[treerock]

> decrease of probability that a particular individual will act, with decrease in group size

I believe the study did show that. I heard an interview with one of the authors on the radio (so my memory may be faulty).

So I don't think it really debunked the bystander effect, rather he made a point along the lines of, 'it doesn't really matter, the more people present means it's the more likely that one of them intervenes'.

[feanaro]

That's interesting. I would be really interested in seeing this repeated and plotted as a function of the number of people in the group, up to ~50.