PS PREFERENCE ASSESSMENT SESSION DESCRIPTION
Please note, this protocol is designed for use by professionals who have experience conducting
preference assessments, and is not a subtitute for formal training.
Fisher, W. W., Piazza, C. C., Bowman, L. G., Hagopian, L. P., Owens, J. C., & Slevin, I. (1992). A
comparison of two approaches for identifying reinforcers for persons with severe and profound
disabilities. Journal of Applied Behavior Analysis, 25, 491-498.
Purpose: This is a validated empirical preference assessment designed to identify preferences for
various stimuli. Research has demonstrated that preference rankings obtained via this assessment
procedure predict reinforcer effectiveness. That is, higher preference stimuli are more likely to function
as more powerful reinforcers than lower preference stimuli. It should be noted that this assessment will
provide a relative preference ranking, because stimuli are compared with each other directly. Therefore,
it is important to include stimuli that are believed to be somewhat preferred. If staff are not familiar
with a student, or know of only a few stimuli that seem preferred, then a structured interview (the
RAISD*) should be conducted with care providers to identify additional stimuli.
Preparation:
Obtain proper consent from guardians.
Define criteria for use of protective equipment, response blocking, and session termination base
on risk for injury.
Materials: Between 6 to 12 stimuli (each will be assigned a number), index cards with paired numbers
including all possible pairs of stimuli, and paired stimulus preference assessment data sheet.
Procedure: Ideally, sessions will be conducted in a room with no other children present and no
materials nearby, other than those required for the assessment. Stimuli are presented in pairs until
each stimulus has been presented with every other stimulus. All problem behavior is ignored.
Pre-session Setup
Setup datasheet and prepare materials.
Setup a chair and table for the student.
When assessing preference of edibles disinfect the table and wash hands (student, session
therapist, anyone handling food).
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PS PREFERENCE ASSESSMENT SESSION DESCRIPTION
Pre-session Sampling
Prior to beginning the assessment, seat the student at the table and allow them to sample each
stimulus. For a toy, show the student how it works (e.g., press buttons, flip pages, turn on) and
then place the stimulus on the table. If the student approaches the stimulus allow them 5-10s
access (for edibles provide a small bite) and then repeat this procedure with the next stimulus.
If the student does not approach the stimulus after 5s, the therapist will prompt the student to
sample the stimulus for 5s. After sampling the item (or consuming the edible), present the
stimulus again for 5s. If the student approaches, allow 5-10s access; if they do not approach
move on to the next stimulus.
Presentation
1. Shuffle the index cards to randomize the sequence of pair presentations. Randomly select one
of the index cards. The two stimuli identified on the card selected should be used in steps 2 - 4.
2. Hold the stimuli in front of the student so that each stimulus is approximately 2 feet from the
student and 2 feet from the other stimulus.
3. If the student approaches one of the stimuli within 5 seconds, immediately give that stimulus to
the student and remove the other stimulus from sight. Allow the student access to the chosen
stimulus for approximately 30 s (or consumption of the edible), then start again with step 1.
4. If the student does not approach either stimulus within 5 seconds, remove both stimuli and then
have the student sample each (separately) for 5 seconds. Represent the stimuli following steps
2 & 3. If the student does not make a selection after the second presentation move to the next
pairing (step 1).
5. If the student avoids either stimulus, remove the item from in front of the student for 5 seconds
and represent following steps 2 & 3. If the student does not make a selection after the second
presentation move to the next pairing (step 1).
6. Repeat these procedures until all combinations have been presented.
Data Collection: Use the Paired Stimulus data sheet. For each stimulus presented, data collectors will
indicate whether the student item was Approach (AP), Consume (C), Avoidance (AV),
or No Response (N). If a presentation of a pair must be repeated (e.g., student did not make a choice,
avoided stimuli) data collectors will indicate the appropriate response in the first columns for the first
presentation, and then indicate results in the second column for the second presentation.
