Expectancy and Magnitude of Reaction to a Noxious UCS

ABSTRACT The relationship between expectancy and magnitude of reaction to a noxious UCS was examined in studies using a classical conditioning paradigm, in habituation studies, and in studies using a count‐up to stimulus presentation. An initial hypothesis that accurate expectancy reduces reactivity was found inadequate, and replaced by one that stated that accurate expectancy facilitates habituation. Although this hypothesis was consistent with the data reviewed, it was concluded that it, too, requires modification. The final hypothesis proffered was that accurate expectancy facilitates habituation when it fosters appropriate modulation of attention, which, for highly threatening stimulation, consists of a degree of restriction of attention to begin with, followed by increasing attention to new elements of the stimulus complex as reactivity to old elements is reduced.