Merging separately established stimulus classes with outcome-specific reinforcement.
Adults can merge separate equivalence classes when unique reinforcers mark each class, but one size does not fit all.
01Research in Context
What this study did
Four adults learned two separate sets of matching tasks. Each set had three pictures that went together.
Next, the pictures were linked by special tokens. If you picked the right match, you got a unique token for that set.
The team watched to see if the two sets would merge into one big six-picture class.
What they found
Two adults merged the classes right away. A third needed a few extra tests with no tokens. One adult never merged them.
Success was mixed. Most could do it, but one person could not.
How this fits with other research
Saunders et al. (1988) first showed classes can merge without any extra rewards. Johnson et al. (2014) now shows that special tokens can also make it happen.
Vaidya et al. (2021) used shared reward pictures and got the same kind of merger. Both studies say reinforcers can act like glue between classes.
Emmelkamp et al. (1986) found that kids with language delays never formed classes. The adults here had no language issues, which may explain why most could merge.
Why it matters
If you teach in chunks, you can later link the chunks using unique rewards. Try giving each chunk its own token, badge, or song. Then test if the learner treats all items as one big class. If not, probe without rewards a few times before giving up.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Give each training block its own special token, then test if the learner links items across blocks.
02At a glance
03Original abstract
This study extended previous research on equivalence relations established with outcome-specific reinforcers to include the merger of separately established stimulus classes. Participants were four adults. Conditional discriminations AC and BC were trained first. Correct selections of C1 (C2, or C3) in the presence of A1 or B1 (A2 or B2, or A3 or B3) were followed by red (blue, or white) tokens; tokens were exchanged for value added to three participant-selected gift cards. Outcomes on equivalence tests for three-member classes ABC were positive. DF and EF were trained with the same reinforcing consequences, and tests were positive for three-member classes DEF. Results of class merger tests with combinations of stimuli from the ABC and DEF classes (AD, FB, etc.) were immediately positive for two participants, demonstrating six-member classes ABCDEF with reinforcers as nodes. Merger tests for a third participant were initially negative but became positive after brief exposure to unreinforced probe trials with reinforcers as comparison stimuli. Following class merger, tests for matching the reinforcers to samples and comparisons were also positive. Class-merger test results were negative for a fourth participant. The results provide the first demonstration of eight-member equivalence classes including two outcome-specific conditioned reinforcing stimuli.
Journal of the experimental analysis of behavior, 2014 · doi:10.1002/jeab.61