Effects of uncertainty about the behavior of a phobic stimulus on subjects' fear reactions.

19 rat-phobic female college students were repeatedly exposed to a live rat on a nearby platform under instructional conditions designed to induce different expectancies about the probability of the rat remaining on the platform. Although the rat's behavior was the same in both conditions, Ss who were led to believe that the rat might leave the platform evidenced significantly greater cognitive and physiological arousal to repeated rat exposures than did Ss who were informed that the rat would definitely not leave the platform. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)