"It was postulated that people characteristically defend their beliefs . . . by avoiding exposure to contradictory information . . ‥ Since the person is unmotivated to develop a defense of his belief to the extent that he considers it invulnerable, it was hypothesized that such beliefs are more effectively immunized against persuasion by preexposure to counterarguments . . ‥ Second, since the person is unpracticed in the defense of such beliefs, it was predicted that immunizing pretreatments would lose effectiveness to the extent that they required the person to participate actively . . . in the defense. Finally, an interaction effect was predicted such that the detrimental effect of requiring active participation is greater with the defense involving pre-exposure to the counterarguments than with the supportive defense." The hypotheses were supported. From Psyc Abstracts 36:04:4GD27M. (PsycINFO Database Record (c) 2006 APA, all rights reserved)