On the origins of emergent differential sample behavior.
Hold the comparison side still when you add new samples so emergent differential choices appear free.
01Research in Context
What this study did
The team added new sample pictures to a two-choice matching game. The new samples looked just like the old ones, but the comparison pictures stayed the same.
They watched to see if learners would treat the new samples differently without extra teaching.
What they found
Differential responding showed up only when the comparisons matched the familiar samples. The learners’ new choices seemed to follow the same reinforcement history as the original set.
The result supports the idea that equivalence is learned, not built in.
How this fits with other research
Madden et al. (2003) asked learners to name sample pictures aloud and saw better delayed matching. Both studies tweak the sample side of the task, yet Ahlborn et al. (2008) kept the comparisons unchanged while Madden et al. (2003) required overt naming. The two papers agree that small sample changes can steer accuracy.
Dingus et al. (2025) later added talk-aloud rules to auditory equivalence training. They also found timing matters: delay the talk until after first tests. Together with Ahlborn et al. (2008), the pair shows that controlling what happens around the sample—identity or naming—shapes emergent performance.
Ming et al. (2017) note that ABA rarely studies “difference” relations. Ahlborn et al. (2008) fills part of that gap by showing how differential responding to new but similar samples can emerge without direct teaching.
Why it matters
When you expand an equivalence set, keep the comparison stimuli identical to the baseline set. This tiny move lets new sample functions emerge without extra trials. Try it next time you add photos, icons, or words to a learner’s matching program.
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02At a glance
03Original abstract
Two experiments evaluated the source(s) of emergent differential sample behavior in pigeons. Initially, pigeons learned two-sample, two-alternative symbolic matching in which different patterns of sample responding were required to produce the comparisons. Afterwards, two other samples nominally identical to the comparisons were added to the matching task. On new-sample trials, completion of either sample-response requirement produced comparison alternatives which were either the same as or different from the alternatives on the familiar-sample trials. Differential responding to the new samples developed only when the comparisons were the same as the familiar samples. The results are consistent with acquired sample equivalence and adventitious reinforcement accounts of emergent sample behavior and are inconsistent with bidirectional transfer (symmetry) between the response patterns explicitly required to the originally trained (familiar) samples and the subsequently reinforced comparisons.
Journal of the experimental analysis of behavior, 2008 · doi:10.1901/jeab.2008.90-61