Stimulus class formation and stimulus-reinforcer relations.
Shared reinforcers can add new items to a stimulus class without direct training.
01Research in Context
What this study did
The team worked with adults who had intellectual disabilities. They used an arbitrary-matching game with pictures and objects. Some items were never trained together, but they all led to the same food reinforcer.
What they found
Four-member stimulus classes formed even for items that were never directly matched. The shared reinforcer pulled new stimuli into the class. No extra training was needed.
How this fits with other research
Dube et al. (1987) showed the same pattern two years earlier. Aman et al. (2002) later got the same effect with mild shock instead of food. Fields et al. (2012) found that one meaningful stimulus in the class speeds formation for college students. Together the studies say: whatever shares a consequence becomes related.
Why it matters
You can grow stimulus classes without extra trials. Pair new pictures, words, or tokens with the same reinforcer that already powers the class. The learner gets new relations for free, saving you teaching time and helping skills spread naturally.
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02At a glance
03Original abstract
This study examined stimulus class membership established via stimulus-reinforcer relations. Mentally retarded subjects learned conditional discriminations with four two-member sets of visual stimuli (A, B, C, and D). On arbitrary-matching trials, they selected comparison stimuli B1 and B2 conditionally upon samples A1 and A2, respectively, and C1 and C2 conditionally upon B1 and B2, respectively. On identity-matching trials, they selected all stimuli as comparisons conditionally upon identical stimuli as samples. Throughout training, correct selections of A1, B1, C1, and D1 were followed by one reinforcer, R1, and those of A2, B2, C2, and D2 were followed by another, R2. Subsequent tests documented the formation of two four-member stimulus classes, A1-B1-C1-D1 and A2-B2-C2-D2. The class membership of the A, B, and C stimuli could have been based on equivalence relations that resulted from the arbitrary-matching training. D1 and D2 had never appeared on arbitrary-matching trials, however. Their class membership must have been based on relations with R1 and R2, respectively. Results thus confirm a previous finding that stimulus classes can be expanded via stimulus-reinforcer relations. They also define more precisely the potential nature of those classes and the conditions under which class membership can be established.
Journal of the experimental analysis of behavior, 1989 · doi:10.1901/jeab.1989.51-65