We all have very unreliable memories. We may think we have a good memory and on some subjects we do, but if you were ever asked to swear your life on a memory then don't.
Here are a couple of examples:
1] A psychologist interviewed a group of children who attended a school that had undergone a trauma, like a shooting where kids had died or a fire. She then went back and re-interviewed the students a year later. What she found was that the kids who hadn't been at school when the incident happened had a more vivid and detailed memory of the event than did those who were there. This is despite the fact that they couldn't have experienced the events they claimed to of seen.
2] Someone I know was a young man when his Dad died. It was a very emotional time for the family which is quite large. The death took place in a hospital bed. The memory of my friend was of holding his Dad's hand as he died. He felt the life blood leave his father's hand.
My friends younger brother who was only 12 at the time was not in the hospital at the time of his Dad's death. However he too has a memory of holding his Dad's hand and sitting at the bedside as his Dad died. These conflicting memories have created disagreements between these brothers. As if one wants to steal his brothers memory.
I don't believe this is the case. I think the younger brother has relived the death of his father so many times he has transferred bits of his brothers experience onto his memory. He has done it so convincingly that he truly believes he was there.
Try remembering what you saw, did yesterday and if someone you know was there what they think happened. You could be surprised.