Kelleher (1956) also compared different types of schedules of reinforcement (i.e., ratio
vs. interval schedules). He trained chimpanzees to press a lever in order to receive tokens on
both a fixed ratio schedule and a fixed interval schedule. He found that responding under both
the FR and FI token schedules were similar to what one would expect under FR and FI simple
schedules of reinforcement: a break-run pattern and a scallop effect were observed in the FR
schedules and the FI schedules respectively