Tuesday, August 19, 2008

School killings in Krugersdorp

Sad news: American-style school violence has reached South Africa. On the morning of August 18th, a matriculant at the Nic Diederichs Technical High School in Krugersdorp attacked fellow students and two gardeners with what appeared to be a katana, killing one and wounding three. Unfortunately, the Krugerdorp community and the South African media has responded idiotically - the leading hypothesis seems to be that Satan and the heavy metal band Slipknot, and specifically their song "Disasterpiece", is to blame. Here, for example, is News24:

Community leader, Pierre Eksteen, who is in charge of a school support network for children, told reporters outside the deserted school grounds that Satanic music was probably the cause of the attack.

"He came here camouflaged as the guys from Slipknot. We know the wrong kind of music, and drugs have bad effects. Young people need to be informed of the effects of bad Satanic music," said Eksteen.

Now, it could be the cause of this tragedy is Satanism and "bad music" but, given the counterfactual nature of causality, it is impossible to tell in a specific case because n=1. In other words, it's impossible to establish causality because confounds and third-factors cannot be ruled out. Correlation of course does not prove causation, so perhaps teenagers who are troubled to begin with tend to be both prone to violence and attracted to Satanism and heavy metal. Disentangling the direction of causality is possible with general studies but, unfortunately, the scientific literature on the media's influence on violent behavior is infested with moral panic, ideology and unnecessary shouting. However, a quick look through the literature turned up two interesting studies. The first, a review of meta-analyses published in The Lancet finds:
There is consistent evidence that violent imagery in television, film and video, and computer games has substantial short-term effects on arousal, thoughts, and emotions, increasing the likelihood of aggressive or fearful behaviour in younger children, especially in boys. The evidence becomes inconsistent when considering older children and teenagers, and long-term outcomes for all ages. The multifactorial nature of aggression is emphasised, together with the methodological difficulties of showing causation. Nevertheless, a small but significant association is shown in the research, with an effect size that has a substantial effect on public health. By contrast, only weak evidence from correlation studies links media violence directly to crime. (Emphases added).
In other words, we know the media has a small but statistically significant short-term influence on aggressive behavior in young children, but there is no consistent signal for long-term behavior or older children. Dealing specifically with the influence of heavy metal, Roberts, Christenson, and Gentile (pdf) conclude:
The best way to phrase the relation is to say that white adolescents who are troubled or at risk gravitate strongly toward the style of music that provides the most support for their view of the world and meets their particular needs: namely, heavy metal (p. 162).
Roberts et. al., therefore, conclude that there likely isn't a causal relationship between heavy metal and troublesome behaviors - troubled teens are drawn to heavy metal, heavy metal doesn't turn teens bad.

The literature on the media and violence is truly massive, and the above doesn't come close to being exhaustive, systematic or even representative. Nevertheless, it's clear that the knee-jerk community and media reaction - "Satan!" "Heavy metal!" - is unjustified and irresponsible. The causal relationship (if any) between violence and Satanism or heavy metal is in general unclear and difficult to establish and impossible to determine in a specific instance. While I think he is being somewhat too simplistic, I tend to agree with Ray Hartley from The Times:
Let’s hope that, in their rush to find supernatural causes for this tragedy, the good folk of Krugersdorp don’t forget to examine themselves. For, I fear, the real cause of this tragedy lies closer to home... Perhaps somewhere in that adolescent stream of crap that streams from Slipknot, he found a channel for his rage. Rage that may have come from school or from home or both - who knows. But to argue in all seriousness that this outlet for his real rage was the cause of his rage is facile and short-sighted. It will be a popular theory because it excuses those who responsible for raising this child in a nurturing, caring and protected environment from responsibility for their failings.
(Hat tips: Skeptic South Africa and Yet Another Sceptic's Blog. See also: "The devil didn't make him do it").


  1. Excellent analysis. I'm glad someone went to the effort to expose the science behind the effects of heavy metal etc. It's sad to see sensationalism and superstition win out over science. (Yay alliteration!)

  2. Thanks... It's amazing how silly the media can be. We're not quite at American levels of media idiocy yet, but we seem to be getting there at an alarming rate.

  3. Uh, dude, you can establish causation in cases where n=1. You just need decent information about the contributing factors, and to be able to rule out serious competing hypotheses. This may depend on some statistical inferences in other areas. That's not to say that you're generally wrong here - I pretty much agree with you. In cases (agreed, sad ones) like this the media interpretation ignores strong competing hypotheses like common cause inferences - e.g. that isolated, angry dangerous boys happen (sometimes) to like some kinds of music, and too quickly to be realists about bogus explanations such as appeals to 'satan'.

  4. How do you "rule out serious competing hypotheses" when n=1?

  5. Been a long day, so haven't read the whole post in detail yet, but so far I agree with YASB. Good post!

  6. I'm with Spurt on this:

    (1) I'm going to assume that nobody has ever used a gigantic springboard of the type used by gymnasts to bounce a dead cow such that it lands on a Faberge egg. Suppose that somebody did it once, so that n=1. Do you really want to say that anyone who says that the egg broke because a dead cow fell on it isn't making a justified claim?

    (2) What about basic physical laws? Are you really saying that our knowledge of them is primarily statistical? (I think that would be a pretty controversial position in physics and philosophy of physics.)

  7. Thanks for interesting coverage. I listened in amazement this morning as a 'reformed satanist' on SAFM informed us that Satanists are routinely required to break up families, collect up to 150l of blood, cause the demise of christian churches and so on. It's You magazine in the 80s all over again.

    I did read a short article this morning which suggested that the same things happen in our brain in response to violence, disgusting things etc whether those are in music, movies or books. The upshot was that it's not just heavy metal videos or GTA4 that cause our brains to react in certain odd ways.

  8. Why the hell do we always have to be put in the same groups as these killers?? just cus we listen to metal doesnt mean that we're gunna kill people!! i wish that the ignorance of other people would just dissapear, or, in the words of Anton LaVey: "if only ignorance and stupidity were painful.."

  9. If I read it correctly I agree with this article. I listen to metal, its an outlet for rage so I don't take it out on the stupidity in this world. I have no clue why we haven't blown ourselves up as a species yet, considering the way humans go through life like sheep, happy in the little biosphere looking for the next blade of grass to fill there stomachs, or the next person to blame THEIR problems on, ignorant of the ACME Anvil about to fall and kill them. But furthermore I have though about hurting someone,...... sure hasn't everybody, anger is universal. The reason I never acted on the impulses,...... very simple answer :

    My parents actually GAVE A DAMN about me and taught me the right way to live. It has absolutly nothing to do with metal. Metal did not make me angry. I am an angry individual, thus I gravitate to Metal. We live in an age where children are having children, before they themselves understand the world. So how are they to raise their children in the right way when they themselves are children. Most children do not have respect, its not in their vocabulary. So if they are never taught respect, how do they teach it to their children. Respect for their neghibor, respect for life, respect for anything, when all the know is me, me, me, me, because they have been left to teir own vices for most of their adolescence