exemplar activities

Unit 7 Activity 6 - Switch Use

A mouse is an input device into a computer that enables you to move a pointer on the computer screen. This is achieved by sliding the mouse across a smooth horizontal surface. The mouse also has one, two or three buttons which when pressed cause the computer to perform an action.

A roller ball is an alternative to a mouse. It works in a similar way, but it is a stationary device wherby the user simply slides the hands or fingers over the ball to turn it and therefore is more suitable for a person with gross motor difficulties. It does, however, require fairly accurate fine motor control, although the speed of response to movements can be adjusted. Some roller balls may also have a drag lock to separate a co-ordinated button press and pointer movement into two distinct actions. Because it is easy to accidentally move the ball when operating the buttons, external switches can be attached to the roller ball.

As explained in a previous unit, I work with a group of young children who have profound and multiple learning difficulties, visual and auditory difficulties and restricted physical movements. All of the children use switches to produce simple cause and effect rewards, but none are at the cognitive stage of making use of a mouse or roller ball.

In December 2000 a new child joined my group. The child has quadriplegic cerebral palsy. He is registered blind as a result of a severe cortical visual impairment. Up to that point he had occasionally activated a switch fastened to a latching device to turn on and off a tape recorder whilst lying on a resonance board. This, however, appeared to be largely due to involuntary movements. He had never worked on a computer. In consultation with the teacher from his previous class I set the following two targets for his ICT work:

1. To demonstrate a reaction to an auditory reward from a computer/tape/switch toy.
2. To activate a switch independently in order to gain an auditory reward.

In class the child sits in a Taylor Expressions chair and requires a Hensinger neck support. This is a very large chair with a big tray attachment and I found that no matter where I placed the chair I could not get it near to the computer screen despite the monitor being placed on a height adjustable trolley. I therefore tried him in a Tumble Forms floor seat and am now successfully able to get him close to the screen by lowering the trolley and pulling out the retractable shelf.

I started by offering him a number of different switches. When sitting, the child's arms naturally go into flex so that his elbows are bent with his hands close to his shoulders. It therefore relies on an adult gently stretching out and holding his arms to activate any pad or switch on the shelf. A grasp switch proved to be unsuccessful, as once in place, he is unable to slacken his grip on the switch without adult intervention. In a sitting position it began to appear that target 2 may be never be achieved. Finally I attached a Tash leaf pressure pad head switch to the side of his seat. Initially random head movements activated the switch but he eventually began to still whenever an auditory reward was offered. After only a few weeks he is now beginning to respond more consistently to a range of auditory stimuli and appears to be moving his head with more purpose once the reward finishes. As yet he is showing no awareness of any visual stimuli. So far the switch has always been fastened to the right side of his chair, the side which he gravitates to naturally. I now intend to attach it to the left side and monitor the reactions.

To extend the childs experience of switches I brought in the Rifton prone angled wedge. With the child lying in prone on the wedge and his arms hanging over the front he is able to reach a large dome switch. He is left hand dominant and so the switch is placed slightly to the left of midline. To date his pressing of the switch seems largely incidental through involuntary movement, but already he is beginning to lift his head in response to the auditory reward.

With the above arrangements in place I feel confident that the child will now make progress in his ICT work and achieve his targets fully in the course of the school year.

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