Flicker/Blink

From Library

The Issue: A large share of the web community views moving, flickering and blinking objects as annoying and rude. Users may try to turn off or hide any such objects on the screen before perusing the content. Other visitors simply avoid pages with elements that they find annoying. Beyond the accessibility issue for people with disabilities, where such elements make the page difficult to use properly, web designers who persist in using flashing objects may find the visitor count drop simply because it annoys users.

STANDARD 5.1

Web site screen elements will not have a flicker rate with a frequency between 2Hz and 55Hz. (2 to 55 flashes per second).

 Comment: People with cognitive of visual disabilities may have trouble processing 
 information on the screen fast enough to read the content if it is flickering. Further, 
 movement can cause such distractions that reading the rest of the material may be 
 difficult or impossible.

 Screen elements that flicker in the proscripted range can trigger epileptic seizures
 in visitors with a susceptibility to such seizures.

 HTML Elements Affected: <img>, <object>

STANDARD 5.2

A mechanism will be in place to allow users to turn off screen elements that flicker.

 Comment:  If you insist on using elements that flicker or blink, you cannot assume 
 that user agents (browsers) have a mechanism that controls that behavior for those 
 users vulnerable to the adverse effects.

 Therefore, you must provide some way to turn off the effect yourself in a clear,
 easily-identified way.

 HTML Elements Affected: <img>, <object>

STANDARD 5.3

The use of the blink element is prohibited.

 Comment:  In addition to being extremely annoying to your visitors, the blink element
 also can cause seizures in sensitive individuals.

 HTML Elements Affected: <blink>