Jacobs, E. A., & Hackenberg, T. D. (2000).
Human performance on negative slope schedules of points exchangeable for money: A failure of molar maximization.
Journal of the Experimental Analysis of Behavior,
73, 241-260.
Panel pressing was generated and maintained in 5 adult humans by
schedules of points exchangeable for money. Following exposure to
a variable-interval 30-s schedule and to a linear
variable-interval 30-s schedule (which permitted points to
accumulate in an unseen "store" in the absence of
responding), subjects were exposed to a series of conditions with
a point-subtraction contingency arranged conjointly with the
linear variable-interval schedule. Specifically, points were
added to the store according to the linear-variable interval 30-s
schedule and were subtracted from the store according to a ratio
schedule. Ratio value varied across conditions and was determined
individually for each subject such that the subtraction
contingency would result in an approximately 50% reduction in the
rate of point delivery. Conditions that included the subtraction
contingency were termed negative slopeschedules because
the feedback functions were negatively sloped across all response
rates greater than the inverse of the variable-interval schedule,
in this case, two per minute. Overall response rates varied
inversely with the subtraction ratio, indicating sensitivity to
the negative slope conditions, but were in excess of that
required by accounts based on strict maximization of overall
reinforcement rate. Performance was also not well described by a
matching-based account. Detailed analyses of response patterning
revealed a consistent two-state pattern in which bursts of
high-rate responding alternated with periods of prolonged
pausing, perhaps reflecting the joint influence of local and
overall reinforcement rates.
Key words: maximization, matching, feedback functions,
variable-interval schedules, negative slope schedules, panel
press, adult humans