The results of Kelleher’s (1956) study were replicated by Waddell, Leander, Webbe, and
Malagodi (1972) with rats as subjects. In this study, the rats were on an FR 1 (FR 20) schedule
of reinforcement for lever pressing. Following the FR 1 (FR 20) schedule, lever pressing was
reinforced on an FR 2 (FR 20) and finally an FR 3 (FR 20) schedule. After the FR schedules, the
rats were placed on an FI schedule of token exchange, ranging from 1.5 to 9 minute intervals.
Waddell et al. noticed similar effects as Kelleher when comparing FR and FI schedules. In
addition, they found that pauses in responding increased as the exchange schedule increased,
demonstrating that responding is dependent on both the production and the exchange schedules
of reinforcement and that these changes in responding are similar to simple schedules of
reinforcement.