Georgia Tech Research Institute
 
Accessibility Assistant

Accessibility Assistant

Issues

Touchscreen Interfaces: Issue 2 of 3

Issue: Touchscreen controls are easily activated and do not provide tactile feedback, often resulting in unintentional control activations.

A touchscreen interface with a set of three buttons is shown.  The buttons are very small and tightly spaced.

Touchscreens require very little pressure to activate controls. The low strength requirement is beneficial to users with limited upper body strength, but can cause problems for other users, especially if controls on the touchscreen are small or closely spaced. When controls are small or closely spaced, users who have upper mobility impairments or lack fine motor control will have difficulty activating specific controls without also activating adjacent controls. Users without vision may inadvertently activate touchscreen controls while moving their hands over the control panel to locate hardware controls. Because no tactile feedback is provided by touchscreen controls, if redundant visual and auditory feedback is not provided when controls are activated, these accidental activations may go unnoticed.

Populations Impacted: Users who are blind; users with upper mobility impairments.

Potential Solutions:
  • Ensure that buttons are large and are spaced far enough apart to minimize the possibility of accidental activation of adjacent buttons. When designing a touchscreen interface, include adequate space between buttons. According to the Human Factors Design Standard (HFDS), touchscreen buttons should be between 0.75" and 1.5" along each side, with spacing between buttons of 0.13" to 0.25". This will help ensure that a user who does not have fine motor control is able to activate a button without accidentally activating adjacent controls.

  • A touchscreen interface with a set of three buttons is shown.  The buttons are large and have space between them.
  • Provide an alternate display mode with larger, widely spaced controls. If the normal display cannot be made accessible, providing an alternate display mode with larger, more widely spaced controls, even if it contains only the most frequently used controls, will be useful for users who lack fine motor control.

  • Provide alternatives to the touchscreen to facilitate interaction by users with disabilities. Touchscreen functionality could be replicated in a fixed or attached auxiliary control panel using control elements with functionality, position, and status that are easily discernible by touch. A voice display could be integrated with the control panel, so that feedback is presented in an auditory fashion as well. For example, using a numeric keypad as an input device, the user could navigate through options that are voiced, without having to rely on vision to perceive the screen contents. The voice display approach could be combined with voice recognition for hands-free device operation.

  • Provide visual and auditory feedback when user input is received. Providing visual and auditory feedback when user input is received can make up for the lack of tactile feedback, and helps users detect unintentional activations. Visual feedback can be provided in the form of salient visual changes in the display. Audible feedback might consist of simple tones, or speech output when more descriptive feedback is needed.

  • Allow easy recovery from errors. A "Back" or "Undo" button should be provided to allow users to recover from accidental inputs. Note that a button labeled "Cancel" is somewhat ambiguous; a user may think that a "Cancel" button will cancel the entire transaction, rather than cancel only the most recent input.

Applicable Guidelines:
Section 508 - 1194.25(c), 1194.31(a), 1194.31(f)
Section 255 - 1193.41(a)(3)(e), 1193.31(e)(2)(e)
HFDS - 9.4.2.4
Mercinelli - 2.5