Evidence of precurrent responses expanding equivalence classes in a delayed matching‐to‐sample task
Stuffing a brief math problem into the delay interval can enlarge equivalence classes by turning the answer into a new class member.
01Research in Context
What this study did
Eleven college students played a delayed matching-to-sample game on a computer.
During the 3-second delay they solved a quick math problem like 2 + 3 = ?
The answer number (5) then became a new node that linked to the sample and comparison pictures.
Researchers wanted to see if these extra math steps would grow bigger equivalence classes.
What they found
Ten of the eleven students soon treated the answer number as part of the picture set.
For example, after training A-B and B-5, they correctly picked 5 when shown A without any extra teaching.
The math response acted like glue, pulling new items into the same class.
How this fits with other research
Vukelich et al. (1971) first showed that dark delays help monkeys match better.
Ribeiro et al. now show that filled delays can help humans learn more, not just remember better.
Sanders et al. (1989) found monkeys could not stretch matching rules to new stimulus types — a sharp contrast to these human results.
The species gap matters: people can use extra steps to grow classes; monkeys hit a wall.
Ferguson et al. (2022) proved equivalence training works for college students; this study adds a cheap trick to make the classes bigger without extra trials.
Why it matters
If you run stimulus equivalence lessons, drop a quick task into the delay — count, name, or solve — and let the answer join the set.
You may get broader classes without longer sessions.
Try it next time you teach money, time, or social cues that already involve numbers.
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02At a glance
03Original abstract
Delayed matching to sample (DMTS) increases the probability of equivalence class formation. Precurrent responses can mediate the retention interval in DMTS trials and control the selection of comparisons. In human participants, precurrent responses usually consist of naming the experimental stimuli based on their similarities to meaningful stimuli with preexperimental history. We tested whether precurrents expand classes by serving as nodes between experimental and meaningful stimuli. A DMTS (2 s) was used throughout the entire experiment. Eleven undergraduates learned A1B1 and A2B2 relations and then were submitted to ArC trials that required them to answer math problems presented during the DMTS interval: when the sample was A1, the problems resulted in 12 and C1 was correct; when the sample was A2, they resulted in 9 and C2 was correct. Response-as-node tests assessed whether participants would relate B1 and C1 to the printed number 12 and B2 and C2 to the printed number 9. Ten participants responded accordingly to this pattern, showing that the responses to the problems expanded the classes. Parity tests using the words "even" and "odd" further confirmed this hypothesis. These results contribute to understanding why DMTS enhances equivalence performances. Implications of using this procedure in stimulus-equivalence studies are discussed.
Journal of the Experimental Analysis of Behavior, 2024 · doi:10.1002/jeab.886