On the minimal conditions for the development of a peak-shift and inhibitory stimulus control.

Brinker et al. (1975) worked with pigeons that had learned to peck a key for food. First they gave massed extinction until pecking almost stopped. Then they added a quick 3-minute break with one of three simple changes: food again, no food, or free food with no peck needed.

After the short break they tested how the birds responded to colors close to the training color. They wanted to know if this tiny event could create peak-shift and strong inhibitory control without long contrast histories.

Every 3-minute change produced peak-shift. The birds pecked most at a color pulled away from the original training color. They also showed strong inhibition near the old unreinforced color.

The result was the same whether the break gave food, no food, or free food. Just stopping extinction for three minutes was enough to sharpen stimulus control.

Baer (1974) showed that massed extinction alone can steepen generalization gradients. P et al. add one small step: a 3-min interpolated event right after extinction. This tiny pause flips the gradient into a peak-shift.

Schmidt et al. (1969) got peak-shift by making reinforcement duration cues stand out during training. P et al. prove you do not need fancy training. A short break after extinction does the job.

Ginsburg et al. (1971) found that longer extinction creates bigger contrast. P et al. show the opposite angle: after extinction, even a brief change can reset control.

You can create clear peak-shift and tight stimulus control without extra training or long contrast histories. After an extinction session, simply insert a brief change of any kind—maybe a quick snack break or a shift to non-contingent reinforcement. This small move can sharpen discrimination and reduce errors when you probe new stimuli. Try it next time you need to tighten stimulus control fast.