One of the shortcomings of the particular research that Latane and Darley did is that the underlying assumption, and this was kind of part of their starting premise, was that if you want to look at bystander intervention, it doesn't really matter whether you're dealing with a murder in New York in the 1960s or whether you're dealing with students sitting in a room seeing white smoke coming out of a vent duct, in other words they argue that this is a case of a general category of phenomena, such as an emergency, and that people sometimes act and sometimes don't in an emergency.

In real life, we do know that the likelihood of intervention depends very much on the nature of the emergency and where it takes place, and what attribution we place on the causes of that emergency. People are less likely to intervene if somebody who is experiencing an emergency looks a bit scruffy like a drunk, or a drug addict, because they make a certain attribution that almost that particular emergency is self-induced. In other conditions, people as soon as they witness an emergency, will of course make some kind of attributions about what caused that emergency and on basis of that will make a decision whether to intervene or not.

And of course I think the key thing to bear in mind is that in emergencies where somebody's own life is threatened are probably the ones where people are least likely to intervene, which is exactly why the cases when they do attract so much attention and people are hailed as heroes. The whole concept of 'bystander' is not simply a description of somebody's position in a situation, it is also a moral category. To say that somebody's a bystander is in many instances an accusation - somebody who stood by as something drastic happened. On the other hand, to say, in other situations to say that someone is a bystander is an excuse for non-action.

To say "I'm not the perpetrator, I was merely a bystander." and this is quite an important thing to bear in mind, which psychologists often fail to consider. And that is that we're not dealing, in everyday life when we talk about bystanders these are not neutral categories and mere descriptions, they're also a way of attributing blame, excusing somebody's behaviour or making a moral judgement about somebody's actions in a particular emergency situation.