Quantum Physicists tell us that observing a thing alters the thing being observed.  Some even say that the observer, us, decides what it is we observe.  What I haven't seen explained in any of the Quantum books I've read so far is why when a group of people observe something they all see essentially the same thing.

If several people look at a moving something in a tree you don't have one person seeing a raven, another seeing a squirrel, another seeing a monkey, etc.  They all see the same "object".

I have my own theory on how this happens.  I think our subconscious minds communicate with each other so that when several people look at something their subconscious minds try to figure out what it is and when they come to a consensus, the image is sent to the conscious mind of each observer. 

I have done no research on this, but it makes sense to me.