Some of the names and body counts are all too familiar: Littleton, CO (Columbine)/15 dead, 23 wounded; Virginia Tech, VA/32 dead, 15 wounded; West Paducah, KY/3 dead, 5 wounded; Springfield, OR/2 dead, 22 wounded; Jonesboro, AR/5 dead, 10 wounded...
Some are familiar to a few: Bethel, AK/2 dead, 2 wounded; Moses Lake, WA/3 dead, 1 wounded; Richmond, VA/2 wounded; Gary, IN/1 dead; New York, NY/2 wounded; Granite Hills, CA/4 wounded...
School shootings are a statistically insignificant problem in the US. According to the CDC, there were 116 deaths from homicide at school between 1999 and 2006, a rate dropping from 0.07 to 0.03 per 100,000 every year or 16.5 deaths per year. That's about 1.25 student homicides per month. As a reference, about 100 deaths and 500 injuries (in a larger population) are caused in the US every year by lightning strike. The CDC calculates the rate of casualty (killed and wounded) by lightning in military personnel from 1998 to 2001 as 4.7 - 5.8 per 100,000 person years. From 2000 to 2005 the rate of fatality in auto accidents in the US was between 14.6 and 15.0 per 100,000 person years*. In other words, you're nearly 500 times* more likely to die in an auto accident than a student is likely to be murdered at school in any given year.
* (snapshot of my Excel sheet, data from the links provided)
So if school shootings like the one at Northern Illinois University are so "statistically insignificant", why bother with them?
One reason is that they get splashed all over the news. It's no secret that "if it bleeds, it leads", especially in local TV news. Another is that we find them shocking -- children are not supposed to die by homicide, and they are especially not supposed to commit homicide. Finally, I think because it's hard to see a story about school shootings, especially those committed by kids, and not ask "Why?".
Violent Crime in America
Absolute numbers of violent crimes in America peaked in the early 90's (murder in 91, rape in 92, aggravated assault in 93). When adjusted for population, murder peaked in 1980 and both rape and aggravated assault in 1992. Since 1992, the murder rate has fallen 29%, rape has fallen 28%, and aggravated assault 35%. It's clear that the trend since the early 90's is down but not entirely clear if that rate will continue to drop or if it has leveled out, especially in assaults. The sharp rise between 1960 and 1992 is mysterious and interesting. The rate of aggravated assaults increased almost fivefold and has since dropped to about threefold, rape increased about fourfold and has since dropped to threefold. Murder peaked at about twice the 1960 level and has since fallen to near the 1960 level.
There are undoubtedly demographic drivers for at least part of this change. In 1960, 14% of the population was 15 - 24. From 1973 to 1980, it was 19% of the population. Similar 5% changes happen in the 5 - 14 and 25 - 34 cohorts. With finer data buckets, I suspect we might find a decent correlation between violent crime and a specific age group. According to Criminal Justice in America:
Changes in the age makeup of the population are a key factor in the analysis of crime trends. It has long been known that men aged 16 to 24 are the most crime-prone group....Between 40 and 50 percent of the total arrests during [the 70s] could have been expected as a result of the growth in the total population and in the size of the crime-prone age group.
It would take a bunch of leaps to conclude that I understand exactly what the demographic effect is, but I do grok that up to 50% of the arrests might have been caused by demographic effects. So maybe 220 of those 440 aggravated assaults were demographics in action. That still leaves a peak of almost three times the original rate, and us currently at about 144, 75% over the 1960 rate. Where does that increase come from?
Effects of Violent Media Imagery
I have spent much of my professional life (more than 15 years, total) in the video or computer game business. It is a public article of faith in that business that violent video games have no effect upon the behavior of people who play them. There are similar claims made by the movie and TV industry.
But there are reputable studies which conclude the exact opposite: violent screen imagery has a clear effect upon watchers:
Research on violent television and films, video games, and music reveals unequivocal evidence that media violence increases the likelihood of aggressive and violent behavior in both immediate and long-term contexts.
Well-supported theory delineates why and when exposure to mediate violence incrases aggression and violence. Media violence produces short-term increases by priming existing aggressive scripts and cognitions, increasing physiological arousal, and triggering an automatic tendency to imitate observed behaviors. media violence reduces long-term effects via several types of learning processes leading to the acquisition of lasting (and automatically accessible) aggressive scripts, interpretational schemas, and aggression-supporting beliefs about social behavior, and by reducing individuals' normal negative emotional responses to violence (i.e., desensitization).
Youth Violence: A Report of the Surgeon General, released in early 2001, reports:
The most recent and comprehensive meta-analysis of media violence was conducted by Paik and Comstock (1994), who examined effect sizes from 217 empirical studies on media violence and aggressive and violent behavior published between 1957 and 1990. The analysis indicates clearly that brief exposure to violent dramatic presentations on television or in films causes short-term increases in the aggressive behavior of youths, including physically aggressive behavior. Across all the randomized experiments, the unweighted average effect size was large (r = .37).4 When only experiments examining physical aggression as the outcome were examined, the effect size was also large (r = .32).
A follow-up study of over 300 people in the U.S. sample 15 years later suggested that media violence has a delayed effect on aggression (Huesmann et al., submitted). There was a small to moderate longitudinal correlation between childhood television viewing and a composite measure of young adult aggression (physical, verbal, and indirect aggression) for both men (r = .21, N = 153, p < .01) and women (r = .19, N = 176, p < .01). When the outcome was limited to physical aggression, the correlations were smaller (r = .17 and r = .15, respectively).
It's important to understand what is and isn't being said here. No one is saying that playing a violent video game once or watching an episode of your favorite cop show is going to turn anybody immediately into an axe murderer or serial killer. What is being said is that there is well supported theory about how exposure to violent images might increase the likelihood of later aggressive or violent behaviour and that both statistical and experimental studies validate that effect in the short and long term.
Human behaviour is generally too complex to assign a single "cause" to any given "effect". In the quotes above, the statistical information suggests that media exposure can explain between 15% and 37% of the increased aggressive or violent behaviour.
OK, that's enough for today. In an upcoming post or two, I'll explain the theories of arousal and desensitization and then present some of the studies validating those theories. I'll introduce you to Lt. Col. Dave Grossman, former West Point psychology professor and current Professor of Military Science at Arkansas State, who's written extensively on the effects of military training, conditioning, and PTSD, and who now trains medical and mental health professionals in how to prevent killing. Col. Grossman's discipline of "killology" and models of how training and authority break down the innate resistance to killing will help explain how media violence and especially first person shooter video games condition watchers and players similar to the way boot camp indoctrinates soldiers. Finally, we'll talk about how and why media has changed over the last half-century to increase levels of conditioning, and what changes we can make to reduce the effects.