B.1 Preference assessments
A preference assessment is a structured way to find out which items, foods, activities, or social interactions a client prefers, so the supervisor can choose likely reinforcers for teaching and behavior plans. RBTs run these assessments by following the supervisor's protocol exactly, recording the client's choices or engagement, and summarizing the results. Preference shows what a client chooses; it does not by itself prove an item will reinforce behavior.
What the outline says
Task B.1 in content area B, Behavior Assessment (8 of the 75 scored questions): "Conduct preference assessments (e.g., multiple stimulus, paired stimulus, free operant)."
Why preference assessments matter
A consequence is a reinforcer only if it increases the behavior it follows, and items a client does not value rarely do that. Guessing ("most kids like stickers") or relying only on what others report often misses the mark. Preference assessments give the team objective data on what this particular client chooses right now.
Preferences are not fixed. Satiation (recent, extended access) temporarily lowers an item's value, and deprivation (going without) temporarily raises it. A tablet that ranks first in the morning may rank lower after the client has used it all through lunch. That is why many teams run brief assessments often, sometimes right before a session.
A preferred item is a likely reinforcer, not a guaranteed one. A reinforcer assessment, in which the item is delivered contingent on a response to see whether the response increases, tests whether it actually works. If a top-ranked item is not increasing correct responding in a program, the RBT reports the data to the supervisor.
Indirect and direct methods
Indirect methods ask rather than observe: interviewing caregivers, giving surveys or checklists, or asking a client who can answer. They are quick and a good place to start, but reports do not always match what a client actually picks.
Direct methods present the real items and record what the client does. The main direct formats follow.
The main direct formats
- Single stimulus (successive choice): items are presented one at a time and the RBT records whether the client approaches or engages with each one. It does not require choosing between items, so it suits clients who do not yet choose among several items. Its limit is that a client may approach everything, which says little about relative preference.
- Paired stimulus (forced choice): items are presented two at a time and the client picks one. Each item is paired with every other item, and positions are varied so each item appears on the left and the right. With n items there are n × (n − 1) ÷ 2 pairs, so 6 items take 15 trials and each item is presented 5 times. It gives a clear ranking but takes a long time with many items.
- Multiple stimulus without replacement (MSWO): several items are placed in a row. After the client picks one and has brief access, that item is left out and the remaining items are rearranged for the next trial. The order of selection gives a ranking in fewer trials than paired stimulus. The supervisor may ask for several administrations to get a steadier ranking.
- Multiple stimulus with replacement (MSW): like MSWO, but the chosen item goes back in the array. A strongly preferred item may be picked every time, so MSW identifies the top item but tells you little about the rest.
- Free operant: all items are freely available for a set time, often a few minutes, and the RBT records how long the client engages with each one. Nothing is taken away, which makes it a good choice for clients whose problem behavior is triggered by item removal.
Running a trial-based assessment step by step
- Review the protocol and gather exactly the items the supervisor listed. If you think another item should be included, suggest it; do not add it on your own, since the supervisor considers allergies, diet, and caregiver wishes.
- Prepare the area. Remove competing items, such as a sibling's tablet, that could draw the client away from the array.
- If the protocol includes sampling, give brief access to each item before the first trial so the client has recent contact with all of them.
- Place items at equal distances and within reach, so choices reflect preference rather than ease of reach. Vary positions as the protocol directs.
- Give the instruction in the protocol and wait for a response that meets the definition of a selection or approach. Record exactly what the definition says: looking is not touching.
- After a selection, give brief access for the time the protocol sets (edibles in small pieces to limit satiation), then start the next trial.
- Follow the protocol's rules for problem situations, such as blocking a reach toward both items in a paired trial and presenting the pair again, or ending an MSWO administration when the client makes no selection within the set time.
- Respect assent. If the client repeatedly pushes items away or leaves, stop presenting trials and inform the supervisor. If problem behavior occurs, follow the behavior plan, record it, and report it.
Summarizing the data
Paired stimulus and single stimulus: selection or approach percentage = times chosen ÷ times presented × 100. A puzzle chosen 6 of the 8 times it was presented scores 75%. List items from highest to lowest.
MSWO: record which item was selected on each trial. The first item chosen ranks 1. If the protocol averages ranks across administrations, an item ranked 2nd, 1st, and 3rd has an average rank of (2 + 1 + 3) ÷ 3 = 2.
Free operant: total engagement time with each item, often also expressed as a percentage of the session. Four minutes with a puzzle in a 10-minute session is 40%.
Rankings are relative. An item that ranks fifth was less preferred than most items in that array, but it may still function as a reinforcer, especially when it is not competing with more preferred items. Adding a new, highly preferred item to the array can move everything else down a place. Foods also tend to be chosen ahead of toys and activities when both are in the same array, so supervisors often assess edible and leisure items separately.
