Macdonald triad

The Macdonald triad (also known as the triad of sociopathy or the homicidal triad) is a set of three behavioral characteristics that has been suggested, if all three or any combination of two, are present together, to be predictive of or associated with later violent tendencies, particularly with relation to serial offenses. The triad was first proposed by psychiatrist J.M. Macdonald in "The Threat to Kill", a 1963 paper in the American Journal of Psychiatry. Small-scale studies conducted by psychiatrists Daniel Hellman and Nathan Blackman, and then FBI agents John E. Douglas and Robert K. Ressler along with Dr. Ann Burgess, claimed substantial evidence for the association of these childhood patterns with later predatory behavior. Although it remains an influential and widely taught theory, subsequent research has generally not validated this line of thinking.

The triad links cruelty to animals, obsession with fire setting, and persistent bedwetting past a certain age, to violent behaviors, particularly homicidal behavior and sexually predatory behavior. However, other studies claim to have not found statistically significant links between the triad and violent offenders.

Further studies have suggested that these behaviors are actually more linked to childhood experience of parental neglect, brutality or abuse. Some argue this in turn results in "homicidal proneness". The "triad" concept as a particular combination of behaviors linked to violence may not have any particular validity – it has been called an urban legend.

In Singer and Hensley (2004), arson, or fire-setting, is theorized to be a less severe or first shot at releasing aggression. Extensive periods of humiliation have been found to be present in the childhoods of several adult serial killers. These repetitive episodes of humiliation can lead to feelings of frustration and anger, which need to somehow be released in order to return to a normal state of self-worth. However, the triad combination has been questioned in this regard also, and a review has suggested that this behavior is just one that can occur in the context of childhood antisocial behavior and isn't necessarily predictive of later violence.

FBI Special Agent Alan Brantly believed that some offenders kill animals as a rehearsal for killing human victims. Cruelty to animals is mainly used to vent frustration and anger the same way firesetting is. Extensive amounts of humiliation were also found in the childhoods of children who engaged in acts of cruelty to animals. During childhood, serial killers could not retaliate towards those who caused them humiliation, so they chose animals because they [animals] were viewed as weak and vulnerable. Future victim selection is already in the process at a young age. Studies have found that those who engaged in childhood acts of cruelty to animals used the same method of killing on their human victims as they did on their animal victims.

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