Response specificity in animal timing.

Northup et al. (1991) watched pigeons in a peak-timing box. Birds could peck two keys at any moment. Food arrived only after 20 seconds of steady pecking. The team asked: do the birds track the 20-second rule, or do they copy their own past peck rhythm?

They ran a single-case design and switched the required response pattern between sessions. The birds’ timing stayed put, but the exact peck style also mattered.

Neither factor won. The pigeons used both the clock and their favorite way of pecking. When the two cues clashed, the data landed in the middle—an inconclusive split decision.

Rutter et al. (1987) saw the same tug-of-war earlier: stimulus cues and reinforcer cues pulling together. Their birds also showed mixed control, so the 1991 result is a close cousin, not a shock.

Cippola et al. (2014) moved the question to college students. People picked undefined choices after odd durations, proving temporal cues alone can drive exclusion. This extends the pigeon work to humans and shows the effect survives across species.

Aman et al. (1987) found pure stimulus control with trace stimuli, a clean positive finding. Northup et al. (1991) looks messier, but the tasks differ: trace gives clear signals, while peak lets cues overlap. The studies don’t clash; they map different points on the same control spectrum.

For BCBAs, the lesson is to watch both the clock and the child’s unique response style. When teaching a learner to wait two minutes before touching a toy, check if they also rely on a special hand wave or foot tap. If progress stalls, shift one cue—change the time, the movement, or both—then measure again.