Saturday, 30 April 2011

Sensory Perception or Deception?

The Scottish poet Norman MacCaig (1910-1996) describes how “...into my, and your, five ports of knowledge come many cargoes and we should unship the lot.” (MacCaig, 1979, p84) While we have five senses and they bring us everything we know of the world, they can also prove unreliable and deceptive. Our brains can play “tricks” on us, send conflicting messages, and can misunderstand or misinterpret what the senses pass to them. However, for many people the senses can be damaged or manipulated by others causing them considerable difficulties in understanding or coping with the world they inhabit. I plan to examine how sensory perception is not to be depended on, can be unreliable and can be positively reordered by the intervention of others.

For example, it is widely thought that the illusion of depth in illustration was first developed in the Renaissance with Giotto’s ‘Jesus Before the Caïf’. However, Lascaux, a complex of caves in southern France, demonstrates through its cave-paintings that its unknown, prehistoric artists had their own grasp on perspective: they even used the natural curving and jutting of the cave walls to convey depth and movement. Artists have, then been ‘tricking’ our visual perception for thousands of years, from the times of the so-called primitive Neanderthals to the present day. And we seem to like it, as the popularity of, for example, Escher’s visual conundrums testify.

Sight is obviously one of our strongest senses, in use every minute of the day until we fall asleep (but even our dreams operate in a visual world); however, it can be demonstrated that the senses of touch, hearing, smell and taste are equally capable of being deceived. For example, we are familiar with eating a packet of Starburst sweeties without looking at the wrappers; your taste buds might tell you that you are eating something with the flavour of lime but when you look at the wrapper it tells you its flavour in fact is strawberry.

The day to day tricks and illusions created by our brains and senses are very powerful. So what must it be like to be sensorily impaired or deprived. What do we know of the 'pathology' of sensory malfunction? I will look at a number of areas where individuals are faced with significant sensory problems: for example, deliberate sensory deprivation (both willing and enforced); deprivation due to trauma; autism and, finally, the fairly common condition known as Attention Deficit Hyperactivity Disorder (ADHD).

Sensory deprivation is a controversial subject, with allegations the technique has been used in numerous detainment facilities such as, Guantanamo Bay as an interrogation tactic. Thousands of prisoners around the world are kept in solitary confinement, often with a severe level of sensory deprivation. It is thought that sensory deprivation can make people much more open to suggestion . During experiments in this area most subjects would give up non-compliance after 72 hours as the boredom and oppression of the conditions became overpowering. There have also been many experiments of extreme isolated situations (such as living in the Arctic and during space travel). The European Space Agency started Mars500 in 2010, when six ‘astronauts’ boarded an artificial spaceship near Moscow to find out what two years in an isolation facility would do. How someone will cope with isolation may depend on personality type. Results from experiments show that there are increased rates of disturbances of mood, psychiatric disorder, tension between captives, and a disruption of sleep rhythms; extended or forced sensory deprivation can result in extreme anxiety, hallucinations, bizarre thoughts and depression. However, short-term sessions of sensory deprivation are described as relaxing and encourage meditation

Trauma can cause our senses to act irregularly and send mixed messages to our brains. A phantom limb is the sensation that an amputated or missing limb is still there and is moving as normal. Approximately 80% of people who have suffered an amputation experience phantom sensations in their amputated limb, and the majority of the sensations are painful. In the early 1990s, Tim Pons, at the National Institutes of Health, showed that the brain can reorganize itself the if sensory input is cut off resulting in pain and discomfort. Many individuals who have suffered some sort of trauma resulting in a sensory deprivation learn to compensate with the use of their other senses. Dan Kish, a 41-year-old blind man from California has pioneered a bat-style echolocation technique to visualise his surroundings. The technique is being piloted in Glasgow, where 10 children aged 5 to 17 are learning how to build up detailed images of the world around them by clicking their tongue and interpreting the sound as it echoes back. There is emerging evidence that blind people can harness their sense of hearing to interpret reflected sound and create detailed mental images of their surroundings, including the distance, size and density of objects.

Many of those who suffer from a form of autism find it difficult to grasp sensory perception and the depth and pervasiveness of sensory dysfunction. We were all taught that we have five senses from an early age and instinctively understand how these work. People with autism, though, have far more complex senses: they interact and react differently, and recent research suggests they possess an extra two: proprioception refers to the way our body communicates with our joints, tendons and muscles and in children with autism this can malfunction; the vestibular sense refers to a person’s sense of balance and movement and challenges in this area may express themselves in multiple ways, either creating intolerance to or cravings for movement or problems with balance. To complicate matters, people on the autistic spectrum can be hypersensitive (over active) or hyposensitive (under active) to the senses, or both.

ADHD and sometimes cerebral palsy can also pose challenges; people with these conditions can have trouble regulating and focusing their attention. Feurstein’s ‘Tactile Instrumental Enrichment’ program uses cognitive or key thinking processes, one of which focuses on using our senses to gather information to teach intelligence; this has proved particularly successful with children with ADHD. It forces them to limit their attention to one particular sensory process. Feurstein’s program has now been developed to be used with blind children. Initially, pencil and paper were used to teach this new way of learning but, in order to make this accessible to the blind, different shaped tokens were developed and symbols used. It is widely believed that people who lose one sensation compensate with the enhancement of another sensation. With visual perceptual difficulties it is argued that you can compensate for this cognitively. For example, the chef, Jamie Oliver is colour blind but he 'knows' what looks good on a plate and has compensated for his difficulty cognitively by learning what works. We learn to compensate for missing senses.

Despite all of these, arguably, “deficit” sensations, can new developments in sensory perception be used to enrich lives? If we look at developments in the field of Virtual Reality (VR) we can see some hope for this wide variety of ‘patients’.

Virtual reality (VR) as a form of therapy began in the early 1990s. Developed by Dr. Ralph Lamson, virtual reality was used to solve his own fear of heights. It is now widely used to treat a wide variety of sensorily challenged people. In 1996, Dr. Hunter Hoffman of the University of Washington’s Human Interface Technology Laboratory and Dr. David Patterson of Seattle’s Harborview Hospital Burn Centre devised a new psychological pain control technique which relied on diverting attention using virtual reality. Diverting attention is particularly useful in burn pain as pain perception is said to be largely psychological. ‘Snow World’, a virtual reality system that lets users walk through wintry environments and throw snowballs at targets, proved to be an alternative to strong drugs which tended to leave patients dazed and disconnected

Drugs, vibration therapy and acupuncture have been used in the past to help those who have problems with sensing phantom limbs, but a team of researchers at the University of Manchester experimented with a technology of "immersive virtual reality" to combat this discomfort. The researchers reported that phantom limb pain could be relieved by attaching the sufferer's real limb to an interface that allows them to see two limbs moving in a computer-generated simulation.

Virtual reality therapy has also proved useful in treating ADHD. Virtual reality technology allows the child to role-play in a virtual classroom where different situations can be practised and then discussed. The therapist in charge of the virtual reality world can work with the child to improve their concentration skills, as they are able to practise concentrating on specific tasks while different distractions are introduced. They are also able to interact with the teacher and classmates, allowing them to develop social skills and learn to stay on task.

Our senses, however deceptive, can bring us great pleasure but when they malfunction the result can be traumatic. New developments in sensory perception allow us to intercept our senses and take back, a little, control.

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