Have there been any studies or exist any statistics on how often people fail to somehow intervene in the event of an emergency where violence is involved? I'm primarily interested in North America (and exclusively interested in developed nations). For example how often does it happen that an assault takes place where even though there are witnesses, not one phones for police (as in the case with Kitty Genovese)?
This question pertains to the bystander effect. Basically I'm asking what is the prevalence of it, in the sense is it more likely than not for someone to somehow assist when clearly someone needs help?
In a psychology class I took we were taught this is the reason for the bystander effect:
I personally don't find this a convincing argument, as it seems all they did was break things down into small steps. For example step #3 is almost negligible because simply calling 911 isn't assuming too much responsibility. And for #4 you just need to know the number 911.