Memory conformity

When we remember what something 'should' look like, we will often construct a memory to fit the mould. 

False memories can also happen to groups and could lead to mass delusions. People were shown a fake CCTV footage of a shop robbery and discussed what they’d seen. One of the participants introduced false ideas: the thief had a gun, right? Three in four people later recounted these fabricated ‘facts’ when questioned.