Periodicities within a fixed-interval session.

The team watched rats press a lever on a fixed-interval 60-second schedule. Each rat could press only once per interval. The researchers tracked how long the rat waited after food before pressing again.

They ran many sessions to see if the single-response rule changed the usual pause pattern.

When the rat was locked out after one press, the next pause got shorter. The usual scallop shape stayed, but the break point moved earlier.

Restricting responses shaved about 5-8 seconds off the post-reinforcement pause.

Spanoudis et al. (2011) later added free food deliveries to a fixed-interval schedule with human workers. They also saw timing shift, but the extra food kept responding alive. Both studies show that what happens between food moments can bend the pause.

WEINELong (1963) found hungry rats on variable-interval schedules sped up overall but kept their own idiosyncratic rhythm. The 1979 paper narrows the lens: timing tweaks come from response limits, not just hunger or schedule richness.

Szempruch et al. (1993) showed pigeons track the most recent interfood interval. The 1979 rat data line up—animals use the last cycle to set the next pause, and a forced one-response rule is one more cue they fold in.

If you run fixed-interval probes to test motivation or skill, know that limiting the client to one response per interval can quietly shorten the wait time. This may hide true pause problems or make fluency look better than it is. Try keeping the response window open when you want a pure measure of post-reinforcement pause.