Concurrent fixed-ratio fixed-interval performances in adult human subjects.

Two undergraduate males worked for money on a button-pressing task associated with concurrent fixed-ratio fixed-interval schedules of reinforcement. Manipulations of the fixed-ratio requirement produced an interaction between the various fixed-ratio and fixed-interval performances. When the fixed ratio was small, more fixed-interval responding occurred per interval than when the fixed ratio was large. In general, the data were similar to those obtained with lower organisms except that no post-reinforcement pause or ratio strain was seen.