DISCRIMINATIVE FUNCTIONS BASED ON A DELAY IN THE REINFORCEMENT RELATION.

CHUNG (1965) worked with three pigeons in a small lab chamber.

A red or green light came on. The bird had to peck the key.

Food never arrived right away. A short chain of other pecks had to finish first.

The team asked: can the color still control pecking when it is split from food by extra work?

All birds learned to peck fast on the food color and slow on the no-food color.

When the colors were swapped, the birds swapped their speed in only a few sessions.

Stimulus control held even though the real food came many seconds after the cue.

McGrother et al. (1996) saw the same thing in a different way. Their pigeons told methadone from cocaine without any extra training. Both studies show cues can gain power even when the payoff is delayed or never directly linked.

Blanchard et al. (1979) looked at compound cues. They found weak parts of a good cue gained power, but weak parts of a bad cue did not turn the birds off. CHUNG (1965) adds the time gap; together they show both what the cue looks like and when it appears matter.

Retzlaff et al. (2017) used rich-to-lean switches. Birds tried to escape the lean signal, proving it had become aversive. CHUNG (1965) shows the same gap can still build good control if the final food stays reliable.

Your client may finish several tasks before the reinforcer arrives. This paper says the last cue before the work still drives behavior, so keep that cue clear and consistent. If you need to reverse a discrimination, do it; the learner can switch fast.