preference-assessment

# Preference Assessment ## Purpose Preference assessments systematically identify stimuli that an individual approaches, engages with, or selects when given the opportunity. Identified high-preference stimuli are **candidates** for use as reinforcers, but preference does not guarantee reinforcing function — that must be verified through contingent delivery and measurement of its effect on behavior. ## Step 1: Stimulus Identification ### Reinforcer Assessment for Individuals with Disabilities (RAISD; Fisher et al., 1996) A structured caregiver interview used to generate the list of stimuli to include in formal preference assessments. **Procedure:** 1. Interview caregiver using the RAISD form 2. Ask about potential reinforcers across categories: - **Visual:** Things the individual likes to look at - **Auditory:** Sounds, music, voices the individual enjoys - **Olfactory:** Smells the individual seeks out - **Tactile:** Textures, touch, vibration the individual prefers - **Edible:** Foods and drinks the individual prefers - **Social:** Interactions, games, praise the individual responds to - **Activity:** Things the individual likes to do 3. For each item identified, ask: "If [individual] had free access, how long would they engage with it?" 4. Rank items within each category by reported engagement duration 5. Select top 5-8 items across categories for formal assessment **Clinical Tip:** Always include items from multiple sensory categories. Caregivers often over-report edibles and under-report social or activity-based items. ## Step 2: Formal Preference Assessment Methods ### Free Operant Observation (Roane et al., 1998) **Purpose:** Identify preferences in the most naturalistic way — observe what the individual approaches and engages with when given free access. **Procedure:** 1. Arrange 8-10 items in the environment (on a table, floor, or across the room) 2. Allow free access for 5 minutes with no demands 3. Record duration of engagement with each item using momentary time sampling (MTS) or continuous duration recording 4. Calculate percentage of total time engaged with each item 5. Rank items by engagement duration **Scoring:** Percentage of intervals or duration engaged with each item. Items above 50% engagement = high preference. Below 10% = low preference. **Advantages:** Low response effort, usable with individuals who cannot make discrete choices, captures approach behavior naturally. **Limitations:** May be influenced by stimulus proximity, does not require a discrete selection response, social items difficult to include. ### Paired Stimulus (Forced Choice) Preference Assessment (Fisher et al., 1992) **Purpose:** Most widely used formal assessment. Each item is systematically paired with every other item. **Procedure:** 1. Select 5-8 items from RAISD 2. Present two items simultaneously, equidistant from the individual 3. Record which item the individual approaches/selects within 5 seconds 4. Remove both items; if one selected, deliver 30 seconds of access 5. If no selection within 5 seconds, re-present the pair (up to 2 additional trials) 6. Each item is paired with every other item twice (positions counterbalanced left/right) 7. Total trials = n(n−1) where n = number of items **Calculating Preference Hierarchy:** Percentage = (Number of times item selected ÷ Number of trials item was presented) × 100 - **High preference:** ≥ 80% - **Moderate preference:** 50-79% - **Low preference:** < 50% **Advantages:** Strong correspondence with reinforcer assessments. Systematic. Produces a clear hierarchy. **Limitations:** Time-intensive (28 trials for 8 items). Requires discrete selection response. ### Multiple Stimulus Without Replacement (MSWO; DeLeon & Iwata, 1996) **Purpose:** Efficient alternative to paired stimulus that produces a complete hierarchy. **Procedure:** 1. Arrange 5-8 items in a horizontal array (random position) 2. Present the array; record which item the individual selects first 3. Remove selected item; deliver 30 seconds of access 4. Re-present remaining items in a newly randomized arrangement 5. Continue until all items are selected or 30 seconds elapse without a selection 6. This constitutes one trial block. Conduct 5+ trial blocks 7. Randomize array position across every presentation **Calculating Preference Hierarchy:** For each item, calculate: Percentage = (Number of times selected first ÷ Number of times available for selection) × 100 Rank items from highest to lowest percentage. This accounts for the fact that items selected later in the sequence had fewer opportunities for selection. **Advantages:** More efficient than paired stimulus. Produces a hierarchy in fewer trials. Strong correspondence with reinforcer effectiveness. **Limitations:** Requires ability to scan an array and make a selection. Position bias can be an issue — randomize positions rigorously. ### Brief MSWO Conduct 1-3 trial blocks rather than 5+. Useful for: - Quick reassessment before sessions - Populations with rapidly shifting preferences - Settings where extended assessment is impractical - Identify top 1-2 items quickly for immediate session use ### Single Stimulus Engagement (Pace et al., 1985) **Purpose:** For individuals who cannot make a choice between stimuli (severe motor impairment, limited scanning ability). **Procedure:** 1. Present one item at a time for 5 seconds 2. Record approach (reaching, looking, vocalizing) within 5 seconds 3. If approach occurs, deliver 30 seconds of access 4. Present each item 3-5 times in random order 5. Calculate approach percentage per item **Advantages:** Low response requirement. Accessible for individuals with severe disabilities. **Limitations:** Does not produce a true hierarchy (each item evaluated independently, not against others). Subject to acquiescence bias — many individuals approach anything presented. ## Stimulus Categories | Category | Examples | Considerations | |----------|----------|----------------| | Edible | Snacks, drinks, candy | Satiation is rapid; use small portions. Check dietary restrictions and allergies. | | Tangible | Toys, fidgets, books, tech | Can be paired with social delivery for combined value. | | Social | Praise, tickles, high-fives, songs, conversation | Must be delivered by someone whose attention functions as a reinforcer. | | Activity | Swinging, jumping, walks, screen time, preferred tasks | Often requires more time to deliver as consequence. | | Sensory | Vibration, textures, lights, sounds | Particularly relevant for automatic reinforcement. | ## Preference vs. Reinforcer **Critical distinction:** A preference assessment identifies stimuli the individual selects or approaches. A **reinforcer assessment** demonstrates that contingent delivery of that stimulus increases the future probability of a behavior. **Correspondence research findings:** - High-preference items function as reinforcers ~70-80% of the time (DeLeon et al., 2001) - MSWO and paired stimulus show the best correspondence with reinforcer value - Free operant shows moderate correspondence - Single stimulus shows weakest correspondence - Low-preference items rarely function as reinforcers - Medium-preference items are unpredictable — verify with contingent reinforcer assessment **Verify reinforcer status by:** 1. Select a known or novel behavior 2. Deliver the preferred item contingent on the behavior 3. Compare behavior rate during contingent delivery vs. baseline (no consequence) or non-contingent delivery 4. If contingent delivery produces higher rates → confirmed as reinforcer ## Reassessment Schedule - **Before every session** (brief MSWO): Ideal but not always feasible. At minimum, offer a brief choice before session start. - **Weekly:** For individuals with rapidly shifting preferences, those new to services, or when motivation appears to fluctuate. - **Monthly:** For individuals with stable preference profiles. - **After major life changes:** New medication, new environment, developmental shifts, seasonal changes. ## Practical Considerations - **Novelty effects:** New items may be selected due to novelty, not enduring preference. Include both novel and familiar items. - **Satiation:** Rotate reinforcers within and across sessions. Monitor for decreased engagement as a sign of satiation. - **Deprivation:** Brief deprivation of a preferred item before a session can increase its reinforcing effectiveness (establishing operation). - **Presentation:** Ensure items are equally accessible — equidistant, visible, and reachable. Control for position bias. - **Social validity:** Include items that caregivers consider appropriate and sustainable for ongoing intervention. - **Age-appropriateness:** Select stimuli that are chronologically age-appropriate, particularly for adolescent and adult learners. ## Key References - DeLeon, I. G., & Iwata, B. A. (1996). Evaluation of a multiple-stimulus presentation format for assessing reinforcer preferences. *Journal of Applied Behavior Analysis*, 29, 519–533. - Fisher, 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. - Fisher, W. W., Piazza, C. C., Bowman, L. G., & Amari, A. (1996). Integrating caregiver report with a systematic choice assessment to enhance reinforcer identification. *American Journal on Mental Retardation*, 101, 15–25. - Pace, G. M., Ivancic, M. T., Edwards, G. L., Iwata, B. A., & Page, T. J. (1985). Assessment of stimulus preference and reinforcer value with profoundly retarded individuals. *Journal of Applied Behavior Analysis*, 18, 249–255. - Roane, H. S., Vollmer, T. R., Ringdahl, J. E., & Marcus, B. A. (1998). Evaluation of a brief stimulus preference assessment. *Journal of Applied Behavior Analysis*, 31, 605–620. - DeLeon, I. G., Iwata, B. A., Conners, J., & Wallace, M. D. (2001). Examination of the effects of stimulus preference and reinforcer value on response rate. *Journal of Applied Behavior Analysis*, 34, 51–73.