Georgia Tech Research Institute
 
Accessibility Assistant

Accessibility Assistant

Issues

Indicator Lights (4 of 4)

Issue: Overuse or misuse of indicator lights reduces their effectiveness.

A kiosk is shown with four indicator lights illuminated on different parts of the device.

Indicator lights can be useful for communicating status to users or attracting the attention of users. However, overuse of indicator lights (especially lights with strong attention-getting qualities such as flashing or brightness) or misuse of indicator lights can be an irritation or a distraction to users, and can cause the lights to lose their attention-drawing power.

Populations Impacted: All users with vision.

Potential Solutions:
  • Avoid overuse of indicator lights, particularly for non-critical information. "Overuse" of indicator lights is subjective, and the threshold will vary from machine to machine. Generally, indicator lights should be used to communicate information that is important to the user (for example, that user input is required or that an error has occurred), and should not be used for decorative purposes, or to communicate information that is obvious in other ways (for example, a power light is unnecessary if it is obvious from the user interface that the machine is on).

  • The intensity of indicator lights should commensurate with their importance. The use of intense indicator lights (larger, brighter, flashing) should be reserved for situations where it is important to attract the user's attention (for example, when action is required or an error has occurred). More subtle (smaller, dimmer, non-flashing) indicator lights should be used for more mundane purposes, such as acknowledging successful user input.

  • Ensure that the characteristics of indicator lights follow standard conventions. The Human Factors Design Standard (HFDS) describes the following conventions:

    • Red indicates error or malfunction conditions.
    • Yellow indicates delays or situations where rechecking is necessary.
    • Green indicates satisfactory conditions, or that it is OK to proceed with an operation or transaction.
    • Blue should be used as an advisory color.
    • White indicates a physical position or an action in progress.
    • A bottom-to-top or left-to-right movement in an array of indicator lights should represent increasing values.
Applicable Guidelines:
HFDS - 6.2.2.1.27, 6.2.2.3.3, 6.3.3.5