In 1907, Hereward Carrington exposed the tricks of fraudulent mediums such as those used in slate-writing, table-turning, trumpet mediumship, materializations, sealed-letter reading and spirit photography. between 1908 and 1914 the Italian medium Francesco Carancini was investigated by psychical researchers and they discovered that he used phosphorus matches to produce "spirit lights" and with a freed hand would move objects in the séance room.
Mediums obtain messages from the spirit world in different ways. Some receive intuitive information, in which images and words appear as mental impressions that are then relayed along to the living. In other cases, a medium may hear actual auditory messages or see actual images of these messages. Many people who do spirit communication regularly find that the dead can be quite a chatty bunch sometimes. If they've got something to tell you, they're going to make sure you get told. What you choose to do with the information is up to you, but a lot of mediums, it can feel like they've got someone's dead granny screaming in their ears, and if they don't pass that message along to you, she's not going to shut up.