ABA Fundamentals

Probability and radical behaviorism.

Espinosa (1992) · The Behavior analyst 1992
★ The Verdict

Treat each response as a coin flip to turn vague statements about probability into countable data.

✓ Read this if BCBAs who run free-operant sessions and want a quick metric for reinforcement density.
✗ Skip if Clinicians working only with ratio or interval schedules that already preset probability.

01Research in Context

01

What this study did

Davison (1992) asked a simple question. What do we mean when we say a rat's bar press has a a large share chance of payoff?

The paper builds a math tool. It treats each peck or press as a coin flip. Heads equals reinforcement. Tails equals extinction.

The author shows how to read a cumulative record like a running scoreboard of these coin flips.

02

What they found

Probability is just the count of reinforcers divided by total responses. Nothing lives inside the bird or rat.

The same math works for both reinforcement and extinction. You only change the coin's bias.

This gives BCBAs a ruler. You can now say, 'Today the coin landed on reinforcement a large share of the time.'

03

How this fits with other research

Coe et al. (1997) tested the idea with real pigeons. The birds picked the least common stimulus above chance. Their data fit the coin-flip model.

Jarmolowicz et al. (2021) push the same theme forward. They ask for applied quantitative analysis of behavior, echoing M's call for numbers in daily practice.

Crossman et al. (1985) add a twist. They say generalization is quantal, not smooth. M's coin-flip view is also quantal, each response is a discrete hit or miss.

04

Why it matters

Stop guessing about motivation. Start counting. Track every response and its consequence for one session. Turn the totals into a simple percentage. Share that number with your team and parents. It gives a clear, math-based picture of how the contingency is working right now.

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→ Action — try this Monday

Tally responses and reinforcers for one client, post the percentage on the data sheet.

02At a glance

Intervention
not applicable
Design
theoretical
Finding
not reported

03Original abstract

The concept of probability appears to be very important in the radical behaviorism of Skinner. Yet, it seems that this probability has not been accurately defined and is still ambiguous. I give a strict, relative frequency interpretation of probability and its applicability to the data from the science of behavior as supplied by cumulative records. Two examples of stochastic processes are given that may model the data from cumulative records that result under conditions of continuous reinforcement and extinction, respectively.

The Behavior analyst, 1992 · doi:10.1007/BF03392585