Procurement time as a determinant of meal frequency and meal duration.
Time spent waiting functions like money: longer waits cut how often behavior occurs but make each bout bigger.
01Research in Context
What this study did
The team built a tiny foraging game for eight rats.
To earn each food pellet the rat first waited a set number of seconds.
The wait could be 2, 4, 8, 16, 32, or 64 seconds.
After the wait the rat could eat as much as it wanted before starting again.
The scientists watched how often the rats started meals and how big each meal was.
What they found
When the wait grew longer the rats ate fewer meals.
Each meal became larger so total daily food stayed the same.
Time worked like a price: higher cost made the rats bunch their eating into fewer sittings.
How this fits with other research
Fraley (1998) later saw the same pattern with pigeons.
Birds faced longer fixed-interval response delays and also grouped work into fewer, longer bouts.
Eisenmajer et al. (1998) looked at the flip side: unsignaled 3-s delays after each peck.
Those short, hidden delays still slashed response rates and made behavior fragile.
Together the three studies show any kind of delay—before or after the response—acts as a cost that shrinks the number of times an animal is willing to try.
Why it matters
Your client may face hidden delays: staff walk to the cabinet, open packages, or chat between trials.
Each extra second quietly raises the cost of working.
Expect fewer initiations, longer breaks, and bigger bursts of responding when reinforcement finally arrives.
Cut dead time to keep response rates steady—have edibles pre-portioned, deliver fast, or signal the wait so the learner knows when to try again.
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Pre-load a small cup with the exact number of edibles and keep it within arm’s reach to shrink delivery time under one second.
02At a glance
03Original abstract
Foraging involves the expenditure of both time and effort in the acquisition of food; animals typically modify their meal patterns so as to reduce these expenditures or costs. The contribution of time, as compared with effort, to the overall cost perceived by an animal is not known. We investigated the effect of foraging time as a cost independent of effort by measuring the meal patterns of rats living in a laboratory foraging simulation in which they earned all their daily intake. They pressed a bar once to initiate an interval (procurement interval) leading to the presentation of a large cup of food from which they could eat a meal of any size. As the length of the interval increased from 1 s to 46 hr, meal frequency decreased regularly. Meal size increased in a compensatory fashion, and total daily intake was conserved through an interval of 23 hr. The changes in meal frequency occurred because of changes in the rat's latency to bar press after each meal. The functions relating meal frequency and size to the procurement interval were of the same shape as those seen when cost is the completion of a bar-press requirement, which entails the expenditure of both effort and time. When the bar-press requirement was increased to 10, meal frequency was reduced, but time and effort did not appear to simply add together in the rat's perception of cost. These data reveal that time is preceived to be a cost by rats foraging in this laboratory environment. These results suggest that the time parameters of foraging are different from those of consumption.
Journal of the experimental analysis of behavior, 1995 · doi:10.1901/jeab.1995.63-295