Lever holding under free-operant avoidance.

Rats pressed a lever to avoid mild shock. The longer they waited between presses, the closer the next shock got.

The team watched two things: how fast the rats pressed, and how long they held the lever down. They wanted to know if hold time could serve as a new yardstick for avoidance strength.

When the warning time before shock grew longer, the rats pressed more slowly. At the same time, each hold of the lever grew longer.

Surprise: the total seconds the lever stayed pressed each session stayed almost the same. Hold time acted like a hidden clock that keeps the session balance steady.

Catania et al. (1966) ran the same shock schedule one year earlier and saw the same drop in press rate, but they never looked at hold time. Bloomfield (1967) adds the missing piece.

Reberg et al. (1979) later split the warning time into press-to-shock and release-to-shock parts. They showed you can dial hold time up or down by changing just the press interval, proving the 1967 pattern is controllable.

Hineline et al. (1970) tried to explain why total hold stays flat. They pitted two big theories against each other and found neither fit perfectly, so the steady clock idea still stands.

If you run avoidance or escape tasks, track how long the learner keeps the response engaged, not just how often it happens. A stable hold time can signal steady motivation even when rate drifts. Next time you adjust warning intervals, watch for this hidden constant—it may tell you more than frequency alone.