Selected abstracts from the Journal of the Experimental Analysis of Behavior, March 1993.
Equivalence classes can form via negative-comparison control—check which stimulus is actually controlling before assuming positive-comparison learning.
01Research in Context
What this study did
Three adults learned a two-choice matching task. They saw two sample pictures, then picked from two comparison pictures.
Training pushed them to notice which picture was NOT like the sample. Researchers wanted to know if this "negative-comparison" teaching would build new equivalence classes.
What they found
All three adults later matched new pictures that had never been trained together. Their classes followed the negative-comparison rule, not the usual positive one.
The result shows equivalence can grow from noticing what something is NOT.
How this fits with other research
Alonso-Álvarez et al. (2018) later added color cues to do the same thing. Their adults also formed equivalence classes, proving the idea works with extra help.
Rapport et al. (1996) asked college students to describe their own matches. Most could say why they picked each picture, showing the new relations felt real to them.
van Schrojenstein Lantman-de Valk et al. (2006) tried the same training with pigeons. The birds did NOT form equivalence classes. The clash disappears when you see pigeons learn differently than people.
Why it matters
Before you call a skill "mastered," test which stimulus is really in charge. Run a quick probe where the wrong item changes. If the learner keeps picking the same picture, negative control is at work. Adjust your teaching to highlight the correct features, not just remove the wrong ones.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Add two probe trials where the usual wrong comparison becomes the new correct choice—see if the learner still picks the old "right" picture.
02At a glance
03Original abstract
Three adult subjects were taught the following two-sample, two-comparison conditional discriminations (each sample is shown with its positive and negative comparison, in that order): A1-BlB2, A2-B2Bl; Bl-ClC2, B2-C2C1; and Cl-DlD2, C2-D2D1. A teaching procedure was designed to encourage control by negative comparisons. Subjects were then tested for emergent performances that would indicate whether the baseline conditional discriminations were reflexive, symmetric, and transitive. The tests documented the emergence of two classes of equivalent stimuli: Al, B2, Cl, D2 and A2, BI, C2, Dl. These were the classes to be expected if the negative comparisons were the controlling comparisons in the baseline conditional discriminations. The negative comparisons, however, were not the comparisons that subjects were recorded as having chosen in the baseline conditional discriminations. Differential test results confirmed predictions arising from a stimulus-control analysis: In reflexivity tests (AA, BB, CC, DD), subjects chose comparisons that differed from the sample; one-node transitivity (AC, BD) and "equivalence" (CA, DB) tests also yielded results that were the opposite of those to be expected from control by positive comparisons; symmetry tests (BA, CB, DC), two-node transitivity (AD) tests, and two-node "equivalence" (DA) tests yielded results that were to be expected from control by either positive or negative comparisons.
Journal of applied behavior analysis, 1993 · doi:10.1901/jaba.1993.26-505