McFarland, J. M., & Lattal, K. A. (2001).
Determinants of reinforcer accumulation during an operant task.
Journal of the Experimental Analysis of Behavior,
76, 321-338.
Responses by rats on an earn lever made available food pellets
that were delivered to a food cup by responses on a second,
collect, lever. The rats could either collect and immediately
consume or accumulate (defined as the percentage of multiple earn
responses and as the number of pellets earned before a collect
response) earned pellets. In Experiment 1, accumulation varied as
a function of variations in the earn or collect response
requirements and whether the earn and collect levers were
proximal (31 cm) or distal (248 cm) to one another. Some
accumulation occurred under all but one of the conditions, but
generally was higher when the earn and collect levers were distal
to one another, particularly when the earn response requirement
was fixed-ratio (FR) 1. In Experiment 2, the contributions of
responses and time to accumulation were assessed by comparing an
FR 20 earn response requirement to a condition in which only a
single earn response was required at the end of a time interval
nominally yoked to the FR interval. When 248 cm separated the
earn and collect levers, accumulation was always greater in the
FR condition, and it was not systematically related to
reinforcement rate. In Experiment 3, increasing the earn response
requirement with a progressive-ratio schedule that reset only
with a collect response increased the likelihood of accumulation
when the collect and earn levers were 248 cm apart, even though
such accumulation increased the next earn response requirement.
Reinforcer accumulation is an understudied dimension of operant
behavior that relates to the analysis of such phenomena as
hoarding and self-control, in that they too involve accumulating
versus immediately collecting or consuming reinforcers.
Key words: accumulation, distance, travel, response requirements,
effort, lever pressing, rats