Williams, B. A. (2001).
Two-factor theory has strong empirical evidence of validity.
Journal of the Experimental Analysis of Behavior,
75, 362-366.
Traditional two-factor theory is supported by parallels in the
clinical literature. Theoretical problems with two-factor theory
are obviated by the role of safety signals, which serve as
positive conditioned reinforcers and retard the extinction of
conditioned fear.
Key words: avoidance learning, safety signals, conditioned
reinforcement, learned helplessness