Trying to understand why there are people with psychopathy or who end up as serial killers is something that forensic psychology has tried to find out.

MacDonald’s triad has been one of the models that has tried to shed light on this, not without receiving criticism and not without being scientifically proven.

Be that as it may, the model is interesting, and its three variables are certainly factors that seem logical to be related to aggressive adulthood. Let’s see what they are.

MacDonald Triad: what is it?

The MacDonald triad, also called the sociopath triad, is a model proposed by psychiatrist John Marshall MacDonald in which the idea that sociopaths have three common traits is supported . This model was presented in his 1963 article ‘The Threat to Kill’, published in the American Journal of Psychiatry.

According to the model, most people who commit violent crimes in adulthood can be found in a childhood marked by aggressive behaviour , such as pyromania and animal cruelty, as well as urinating on themselves. Theoretically, people like serial killers have manifested at least two of these three behaviors in their childhood, which would have a history of mistreatment and abuse behind them.

Factors in explaining antisocial behavior

Three factors are proposed to explain how the psychopathic/sociopathic person’s mind is shaped. These three factors are the following.

1. Pyromania

Pyromania is the tendency to be attracted to fire and produce fires. It has been hypothesized that this behavior, if it manifests itself in childhood, predicts a violent and antisocial adulthood .

According to the model, people who have been humiliated in their childhood feel a repressed anger, which sooner or later will have to be shown.

As children abused by their parents or harassed by their schoolmates cannot defend themselves, they choose to destroy objects , and fire is one of the most aggressive ways to channel this frustration.

They also feel interest and pleasure in observing the flames being fanned, being aware of how serious it is for the integrity of others if the fire spreads.

2. Cruelty to animals

According to MacDonald himself and people who specialize in serial killers, such as FBI agent Alan Brantly, some serial killers and abusers start, even as children, torturing and killing animals .

This behavior can be interpreted as a kind of training for what they will end up doing as adults with their human victims.

The cause of these behaviors, as with fires, is humiliation and frustration at not being able to get revenge on those who have harmed them.

Because they cannot attack their parents or peers who are stronger than they are, these future sociopaths use defenseless animals who will not resist or complain while the child marks, maims or kills them.

Mistreating animals makes them feel in control of the situation , something they don’t have when someone mistreats them. It is to replicate what other people have done to them, they go from being victims to executioners.

3. Enuresis

Enuresis is the academic term for the unintentional release of urine when you are over five years old and sleeping. To be diagnosed, the subject must urinate twice a week for three months.

Both in MacDonald’s model and other authors argue that this variable is related, in one way or another, to presenting pyromaniac tendencies and animal cruelty .

Peeing at the age of five can be extremely humiliating for a child, especially if the parents do not know how to manage it in a healthy way and it is not perceived as a reason for punishment.

It is surprising that this factor is part of the triad, since in itself, is not violent nor is it intentional .

What should be understood is that the subject who suffers it will have less confidence in himself, which will generate a high psychological and emotional discomfort, as well as social rejection in case it transcends to the knowledge of other people.

Reviews of the model

The triad proposed by MacDonald, more than giving light on how psychopaths are formed, has contributed to a misconception of many of them. It is not necessary to manifest this type of behaviour to end up being a serial killer, nor will one end up being a psychopath for having manifested any of these behaviours as a child . The predictability of these three variables is rather low.

Despite the status of MacDonald’s proposal, it should be noted that the study he carried out to reach these conclusions has certain limitations and his interpretation has been too exaggerated.

The study, explained in his article The Threat to Kill , was done with 48 psychotic patients and 52 non-psychotic patients, who presented aggressive and sadistic behaviors. All of them had in common to have tried to kill someone, aged between 11 and 83, half male and half female.

Macdonald used his clinical observation to do his research and it can be said that even he did not believe that the study had any predictive value. His sample was small and not very representative of society as a whole. The problem lies in how the results explained by MacDonald were interpreted .

Other researchers found that the proposed model made a lot of sense, which meant that it would be addressed with samples of different types and sizes. These studies either had very small samples or did not come to the same conclusions as MacDonald and his followers.

However, despite the limitations of these studies, many criminologists assume that the model is valid. In fact, not a few sources in forensic psychology cite the model as being true. Associating pyromania, animal cruelty, and bedwetting with violent behavior in adulthood is a very common practice.

Bibliographic references:

  • MacDonald, John M. (1963). “The threat to kill”. Am J Psychiatry. 120 (2): pp. 125 – 130.

  • Ressler, Robert K.; Burgess, Ann W.; Douglas, John E. (1988). Sexual Homicide Patterns and Motives. New York, NY: Simon and Schuster. ISBN 9780669165593.
  • Singer, Stephen D.; Hensley, Christopher (2004). “Learning theory to childhood and adolescent firesetting: Can it lead to serial murder? International Journal of Offender Therapy and Comparative Criminology. 48 (4): 461-476. doi:10.1177/0306624X04265087
  • Barnard, N.D & Hogan, A.R. (1999). Moving up the chain of abuse pattern shows cruelty to animals is one predictor of violent behavior in adults. Seattle Post-Intelligencer, p. C.1.