Examples and non-examples
| Example | Non-example |
|---|---|
| Before a home session, an RBT runs the supervisor's brief MSWO with five approved leisure items, records the order of selection, and uses the top items as the supervisor directed. | An RBT picks a reinforcer because "kids this age usually like it," without any assessment. |
| In a paired-stimulus assessment, the RBT moves each item between the left and right positions across trials and reports to the supervisor that the client seems to pick whichever item is on the left. | In an MSWO, the RBT returns each chosen item to the array, which turns the procedure into MSW without the supervisor's direction. |
Common mistakes
- Mixing up MSWO and MSW. Without replacement means the chosen item stays out; with replacement means it goes back.
- Treating the top-ranked item as a guaranteed reinforcer. Preference predicts reinforcement; contingent delivery and data show whether it works.
- Using one old assessment for months. Preferences shift with satiation, deprivation, and time.
- Dividing by the wrong number. In a paired-stimulus assessment, divide by the number of times that item was presented, not by the total number of trials.
- Changing the item list or the format on your own. The supervisor chooses both.
How it's tested
Expect to identify a format from a short description (one item, two items, an array with or without replacement, or free access with duration recorded), to pick the right format for a situation (no item removal for a client whose problem behavior is triggered by removals; single stimulus for a client who does not yet choose between items; MSWO for a quick ranking), and to calculate a selection percentage. Watch for answer choices that confuse preference with reinforcement, and for choices in which the RBT changes the protocol instead of following it and informing the supervisor.
Practice questions for task B.1
10 of our 56 questions on this task. The rest are in the Behavior Assessment practice sets and the mock exams.
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Question 1A client chooses from an array of five toys. After each brief play period, the RBT puts the chosen toy back in the array with the others for the next trial. Which preference assessment is this?
Show answer
B: Multiple stimulus with replacement. Returning the chosen item to the array on every trial is what defines multiple stimulus with replacement (MSW).
- A: A paired-stimulus assessment presents two items per trial.
- C: Single-stimulus assessment presents one item at a time.
- D: In MSWO, the chosen item is left out of the array.
Task B.1 · 40-hour curriculum section D
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Question 2In a clinic playroom, several toys are spread out and an adolescent can move freely among them for 10 minutes. The RBT records how long the client engages with each toy. Which preference assessment is this?
Show answer
A: Free operant. A free-operant assessment gives continuous, unrestricted access to items for a set period and measures time spent with each. No item is presented or removed by trial.
- B: Single-stimulus assessment presents one item at a time in separate trials.
- C: MSW uses repeated choice trials from an array.
- D: A paired-stimulus assessment uses trials with two items.
Task B.1 · 40-hour curriculum section D
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Question 3A supervisor asks an RBT to present a client's items one at a time and record whether the client reaches for or engages with each one. Which preference assessment is this?
Show answer
C: Single stimulus. In a single-stimulus assessment, items are presented one at a time and the RBT records approach or engagement. It does not require the client to choose between items.
- A: MSWO presents several items in an array.
- B: A free-operant assessment makes all items available together.
- D: A paired-stimulus assessment presents two items per trial.
Task B.1 · 40-hour curriculum section D
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Question 4Why are preference assessments repeated often, in some cases before each session?
Show answer
A: Preferences shift with satiation, deprivation, and time. The value of an item changes with motivating operations such as satiation and deprivation, and with time. Frequent brief assessments keep the team's list of likely reinforcers current.
- B: There is no BACB rule requiring a preference assessment every session; frequency is a clinical decision.
- C: Items lose value temporarily with satiation; it is not permanent.
- D: Teaching choice-making is not the purpose of repeating an assessment.
Task B.1 · 40-hour curriculum section D · 40-hour curriculum section A
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Question 5In a paired-stimulus assessment, a puzzle is presented 8 times and the client chooses it 6 times. What is the puzzle's selection percentage?
Show answer
C: 75%. Selection percentage = times chosen ÷ times presented × 100 = 6 ÷ 8 × 100 = 75%.
- A: 25% is the percentage of times the puzzle was not chosen (2 ÷ 8).
- B: 60% would be 6 out of 10, not 6 out of 8.
- D: 80% would be 6.4 out of 8, not 6 out of 8.
Task B.1 · 40-hour curriculum section D
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Question 6A supervisor's paired-stimulus protocol has 6 items, with each item paired once with every other item. How many trials does the full assessment take?
Show answer
B: 15. The number of unique pairs is n × (n − 1) ÷ 2 = 6 × 5 ÷ 2 = 15 trials.
- A: 12 is twice the number of items, not the number of unique pairs.
- C: 30 counts each pair twice (6 × 5) without dividing by 2.
- D: 36 is 6 × 6, which would include items paired with themselves and repeated pairs.
