Perception is selective
Witnesses do not record events like cameras. Attention focuses upon some details while other information is never consciously encoded.
Stress can impair observation
Fear, speed, darkness, distance and the presence of a weapon can reduce accurate identification and memory for surrounding details.
Memory is reconstructed
Remembering involves rebuilding an event from stored fragments, expectations and later information rather than replaying a complete recording.
Questions can influence reports
Leading wording, repeated interviews and information from other witnesses can unintentionally alter what a person later remembers.
Confidence can increase without accuracy
Feedback, repetition and official confirmation can make a witness more certain even when the original memory was weak.
Some circumstances improve reliability
Immediate accounts, neutral questioning, good viewing conditions and procedures that prevent suggestion can make testimony more useful.
Corroboration remains important
Physical evidence, recordings, documents and independent witnesses should be used to test rather than merely repeat an eyewitness account.
Evidence notes
Assessment should examine viewing conditions, duration, stress, delay, question wording, prior familiarity, identification procedures, confidence at the first report and independent corroboration.
Ethical questions
How soon after the event was the account recorded?
Was the witness exposed to suggestions or other accounts?
Which parts of the testimony are independently corroborated?
Conclusion
Eyewitness testimony can be useful but should not be treated as automatically reliable. Its weight depends upon observation conditions, interviewing methods and support from independent evidence.