A Critical Review of the Support for Variability as an Operant Dimension
Variability may ride on extinction processes, so track which specific responses are being lost.
01Research in Context
What this study did
Nergaard et al. (2020) read every major paper on reinforcing behavioral variability.
They asked a simple question: does the reinforcer really strengthen "variability," or just the separate moves that make up the varied pattern?
The team wrote a critical review, not a new experiment.
What they found
The authors say variability is not a special operant dimension.
Instead, when a lag schedule pays off for new sequences, it quickly stops paying off for old ones.
The old forms go away through extinction, so only new forms stay—making the pattern look "variable."
How this fits with other research
Doughty et al. (2015) and Galizio et al. (2018) see the same data and reach the opposite conclusion.
Their pigeon and human studies show that variability extinguishes on its own and resurges later—clear signs of direct operant control.
Nergaard answers: those effects can still be explained by extinction of specific response chains, not by reinforcement of the abstract property "variability."
Why it matters
If variability is only a side effect of extinction, you must plan for the drop-off of old forms when you write lag schedules.
Watch which exact responses are being extinguished, not just whether the client is "being varied."
Pair new exemplars fast so the learner always has reinforced options, and probe periodically to check that the old forms do not sneak back in.
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02At a glance
03Original abstract
There is abundant evidence that behavioral variability is more predominant when reinforcement is contingent on it than when it is not, and the interpretation of direct reinforcement of variability suggested by Page and Neuringer, Journal of Experimental Psychology: Animal Behavior Processes, 11(3), 429–452 (1985) has been widely accepted. Even so, trying to identify the underlying mechanisms in the emergence of stochastic-like variability in a variability contingency is intricate. There are several challenges to characterizing variability as directly reinforced, most notably because reinforcement traditionally has been found to produce repetitive responding, but also because directly reinforced variability does not always relate to independent variables the same way as more commonly studied repetitive responding does. The challenging findings in variability experiments are discussed, along with alternative hypotheses on how variability contingencies may engender the high variability that they undeniably do. We suggest that the typical increase in behavioral variability that is often demonstrated when reinforcement is contingent on it may be better explained in terms of a dynamic interaction of reinforcement and extinction working on several specific responses rather than as directly reinforced.
Perspectives on Behavior Science, 2020 · doi:10.1007/s40614-020-00262-y