Cumulative Record. Chapter 28: The Operational Analysis of Psychological Terms. Quote 39

In a rigorous scientific vocabulary private effects are practically eliminated. The converse does not hold. There is apparently no way of basing a response entirely upon the private part of a complex of stimuli. A differential reinforcement cannot be made contingent upon the property of privacy. This fact is of extraordinary importance in evaluating traditional psychological terms. (pp. 423-424)