Approach Responses - defined generally as the student moving toward the stimulus, with any part
of the body, within 5 s of stimulus presentation, and may include at least one of the following
responses directed at one of the stimuli presented:
Reach - Moving hand toward object such that the hand moves at least 6 inches from its previous
position and moves toward the object
Positive Vocalizations - Asking for the object, stating name of object in conjunction with leaning
toward or reaching for object, laughing
Smile - Smiling within 5 seconds upon presentation while looking at object for 3s
Lean - Leaning toward object at least 4-5 inches from original position
Eye Contact - Eyes looking at the object for at least 3 continuous seconds
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PS PREFERENCE ASSESSMENT SESSION DESCRIPTION
Consummatory Responses defined generally as interaction with the stimulus, moving towards the
stimulus, consuming the stimulus (for edibles and tangible stimuli), or engaging in the activity (when
the stimulus was an activity, such as playing catch with the therapist). This includes any attempt to
Consumption may be defined differently for different types of stimuli:
Visual stimuli - 3 continuous seconds of eye contact
Edible stimuli - eating object without spitting or taking any portion out of mouth (does not
include edibles which leave the mouth due to drooling)
Auditory stimuli- Leaning toward music for 3 continuous seconds, rocking, or clapping to the
music; vocalizing, humming or singing for 3 continuous seconds
Vestibular stimuli - Sitting on the object and either attempting to rock or swing for 3 continuous
seconds
Olfactory stimuli - Being within 6 inches of object for 3 continuous second
Tactile stimuli - Tolerating object for 3 seconds (leaning toward, holding or grasping, putting
hand in on object). Holding or grasping object for 3s.
Social stimuli- Tolerating or allowing the therapist to provide the social stimulus without
pushing, pulling away, or attempting to aggress for 3s
Avoidance Responses Includes actively pushing/throwing away objects or moves body away
within 3s of presentation, or nega
No Response - Exhibiting no reaction to the stimuli within 5s of presentation.
Scoring - on the Paired Stimulus data sheet, use the following scoring code for each stimulus:
P student engages in an approach response
student engages in a consumatory response
student engages in an avoidance response
Data Summary and Analysis
Determine the total number of times each stimulus was presented (trials). This will be the
equal to the total number of stimuli examined minus one. That is, if 12 stimuli were
examined, then each one was presented with all the others for a total of 11 presentations.
For each stimulus, determine the number of times it was scored as approached and
consumed (AP and C). Take that number and divide by the total number of presentations
student approaches, then throws the item, it should be scored AP and AV- and thus not
Sort the data in Excel so the stimuli are sorted from higher to lower preference. Graphically
depict the preference hierarchy, with the stimuli listed on the x-axis, and the percentage of
trials approached and consumed on the y-axis.
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PS PREFERENCE ASSESSMENT SESSION DESCRIPTION
Graphically depict the preference hierarchy, with the stimuli listed on the x-axis, the percentage
trials each stimulus was selected on the primary y-axis, and (optional) the rate of problem behavior
on the secondary y-axis (use a double-bar bar graph or bar/line graph to depict preference and rate
of problem behavior).
Interpretation of Results: This assessment procedure has been validated, and there is a high
probability that the top ranked stimuli will function as more powerful reinforcers than the lower
ranked stimuli. Generally speaking, stimuli approached and consumed over 80% of trials are
considered high-preference stimuli. Of course, reinforcer effectiveness is not absolute, and a
function of other factors including the response and the availability of other reinforcement.
However, with all these factors being equal, the preference hierarchy obtained should generally
predict reinforcer effectiveness.
*RAISD Reinforcer Assessment for Individuals with Severe Disabilities is structured parent
interview designed to identify stimuli to evaluate in a preference assessment.
Fisher, W.W. Piazza, C.C., Bowman, L.G., & Amari, A. (1996). Integrating caregiver report with a
systematic choice assessment. American Journal on Mental Retardation, 101, 15-25.
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PS PREFERENCE ASSESSMENT SESSION DESCRIPTION
Paired Stimulus Preference Assessment
Name: ________________ Date: ____________________________
Data Collector: _________________ Primary/Reliability (circle one)
Item 1:
1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 1 10 1 11 1 12 1 13
Item 2:
2 3 2 4 2 5 2 6 2 7 2 8 2 9 2 10 2 11 2 12 2 13
Item 3:
3 4 3 5 3 6 3 7 3 8 3 9 3 10 3 11 3 12 3 13
Item 4:
4 5 4 6 4 7 4 8 4 9 4 10 4 11 4 12 4 13
Item 5:
5 6 5 7 5 8 5 9 5 10 5 11 5 12 5 13
Item 6:
6 7 6 8 6 9 6 10 6 11 6 12 6 13
AP- approach C consume N no response AV - avoid
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PS PREFERENCE ASSESSMENT SESSION DESCRIPTION
Item 7:
7 8 7 9 7 10 7 11 7 12 7 13
Item 8:
8 9 8 10 8 11 8 12 8 13
Item 9:
9 10 9 11 9 12 9 13
Item 10:
10 11 10 12 10 13
Item 11:
11 12 11 13
Item 12:
12 13
Item 13:
AP- approach C consume N no response AV - avoid
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