B.1 · Behavior Assessment

Preference assessments

Review how choices and engagement are recorded in paired-stimulus, free-operant and multiple-stimulus-without-replacement assessments under a supervisor’s protocol. Examples distinguish relative preference from evidence that a consequence increases future responding.

Task B.1: Conduct preference assessments

The rule

Identify a preference assessment by how choices are arranged and recorded. Establish a reinforcer by measuring its effect on future responding.

Look for simultaneous pairs, free access over time, or an array that shrinks after selections. Follow the supervisor’s protocol, including access periods and how refusals are recorded.

Key terms
MSWO
Multiple stimulus without replacement: selected items are removed from subsequent choice arrays.
Reinforcer
A consequence shown to increase the future behavior it follows.

What to look for

DistinctionLook forHow to decide
Paired stimulusTwo items presented at a timeRecord selections across the scheduled pairs.
Free operantSeveral available activities without repeated choice trialsMeasure engagement while free access continues.
MSWOSeveral items; selected item is removed for later choicesRecord the selection order without replacing selected items.
Preference versus reinforcementSelection versus future response changeTreat a preferred item as a candidate reinforcer and evaluate its effect on responding.

Worked examples

Paired stimulus and MSWO

Watch what happens after a choice

In one assessment, an RBT presents a puzzle and a spinner, then the puzzle and crayons, then the spinner and crayons according to a schedule. In a second assessment, all three appear together. After each selection and brief access, the selected item is removed and the remaining items are rearranged.

Relevant facts

  • The first procedure uses scheduled pairs.
  • The second starts with an array and removes each selected item from subsequent choices.

First: paired stimulus. Second: multiple stimulus without replacement (MSWO).

Two at a time versus a shrinking array

Use the initial choice arrangement together with the removal and replacement rules to identify the procedure. MSWO removes selected items from subsequent arrays.

Free operant and reinforcer evidence

Separate engagement from effect

During a five-minute free-access observation, Theo spends three minutes with blocks, one with drawing materials and one with neither. The RBT does not remove activities or repeatedly ask for a choice.

Relevant facts

  • Activities remain continuously available throughout the observation.
  • Blocks receive the most observed engagement.

This is free-operant preference assessment; blocks are a candidate reinforcer.

More engagement with blocks → evidence of relative preference

The three minutes with blocks measure engagement. To demonstrate reinforcement, the supervisor would evaluate whether contingent access increases a specified future response.

What changes the answer?

Keep blocks as the most-engaged activity. Change the evidence available.

  • The learner spends more time with blocks than drawing materials.

Only engagement was measured.

Report preference.

The observations describe engagement. Evaluating reinforcement requires measuring the effect on a target response.

Contingent block access reliably increases the target response.

That additional evidence supports reinforcement.

The conclusion concerns an observed behavior change.

Choosing something and having it strengthen another behavior are different findings.

Remember

  • Identify the arrangement before naming the assessment.
  • Preference suggests what to evaluate; reinforcement requires an effect.
Sources for this topic

Reviewed 2026-09-30 · B.1 version 3.