Switches can be operated by almost any movement and part of the body - by finger, hand, arm, elbow, chin, head, cheek, shoulder, knee, foot, tongue, eye-brow, and so on.

Some switches are very small and light, others are large, colourful and require a hefty kick. Most switches are operated by touch, but some can detect movements such as raising or lowering a limb. Touch-sensitive computer screens can also be used as switches for operating simple cause and effect software.

A number of factors need to be considered when choosing which switch to use with a pupil. These factors include:

• the pupil’s physical abilities and how easy it is physically to activate the switch
• the child’s cognitive abilities and how easy it is to understand how to activate the switch
• the child’s motivation and self-esteem and how interesting the task is as well as how much effort has to be put in to gain an effect from switch activation

Some switches can seem physically easy to operate, but may be difficult for the child to perceive or understand.  For example an infra-red switch may be physically less demanding for the child to activate but, because there is no direct contact needed and because it gives no auditory feedback it may be too difficult for the child to understand that he or she is responsible for activating the switch.

Similarly, a mercury tilt switch, perhaps attached to a wrist or headband, is physically easy to operate. But, because these switches provide no feedback, it may be difficult for the user to understand the cause / effect relationship.
 

Case Study: Bobby Bobby, a 4 year old boy, was responsive, cheerful and sociable with severe physical disabilities (cerebral palsy, spastic quadriplegia) and little motor coordination or control; visual impairment, ocular motor apraxia and horizontal nystagmus; no speech; delayed language development; and learning difficulties. He appears as alert, interested in new experiences and activities and motivated to interact. Questions remain as to the severity of his visual impairment, though he has been reported as able to match some colours.  He was reported to be showing interest in a number of different activities.  These included swimming, music, snack times and action song games. He consistently favoured music played by certain bands. Bobby showed some understanding of others’ speech, anticipating interactions like “Hello, how are you”, responding by ‘thumbs up’ sign, and recognising a few nursery rhymes, especially “Baa baa black sheep”. During movement therapy he rocked to the music and anticipates the movements of action songs. Vocalisation was severely limited and work had begun on introducing Makaton signing, in the same way as with others in his class and school.  (Signs were made both within his possible field of vision and moulded on him.) Providing he was appropriately positioned with a table in front of him, he used his hands to operate a simple touch switch effectively. Switches he used were adequate, as long as they were very firmly anchored  to a stable surface in front of him. For a single switch, midline position was desirable. After operating a single switch, he was tried with two switches, encouraging him to choose between them in order to operate his preferred tapes. Bobby demonstrably understood this task, discriminated between the two, and reliably chose the ‘Favourite Music’ switch. He was able to select the one he wanted on location alone, but use of different tactile materials on the different switches was also introduced.

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