There are excellent automated tools on the web which are regularly used for web accessibility testing, for example, accessibility validators like Wave or web developer Firefox extensions or Luminosity Contrast Ratio Analyser or FireEyes.
As accessibility expert Glenda Sim explained at Webstock recently 27% of testing for accessibility can be done automatically. Such testing can establish whether the basics of accessibility have been achieved.
But she also said that what she called ‘hands on’ testing and we call real world testing, is the final arbiter of accessibility. Automated tools will not take the place of live human testers.
Downloading a screen reader and testing using a sighted person, even with the screen turned off, although that may be a salutary experience in itself. Is no substitution for the real thing. A person who can see well won’t have the same way of thinking or perceiving information as a blind person.
Of course real world testing is not about blindness alone. Other disabled people experience their own particular barriers to using web sites. They may have low vision, which is a very different experience from blindness, or they may have physical impairments that prevent them from using the mouse or the keyboard, For Deaf the written language is not their first language. Others may take medication that impairs their concentration. Yet others may have dyslexia or cognitive difficulties. Their experience or way of seeing, perceiving and processing information cannot be simulated either.
Disabled people using computers will be reasonably accustomed to impairment, and have a level of competence in using their technology a non-impaired person would not be expected to have. It is impossible, and rather insulting, to simulate the experience of another person in this context. In the real world no one is ever suddenly confronted with impairment and expected to function immediately and efficiently with or without different technology. Simulation is not therefore an option.
There is no escaping the imperative of listening to the voices and experience of disabled people. We are the best experts on our own experience.
The most important thing about real world testing is that it identifies accessibility problems not found in the rest of the accessibility testing process. When fixed all visitors to your site will have a better experience.