Access methods are the way in which an individual can interact and control a communication system. Working with clients to match them with an appropriate, consistent access method is essential for maximising their potential for communicative competence. There are several different methods, though each requires different skill sets. These may need to be acquired by the person you are supporting. Such skills must either be already present or be capable of development through repetitive practice:
1. Direct Selection
The device user will move a body part, generally their finger, to make direct contact with the device screen. For many this is by far the most efficient method of interacting with a device, though speed, accuracy & fatigue all need to be considered. A stylus or a physical head-pointer can also be utilised.
- Finger, or toe isolation, is possible through the assistance of keyguards and touch guides (can assist poor vision, tremor problems, or weak hand-control)
- Adequate visual & spatial processing skills
- Activation can be controlled by initial touch or by release, modulated by timers
2. Head Pointing
Involves the use of infra-red emitted from the device & a reflective dot placed on the user’s forehead, cap or glasses. Head pointing is an access method that is an excellent option to consider if alternative access is required. It is less tiring than eye gaze technology, is much cheaper & is less reliant on precise positioning. With head pointing an individual can control a cursor on the device screen that mirrors the movement of the reflective dot, making selections through an adjustable dwell feature.
- Stable head and neck support
- Independent control of horizontal and vertical head movement. Limited movement in horizontal or vertical planes will not greatly impact use as calibration can increase movement sensitivity.
- Adequate visual processing skills
- Can be used in conjunction with a switch activation to select locations once dwell has locked on
3. Eye Gaze
Eye gaze technology tracks the movement of an individual’s eyes through the combination of sensor & camera technology. This gathered information is interpreted in real time & represented on the device screen. This technology can be incredibly powerful for those who have lost their ability to voluntarily control motor movement of limbs or even the head.
- Voluntary and consistent control of eye movements. Eye gaze is able to track movement of one eye only if necessary
- Stable and consistent positioning
- Sufficient energy, concentration & attention. Eye gaze technology can be tiring to use during extended periods of time
- Adequate visual processing skills
- Does not suit all eye types eg watery or drooping eyes
- Can be sensitive to daylight & artificial lighting
Switching allows a client to control scanning patterns across locations pre-programmed into a device. The activation of one or two switches together provides a user with vocabulary selection as a cursor scans methodically from quadrant to quadrant, or location to location in a vertical or horizontal progression. In one-switch scanning a pattern will automatically move through the lines of vocabulary on the screen until the user needs to tap the switch again when it is in position over the actual word they want to generate. In two-switch scanning, one switch is used to control the scanning and the other is used for selection of the word. This method is useful for those requiring less precise motor skills.
- Very low barrier for entry. Individuals can access systems through using one or two switches. Switches can be placed in any location on a wheelchair or may be carried.
- Switches may be accessed through the hand, fingers, arm, head, leg or breath. There are many varieties including ones that are incredibly sensitive (eyebrow switch) or large & durable (big-red switch) so as to present a big target.
- One-switch scanning is more difficult. The individual will need to combine the skill of timing with tapping on the switch. Two-switch scanning gives more control to the user as they control the speed of the scan through switch number one.
- Does not necessarily need visual perceptual skills as auditory prompting can be used to guide the user. This can be delivered in a different voice (perhaps via headphones) to the main speech output voice.
- Can be used as a selection method when combined with head pointing & eye gaze.
Other slightly different access methods comprise the use of a:
- Different-sized, stabilised joysticks (perhaps with additional column-mounted switches)
- Large & small-scale custom trackballs
- Switch-adapted mouse
It is vital when working through access methods that a team approach is used to properly assess an individual’s holistic needs. Occupational therapists are extremely valuable for their insights into optimal positioning & functional use. Speech pathologists become heavily involved in selecting appropriate devices that have the best vocabulary system for the client.
Hit this link to discover more about a simple, step by step approach known as “Core Scanner”