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

2. 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

3. 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

4. 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

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

6. 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+

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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)

13. 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

14. 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

15. 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

16. 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)