforcement when you set up concurrent schedules in classrooms or clinics. If a student must wait 10 s to move from one task to another, expect choice to drift toward the richer side exactly as the matching equation says. Keep the wait under 10 s unless you need the extra control—longer buys you nothing.
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02At a glance
03Original abstract
Six pigeons were trained on concurrent variable-interval schedules in which responding on fixed-interval schedules was required to give access to the alternate schedule. Responding on the concurrent schedules was not allowed, after changing over had commenced, until the changeover schedule had been completed. In Parts 1 to 3 of the experiment, the changeover fixed-interval schedules were equal and were 0 s, 10 s, and 20 s, respectively. In each part, the relative frequency of reinforcement obtained on the concurrent schedules was varied over at least five conditions. In Part 4, the concurrent schedules were equal, and one changeover fixed-interval schedule was twice the other. Under these conditions, the absolute sizes of the changeover schedules were varied. Increasing the changeover requirement from 0 s to 10 s (Parts 1 and 2) resulted in increases in the sensitivity of behavior allocation to reinforcers obtained, but no further increase was obtained when the changeover schedules were increased to 20 s (Part 3). In Part 4, performance was biased towards the concurrent schedule that took less time to enter. These results are consistent with a subtractive punishment model of travel in which the degree of punishment is measured by the number of reinforcers apparently lost from a schedule when the subject changes to that schedule. Absolute times spent on the main keys could be accurately described by a previous model of changeover performance.
Journal of the experimental analysis of behavior, 1991 · doi:10.1901/jeab.1991.55-47