Guns, Testosterone, and Aggression:
An Experimental Test of a Mediational Hypothesis
The “weapons effect”—that merely seeing a weapon increases aggression—is well-documented
(Anderson, Benjamin, & Bartholow, 1998; Bartholow, Anderson, Carnagey, & Benjamin, 2005;
Berkowitz & LePage, 1967; Bettencourt & Kernahan, 1997; Killias & Haas, 2002). However,
the physiological mechanism behind the weapons effect has not been investigated.
Perhaps the hormone testosterone is the physiological trigger for the weapons effect. After all, for
species ranging from chickens to monkeys, testosterone injections increase aggressiveness
(Ellis, 1986). Furthermore, some laboratory and field studies involving human participants have also found
strong positive relationships between testosterone and aggression (Archer, 1994; Campbell, Muncer, &
Odber, 1997; Dabbs, Carr, Frady, & Riad, 1995; Dabbs, Jurkovic, & Frady, 1991). Thus, it may be that
seeing a weapon triggers a surge in testosterone which, in turn, triggers aggression.
Although some evidence suggests that surges in testosterone trigger aggression, there is no direct
evidence that seeing a weapon triggers testosterone surges. However, some indirect evidence suggesting
that seeing a weapons could trigger an
increase in testosterone comes from
research on the “challenge
hypothesis” (Wingfield, Hegner, Dufty, & Ball, 1990).
Originally developed to explain aggressive behavior in male pair-bonded birds, the challenge