Inference Group

Search :
hands-free writing

Special Needs

Dasher is highly appropriate for computer users who are unable to use a two-handed keyboard. One-handed users and users with no hands love Dasher. The only ability that is required is sight.

Dasher can be driven using a mouse, a trackpad, a touchscreen, a rollerball, or a joystick - any two-dimensional pointing device that can take over the role of a mouse. A foot mouse and a head mouse are additional options.

It can also be driven using an gazetracker, giving a completely-hands-free writing system. After one hour's practice, some users are able to write at more than 20 words per minute using Dasher with an gazetracker. Experienced users reach 30 words per minute. We got these results with the Quick Glance gazetracker from EyeTech Digital Systems.

For a movie demonstrating Dasher with an gazetracker, see the demonstration page.

Compared to an gazetracker + on-screen keyboard, Dasher is

  • faster
  • more accurate
  • more fun

Further information

Headmouse information

UK contacts

The Dasher project enjoys links with the ACE Centre in Oxford, and with Ability Net. Ability Net has 11 centres around the country who can help disabled people use whatever technology is appropriate for them, including Dasher. The ACE centre specializes in children with severe disabilities.

Frequent questions

I am paralyzed from the shoulders down. What do I need to make Dasher work for me?
Do you have a PC? (Linux or Windows) Can you use a head-mouse? Or any other sort of mouse? Perhaps a mouth-stick that controls the mouse coordinates? If so, simply download the latest version of Dasher, and you should be able to write with Dasher.
If standard mice and head-mice are not an option, then you'll need an gazetracker that can take over control of the mouse.
We used a system from Eyetech called Quickglance. See below for links to other gaze-trackers.

Hardware options

Here are some links giving information about non-standard mouse devices.

  • Keyboard alternatives have Many mouse devices and a detailed Pointing device compatibility chart. They have now moved to Solutions for Humans.
  • Head mouse, Highly recommended: Smart-Nav Head mouse from NaturalPoint (formerly sold as the TrackIR; don't buy a TrackIR now, however, as the current (2005) TrackIR is now specialised for gaming)
  • Costs about $150-$300, uses one reflective dot stuck to your head and a small camera attached to your windows machine. (No linux version is currently available, but if NaturalPoint hear there is demand, I think they might respond!)
    We recommend this device because it is cheap, easy to set up, and versatile. Here's a review of this head mouse.
    You can stick the dot on your finger or toe to make a finger-mouse or toe-mouse. We got best results by putting the dot on an extension so as to get accurate amplification of the body motion. Equivalently, put the reflective dot on the tip of a baseball hat. SETTINGS - for our first TrackIR, bought about 2002: We put Natural Point's "speed" control at its maximum (but not 2x) and its "smooth" control towards "-". For the smartnav3, we put the smoothing control to its smallest value (slider to the left), and the speed controls (for x and y amplification) in the middle; I wasn't sure whether I preferred Relative or Absolute mode. Further advice from users.
    Other headmice: We very highly recommend the Origin Instruments HeadMouse Extreme , which feels a lot like a Navpoint smartnav to use, but has the advantage that it works instantly as a USB mouse, requiring no software at all. So it works on linux and mac too! The price is about $1000 - pretty steep! But a very good product.
  • ACE is a UK centre of information, support, and training for parents and professionals in the use of technology for young people in education who have communication difficulties, both in speaking and/or writing.
  • Skipper ( includes advice about making your own custom hardware to enable control of your on-screen mouse and other other aspects of your computer. Free software is included for linux machines.
  • Head-mouse From MouseVision Inc: VisualMouse (VM) software - widely used by disabled people, can be downloaded from free of charge. VM is a pointing device using a webcam that recognizes head motion (with no gear on the head). It works with Windows 98/ME/2000. [23/8/02.]
  • A free headmouse. It runs under Windows.
  • GyroMouse - Free space mouse - good for people with limited reach - and could probably be used as a head mouse or foot mouse.
  • Carpal tunnel-friendly mouse: One Dasher-user recommends the hand-held IBM GlidePoint mouse.
  • Gazetrackers: Eyetech - we used their Quickglance gazetracker, which costs about $3000. Very good value. We used the following settings: Setup->More Options->Update Rate 30, Smoothing Factor 1 or 2. (in contrast to the defaults which are 10, 7). Further info about the system is provided here.
  • Gazetrackers: Applied Science Laboratories
  • Gazetrackers: Eyegaze (LC) A high-quality tracker, and very easy to use. Works with Dasher, Though LC technologies have not pushed this opportunity (as of Oct 2005).
  • Eye response Erica A high-quality tracker, and easy to use. Comes with sensible patented features such as an automated zoom whenever you dwell-click on a small piece of the windows display. Works with Dasher, and Eye response ship their product with Dasher. They are actively working (as of Octo 2005) on making their gaze tracking software change its behaviour when you are using Dasher (very responsive behaviour is good for Dasher). ($8000 for a complete system based on a tablet PC)
  • Tobii's MyTobii -- the king of gaze-trackers - this one tracks both eyes and is robust to enormous head motions. Very impressive. About $25,000.
  • Metrovision, who make Visioboard I have used Dasher with the visioboard. It is a good gazetracker, incorporating a second camera that does head-tracking. Another good feature is the well-designed user interface. Recalibration of the gazetracker happens automatically if the system detects a drastic problem (eg a huge head movement). So I think this system is good for a lone disabled person to use. It is a large system, made up of a screen on a stand and two computers, one for eyetracking and one for you to run windows on. When you make a big head movement, the quality of tracking is not so good.
  • More about gaze control: see the Cogain site for Gazetalk software that works with Dasher.
  • Foot-control: Vik writes:
    "I thought you might like to know that I have been running the Linux version of Dasher on the Sony Playstation 2. I used the Sony "Dance Mat" controller to control Dasher with my feet. This is a relatively low-cost platform with a variety of controllers available, some of which may suit certain disabilites."
  • Trackers and software from Madentec
  • Usernomics ergonomic-products website

