The Problem of Class Breakdown in Sidman’s (1994, 2000) Theory about the Origin of Stimulus Equivalence
Equivalence needs many exemplars, not just reinforcement, to stay solid.
01Research in Context
What this study did
Alonso-Alvarez (2023) looked at Sidman’s old idea that reinforcement alone creates stimulus equivalence.
The paper says that idea is too simple. Classes can break apart when the learner can’t tell which new relations will pay off.
The author argues you need many examples, not just one contingency, to keep the class together.
What they found
The review found that equivalence does not always emerge from reinforcement.
Without extra training, learners may link the wrong stimuli and the class collapses.
How this fits with other research
Silguero et al. (2023) ran a direct test the same year. They showed that conflicting reinforcers stay inside the class, even when the reinforcer is trained first. This backs the critique.
Davison et al. (2002) did the groundwork. They used many exemplars to give adults contextual control over equivalence. Their data support the fix Alonso-Alvarez now urges.
Schedlowski et al. (2025) reviewed memory work with dementia patients. Mixed results line up with the warning: weak designs let classes break.
Why it matters
If you teach conditional discriminations, do not assume the equivalence will stick. Build in multiple-exemplar drills early and probe often. Watch for class breakdown and add more examples when generalization wobbles.
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02At a glance
03Original abstract
Sidman (1994, 2000) hypothesized that equivalence relations are a direct outcome of reinforcement contingencies. This theory is problematic because contingencies do not always result in equivalence. Sidman proposed that equivalence relations may conflict with analytic units, the other outcome of contingencies (e.g., in conditional discriminations with common responses/reinforcers). This conflict may result in a generalized class breakdown and a failure to pass equivalence tests. This is more likely in nonhumans, very young humans, etc. The conflict can also result in a selective class breakdown and success in equivalence tests. This occurs after experience shows the organism the necessity and utility of this process. The nature of that experience and the class breakdown processes were not described by Sidman. I explored the implications of the following hypotheses for Sidman’s theory. First, conditional discriminations with a common response/reinforcer result in a generalized class breakdown when participants fail to discriminate emergent relations incompatible with contingencies from those compatible. Second, learning to discriminate between the two requires a history of multiple exemplar training (MET). This implies that equivalence class breakdown is a common response to exemplars that have nothing in common except their relations. This, however, contradicts Sidman’s views about the impossibility of such process in the absence of a complex verbal repertoire. If that type of learning from MET is possible, then the possibility that MET results in the selective formation of equivalence classes must be admitted, and the utility of hypothesizing that equivalence is a direct outcome of reinforcement contingencies can be questioned.
Perspectives on Behavior Science, 2023 · doi:10.1007/s40614-023-00365-2