Three conceptual units for behavior.

Coleman (1987) lined up three ways to slice behavior into units. The old S-R reflex, Kantor’s behavior segment, and Skinner’s three-term contingency.

The paper judged each unit on clarity, ease of use, and fit with real data. No new experiment was run; it was a conceptual scorecard.

Skinner’s A-B-C won. Antecedent, behavior, consequence gives both description and prediction in one tidy package.

S-R skips the consequence. Kantor adds too many parts. A-B-C keeps things simple and still explains why the response keeps happening.

Capio et al. (2013) extends the story. Pigeons in a matching-to-sample task fit better with a four-term unit that adds a second stimulus. The extra term is not a rejection; it is a zoom-in on conditional discrimination.

Poling et al. (2020) also extends the unit. They split the antecedent into MO and SD parts and show how the two talk to each other. Your A-B-C stays, but now you watch motivation and cues separately.

Kunz et al. (1982) used pigeons to show whole response chains can act as one unit. It backs R’s point: pick the smallest unit that still holds together under reinforcement.

When you write a behavior plan, pick the unit that carries the pay-off. Use A-B-C for most cases. Add a fourth term if the learner must tell two stimuli apart. Track MO–SD splits when reinforcers stop working. Keep the unit small, but don’t leave out the part that matters.