The effects of nodality on the formation of equivalence classes.
Shorten the path between first-taught and tested stimuli to make equivalence pop out sooner.
01Research in Context
What this study did
The team built equivalence classes with adults who had no diagnosis.
They changed how many "nodes" sat between two linked pictures.
Some pairs had one node, others had two.
The adults learned by matching pictures on a computer screen.
What they found
One-node pairs won control faster.
Two-node pairs took more practice.
After many rounds every relation worked, but the short path still felt easier.
How this fits with other research
Einfeld et al. (1995) ran the same match-to-sample game with twelve adults and saw the same speed order.
Brown et al. (1994) moved the idea into a classroom. Three students with intellectual disability learned sight-word classes. Symmetry came first, then one-node links, then two-node links.
Chand et al. (2022) added tighter controls and still found the nodality effect, proving the pattern is not a lab fluke.
Christian et al. (1997) flipped the script: they pre-trained big five-node classes, then showed that extra nodes later helped new classes form faster. This seems opposite, but the key is timing. Early in training more nodes slow you down; after classes are solid, more nodes act like extra practice and speed the next round.
Why it matters
When you plan stimulus equivalence lessons, put the closest relations first. Teach A-B and A-C before you ask for B-C. Let the short path lock in, then stretch the chain. You will see fewer errors and faster emergence, no matter the learner’s age or label.
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02At a glance
03Original abstract
A four-member equivalence class (A----B----C----D) can be formed by training AB, BC, and CD. The nodal stimuli, B and C, mediate all of the derivative (transitive and equivalence) relations in the class. The derivative relations AC, CA, BD, and DB are separated by one node, whereas AD and DA are separated by two nodes. How do the number of nodes that separate the stimuli in a derivative relation influence the induction of stimulus control exerted by that relation? Seven college students learned two four-member classes made up of nonsense syllables. After training, all derivative relations were presented repeatedly without informative feedback. Stimulus control exerted by each derivative relation was assessed concurrently. For the 7 subjects, control exerted by the derivative relations increased gradually with repeated presentations. With 6 of the 7 subjects, the one-node relations exerted more control than the two-node relations during the process. However, the disparity between the one- and two-node relations decreased with repeated presentations. Eventually, all derivative relations exerted complete control. The control exerted by derivative relations during induction was inversely related to the number of nodes separating the terms in the derivative relations. These results demonstrate that nodal distance is a determinant of the relatedness of stimuli in equivalence classes. The findings are discussed in terms of remote association, semantic memory networks, and the study of transitive inference.
Journal of the experimental analysis of behavior, 1990 · doi:10.1901/jeab.1990.53-345