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All hell breaks loose when our senses go haywire

5 February 2022

9:00 AM

5 February 2022

9:00 AM

The Man Who Tasted Words: Inside the Strange and Startling Worlds of Our Senses Guy Leschziner

Simon & Schuster, pp.336, 16.99

Jesus is a Malteser. You might say I’m a liar or accuse me of the most egregious heresy, but the fact remains that Jesus is a Malteser. This is because I have a neurological quirk known as synaesthesia, commonly described as a fusing of the senses. Its most common manifestation prompts people to see colour when they hear music. But my version is the rare lexical-gustatory kind, which means that I can taste words; and so Jesus is a Malteser, Sam is tinned tuna and Donald is a rubber duck bobbing around in vinegar.

This could seem nightmarish: life as a constant assault of rubber ducks and whiffy fish — a gustatory whack-a-mole — but it produces no intrusion. I consider it nothing other than a party trick, although it can also be useful as an aide-memoire. When starting a new job it has helped me remember colleagues’ names: the nice lady on reception is a salty white pebble and the security chap is a packet of Cheese & Onion Ringos.

In The Man Who Tasted Words, the neurologist Guy Leschziner presents case studies of people whose senses have been sent awry through a genetic glitch, external injury or the ageing process, wildly altering their perception of the world and prompting them to question what is real. Given the title, I was expecting a jaunty pop-science read about people like me whose sensory worlds are scattered with rubber ducks, crunchy sand and chocolate gnomes. Instead, I encountered blindness, amputations, strokes, seizures and suicide. Fascinating, yes, but often distressing.

Leschziner’s first case study is Paul, a man who cannot feel pain. What might seem like a superpower is quickly revealed to be a curse: Paul and his similarly afflicted sister spent their childhoods leaping from garage roofs, breaking legs, knocking out teeth and pressing their palms to the glass fireguard: ‘We used to love to hear the sizzling of our skin.’ Another sufferer of CIP (congenital insensitivity to pain) enjoyed a hearty outdoor life but acquired so many spinal fractures that his legs eventually had to be amputated. The loss of his active life was too much to bear and he killed himself.

An equally alarming case study is Nina, who gradually lost her sight but found that the darkness she was living in soon became full of whirling, springing colours. In what sounds like a Twilight Zone horror, these colours merged to form ‘zombie faces’, with ‘blood dripping from their eyes, and gnarly teeth’. Mercifully, the bloody zombies were not constant, and she often saw Bart Simpson and Mickey Mouse too. This is Charles Bonnet syndrome, where the loss of sight prompts the brain to create visual hallucinations. Imagine it like a wilful child: tell it there is to be no more CBeebies and it will turn to Netflix instead. Let your rules be damned: it will watch something.

Meanwhile, Bill Oddie is encountering something similar. His sharp bird-watcher’s hearing is failing and his brain, unhappy at being deprived of such keen sound, has created brass band music for him instead, as well as hits of the interwar period such as ‘All the Nice Girls Love a Sailor’. His life now has a soundtrack. Leschziner says this is because the brain is a ‘prediction machine’, drawing in sensory input and producing a response. But it lacks the ability to work constantly at full tilt, recreating everything, recalling everything and anticipating everything; so instead ‘we predict the most plausible explanation for what we perceive to be happening, based on an internal model of the world as we understand it’. The system is knocked askew if, for example, a person experiences hearing loss; with the usual sensory inputs gone, the brain can deceive us by making its own weird guess at what is happening out there.

This can also occur due to psychiatric illness, and Leschziner describes the harrowing experience of visiting a chronic schizophrenia patient who kept screaming ‘Don’t do that!’ as she could ‘hear’ him urging her to stab or hang herself. Here is a terrifying result of the brain getting its guess wrong.

These case studies prompt us to ask: what is reality? You know the apple is sweet because you can taste it, but your senses might be lying to you. Leschziner likens this to the fraudulent little man behind the curtain in The Wizard of Oz. All we can do, then, is cling to what can be objectively measured, tested and proven. Everything else is slippery and changeable. There is a lesson here for those alarmingly passionate Twitter activists who value feelings over evidence: ‘We ignore the basis of reality at our peril.’

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