Task B.1 · 40-hour curriculum section D
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Question 7In a paired-stimulus assessment with 5 items (each paired once with every other item, so each item is presented 4 times), the client chose bubbles 4 times, music 3 times, a ball 2 times, a puzzle 1 time, and blocks 0 times. What is music's selection percentage and rank?
Show answer
D: 75%, ranked second. Music was chosen 3 of the 4 times it was presented: 3 ÷ 4 × 100 = 75%. Bubbles (4 of 4, 100%) is higher, so music ranks second.
- A: 30% divides by all 10 trials instead of the 4 trials in which music was presented.
- B: 60% divides by 5, but music was presented 4 times.
- C: Bubbles was chosen on every presentation, so music is not first.
Task B.1 · 40-hour curriculum section D
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Question 8Compared with a paired-stimulus assessment, what is a key advantage of MSWO?
Show answer
D: It yields a ranking of items in less time. MSWO produces a preference hierarchy with fewer trials than presenting every possible pair, which makes it practical for frequent use.
- A: MSWO is built on choices from an array.
- B: In MSWO, the chosen item is removed after brief access and not returned to the array.
- C: Like other preference assessments, MSWO identifies preference, not reinforcing effects.
Task B.1 · 40-hour curriculum section D
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Question 9In a multiple-stimulus-with-replacement assessment, a client picks the same tablet on nearly every trial. What is the main limitation of the results?
Show answer
C: They show little about how the other items rank. Because the chosen item returns to the array, a strongly preferred item can be picked every time. MSW identifies the top item but gives little information about the relative preference of the rest.
- A: Preference does not prove reinforcing effects for every task.
- B: Consistent choice of one item does not show misunderstanding.
- D: Choosing the tablet repeatedly suggests it is highly preferred.
Task B.1 · 40-hour curriculum section D
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Question 10During a free-operant preference assessment, what does the RBT typically record?
Show answer
B: How long the client engages with each item. Free-operant assessments measure the duration of engagement with each available item. More time spent with an item indicates stronger preference.
- A: Order of selection with removal is MSWO data.
- C: Approach to one presented item is single-stimulus data.
- D: Choosing between pairs is paired-stimulus data.
Task B.1 · 40-hour curriculum section D
Answer every question to see your score.
Key terms
| Preference assessment | A preference assessment is a structured way of identifying which items or activities a person prefers, to find stimuli likely to work as reinforcers. |
|---|---|
| Single stimulus preference assessment | In a single stimulus preference assessment, items are presented one at a time, and the person's approach or engagement with each item is recorded. |
| Paired stimulus preference assessment | In a paired stimulus preference assessment, items are presented two at a time, and every item is paired with every other item, to produce a preference ranking. |
| Multiple stimulus without replacement | In a multiple stimulus without replacement (MSWO) preference assessment, several items are presented together, and each chosen item is removed from the array before the next choice. |
| Multiple stimulus with replacement | In a multiple stimulus with replacement (MSW) preference assessment, several items are presented together, and the chosen item is returned to the array before the next choice. |
| Free operant preference assessment | A free operant preference assessment gives a person open access to several items at once and records how long they engage with each. |
| Reinforcer assessment | A reinforcer assessment tests whether a stimulus actually works as a reinforcer by delivering it contingent on a response and measuring whether that response increases. |
| Satiation | A temporary decrease in how effective a reinforcer is, caused by recent contact with a lot of that reinforcer; it also makes behavior that produces it less likely. |
| Deprivation | A period without access to a reinforcer, which temporarily increases its value and makes behavior that has produced it in the past more likely. |
| Motivating operation | An environmental variable that temporarily changes how reinforcing a stimulus is and changes how often behavior that has produced that stimulus occurs. |
| Percentage | A percentage is a ratio expressed as parts per 100: the number of occurrences divided by the total, multiplied by 100. |
| Duration | Duration is how long a behavior lasts, measured from the moment it starts (onset) to the moment it ends (offset). |
| Establishing operation | A motivating operation that increases the reinforcing value of a stimulus and makes behavior that has produced that stimulus more likely to occur. |
| Assent | A client's own willingness to participate, shown through words or behavior, which is separate from the legal consent given by a guardian or the client. |
| Positive reinforcement | Positive reinforcement occurs when a stimulus is added or presented right after a behavior and, as a result, that behavior becomes more likely in the future. |
| Operational definition | An operational definition describes a target behavior in observable, measurable terms so that different observers can agree on when it does and does not occur. |
| Procedural fidelity | Procedural fidelity is the degree to which an intervention is carried out exactly as written in the plan; it is also called treatment integrity or procedural integrity. |
| Reliability | Reliability is the consistency of measurement: a reliable measurement system gives the same values each time the same behavior is measured. |