Assistive Technology: Alternative Pointing Devices

Contributed by Mel Pedley

Alternative pointing devices can be used to replace a standard mouse or as a supplement to other navigation methods. In many situations, they can be used alongside keyboard emulation software where keyboard access, or usage, is restricted.

A special adaptor that helps people with hand tremors control a computer mouse more easily. The device uses an approach similar to the "steady cam" technology found in camcorders to filter out shaking hand movements and can be adjusted depending on how severe the tremor is. It is also able to recognise multiple clicking on a mouse button caused by shaky digits.

Currently in the prototype stage, IBM has said that it will produce the devices, with partners Montrose Secam, for the retail market. The device is expected to cost about £70.

Usage:

Users with hand tremors

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This is a portable mouse that can be mounted on the edge of a notebook keyboard and controlled by the thumb and first finger or held in the palm of a hand. Although slightly strange to use at first, it can become very intuitive. There are also left and right handed mice as well as thumb operated mini trackballs that provide palm support.

Usage:

Users with dexterity difficulties.

Users with physical impairments.

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Haptic Devices

A haptic interface is a device which allows a user to interact with a computer by receiving tactile feed back and can be used by people with disabilities or people who learn best through tactile or kinesthetic experiences. This technology was initially cost prohibitive but is now incorporated into mainstream devices such as Logitech's iFeel MouseMan and Betacom's motorised ScreenRover that also incorporates an audible output.

These 2-dimensional haptic devices can be used to aid computer users who are blind or visually disabled; or who are tactile/kinesthetic learners, by providing a slight resistance at the edges of windows and buttons so that the user can "feel" the Graphical User Interface (GUI). This technology can also provide resistance to textures in computer images which enables computer users to "feel" pictures such as maps and drawings.

Usage:

Blind, or visually impaired, users.

Users with learning difficulties.

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Head Mounted Pointers

This is a head-mounted device that uses optical sensors to detect head movement that is then relayed to the mouse pointer. Typing is performed using onscreen Keyboard Emulation software.

Usage:

Users with severe physical impairments.

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Joysticks

Used as an alternative to a standard mouse pointer but it may need specialist software to maximise access usage. As with standard mouse pointers, there is a range of joysticks available with different forms of grip, and movement controls, to suit user needs and it may be possible to customise standard joysticks with specially designed grips as appropriate. The responsiveness of the joystick controls may also be customised using the standard OS interface.

Usage:

Users with dexterity impairments.

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Mouse Keys

This enables the keyboard arrows to be utilised as an alternative to a mouse or joystick. This facility is standard within many operating systems and can be very useful for someone who uses a head pointer or a key-guard and who might find it difficult, or impossible, to use a mouse.

Usage:

Users with dexterity difficulties.

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Mouse mats are normally placed upon a computer desk and/or near the keyboard. However, this can pose problems for people with spinal problems, upper limb problems or those confined to wheelchairs. Alternative mouse mats can be attached directly to the upper leg of a user for maximum accessibility or a small table attached directly to a wheelchair for use with the mouse/joystick.

Usage:

Users with dexterity difficulties.

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Touch Pads

These devices enable a user to control a standard cursor by means of small finger movements on the Touch Pad's surface. Selections can be made by either tapping the Touch Pad surface gently or using the programmable buttons that are often part of the unit. Because the units are relatively small and light, they can be used in situations where a normal mouse is not practical. They can be placed on the knee of someone with limited gross limb movement; in situations where there is reduced phyical strength; or they may be used to alleviate the problems caused by Repetitive Stress Injury.

Usage:

Users with severe physical impairments.

Users with dexterity difficulties.

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Touch Screens

Devices which enable a user to control a computer by pointing or touching an area of the screen. Most touch screens use a clear plastic window placed in front of a standard monitor and may be used as a keyboard alternative. They should work with any mouse-driven software, but it must be remembered that mouse-driven programs are designed for small cursors rather than large fingers so, although it is a very direct method of access, some users may not be able to locate the precise, often small, areas required. Therefore, some touch screens may need to be calibrated for the individual user and/or require additional specialist software.

Usage:

Users with dexterity difficulties.

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A trackball is basically an upside-down mouse where the mounted ball is moved by the hand resulting in less gross hand and arm movement for a given pointer movement. Large trackballs with a billiard-sized ball (with or without extra middle buttons) may be of use in situations where the user has poor "grip skills" or poor fine motor control. Some trackballs have extra toggle switches available for holding the left and right buttons down or are also available as joysticks. A foot-operated trackball is also available.

Usage:

Users with dexterity difficulties.

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