Killing begets killing: evidence from a bug-killing paradigm that initial killing fuels subsequent killing.

Killing appears to perpetuate itself even in the absence of retaliation. This phenomenon may occur in part as a means to justify prior killing and so ease the threat of prior killing. In addition, this effect should arise particularly when a killer perceives similarity to the victims because similarity should exacerbate threat from killing. To examine these ideas, the authors developed a bug-killing paradigm in which they manipulated the degree of initial bug killing in a "practice task" to observe the effects on subsequent self-paced killing during a timed "extermination task." In Studies 1 and 2, for participants reporting some similarity to bugs, inducing greater initial killing led to more subsequent self-paced killing. In Study 3, after greater initial killing, more subsequent self-paced killing led to more favorable affective change. Implications for understanding lethal human violence are discussed.