Seances took two broad forms as the movement matured. Mental mediumship centred on trance speech, automatic writing or clairvoyant impressions delivered by a medium in an altered state, while physical mediumship promised phenomena observers could witness directly: raps and knocks, moving furniture, materialised limbs or full figures, and objects appearing or disappearing in darkened rooms, forms of demonstration that drew the most sustained scientific attention and the most damaging exposures. Serious investigators took the claims seriously enough to test them: physicist William Crookes conducted extended experiments with the medium Florence Cook in the 1870s and published findings sympathetic to genuine phenomena, while the Society for Psychical Research, founded in London in 1882, brought systematic and often sceptical scrutiny to physical mediumship across decades of casework. That scrutiny caught real and repeated fraud.
Numerous prominent physical mediums, including cases investigated by the Society for Psychical Research and by individual researchers such as Harry Houdini, who made exposing fraudulent mediums a personal campaign in the 1920s, were caught employing trick cabinets, confederates, and sleight of hand, findings that historians of the movement treat as well documented fact rather than mere accusation even as they recognise that fraud exposure never fully explained away every reported phenomenon to sceptics' or believers' satisfaction. Modern Spiritualism survives today as an organised, registered religion with its own churches, chiefly in Britain, the United States and Brazil, holding the seance as one practice among a broader theology and pastoral life.