Psychic shield

Psychic shields were utilised by a family of four time tourists when going to watch the 1966 World Cup Final in preparation for the 1966 Dalek invasion of Earth. Although they looked like a regular human family to passers-by, the Fourteenth Doctor was able to recognise blue "fringing" around the edges of their disguises due to not being properly adjusted and used his sonic screwdriver to unveil their true forms. (COMIC: Liberation of the Daleks)