Testing the temporal stability of individual differences in the acquisition and generalization of fear.

We studied the temporal stability of individual differences in the acquisition and generalization of fear. Seventy-one participants were tested in two almost identical fear-acquisition and fear-generalization sessions (separated by 8 months). Acquisition and generalization were measured by the fear-potentiated startle, the skin conductance response, and online expectancies of the unconditioned stimulus. To control for the effects of previous experience, different stimuli were used for half of the participants in Session 2. Acquisition and generalization did not differ across sessions or as a function of the stimuli used in Session 2, and a significant proportion of individual differences in these processes was stable over time (generalizability coefficients ranged from 0.17 to 0.38). When the same stimuli were used, acquisition measures showed compromised stability. The results are discussed in terms of their theoretical and applied implications.