Types and Definitions

What are the Types of Disabilities and Limiting Conditions?

There are a variety of different visual conditions that could limit a person attempting to play a game. The primary categories encountered in gaming are limitations in vision are listed below.

  • There are three major types of visual disabilities: blindness, low vision, and color blindness. Each has a different effect on the person’s ability to play a game.


  • Blindness is usually defined as “the loss of vision, not correctable with lenses” [1]. People who are totally blind cannot play games that rely on visual cues to prompt a player. They must rely on sounds or special hardware such as force feedback to indicate when they need to act.

Low Vision:

  • Low vision is related to blindness. A person with low vision can detect light, perhaps see some motion, but is very limited as to what they can see.
    A more detailed definition of low vision is “a visual acuity of 20/70 or worse in the better eye using a best-corrected spectacle correction, or visual fields of 20° (twenty degrees) or less.
  • However, a more functional definition is that low vision comprises any vision loss that adversely affects the performance of daily activities.” A related term is “legally blind”. “Legal blindness is defined as visual acuity of 20/200 or worse in the better eye with correction, or visual fields of 20° or less in the better eye. “
  • In either of these cases, users could play games provided there was some degree of magnification of the screen. Users could respond to visual and sound cues, but their ability to see a wide area of the game may be restricted by the magnification of the screen.

Color Blindness:

  • Color blindness is an inability to detect certain colors. It ranges from total color blindness, where the person perceives the world as shades of gray, to more common types where a person does not perceive the differences between red and green or yellow and blue correctly.
  • This condition is more common among men than women. Studies have shown that from 5 to 8% of all men and about 0.5% of women have some degree of color blindness.
  • The effects of color blindness have been studied and design guidelines have been created. An example of such guidelines can be seen in an article in the British Telecommunications Engineering Journal in January 1999 entitled “The eye of the beholder – designing for color-blind users”. A pdf version of this article can be found at http://more.btexact.com/people/rigdence/colours/colours.pdf.
  • The effects of color blindness are more pronounced under certain game color schemes. An example from the past was the Firaxis game “Sid Meier’s Alpha Centauri”. The primary color scheme was mostly red and green, which caused problems for some players. This was quickly addressed through the release of a patch, which provided alternate art for the game.

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