Can prepared fear conditioning result from verbal instructions?

Evolutionary fear-relevant stimuli such as snakes or spiders are thought to be prepared to elicit fear reactions. This implies that the acquisition of conditioned fear responses is facilitated when these stimuli serve as conditioned stimuli (CSs). Moreover, extinction of conditioned fear responses is delayed when CSs are prepared stimuli. The research presented in this article addresses the question whether such selective learning effects can be obtained even when participants do not experience pairings of CSs and US but receive only instructions about those pairings. Two experiments were conducted in which participants were verbally informed about the relationship between fear-relevant and fear-irrelevant CSs and the presence of an electrical stimulus (US). However, CSs were never actually paired with the US. US expectancy ratings and skin conductance responses were recorded during multiple CS only trials. In the first experiment, we observed acquisition, extinction and reinstatement of fear on the basis of instructions, but these effects were not modulated by the fear-relevance of the CSs. In the second experiment, we manipulated whether participants actually experienced the CS-US contingencies or were merely instructed. We obtained facilitated acquisition for the merely instructed fear-relevant CS+. We discuss these results in relation to the evolutionary fear learning model of Öhman and Mineka (2001) and the expectancy bias model of Davey (1992)