Is it possible to have an imaginative disability; an
impairment or deficit in or of the mind’s eye?
Before she died and for somewhere in the region of a
quarter of her life my grandmother was blind in one eye (one of the physical one’s that is,
not the 'inner' one). She could easily have arranged for a second cataract
operation to restore her stereoscopic vision, yet she was too distrustful of
the doctors and too unconvinced of the benefits that she chose instead to
manage with only monocular vision. I remember once at the family dinner table
we all decided to compare our monocular skills by trying to replace the lid of a pen and my grandmother was by far the most skilful at this task. She had
evidently developed compensatory skills that allowed her to function very well despite
her depthless vision. For many people such a disability would be a great loss -
the neurologist Oliver Sacks has commented widely on what he believes is a
great impoverishment in his visual perception following a melanoma that
deprived him of vision in one eye - but for my grandmother the possibility of
renewed depth perception wasn’t even worth a short visit to her local hospital.
Disabilities clearly affect people in different ways
and nobody would seriously suggest that all disabilities are equal. Having only
one functioning eye is undoubtedly a disability but in comparison with complete
blindness it presents a relatively trivial setback. But what about loss or damage to the “third eye”? What might such an
impairment or deficit consist of and does it really make sense to call it a disability
at all?
In 2010 Discover magazine published an article about an
Edinburgh building surveyor MX who found that his inner eye had suddenly become
blind following an operation on his coronary artery at the age of 65.
Neurologists conducted a variety of experiments and scans to determine what
might be causing MX’s visualisation loss and they, and MX himself, were
surprised to find that only one of the many experiments they conducted showed
any marked difference from standard results obtained from other individuals of
the same age, profession etc. The test used is thought to require the ability
to mentally rotate diagrams of three-dimensional forms. Ordinarily test
subjects take twice as long to mentally rotate the diagrams 180% as they would
to mentally rotate them 90%. In MX’s case though it took him no longer to
rotate a diagram from 180% than than 90% yet in every other respect there was
no appreciable divergence between his visual performance and those of normal
individuals.
How might we interpret this account? The scientists
involved took the view that some form of blindsight must be involved.
Blindsight is a rare condition in which people have no conscious vision yet they
are able to perform certain tasks – even quite complex ones like walking through
a room full of obstacles – as if they were fully sighted. A common explanation of
blindsight – although further evidence
is needed - is that human visual perception involves two visual systems working
in tandem: a more recently evolved conscious system and an older more primitive
unconscious system that remains unaffected in cases of blindsight.
Just as with the difference between monocular vision
and total blindness a straightforward comparison between blindsight and third
eye blindness should probably be avoided. Blindsight is recognised as a
disability because it has very clear repercussions for visual functioning
whereas, if MX’s case is anything to go by, the impact of visualisation loss is
comparatively negligible.
Nonetheless, perhaps we shouldn’t be too hasty in
dismissing third eye blindness. According to the Discover article, MX felt his
inner vision had previously been a source of genuine pleasure that allowed him
to run “through recent events as if he
were watching a movie. He could picture his family, his friends, and even
characters in the books he read.” But this is where the account becomes a
little unclear. Had MX become unable to recall the appearance of his friends
and family and of things seen in the past? If he was suffering from some form
of visual amnesia then surely the researchers would have detected this
right from the outset. Other plausible explanations are possible though. Perhaps
MX’s capacity to derive pleasure from
visual cognition had been affected by the operation.
Perhaps his sense of past pleasures had somehow become exaggerated or distorted.
One of the things that makes discussions about mental
imagery so fraught is that people have very different emotional attachments to such aspects
of their subjectivity. Just as Oliver Sacks deeply regrets the loss of his
stereoscopic vision and my grandmother barely bothered about it, so too do opinions
differ greatly about what might well be essentially the same underlying phenomenology
of visualisation.
Certainly when individuals claim to ‘see’ vivid
images in their mind’s eye we should be sceptical of what it is that they
actually mean. Time and again when such claims are tested, the images reported
turn out to provide much less information than their owners are initially
willing to claim. Once again the difficulty would seem to derive from the feeling of vividness rather
than the quality or quantity of information available.
Whatever the differences between individuals in terms
of the accounts they are prepared to give of their subjectivity it would seem
to be vital to distinguish as sharply as possible between the emotional aspects
of visualisation and the function: the ability. If visualisation doesn’t provide
any kind of functional advantage then it makes no sense to call it an ability, though we
might very well call it a pleasure. Likewise, being unable to visualise cannot
be said to be a dis-ability.
But if it is true that visualisation consistently fails
to provide the abilities that are attributed to it then it must be unique
amongst all pleasures. Perhaps this offers us a vital clue. Evolution never
bestows pleasures unnecessarily, especially pleasures of the magnitude of
imaginative visualisation. MX may have functioned perfectly well on all of the
tests of visualisation ability but I wonder how much his motivation to create
and consume representations had been affected – I suspect it was greatly reduced.
So, perhaps we can put forward a speculative hypothesis: visualisation might
not be an easily quantifiable ability in the ordinary sense but perhaps it's utility is of a more pervasive kind; as an inducement - possibly the most powerful one we possess - to
make, describe and to consume visual representations.
