04/07/2013 12:14 BST | Updated 02/09/2013 06:12 BST

The Ghosts Are Real

When I was a teenager I dreamt of a haunted telephone box; however, when I went to investigate I discovered that the ghost inside the telephone box was me. What did this peculiar dream mean? One doesn't need to be Sigmund Freud to identify several themes associated with adolescent angst, such as self-absorption, confusion about identity, and the need to communicate and be understood. The interesting thing about this dream is that my unconscious dramatized these themes in the form of a ghost story.

Do ghosts exist? Yes, of course they do. There are simply too many reports of ghostly sightings to doubt their existence; however, explaining the nature of ghosts is a different matter. Two theories predominate. The first is that ghosts are revenant spirits and the second is that ghosts are a psychological phenomenon. Today, we tend to favour the latter position, but just because something is psychological does not mean that it isn't real. Your memories - for example - are every bit as real as a lion, a brick, or an atom. Although a brain scientist might argue disparagingly that memories are a mere by-product of underlying biological processes, this doesn't make them any less real. They are simply real in a different way.

There is widespread agreement in literary circles that Henry James's 'The Turn of the Screw', published in 1898, was the first psychological ghost story. The plot isn't complicated: a governess becomes convinced that two former employees are wielding a malign influence over her wards. She challenges their supernatural authority and one of the children dies as a consequence. What makes it psychological is the way the story is told. We can't help but wonder if the ghosts are real or imagined? Moreover, we can't stop ourselves from engaging in a little amateur psychoanalysis. Is there some connection, we ask, between the supernatural occurrences and the prim governess's repressed sexual feelings? James set something of a precedent in this respect, because the psychological ghost story has since become associated with many women writers of note (Edith Wharton, May Sinclair, Shirley Jackson) whose work might be described as crypto-feminist.

The inspiration for 'The Turn of the Screw' is reputed to be a tale told to James by the Archbishop of Canterbury; however, another significant influence should also be acknowledged. It can't be accidental that the author of the first psychological ghost story was also the younger brother of William James, the most senior figure in the history of American psychology and an enthusiastic ghost hunter.

The psychological ghost story is extremely powerful, even to modern readers, because it does not depend on credulity for its effect. We are not asked to believe in disembodied, vengeful spirits, but the self-evident truth of the human mind. Thus, the ghosts are real - as real as our memories and our forbidden wishes. This is extremely revealing, because it shows that what we humans fear most, is not the strange and uncanny, but ourselves.