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Touch is first among the senses. So, asks Mark Lythgoe, what happens when our wires get crossed?
Thursday June 9, 2005
"Touch functions on many levels of adaptation, first to make survival possible and then to make life meaningful." - T B Brazelton, 1990
In 1972 John Berger pointed out in his book Ways of Seeing that "seeing comes before words". That is sight before language. But in terms of your development, touch comes before both. In fact, it may well be through the haptic sense that you learn to know and find your place in the world.
Before you are born you begin exploring yourself and what's around you. As early as eight weeks into gestation you are able to respond to a gentle touch on the cheek. By 12 weeks you begin sucking your thumb and even make licking movements as you start to discover your environment. At 32 weeks you are able to decode a rich array of sensory information from the world in the form of temperature, pressure and pain, and touch is the medium for this knowledge. You are perceiving the world through touching it, or being touched by it.
Richard Gregory, emeritus professor of neuropsychology at the University of Bristol, described, when I met him in February, the remarkable case of a man who was blind from birth and regained his sight after a corneal graft. After the operation he could, to Gregory's surprise, walk down hospital corridors without holding on to walls. Soon after leaving hospital he asked the professor to take him to the Science Museum to see an exhibit of a simple lathe. With the lathe in the glass case he was unable to say anything about the object. When the case was removed and he was allowed to run his hand over the machine, he understood everything about it. "Now that I've felt it I can see," he said.
Bizarrely, he was effectively "blind" to objects he hadn't touched: he had to make the connection between the feel and image of the lathe before he could see it. It is impossible for those of us with normal vision to imagine this predicament - to be blind to an object you can see in front of you - yet it suggests that in some way we can see with touch, even that we need touch to see. In other words, there is far more crosstalk between our senses than we might imagine.
I recently interviewed James Wannerton, a synaesthete who has a neuronal crosswiring between two of his senses. The interview was part of a TV programme investigating the nature of Einstein's genius and its relationship to increased connectivity in the brain. Each time James heard a word he would get a sharp, involuntary taste in his mouth, because of a mixing of his taste and hearing senses. "Yoghurt and wafers, Albert Einstein tastes of yoghurt and wafers," he announced as I said the words to him.
This unusual crosswiring between brain areas can cause the most peculiar sensations. Imagine mixing touch with vision, which is impossible, yet strangely not as far fetched as you might think. Professor Vilayanur Ramachandran tells of a blind patient who began to notice that whenever he touched objects or read braille his mind would conjure up vivid images or flashes of light, and another who experienced a vivid bitter taste in his mouth when shaping hamburger patties with his hands.
It would appear that touch is not always touch; that the organisation of our brain dictates how we experience our sensations. The brain has different regions that control different functions and it was thought that the visual part was just for seeing. This would seem not to be the case. If you are blind from early in life, you become very good at detecting small distances between two points (as in braille). Apparently, this new-found "vision" is in part due to touch taking over or reorganising the visual part of the brain so that you have better touch sensitivity.
The tactile sense develops prior to others and is not as confined to discrete boundaries. But could it underpin our ability to communicate? Imagine that you are wearing a blindfold and holding two shapes, one like a piece of shattered glass with many jagged edges, the other a softly rounded blob. I'm going to give you two nonsense words, "booba" and "kiki", and I want you to associate each with a shape. My guess is that you would partner booba with the rounded shape and kiki with the jagged one. If you did, you'd be one of the 98% who would do the same. Along the same lines, we might also say that the taste of lemon is sharp; here we are associating shape and taste. Could this simple representation of the characteristics of shapes that we have touched (or seen) as sounds or words be the building block for language as a form of communication?
Sensations provide your conscious and subconscious with an awareness of the internal and external conditions of your body. The skin feeds you information on temperature and, if you are in danger of damaging your delicate tissue, pain or pressure. Yet you also have a kind of internal "touch". Nineteenth-century neuroanatomist Sir Charles Bell called this the sixth sense: proprioception, your unconscious interpretation of the sensory feedback derived from muscle, tendons and joints that enables you to keep track of your body in space. You can test this sense by placing your right hand out of sight above your head. Keeping it still, use your left index finger to touch your right thumb. It is not always easy to make an immediate connection with your thumb. If you did contact it directly, you'll be glad to hear it's thanks to proprioception.
This leads me to "the disembodied woman" Christina, a patient of neurologist Oliver Sacks who had lost her proprioception. She had difficulty walking and standing as she would "lose" her body in space. This may be similar to the feeling you get if your leg "goes to sleep". As Christina's sense of touch was unaffected, she could find her body image via touch by riding in a convertible car and letting the wind brush against her skin, thus enjoying the feeling of embodiment once again.
Yet touch is more than a mechanism by which we sense the world around us. It is a two-way process that provides a complex exchange between people: it establishes a relationship or connection and creates a dialogue. To start a haptic communication you need to be within "arm's reach", which is more than just an idiomatic expression, but defines a special spatial relationship. You touch to experience, to acquire knowledge, but when another is involved you also touch to communicate. Without thinking you transfer information. We even use the phrase "keep in touch" as a metaphor for speaking in the near future.
Touch as communication can elicit chemical and physical changes in the brain and body, and lack of physical contact in the early years can lead to abnormal development in brain areas that deal with emotion. Young children or babies subjected to extreme deprivation of touch may suffer delayed development of mental and motor skills. In the saddest cases, a child could die through lack of contact.
This relationship between touching and knowing is possibly one of the cornerstones for our human experience and communication. Touch is many things and can be described by science in wondrous and infinite detail, yet it was the deafblind Helen Keller who brought us to a core understanding of our relationship with touch: "My hand is to me what your hearing and sight together are to you ... it is the hand that binds me to the world of men and women."
· Mark Lythgoe is a neurophysiologist at the Institute of Child Health (UCL). He will discuss Making Contact: the art and science of touch, with artist Richard Wentworth on August 17 at the V&A where Touch Me: design and sensation runs from June 16-August 29. This article first appeared in the V&A Magazine. http://www.vam.ac.uk/
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