Belke, T. W. (2000).
Studies of wheel-running reinforcement: Parameters of Herrnstein's (1970) response-strength equation vary with schedule order.
Journal of the Experimental Analysis of Behavior,
73, 319-331.
Six male Wistar rats were exposed to different orders of
reinforcement schedules to investigate if estimates from
Herrnstein's (1970) single-operant matching law equation would
vary systematically with schedule order. Reinforcement schedules
were arranged in orders of increasing and decreasing
reinforcement rate. Subsequently, all rats were exposed to a
single reinforcement schedule within a session to determine
within-session changes in responding. For each condition, the
operant was lever pressing and the reinforcing consequence was
the opportunity to run for 15 s. Estimates of k and
RO were higher when reinforcement schedules were
arranged in order of increasing reinforcement rate. Within a
session on a single reinforcement schedule, response rates
increased between the beginning and the end of a session. A
positive correlation between the difference in parameters between
schedule orders and the difference in response rates within a
session suggests that the within-session change in response rates
may be related to the difference in the asymptotes. These results
call into question the validity of parameter estimates from
Herrnstein's (1970) equation when reinforcer efficacy changes
within a session.
Key words: tandem fixed-ratio 1 variable-interval schedule,
Herrnstein's single-operant matching law equation, within-session
response patterns, wheel-running reinforcement, lever press, rats