Head tracking

Also called Head mouse, Head pointing, Head control, Camera mouse

Moving a pointer with small movements of the head, read by a camera or a reflective dot. Hands-free, cheaper than eye gaze, and it needs a steady neck.

What it is

Head tracking turns head movement into pointer movement. A camera watches the face (or a small reflective sticker on the forehead or glasses) and moves the pointer as the head turns and tilts. Selection is by dwell, a switch, or a puff.

It is direct selection for a person whose head is their best-controlled part. A tablet's front camera can do a basic version; a dedicated head tracker does it precisely.

Who it can help

People with good head control and limited hand use: many people with high spinal injury, some with cerebral palsy, some with multiple sclerosis or muscular dystrophy. It is often the right answer where eye gaze fails because of nystagmus or glasses, and it is much less bothered by lighting.

It is wrong for a person whose head movement is involuntary, weak or painful, or who cannot hold the head still for a dwell. It tires the neck over a day, and it tends to fail as a neuromuscular condition progresses, so plan the next method while this one works.

How it works

The tracker reports head position many times a second; software maps that to pointer position, with a gain setting (how far the pointer moves for a degree of head turn) and a smoothing setting (how much jitter to ignore). High gain means less movement per selection but less accuracy; low gain means precise but effortful. Most people settle with the pointer crossing the screen for about 15 to 20 degrees of head turn.

Apple's Head Tracking (in Switch Control and AssistiveTouch) and Android's Camera Switches use the built-in front camera with no extra hardware. Dedicated trackers use an infrared camera and a reflective dot, and work with any computer or communication aid. Selection is usually dwell; some people add a sip-and-puff or a blink switch for clicking.

Getting started

Try the free version first: on an iPad, turn on Head Tracking in the accessibility settings and drive the pointer around a big grid with dwell at 1.5 seconds. Twenty minutes tells you whether the head is steady enough and whether the person finds it natural.

If it is, ask the AAC service to trial a dedicated tracker; the accuracy step up is large. Fix the screen on a mount at eye level and straight on, because head tracking, like eye gaze, needs the geometry between face and camera to stay the same.

Where to get help

Ask for an AAC assessment via your speech and language therapist; head tracking is within scope of the specialised AAC services for people with complex needs. The ACE Centre and CALL Scotland publish guides, and AbilityNet covers head-controlled pointing for computers at work.