Indeed - weapon focus limits the amunt of overall accurate knowledge outside the nature of the weapon itself - henct the name.
Leading questions do change memory - saying such things like "did you see his white trainers" won't have them saying "yes I did", but later on if asked to describe them a significant percentage would say that white trainers were worn.
Other such things include Grue's mentioning of the wording of the questions - "hit the car" got an average speed description of approximately (from memory (no pun intended
)) 15mph lower than "crashed into the car".
One other thing that affects memory is belief. I know of an experiment that implanted a flase memory just my showing the individual an edited photo of themselves with a family member earlier in their life in a different location.
There are so many factors that are involved in memory it won't be feasible to list them here, but the intrigued amongst you can look up eye witness testimony stuff by loftus, or loftus & palmer.
