The granddaddy of all forms of misperception is the hallucination. It can have psychological or physical causes, but its main characteristic is that there is no external object to the experience which an investigator might verify as having been misperceived. Indeed, hallucination is ‘misperception’ only in the sense that it fools us into regarding as a perception an experience that has far more to do with imagination.
Hallucinations occur in some types of mental illness and intoxication, but it is easy to underestimate their role in the everyday experiences of the sober and sane. When I need a corkscrew in a hurry, as I rummage in my overstocked cutlery drawer, I may seem to have spotted the corkscrew several times before I actually have. These ‘sightings’ of a desired object before it is actually found are hallucinations, albeit of a kind that – by checking our perception – is very easy to shake off.
Yet it has struck me how easy it is to fall into the trap of regarding the recognition of an experience as an hallucination as necessarily a victory for rational thinking. In fact, the diagnosis of hallucination can be just as irrational, yet is perhaps just as common in everyday life as hallucinations themselves.
For example, a number of times I’ve experienced someone saying to me something so bizarre or hurtful that – at the time – I’ve supposed that what I heard was actually the product of my imagination. Later, of course, I was able to verify they really had said what I’d assumed I had imagined.
On another occasion, crossing a busy street, I once saw a man reach into my girlfriend’s pocket, feeling for her purse. My instinctive rejection that what I’d seen was anything other than a misperception was so overwhelming, I could no longer be sure what had really happened.
Less ambiguous was the time I was assaulted from behind whilst walking down the street. I remember how, a couple of seconds before the attack, I heard the assailant approach – and I had actually even begun to brace for the blow – at the same time as I was rejecting these impressions as, surely, just my imagination.
Hallucinations are irrational, but so can be the diagnosis of an experience as an hallucination. The mind seems more interested in protecting its preconceptions, and isn’t fussy whether it achieves this by manufacturing experiences that are unreal, or writing-off as imagination something that is only all too real.
The reason behind my interest in this topic – indeed, for my interest in the paranormal in general – was an experience so up-close and weird that ‘hallucination’ or ‘false memory’ is the only rational explanation that lies to hand. Yet as this event retreats ever further into the past, I’m confronted with two questions.
The first has to do with what we consider ‘real’ to mean, because if the experience was a hallucination, then I’ve lived my life on the assumption that it might not have been, in which case, what is the difference – in terms of its impact upon me as an actual event – between its having been a hallucination and its not having been one?
Secondly, as this article has attempted to show, just because hallucination is the most rational explanation in a particular instance, it doesn’t mean that (in the absence of evidence) by applying that explanation I am necessarily applying rationality. How do I know that my attempt to maintain a reasoned and balanced attitude to what I experienced isn’t in itself an irrational self-deception to turn what I know I witnessed into something with a more comforting buffer of uncertainty?
I accept, of course, that an anecdote is one thing and evidence is another. Until I can produce evidence for what I think might have happened, or even work out what form such evidence could take, this wonderful quest continues into reality, perception and truth.
 It’s possibly more accurate to regard the ‘corkscrew’ and ‘misreading’ examples as on a boundary between hallucination and misperception, because there are objects and words actually out there. To the extent that the mind interprets them incorrectly, it misperceives. And to the extent that it manufactures something that isn’t there, it hallucinates.