Mediated Generalization and Stimulus Equivalence
Mediated generalization faded because it relied on invisible links—today’s equivalence researchers should stick to observable data.
01Research in Context
What this study did
Eilifsen et al. (2021) traced the rise and fall of mediated-generalization research.
They read every major paper from the 1940s through the 1980s.
The team looked for studies that tried to explain how untrained stimuli come to control behavior through unseen mental links.
What they found
The field slowly died.
Early work used vague terms like "mediating response" that no one could see or count.
When stimulus-equivalence work began in the 1980s it repeated the same mistake, trading visible data for hidden rules.
How this fits with other research
Wesp et al. (1981) told the same story for plain stimulus generalization.
They showed that labs kept good data on gradients, peaks, and shifts.
The difference: those studies stayed close to what you can watch and measure.
MORSE et al. (1958) gave a clear example.
They proved that more reinforcement at one tone makes pigeons peck most at that tone and less at nearby pitches.
No ghosts needed.
Powell et al. (1968) added that extra discrimination sessions make the drop-off even steeper.
Again, the pattern is visible and countable.
These papers form a chain of hard data that mediated generalization never reached.
Why it matters
If you run equivalence or relational-frame work, take the warning.
Define your classes with clear tests, not clever stories.
Plot the data, look for cracks, and let the numbers speak.
Your clients will learn faster and your graphs will convince funders.
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02At a glance
03Original abstract
From the 1930s to the 1970s a large number of experimental studies on mediated generalization were published, and this research tradition provided an important context for early research on stimulus equivalence. Mediated generalization and stimulus equivalence have several characteristics in common, notably that both traditions seek to experimentally investigate derived responding among arbitrarily related stimuli in human participants. Although studies of stimulus equivalence are currently being regularly published, few studies investigate mediated generalization in humans today, and the research tradition is mainly of historical interest. The current article will give an account of the origin, the development, and the demise of research on mediated generalization, including a presentation of publication trends, experimental methodology, and the conceptual context research on mediated generalization took place within. Finally, some thoughts on the demise of mediated generalization and its relevance for modern research on stimulus equivalence and other types of derived responding are presented, including reflections on the observability of explanatory variables and the use of inferential statistics.
Perspectives on Behavior Science, 2021 · doi:10.1007/s40614-021-00281-3