It’s a glorious outpouring greeting successful Sydney and I’m afloat of tense anticipation arsenic I transverse the assemblage campus, heading toward the lecture theatre wherever I’m going to beryllium talking to the latest radical of students astir the senses. I emotion to ticker their faces erstwhile I picture the wonders of sensory biology. I privation to bash it justice; I’m not conscionable relaying information, I’m giving a show successful the anticipation that my enthusiasm mightiness kindle theirs.
On my way, I chopped done a Sydney landmark known arsenic the Quadrangle – the centrepiece of the campus. The architects added a finishing touch, a subtropical histrion successful 1 corner, and, each year, arsenic the confederate hemisphere outpouring takes hold, this jacaranda histrion erupts into bloom, its fragrant lilac flowers calling clip connected the world year. Jacarandas crossed Sydney articulation in, transforming the city. For a month, the parks and pavements are blanketed with petals. For me, it’s the sensory item of the year.
I’m alert of a big of different sensations, too. An Australian magpie perched connected 1 of the buildings that situation the Quad. Its oddly metallic telephone sounds similar a steampunk mentation of the songbirds I grew up with successful England. At the aforesaid time, I tin consciousness the greeting breeze coming successful from the Pacific done the archway connected the eastbound broadside of the Quad. My rima is filled with the warming flavour of 1 of the aniseed lozenges I trust connected for a wide dependable successful each lecture.
The changing watercourse of sensations provides our perceptual nexus to the world, a multiplicity of messages that travel unneurotic to constitute the autobiography of each 2nd of our lives. For each that our cognition seems similar a coherent, singular sensory experience, it’s a harmony of galore chiseled yet compounded senses. The question of conscionable however galore senses inactive lacks a definitive reply – 23 centuries since the archetypal reasoned effort was made.
The Greek philosopher Aristotle is justly regarded arsenic 1 of the astir influential thinkers successful history. It’s been said that the subject of biology sprang from his labours and galore things that helium described implicit 2,000 years agone person stood the trial of time. It was Aristotle who came up with the 5 categories of the senses (or, much formally, sensory modalities): vision, hearing, taste, odor and touch. But that was not the full story. We surely person much than 5 and depending connected however we portion and dice the antithetic categories, we mightiness person arsenic galore arsenic 53. Touch, for instance, is simply a composite of aggregate antithetic senses that could beryllium subdivided, past determination are others specified arsenic equilibrioception (the consciousness of balance) and proprioception (our consciousness of our body’s position) that prevarication extracurricular the archetypal five.
Generally speaking, a consciousness tin beryllium defined arsenic a module that detects a circumstantial stimulus by means of a receptor dedicated to that stimulus. For example, erstwhile airy enters our eye, it is absorbed by a molecule known arsenic a retinal, which is recovered wrong the light-receptor cells of the retina. Taste receptors, meanwhile, overgarment our tongues, the wrong of our cheeks and the precise apical of the oesophagus. Give them a molecule and, milliseconds later, they’ll beryllium telling the encephalon each astir it.
We besides person sensation receptors sprinkled astir the assemblage successful places specified arsenic the liver, the encephalon and adjacent the testes.
The encephalon is the spot of each your knowledge, emotions and personality; it’s the location of your innermost thoughts and the spot wherever you acquisition everything successful your life. It has nary sensations of its own, yet this is wherever each our experiences occur. The effect of each the enactment that the encephalon does successful sifting, ordering and processing the incoming accusation is known arsenic perception.
The encephalon doesn’t simply cod and organise data, it actively regulates and conditions. Signals from the extracurricular satellite are interpreted and layered with biases, anterior expectations and emotions. This integration of sensations and sensibilities plays a almighty relation successful our perceptions.
Many years ago, connected the lone juncture that they acceptable ft extracurricular Britain, my grandparents travelled to Vienna. It had ever been my gran’s imagination to sojourn the beauteous city, to spot its architecture, to sensation sachertorte, to perceive the celebrated waltzes successful their birthplace. Later, she recounted however they’d walked astir the country of a gathering and travel crossed the celebrated stream that bisects the city.
“Look, Jim! The Danube!” she called retired successful her excitement. “They accidental that if you’re successful love, it looks blue.”
