Eyewitness testimony can hold a lot of weight with jurors. But eyewitnesses aren't always right, and poor investigative practices can make matters worse.
Initial research found witness pupils got bigger when correctly identifying a criminal.
Your memory of an event can be manipulated – and miscarriages of justice can follow.
There's a concern that images posted on social media run the risk of disrupting the accurate identification of people allegedly involved in a crime.
As many as one in 50 people are face blind, meaning they can't tell one face from another.