How can the visually impaired used a computer?
Srinivasu Chakravarthula, Accessibility Manager, Yahoo! India R & D
Most often, people have a question - can a blind person use a computer? If so, do they need a special keyboard or a special computer?
Before answering this question, let me take an example of a typist who never looks at the keyboard but can type with speed and accuracy. How is it possible? Practice! Yes, it’s the same in case of people with vision impairment. They just need to be trained. They do not require a special computer – all they need is assistive technologies.
Firstly, let us understand that vision impairment is of two kinds:
Definition of blindness: http://www.nfb.org/Images/nfb/Publications/fr/fr19/fr05si03.htm
A person who is totally blind would be able to use the computer with the help of screen readers or Refreshable Braille Display. A screen reader is a software application that attempts to identify and interpret what is being displayed on the screen (or, more accurately, sent to standard output, whether a video monitor is turned on or not). This interpretation is then presented to the user with text-to-speech, sound icons, or a Braille output device. Screen readers are a form of Assistive Technology (AT) potentially useful to people who are blind, visually impaired, illiterate or learning disabled.
A Refreshable Braille Display or Braille terminal is an electro-mechanical device for displaying Braille characters, usually by means of raising dots through holes in a flat surface. This would be useful to those who are blind or deaf-blind. Because of the complexity of producing a reliable display that will cope with daily wear and tear, these displays are expensive. Usually, only 40 or 80 Braille cells are displayed. Models with 18-40 cells exist in some note taker devices. A person with low vision would have to opt to use screen magnification software that allows the user to increase/decrease the size of elements, change the contrast, use variety of mouse pointers etc.
With the help of these kinds of assistive technologies, users with vision impairment can use almost all the applications in any computer such as word processing, spread sheets, presentations, internet, email, web designing tools such as Adobe Dreamweaver,programming tools like Visual Basic, .net, database management systems etc.
Although, they rely on audio output, they can work at an amazing speed! All this is possible since assistive technologies provide them the flexibility to read only the information they require. Let’s look at an example of how one can navigate through a web page using a screen reader – Non Visual Desktop Access (NVDA) – a free and open source screen reader.
Now let's understand how the screen reader actually reads. There are several ways to navigate the page using screen reader:
Also, most of the screen readers such as NVDA offer list of elements in a dialog box such as with NVDA, by pressing Insert + F7, user can revoke elements list box that consist of links, headings and ARIA (Accessible Rich Internet Applications) landmarks.
As explained above, users will have a lot of flexibility with these assistive technologies and can perform operations at a rapid speed!
Some of the popular screen readers:
Tip: If you are don’t have time to download the screen reader, but need a screen reader to surf the Internet, just visit http://webanywhere.cs.washington.edu and type the web address, and it will read aloud for you!
Now, let’s talk about people with low vision. Around 60% of people with low vision do not possess enough level of vision to see the monitor and for some, this vision may not be stable. Hence they prefer to use screen readers to avoid strain of the eyes. But the other set of low vision users use Screen magnification software to use the computer. Some of the features that a screen magnifier has include:
Zoom-in and zoom-out the screen
Set the desired contrast for foreground and background
Increase and type of the mouse pointer
Adjust the speed of mouse pointer
Some have screen reading feature as combination
Some of the popular screen magnifiers:
To conclude, with the help of assistive technologies, a person with vision impairment can use computer for everything like any other user!