Do common elements predict class merger: A test of Sidman's theory of equivalence
Recycling the same reinforcer picture across training phases can weld separate equivalence classes into one.
01Research in Context
What this study did
Vaidya et al. (2021) asked a simple question: can shared pictures in the reinforcer slot glue two equivalence classes together? They ran adults through three phases of conditional-discrimination training. In each phase the correct choice produced a picture of an object on the screen. Some pictures repeated across phases; others were new.
The team then tested for emergent relations. If the repeated reinforcer pictures acted like a bridge, the two separate classes should merge into one big class.
What they found
When the reinforcer picture stayed the same across phases, adults treated the formerly separate sets as one class. They picked the untaught matches that the theory predicted.
When the reinforcer picture changed, the classes stayed apart. The common element made the difference.
How this fits with other research
Johnson et al. (2014) tried a similar reinforcer-driven merger but got mixed results: two adults merged right away, one needed extra probes, one never merged. Vaidya’s cleaner design shows that controlling the exact reinforcer image, not just any shared reinforcer, boosts success.
Saunders et al. (1988) first showed classes can merge without any reinforcer at all during probe trials. Vaidya adds a new tool: you can cause the same merger on purpose by keeping one reinforcer picture constant.
Tassé et al. (2013) found that pigeons’ key-peck responses became part of their classes, while van Schrojenstein Lantman-de Valk et al. (2006) found the opposite with pigeons. Vaidya sidesteps that fight by using reinforcer pictures instead of response patterns and shows clear merger with humans.
Why it matters
If you want a learner to treat two sets of words, symbols, or pictures as interchangeable, slip the same reinforcer image into every correct trial across both sets. A shared smiley face, company logo, or favorite cartoon character could do the trick. Test with simple symmetry and transitivity probes after training; if the classes merge, you will see the emergent picks appear without extra teaching.
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02At a glance
03Original abstract
The study presented here investigated the effect of common and uncommon elements on class merger as predicted by Sidman in his reconceptualization of stimulus equivalence suggesting that common elements among contingencies can facilitate emergent performances (1994, 1997, 2000). Eight adult participants were exposed to a procedure that arranged for stimulus-reinforcer correlations in Phase 1 and response-reinforcer correlations in Phase 2 of a 3-phase study. In the common element group, the visual images serving as reinforcers were the same in Phase 1 and Phase 2. In the uncommon elements group, the images serving as reinforcers were different in Phases 1 and 2. In Phase 3, participants were given an opportunity to respond but no feedback was programmed. The results showed that participants' responding was well differentiated in the common element group and undifferentiated in the uncommon elements group. These results are predicted by Sidman's revised formulation of the provenance and scope of equivalence relations. Specifically, these data support Sidman's (1994, 1997, 2000) suggestion that elements of a contingency enter into an equivalence class and common elements among contingencies are sufficient to produce class mergers. The findings highlight an emergent simple discrimination and raise some interesting considerations about the definition of equivalence under the new formulation.
Journal of the Experimental Analysis of Behavior, 2021 · doi:10.1002/jeab.659