Speech synthesis and Dasher (under Linux)

Skipper ( is being integrated with Dasher. [Skipper provides full (and practical) access to everything in Linux and the Internet for people with severe physical disabilities.]

Speech synthesis (under Windows)

Mon 2/5/05 Today I learnt about a system that can be used to capture someone's speech, then synthesize speech that sounds like theirs: ModelTalker seems to be free software, and I believe there are versions for both Linux and Windows.

Speech synthesis and Dasher (under Windows)

Thu 12/12/02: Ronnie Love's directions for getting Dasher to "talk on stop" with a variety of speaking systems.

Tue 1/10/02: cliffn has written a front end for dasher v1.6.8 in VB5 which allows to run Dasher, allows one click to save the text into a file, and allows the file to be read aloud. With a shortcut to the text file on your desktop it is easy to edit and copy and paste to another app.
Tested only on Win 2000 but available for download with a right click on the file name (StartDasherFS.exe) from:; this exe file should be put in the dasher folder alongside dasher.exe.

This text file gives Margaret Cotts's instructions for using Macro Express to connect Dasher 1.6.8 to etriloquist, and further information submitted by other users.

This text file gives information from R. Love about making Dasher talk.

In due course, one of the Dasher developers plans to connect Dasher version 3 directly to FreeTTS.

Web-browsing and Dasher

We haven't connected Dasher to a web-browser yet. Andras Lorincz drew our attention to Coraler (formerly, which offers a nice Dasher-like hypertext navigation environment. A beautiful prototype. I think the idea is that websites should be written in the style of Coraler to make them more disabled-friendly.

The Dasher project is supported by the Gatsby Foundation
and by the European Commission in the context of
the AEGIS project - open Accessibility Everywhere: Groundwork, Infrastructure, Standards)

Site last modified Sat Mar 19 12:11:40 UTC 2016