The point of the experiment was to understand the parameters of social influence around a specific, public behaviour. The researchers chose a street corner and observed how folk responded to differing numbers of stooges, standing & pointing at a 6th floor for just 60 seconds (hence the name).
40% of passersby checked what a single stooge was looking at; the number rose to 85% when 15 stooges are involved.
For me, not only does this illustrate the power of social influence brilliantly (heuristic no.1 = do what the others are doing) but also how we outsource cognitive weight to others (the guy pointing must know something I don't, eh? )
Or, if you're more patient than me, you could scour t'web for a free download of:
Milgram, S., Bickman, L, Berkowitz L. (1969), "Note on the Drawing Power of Crowds of Different Size," Journal of Personality and Social Psychology, 13(1), 79-82
Now, what are those guys over there up to...?