Identifying & Enhancing the Effectiveness of Positive Reinforcement Piazza et al (2011) Fisher et al Ch 9

What is a positive reinforcer? It is NOT based on the topography of the stimulus E.G., I use M&Ms as a reinforcer for potty training It is based on an increase in behavior it is delivered contingent upon

Stimulus Preference Tests Pace et al.(1985) introduced a procedure to test stimulus preference in persons with ID, and then demonstrated the reinforcing properties of preferred vs non preferred items. Since then several methods of assessing preference have been demonstrated

Single Stimulus Assessment Pace et al.(1985) 16 ,each one presented alone “approach” ( reaching, touching) results in 5 sec with the stimulus ( ie, they could eat or play with the item) “No approach” within 5 sec, -> prompt again Still no approach  remove and continue Item chosen 80% of opportunities =preferred Items h< 50% of opportunities = non-preferred Preferred item functioned as reinforcers for an arm raise Non-preferred item did NOT function as reinforcers

Single Stimulus Assessment Limitations There is no ranking if many or all items are approached. Some “preferred” item do not function as reinforcers

Paired Choice Preference Assessment Fisher et al (1992)- replication of Pace(1985) Present 2 items at the same time and see which is chosen. Block attempts to choose both Same procedure as Pace et al. (1985) Identified a rank ordering of all the stimuli Compared to single item procedure and only stimuli “high” on both functioned a SR+

Paired Choice Preference Assessment 2 Limitations of the “choice method” It can take a longer time to do and may not reflect the constantly changing preference for items Choice assessments my prompt aberrant behavior , especially in persons with aberrant behavior maintained by tangible items

Multiple Stimulus Assessment Windsor et al. (1994): 6 items presented at once over 5 sessions, each with 10 trials “which one do you want” < 20sec—get item > 20 sec. “no response” next trial Resulted in a ranking of items but no SR+ test was done

Multiple stimulus Without Replacement test (MSWO) Deleon & Iwata (1996) extended Windsor et al by presenting sets of 7 stimuli and removing chosen items for subsequent presentations Resulted in a finer ranking of less preferred items Preferred items all were demonstrated to be reinforcers

Multiple stimulus Without Replacement test (MSWO) Comparison of (MSWO) to MSW and Paired Rank order- all identified highly preferred items\ For lesser preferred all 3 tests highly correlated MSW fastest(16.5 m); MSWO (21.8) Paired(53.3) Fewer items selected in the MSW MSWO produced a refined ranking

Free- Operant assessment & others Roane et al (1998) Continuous access to an array of stimuli Compared to paired stimulus Free operant quicker and had less aberrant behavior Activity restriction- free operant with restriction of chosen items– more differentiated patterns than simple free operant Duration: I item at a time, measure contact duration- less stable rankings than paired

Other popular methods Vocal Report: only effective with language able persons and may not be the same as actual preference in natural situations Care-giver Nomination: Basically a history of inaccuracies RAISD some improvement as it controls caregiver descriptions Pictorial: Can work with some non-language persons (ABLA-Williams)

Other popular methods/Issues Concurrent Operants. Preference for different treatments Children can choose between 2 nd links by selecting and initial link Group Arrangements, It is possible to gain fairly good measures of preference for different activities of many kids using MTS observations of actual participation The effectiveness of reinforcers does vary with preference assessments

Methods for Evaluating Reinforcement Effects Simple vs Complex responses Simple is better: the objective is not to teach a significant skill Single vs Concurrent operants Single operants are useful for measuring absolute reinforcing value Concurrent operants show Relative reinforcing value Progressive Ratio Schedules (PR) T%he response requirements for a given SR+ are increased within session (e.g., fr5, then FR10, then FR15) to test how much a given SR+ will maintain behavior

Issues Related to Specific Stimuli Choice as SR+ Must control for Choice per se as opposed to preferred items as SR+ Using the same SR+ stimuli, choice has been shown to be more reinforcing However when choice is for low preference stimuli and high Pref are given by the experimenter, kids have chosen the experimentor delivered stimuli Edible Stimuli Edible items will displace leisure items in lower functioning Persons so they should be assessed separately

Factors Influencing Effectiveness of SR+ Rate , quality, and Delay: Reinforcement is more effective at higher rates, with less Delay and with higher quality Variation: Varying Sr+ types will enhance Sr+ value ( from low to medium preference) Changes over time: Studies have shown both change and stability over time. It appears that change is the result of changing EOs Satiation Vs Deprivation: Idiosyncratic (but LW study)