Arbitrary conditional discriminative functions of meaningful stimuli and enhanced equivalence class formation.
Five prior conditional relations make an abstract stimulus as helpful as a meaningful photo for building equivalence classes.
01Research in Context
What this study did
College students tried to build four-member equivalence classes.
Half the classes held only abstract shapes.
The other half replaced one shape with a meaningful picture, like a cat.
Before class training, some abstract shapes already had five conditional relations trained.
Researchers then checked who formed complete classes.
What they found
Bare abstract classes worked only a large share of the time.
Adding one meaningful picture lifted success to about a large share.
Giving an abstract shape five prior conditional relations did the same.
A short history of conditional control was as powerful as built-in meaning.
How this fits with other research
Fields et al. (2012) first showed that one meaningful or discriminative stimulus lifts class formation.
Weissman-Fogel et al. (2015) now proves the lift can also come from pure conditional history, not just meaning.
Ayres‐Pereira et al. (2025) used the same simultaneous protocol but focused on look-alike stimuli.
They found side-by-side comparison was key when items were nearly identical.
Together the three papers say: give the learner either rich prior relations or clear perceptual contrast, and classes form faster.
Why it matters
You can now build equivalence sets faster without hunting for meaningful pictures.
Just pre-train five conditional relations with one abstract stimulus, then drop it into the new class.
This saves prep time and keeps visuals consistent across learners.
Try it next session: run a quick five-trial conditional track with your anchor stimulus, then start the full class.
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02At a glance
03Original abstract
Equivalence class formation by college students was influenced through the prior acquisition of conditional discriminative functions by one of the abstract stimuli (C) in the to-be-formed classes. Participants in the GR-0, GR-1, and GR-5 groups attempted to form classes under the simultaneous protocol, after mastering 0, 1, or 5 conditional relations between C and other abstract stimuli (V, W, X, Y, Z) that were not included in the to-be-formed classes (ABCDE). Participants in the GR-many group attempted to form classes that contained four abstract stimuli and one meaningful picture as the C stimulus. In the GR-0, GR-1, GR-5, and GR-many groups, classes were formed by 17, 25, 58, and 67% of participants, respectively. Thus, likelihood of class formation was enhanced by the prior formation of five C-based conditional relations (the GR-5 vs. GR-0 condition), or the inclusion of a meaningful stimulus as a class member (the GR-many vs. GR-0 condition). The GR-5 and GR-many conditions produced very similar yields, indicating that class formation was enhanced to a similar degree by including a meaningful stimulus or an abstract stimulus that had become a member of five conditional relations prior to equivalence class formation. Finally, the low and high yields produced by the GR-1 and GR-5 conditions showed that the class enhancement effect of the GR-5 condition was due to the number of conditional relations established during preliminary training and not to the sheer amount of reinforcement provided while learning these conditional relations. Class enhancement produced by meaningful stimuli, then, can be attributed to their acquired conditional discriminative functions as well as their discriminative, connotative, and denotative properties.
Journal of the experimental analysis of behavior, 2015 · doi:10.1002/jeab.141