Spatially extended instrumental responses are organized in functional bouts
Reinforcement parameters, not lever proximity, control how long rats stay in a response bout.
01Research in Context
What this study did
Gildea et al. (2025) watched rats press a lever for food.
They changed the fixed-ratio size, food deprivation level, and later removed food.
The team asked: do rats stay near the lever because it is close, or because food keeps the bout going?
What they found
Bouts grew longer when the ratio got bigger and when the rats were hungrier.
When food stopped, bouts shrank fast.
Space mattered little; reinforcement ruled the bout.
How this fits with other research
Lemons et al. (2015) already showed bigger FR-5 ratios make bouts longer.
Gildea et al. (2025) extend that idea by proving the cause is reinforcement, not where the rat lands.
Smith et al. (2014) saw the same reinforcement rule in pigeons with a change-over delay.
Together, the three papers say: across species and tasks, bouts flex with the pay-off, not with simple distance.
Why it matters
If bouts answer to reinforcement, you can stretch or shorten them by tweaking the schedule.
Try thinning a ratio only after the client runs a steady 3-press bout, then watch the bout grow.
You now have a built-in meter for reinforcement strength in any chained task.
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02At a glance
03Original abstract
Instrumental behavior is typically organized into bouts, with distinct behavioral processes seemingly governing within-bout response rate, bout-initiation rate, and bout length. This organization, however, may instead arise simply from the spatial proximity of the organism to the operandum at the end of each response. Two experiments used rats to test the organization of spatially extended instrumental responses into bouts and the sensitivity of bout parameters to critical manipulations. In Experiment 1, rats consecutively pressed two levers located on either side of an operant chamber, reinforced on a tandem variable-time (VT) 150-s fixed-ratio (FR) 1 schedule (Phase 1). The FR requirement was then increased (Phase 2) before food restriction was reduced (Phase 3). In Experiment 2, reinforcement was contingent on pressing a single lever or alternating between two levers in alternating multiple-schedule components. Lever pressing was then extinguished in both components. Regardless of topography, responses were organized in bouts (Experiments 1 and 2). Higher FR requirements increased bout length (Experiment 1), and the response-alternation requirement reduced within-bout response rate (Experiment 2). Both manipulations, along with reduced deprivation and extinction, reduced bout-initiation rates. These results rule out the possibility that bouts of responses emerge from the spatial proximity of terminating and initiating operants.
Journal of the Experimental Analysis of Behavior, 2025 · doi:10.1002/jeab.70058