So why is our murder rate so much higher than other countries, and why do we love guns so much? There's plenty of violence in the media elsewhere.
[WS:] I thought I hinted that in the last paragraph of my posting where I compared US and Japan. Both countries are similar in the high-profile presence of violence in the media, but they differ in social cohesion and norms of behavior. Social cohesion is high in Japan, which also have strict rules of behavior that, inter alia, prohibit violence in personal interaction. By contrast, social cohesion is low in the US, and the "anything goes as long as it suits ME" attitude is prevalent.
That difference suggests difference in the effect of media on legitimation of violence. In Japan, the media influence, which is relatively weak to begin with, competes against strong social norms and rules that often contradict the media influence. Therefore the net effect of the media on behavior is relatively small.
In the US, by contrast, the societal influences are weak to begin with -after all this is the nation of individualists and wannabes - and often inconsistent - for example different institutions promoting contradicting sets of values (e.g. church and state) or the existence of double standards (e.g. "violence is bad, but it is OK to attack certain groups of people"). Therefore, the media effect, even if relatively weak in absolute terms, is not counterbalanced by societal influences, and thus exerts a relatively stronger influence on individual behavior than in countries with strong societal norms.
Another point - the infatuation with violence in the US is mostly symbolic, and takes mainly the form of spectacles, whereas the engagement in actual violence in everyday life is relatively low. By contrast, European are much cooler toward violent spectacles, but they are more likely to personally engage in low-level violence in every day interaction. Pushing, shoving, or hitting among stranger is much more common and accepted in Europe than it is in the US (except perhaps in relatively isolated subcultures).
For example, if you go to a pub in Europe (at least in Eastern Europe, Germany or England) - the chances are that somebody you have never met will be in your face, which often escalates into a shoving match and then a fist fight. In the US, however, such behavior is relatively rare - the US pub scene is rather tame by European standards.
Finally, the range of behavior in the US tends to be more narrow than elsewhere. In the US, it is either sugar-coated every-day niceties, the "polite how are you," the small talk, the avoidance of controversial topics, or just avoidance of any interaction (cf. the NYC subway gaze), and if that sugar coating is blown away - it often flips into the other extreme - going postal, road rage, or shooting sprees. In Europe (and other countries, I presume), otoh, there is a much wider range of behavior - from sugar-coated small talk, to various levels of formality, to verbal assaults or threats, to low-level violence (pushing, shoving), to middle-level of violence (fist fights) and to high level of violence (savage beatings or killing).
To sum this up - media is but one influence on behavior, and there are many other societal variables that often counteract the media influence. However, in countries with a "weak society" and strong corporate influence, such as the US, the effect of the media is not counterbalanced by other societal variables, and thus this effect is relatively stronger.
Wojtek