In pictures: Seeing is Believing

A photograph of medium Helen Duncan during a seance with head covered with 'ectoplasm' Photograph: Senate House Library, University of London/Mary Evans

Lone Chair, 2005, Florencia Durante Photograph: Florencia Durante/freelance

A spirit photograph of Harry Price taken by George Moss, who subsequently confessed to creating fake pictures (including this one), c.1925 Photograph: Senate House Library, University of London/Mary Evans

Photism 1.4 , 2006/7 (from the series Unseen Agents) by Clare Strand Photograph: Clare Strand/freelance

Lila, Native American Princess, 1995 by Fred Ressler Photograph: Fred Ressler/Henry Boxer Gallery

Sequential Opposition, 2006 by Ben Judd Photograph: Ben Judd/freelance

Still from The Last Person, 1998, by Susan MacWilliam Photograph: Susan MacWilliam /freelance

Hideaway, 2003, by Roger Ballen Photograph: Roger Ballen/freelance

Untitled from the series Traces and Presence, 1991, by Tim Maul Photograph: Tim Maul /freelance

Untitled from Tim Maul's series Traces and Presence, 1991 Photograph: Tim Maul /freelance

Harry Price in his National Laboratory of Psychical Research Photograph: Senate House Library, University of London/Mary Evans

A photograph of the blindfolded Helen Duncan during a seance, with 'ectoplasm' trailing from her nose, leading to a coathanger spirit at her side (1933 ) Photograph: UnassignedSenate House Library, University of London

A photograph of the 'Marianne' wall writings at Borley Rectory, an example of so-called automatic writing Photograph: Senate House Library, University of London/Mary Evans

A 'phantom priest' photographed in the church at Arundel, Sussex Photograph: Senate House Library, University of London/Mary Evans

A psychical researcher investigating an allegedly haunted 16th-century bed in Chiswick with Professor Joad, September 15 1932 Photograph: Senate House Library, University of London/Mary Evans