Sensory Substitution

There is an old wives' tale that as one sense becomes less effective, one or more of the other senses becomes keener. So, as your eyes get worse, your hearing improves. Unfortunately this does not actually happen. However the underlying principle that if one sense fails we could utilise one of the other senses to compensate is the basis of a technique called Sensory Substitution.

There are many visual tasks that become more difficult as the vision deteriorates. Everyday tasks such as reading, telling the time and pouring drinks rely heavily on a visual input to effect control. Remove the visual input and the task becomes virtually impossible. Common sense may enable the sufferer to overcome some difficulties, e.g. using light coloured chopping boards for dark food and dark colours for light coloured food. However no amount of common sense can tell you when boiling water has reached the top of the cup when making a cup of tea. Sensory Substitution takes a task and considers if that task could be performed by inputs from one or more of the remaining senses, rather than input from normal vision.

Taking our cup of tea example, if a device could be put at the fill point for the boiling water it may be possible for the device to emit an audio signal to alert the pourer to stop filling the cup. So in this case the hearing function has taken the place of the visual function. Such a device is available through local low vision resource centres.

Typically in low vision work there are two senses that may take the place of sight - touch and hearing. Touch may be used to replace the reading function as in Braille and similar touch based system. It is also possible to use different textures for different items to enable touch recognition. Hearing can be used with talking books and talking watches or clocks.

Many other possibilities are available and most low vision sufferers will develop their own techniques and also experiment within common sense parameters.

It is also possible for some senses to be transferred as in the case of guide dogs. Here the companion animal becomes the eyes and ears of the sufferer and by careful training of both parties a highly developed team is formed.

More information on Sensory Substitution techniques is available from the various charities associated with the visually impaired. Advice on this technique, as well as on eccentric viewing, can also be obtained in the UK from the local Rehabilitation Officers for the Visually Impaired working within the local Social Services department.