Seeing is Beliving

At a place I used to attend there was an incident.  It was serious enough to need a resolution.  Fortunately, the event was recorded and what actually happened could be seen. 
There was someone who was there, and a part of the team who needed to resolve the matter.  He did not see what transpired, and before he saw the footage, was relying on the report of others who saw it.  He said something like “I have never heard so many different versions of the same thing.”
It seems police have confronted the same problem.  Someone 6’2”, white and wearing a yellow shirt may have perpetrated a crime.  Eye witnesses tell them it was someone 5’9”, of Indian appearance, and wearing a blue shirt that did it.  Someone else saw a person 6 foot, native American and wearing a black shirt. And so it goes on.  To one, the person had a beard.  To another, they were clean shaven.  People who saw the same thing, have so many different versions.
I am thinking about such things as on occasions I have been somewhere and when I asked what the other thought, I have been inclined to wonder, did we see the same thing? Their report is completely different to my take.
I am forced to ask myself “how can this be?” To me there can be several reasons for such a thing.  One of the reasons seems to be that people hear or see what reinforces their beliefs.  Someone may be having trouble with a 6’ white fella who, the last time they were seen, was wearing a yellow shirt.  What they see matches that person.
I have no doubt that if a group of us were asked to go outside and look at the same thing, and record what jumped out at us, we would all have different conclusions.  Someone may have just had a bad experience with splinters.  There is a good chance the wood would be what jumps out.  Someone else may have seen an insect hole in the ground.  The grass would be reported.  Another may have spent ages raking up.  Leaves would be what they see.  They all saw the same thing, but all saw it differently.
It seems others also have a particular view of the world, and cherry pick only what reinforces that take.  To me, it is why so much research is sus.  There is a thought someone wants to prove.  They overlook everything that may prove a matter to be otherwise, and hone-in on what re-enforces their outlook.
They have done such things with some studies (I am thinking cigarettes and asbestos).  A person may have needed to prove what their boss wanted (at the very least to recoup their expenses), or they may have had their own agenda.  Something is accepted and takes ages to put right.  In the mean-time, a great many people have suffered.
To me, there can also be outside forces at work.  Sometimes the intention of a matter is stolen away and can be totally blanked out.  What is heard or seen has little resemblance to the intent of what transpired or was said.
I am sure there have been studies done on such things.  No doubt there are reasons given from a to d or I to 4. I only know what I have seen, and it made me wonder.