AN EXPECTANCY MODEL OF LABORATORY PREPAREDNESS EFFECTS

Experiments investigating differential unconditioned stimulus (UCS) expectancy during fear-relevant (prepared) and fear-irrelevant (unprepared) stimuli revealed that (a) a UCS expectancy bias is apparent before conditioning, (b) initial differential UCS expectancy appears in spite of instructions informing the Ss of no UCS presentations, (c) differential UCS expectancies to fear-relevant and fear-irrelevant stimuli dissipate with continued nonreinforcement, (d) differential certain conditions, (e) both UCS expectancy and SCR measures show similar patterns of behavior in the traditional preparedness paradigm, and (f) experiencing CS-UCS pairings appears to reinstate a UCS expectancy bias after it has extinguished. These results are discussed as support for an expectancy model of laboratory preparedness effects.