Higbee (1969, 1974) suggested the conflicting findings on the relative effectiveness of strong vs mild threat may result from arousal of two different kinds of fear by the messages used in research on threat appeal. One type of fear (nausea-type) is aroused by gruesome, vivid descriptions; the other fear (concern-type) is more related to the likelihood that the subject will experience the threat. In research reported here, subjects exposed to nausea-type threat expressed more aggression than subjects exposed to concern-type threat. These results support Higbee's suggestion that nausea-type threat and concern-type threat are different. Indirectly, they support the hypothesis that the conflicting findings are, in part, the result of unequivalent operations for the concept “threat” by different investigators.