Control of responding during stimuli that precede transitions in reinforcement frequency.

Researchers worked with pigeons in a small lab study. They wanted to see if birds would peck at a light that only appeared before food became available.

The light never gave food directly. It just showed up seconds before the schedule switched from no food to occasional food. The team varied how long this "trace" light stayed on.

The pigeons pecked the non-reinforced light. Pecking dropped when the light lasted longer. Surprisingly, how much food came later did not change pecking rate.

Even though the light itself never produced food, it gained control over the birds' responses. Closer temporal proximity to food meant stronger responding.

Skrtic et al. (1982) also saw control fade with longer gaps. They tested memory for two colored keys and found accuracy fell as delays grew from 1 to 9 seconds. Both studies show time weakens stimulus control.

Poling et al. (1977) proved pigeons can learn from stimuli that are never reinforced. Their birds kept pecking during extinction when compound cues signaled food later. Aman et al. (1987) extends this by showing the same happens with pure trace stimuli.

Mandell (1984) asked whether pigeons notice how often food arrives. They could discriminate different rates when food itself was the cue. Aman et al. (1987) differs: the cue was separate from food, and upcoming rate did not matter.

When you chain instructions or signals, remember that control can develop even if the cue is never rewarded. Keep the delay between cue and reinforcement short to maintain strength. If a child responds to your prompt before the reinforcer appears, don't worry — it's normal stimulus control, not faulty timing.