Psychologist Susan Blackmore devoted years of her life studying the paranormal

Imagine me, if you will, in the Oxford of 1970; a new undergraduate, thrilled by the intellectual atmosphere, the hippy clothes, joss-stick filled rooms, late nights, early morning lectures, and mind-opening cannabis.

I joined the Society for Psychical Research and became fascinated with occultism, mediumship and the paranormal — ideas that clashed tantalisingly with the physiology and psychology I was studying. Then late one night something very strange happened. I was sitting around with friends, smoking, listening to music, and enjoying the vivid imagery of rushing down a dark tunnel towards a bright light, when my friend spoke. I couldn't reply.

"Where are you Sue?" he asked, and suddenly I seemed to be on the ceiling looking down.

"Astral projection!" I thought and then I (or some imagined flying "I") set off across Oxford, over the country, and way beyond. For more than two hours I fell through strange scenes and mystical states, losing space and time, and ultimately my self. It was an extraordinary and life-changing experience. Everything seemed brighter, more real, and more meaningful than anything in ordinary life, and I longed to understand it.

But I jumped to all the wrong conclusions. Perhaps understandably, I assumed that my spirit had left my body and that this proved all manner of things — life after death, telepathy, clairvoyance, and much, much more. I decided, with splendid, youthful over-confidence, to become a parapsychologist and prove all my closed-minded science lecturers wrong. I found a PhD place, funded myself by teaching, and began to test my memory theory of ESP. And this is where my change of mind — and heart, and everything else — came about.

I did the experiments. I tested telepathy, precognition, and clairvoyance; I got only chance results. I trained fellow students in imagery techniques and tested them again; chance results. I tested twins in pairs; chance results. I worked in play groups and nursery schools with very young children (their naturally telepathic minds are not yet warped by education, you see); chance results. I trained as a Tarot reader and tested the readings; chance results.

Occasionally I got a significant result. Oh the excitement! I responded as I think any scientist should, by checking for errors, recalculating the statistics, and repeating the experiments. But every time I either found the error responsible, or failed to repeat the results. When my enthusiasm waned, or I began to doubt my original beliefs, there was always another corner to turn — always someone saying "But you must try xxx". It was probably three or four years before I ran out of xxxs.

I remember the very moment when something snapped (or should I say "I seem to …" in case it's a false flash-bulb memory). I was lying in the bath trying to fit my latest null results into paranormal theory, when it occurred to me for the very first time that I might have been completely wrong, and my tutors right. Perhaps there were no paranormal phenomena at all.

As far as I can remember, this scary thought took some time to sink in. I did more experiments, and got more chance results. Parapsychologists called me a "psi-inhibitory experimenter", meaning that I didn't get paranormal results because I didn't believe strongly enough. I studied other people's results and found more errors and even outright fraud. By the time my PhD was completed, I had become a sceptic.

Until then, my whole identity had been bound up with the paranormal. I had shunned a sensible PhD place, and ruined my chances of a career in academia (as my tutor at Oxford liked to say). I had hunted ghosts and poltergeists, trained as a witch, attended spiritualist churches, and stared into crystal balls. But all of that had to go.

Once the decision was made it was actually quite easy. Like many big changes in life this one was terrifying in prospect but easy in retrospect. I soon became "rentasceptic", appearing on TV shows to explain how the illusions work, why there is no telepathy, and how to explain near-death experiences by events in the brain.

What remains now is a kind of openness to evidence. However firmly I believe in some theory (on consciousness, memes or whatever); however closely I might be identified with some position or claim, I know that the world won't fall apart if I have to change my mind.