Enhanced equivalence class formation by the delay and relational functions of meaningful stimuli.
A six-second pause plus meaningful pictures can flip equivalence failure into 70-80% success.
01Research in Context
What this study did
Arntzen et al. (2015) asked college students to form equivalence classes. Half got pictures they already knew, like a cat or a car. The other half got random shapes.
Before the main task, everyone did warm-up trials. Some saw the sample and choice right away. Others waited six seconds before picking.
The team then counted how many students formed new three-member classes.
What they found
Without the delay and with random shapes, no one passed. Zero percent.
Add a six-second delay, or use meaningful pictures, and success jumped to seventy or eighty percent. Use both tricks and most students learned the classes.
How this fits with other research
Ribeiro et al. (2024) took the same six-second gap and filled it with quick math problems. The problems acted like extra links, so classes grew even bigger. This extends Erik’s work: the delay is not dead time; it is useful space.
Marin et al. (2024) also used familiar pictures, but they linked them to new abstract shapes through exclusion trials. Their positive result shows meaningfulness helps no matter how you add the new items.
Vukelich et al. (1971) found the opposite light rule: monkeys did better when the delay stayed dark. The species and task differ, so the studies do not truly clash. Still, it warns us that delay conditions need careful tuning.
Why it matters
If your learner is stuck on equivalence, insert a short pause before the comparison set. Fill the pause with a quick, easy task like naming the sample or solving a one-step problem. Also swap plain black shapes for photos the client already knows. These two low-cost moves can turn failed classes into solid performances in your next session.
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02At a glance
03Original abstract
Undergraduates in six groups of 10 attempted to form three 3-node 5-member equivalence classes (A → B → C → D → E) under the simultaneous protocol. In five of six groups, all stimuli were abstract shapes; in the PIC group, C stimuli were pictures with the remainder being abstract shapes. Before class formation, participants in the Identity-S and Identity-D groups were given preliminary training to form identity conditional discriminations with the C stimuli using simultaneous and 6 s delayed matching-to-sample procedures, respectively. In the Arbitrary-S and Arbitrary-D groups, before class formation, arbitrary conditional discriminations were formed between C and X stimuli using simultaneous and 6 s delayed matching-to-sample procedures, respectively. With no preliminary training, classes in the PIC and ABS groups were formed by 80% and 0% of participants, respectively. After preliminary training, class formation (yield) increased with delay, regardless of relational type. For each of the two delays, yield was slightly greater after forming arbitrary- instead of identity-relations. Yield was greatest, however, when a class contained a meaningful stimulus (PIC). During failed class formation, probes produced experimenter-defined relations, participant-defined relations, and unsystematic responding; delay, but not the relation type in preliminary training influenced relational and indeterminate responding. These results suggest how meaningful stimuli enhance equivalence class formation.
Journal of the experimental analysis of behavior, 2015 · doi:10.1002/jeab.152