This is based on a piece about our research that I was asked to write for a thing after recently being selected to receive the Experimental Psychology Society Prize. The EPS is one of the most venerable and respected learned societies in my field, and it was a real honour for our work to be recognised by them.Whenever old friends get together, it rarely takes long for people to start reminiscing about the past. Amusing (sometimes, bawdy) tales might be told about events that may have occurred many years ago. As a listener, you can find yourself mentally transported back in time, re-living a fondly-remembered episode as if it were playing out in front of you once again. Except – how do you know that you were actually there when the event originally took place? How can you be sure that you’re remembering a faithful representation of what happened, as opposed to a fictitious recollection of an event that might have been entirely imagined? In short, how do we determine whether our memories are real?
We have spent the last few years pondering these questions, seeking answers by undertaking experiments using cognitive neuroscience methods like functional brain imaging of healthy volunteers and studies of neurological and psychiatric disorders, as well as of normal aging. Our aim is to understand how the brain supports our capacity to distinguish what is real from what we imagined, an ability that Marcia Johnson has termed “reality monitoring” which is vital for maintaining confidence in our memories, and in understanding ourselves as individuals with a past and a future. In characterising how these processes might be organised in the brain, we can better understand the way in which they may break down in disorders like schizophrenia, in which perceptions of reality can be altered.
|View of brain showing|
anterior prefrontal cortex
In the field of memory research, scientists sought to use functional brain imaging techniques to identify brain areas that were active when people undertook complex memory tasks like recollecting the context in which previous events were experienced, but found it difficult to characterise what role anterior prefrontal cortex might play. Some studies reported memory-related activation there whereas other, equally well conducted, apparently very similar studies failed to identify activity in that region. We hypothesised that the discrepancy between studies might be because the kinds of information participants were being asked to remember differed according to whether it had been generated by internal cognitive functions such as thought and imagination, or derived from the outside world by perceptual processes.
|Anterior prefrontal cortex (L)|
contributes with areas like the
medial temporal lobe (R)
to reality monitoring
One of the applications of this work has been to inform understanding of the cognitive dysfunction seen in clinical disorders, such as schizophrenia. Although schizophrenia can vary in its presentation, among the positive symptoms often observed are hallucinations, whereby patients report, for example, hearing voices when none are present. It has been suggested by Chris Frith and others that these symptoms may result from a difficulty in discriminating between information that is perceived in the external world and information that is imagined. For example, you might imagine a voice conveying a message, but misattribute that voice as real, coming from another person.
|Regions involved in reality monitoring|
overlap with areas dysfunctional
Thus, although there is much work to do before we can claim to understand the functions supported by anterior prefrontal cortex, evidence is mounting that one of its key roles may be to help us keep a grip on reality.