Choice Under Conditions of Uncertainty

All behavior varies, and behavior under a wide range of circumstances displays high levels of variability. This is especially true under many concurrent schedules of reinforcement, despite those schedules not being designed to elicit unpredictable behavior. A generalized matching analysis was performed to measure the effects of reinforcement on 5-item choice under two conditions: Probabilistic concurrent schedules and threshold-based operant variability schedules. Behavior was analyzed in terms of conditional probabilities, incorporating trial-by-trial response dynamics into the model. Performing this analysis meant overcoming a major difficulty: Obtained reinforcement is not a valid independent predictor of behavior the two are causally interlinked. The method of instrumental variable estimation is utilized to overcome the “endogeneity” of reinforcement, which permits unbiased estimation of the causal influence of reinforcement on responding. The analysis revealed a simple relationship between choices made and the distances traveled to make them. Subjects were more willing to travel through the chamber under the Concurrent schedule than under the Variability schedule. As a result, with respect to predicting a subject’s next response, Concurrent schedules elicited higher levels of behavioral variability than did Variability schedules. However, longer-term behavior under the Variability schedules better resembled a steady-state random process.

Operant Variability and the Evolution of Volition

Volition has been debated for thousands of years: what is it, how is it possible for biophysical beings to behave in a voluntary manner, indeed, does volition exist? Evolution of volition has rarely been part of the discussion. In this paper, I argue that operant-conditioning studies provide evidence for evolved volition. Three attributes are common to operant and voluntary behaviors. One is that responses are goal-directed, purposeful, some say rational, or controlled by reinforcing consequences. A second is that the responses vary – from random-like to repetitive – with predictability (or unpredictability) depending upon contexts and consequences. A third attribute is that responses appear to be self-generated or, in operant terms, emitted. These attributes are found in many species, simple to complex, but species also differ in details. Taken together, the evidence supports an evolutionary basis of volition.