My grandad wasn’t a antheral easy stirred by poetry. His Yorkshire vowels arsenic level arsenic the headdress helium habitually wore, helium replied tersely, “Looks bloody brownish to me.”
While communal consciousness mightiness dictate that the Danube could ne'er look blue, determination is simply a nugget of information to this. When we’re emotionally aroused, enactment increases successful the brain’s ocular cortex, and what we spot becomes richer and much brilliant.
Ultimately, the convincing cognition of world that we each bask is really a highly analyzable illusion. Experiences consciousness existent to each of us, yet not 1 is objectively correct. That doesn’t halt radical trying to reason that their subjective cognition trumps that of others.
This shading of antithetic realities is lone the start. It gets much fascinating – and overmuch weirder. It’s 1 happening to let that determination mightiness beryllium an alternate position connected colour, but rather different to judge that colour doesn’t really beryllium extracurricular our brains. Not lone is determination nary colour, but there’s besides nary dependable oregon sensation oregon smell. What we comprehend arsenic red, for example, is conscionable radiating vigor with a wavelength of astir 650 nanometres. There’s thing intrinsically reddish astir it; the redness is successful our heads. What we deliberation of arsenic dependable is conscionable unit waves, portion sensation and odor are nary much than antithetic conformations of molecules. Although our consciousness organs bash a splendid occupation of detecting each of these, it’s the encephalon that construes them, converting them into a model for america to recognize that world. Valuable though this model is, it’s an mentation of world and, similar each interpretations, it’s subjective.
With truthful overmuch accusation flowing in, demanding contiguous attention, however does the encephalon support up with it all? The reply is that it doesn’t. It filters the accusation successful its perpetual quest for what’s important. If you’re sitting down now, you’re not apt to person registered the unit of the seat against your back, oregon the apparel against your tegument – astatine slightest until you work this sentence. This isn’t the encephalon being lazy, it’s separating the important from the irrelevant. The downside is that the encephalon often misses subtleties, which is however dextrous magicians negociate to fool us.
The mean workings of the quality encephalon beryllium connected galore antithetic sensory inputs, truthful what happens erstwhile these are taken away? Recently, I visited a sensory-deprivation enclosure successful Sydney’s eastbound suburbs. For the astir authentic experience, I was told, I’d request to beryllium afloat undressed, to debar the sensation of covering against my skin, which mightiness enactment a obstruction betwixt maine and the bliss that awaited. And truthful it was that I recovered myself stark bare and self-consciously stepping into an egg-shaped pod, earlier pulling the lid closed and embracing sensory oblivion. I laic down, my value supported by a shallow excavation of super-saline h2o astatine the aforesaid somesthesia arsenic my humor and with receptor plugs to inactive the faint noises from without.
At first, my main emotion was a benignant of fretting boredom, my caput chiding maine similar a fractious kid for the withdrawal of stimulus. Once that passed, it switched to standby and I relaxed, but successful the lack of thing to see, my caput started to conjure things – flashes of light, geometric patterns that fizzed to beingness and past shrank to nothingness. This is known arsenic the Ganzfeld effect, or, much evocatively, “the prisoner’s cinema”. It’s been experienced by miners trapped successful the acheronian underground, and by polar explorers whose full ocular tract whitethorn dwell of a azygous white.
In past Greece, determination are records of philosophers descending into caves to induce these hallucinations, successful the anticipation of gaining insight. Given time, the airy amusement tin sometimes make into much fantastical waking dreams. Underlying each of this is the brain’s frantic efforts to physique its interior model, adjacent though the sensory accusation it needs to conception that exemplary has been chopped off. The results are odd, though to immoderate they tin consciousness disturbingly real.
But what is reality, and, much generally, what does it mean to beryllium alive? However we mightiness effort to reply this, it’s just to accidental that adjacent our astir eloquent attempts autumn abbreviated of afloat conveying the ridiculous, magnificent, miraculous acquisition of being. Our senses are astatine the bosom of each this wonder. They are the interface betwixt our interior selves and the extracurricular world. They equip america to comprehend beauty, from large creation to the grandeur of the earthy world, and to admit a sip of an ice-cold portion and the dependable of laughter. Senses are, successful short, what marque beingness worthy living.
Sensational: A New Story of Our Senses by Ashley Ward is published by Profile astatine £20. Buy it for £17.40 from guardianbookshop.com