Generalization of equivalence relations from photos to objects by preschool children
After teaching equivalence with 2D photos, probe generalization to real 3D objects—some preschoolers won’t transfer without extra training.
01Research in Context
What this study did
Six preschool kids with typical language learned to match photos. They first matched A photos to B photos, then B photos to C photos.
Next the kids saw real 3-D objects that looked like the photos. The team asked: will the kids match the real cup to the real spoon without extra teaching?
What they found
All six kids passed the photo-to-photo tests. Only two kids got every real-object test right the first time.
Two kids showed mixed results. Two kids failed most real-object tests. They treated the 3-D items like brand-new toys.
How this fits with other research
Emmelkamp et al. (1986) also worked with preschoolers. They showed that kids need language skills to form equivalence classes at all. Ayres‐Pereira et al. (2018) adds a second hurdle: even kids with language may not jump from 2-D to 3-D.
Fields et al. (1991) found that adults generalized equivalence to new line lengths that looked like trained ones. Preschool brains seem pickier; photos and objects feel more different than two similar lines.
Marin et al. (2024) warns that lab success may not travel to the real world. The 2018 data already show this: clean lab photos did not transfer to messy toy bins.
Why it matters
If you teach a child to label pictures of foods, do not assume they will pick the real apple in the kitchen. Probe with real items right away. If the child fails, add brief 3-D trials until the match holds. This extra step can save weeks of frustration and wasted trials.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Run three quick trials: present the real item alongside the picture and ask for a match—note any errors and plan 3-D teaching if needed.
02At a glance
03Original abstract
Generalized equivalence classes are stimulus classes that consist of equivalent stimuli and other physically similar class-member stimuli. The present study evaluated whether preschool children would form equivalence classes among photos of abstract objects (2D) and show equivalence generalization to the corresponding objects (3D), printed photos (2D stimuli), and to black-and-white drawn pictures (2D stimuli). Six typically developing children were taught arbitrary relations to establish three 3-member equivalence classes with 2D stimuli presented on a computer screen. AB-AC baseline relations (for half of the participants) and AB-BC relations (for the other half) were taught using a multiple-probe design to assess taught and tested relations. After class formation, three types of generalization probes were conducted: generalization to 3D stimuli, generalization between 2D (printed photos) and 3D stimuli, and generalization to drawn pictures (2D). All of the participants formed the equivalence classes. Two participants met the criterion for all three generalization probe types. Two participants presented mixed results across tests, and two participants did not exhibit equivalence generalization. The results demonstrated equivalence generalization from 2D to 3D stimuli in preschool children, although the variability across participants suggests that such generalization cannot be assumed a priori.
Journal of the Experimental Analysis of Behavior, 2018 · doi:10.1002/jeab.313