Multiple Schedules of Time-Correlated Reinforcement.

Hearst (1960) built a new kind of schedule. Instead of waiting for a set number of presses or a set time, the machine delivered food during short windows that came and went on a clock. The windows were brief and repeated in a pattern.

The animal could press at any time, but only presses inside the window paid off. No ratio or interval rule was ever in force. The goal was to see if these time windows alone could create the same response patterns we see on true ratio or interval schedules.

Without ever asking for a fixed number of presses, the rats still produced the fast burst typical of ratio schedules. The pattern looked like FR even though the schedule never counted responses.

The study showed that brief, clock-based reinforcement windows can generate both interval and ratio response shapes. Schedule control does not always need the usual ratio or interval definition.

Mechner (1958) had described FR bursts in theory two years earlier, but only as a rule-based schedule. Hearst (1960) later proved the same burst can appear when the only rule is a short time window, updating the field’s view of what creates ratio patterns.

Kelley et al. (2023) recently used the same window idea in therapy. They signaled brief “reinforcement available” periods at the start of noncontingent reinforcement so clients could tell when praise was free. Thinning went faster and problem behavior stayed low, showing the 1960 lab trick still works with children in clinics.

Mazur (1983) later ran steady FR and RR schedules and found the burst rate stays the same across ratio types. This supports Hearst (1960): the burst is a core ratio trait, whether the schedule is true ratio or time-correlated.

You can use brief, signaled time windows to shape ratio-like responding without counting responses. In treatment, this means you can thin reinforcement quickly by telling the client “points are only available during this short green light.” In skill teaching, you can create fast, steady work bursts by delivering praise in short, predictable windows instead of after every fifth response. The schedule feels ratio to the learner, but you avoid strict ratio requirements that might evoke ratio strain.