Dr Chris Moulin first encountered chronic déjà vu sufferers at a memory clinic. "We had a peculiar referral from a man who said there was no point visiting the clinic because he'd already been there, although this would have been impossible." The patient not only genuinely believed he had met Dr Moulin before, he gave specific details about the times and places of these 'remembered' meetings.
Déjà vu has developed to such an extent that he had stopped watching TV - even the news - because it seemed to be a repeat, and even believed he could hear the same bird singing the same song in the same tree every time he went out. Chronic déjà vu sufferers are not only overwhelmed by a sense of familiarity for new experiences, they can provide plausible and complex justifications to support this. "When this particular patient's wife asked what was going to happen next on a TV programme he'd claimed to have already seen, he said 'how should I know? I have a memory problem!'" Dr Moulin said.
For the first time, those who suffer chronic déjà vu can help provide sustained research into the problem. "So far we've completed the natural history side of this condition - we've found ways of testing for it and the right clinical questions to ask. The next step is obviously to find ways to reduce the problem," he said.
PhD student Akira O'ConnorPhD student Akira O'Connor, funded by the Economic and Social Research Council, is working with Dr Moulin to find ways of creating the phenomenon in the laboratory. Akira has begun inducing déjà vu in Leeds students using hypnosis, asking students to remember words, hypnotising them to forget and then showing them the same word again to induce a feeling that they've seen it before. The students are then asked to make subjective reports - how déjà vu actually feels - in addition to the data about what they can and cannot remember.
This new programme of research, the Cognitive Feelings Framework (CFF), is unique to the University, and is being conducted by Dr Moulin with ESRC professorial fellow Martin Conway. "By considering subjective experience - feelings - from a cognitive science perspective, we hope to better understand everyday sensations like déjà vu, and also to help understand cognitive impairment, for example in older adults," said Dr Moulin.
"People might suffer from chronic déjà vu, but be unwilling to discuss this with their doctor - any hint of 'mental illness' is, particularly to older people, a taboo subject. But as soon as we found this first patient, we discovered that if you ask the right questions, you find other people have experienced the same thing."
Chronic déjà vu can be distressing to the point of causing depression, and some sufferers have been prescribed anti-psychotics. But Dr Moulin's group believe it is not a delusion, but a dysfunction of memory: "The challenge is to think about what this means. We can use it to examine the relationships between memory and consciousness.
"The exciting thing about these people is that they can 'recall' specific details about an event or meeting that never actually occurred. It suggests that the sensations associated with remembering are separate to the contents of memory, that there are two different systems in the brain at work." Dr Moulin believes a circuit in our temporal lobe fires up when we recall the past, creating the experience of remembering but also a 'recollective experience' – the sense of the self in the past. In a person with chronic déjà vu this circuit is either overactive or permanently switched on, creating memories where none exist. When novel events are processed, they are accompanied by a strong feeling of remembering.
A new collaboration launching this month with the University of York's neuro-imaging lab will provide objective evidence to the subjective reports supplied by the CFF. "When examining someone's subjective experience, it's important to have an idea of whether their subjective account is comparable to other people's," said Dr Moulin. "The neuro-imaging facilities allow us to see if the same areas of brain are activated in different people when they report certain subjective states. Ultimately, we may even be able to pinpoint the neural areas important for conscious states such as remembering."
Dr Moulin is keen to develop a network of patients in Leeds and across the globe who experience chronic déjà vu. "We're finding people all over the world with these problems. Chronic déjà vu sufferers need the reassurance that they're not alone, and we need them to help us learn more about who has it, what causes it, and why."
For more information on Dr Moulin's work see http://elgg.leeds.ac.uk/psccjam/weblog/