The authors studied the modifications in contingent negative variation (CNV) in a group of rupophobic subjects. A slide-projected phobogenic or a neutral stimulus was administered 5 s prior to the warning stimulus (S1). A marked reduction in CNV amplitude and the appearance of post-imperative negative variation were observed when the phobogenic stimulus was applied. No significant variations were noted after administration of a neutral stimulus. The results are discussed on the basis of psychological and neurophysiological findings concerning the relationship between attention, arousal and CNV.