Part of: Images
Last updated: 1 May, 2020
Following this helps people with:
low or no vision: consider providing audio description
reduced or no hearing: captions and transcripts increase access
epilepsy: flashing images can trigger photoepileptic seizures
Autism: video content may over-stimulate and distract
cognitive challenges: video content should be easy to follow
time-pressures: it can be quicker to scan read than watch a video
multitasking: video content may pull attention to the wrong place
Video content and GIFs are less accessible than content presented as text. As well as causing access barriers, adding cognitive load and distracting from other content they can cause serious harm to motion-sensitive users. However, they can also be time-consuming and boring to watch.
We recommend always questioning whether a moving image format is really the best way to present the information.
Text on an HTML page in clear language and a legible font is always going to be accessible to more people than moving visuals. While transcripts and captions can increase access to video content, they bring their own usability issues. For example, clicking or scrolling to find the transcript, or increased cognitive load and eye strain to keep up with captions as they appear.
From miscomprehension to epilepsy triggers, there are a lot of possible issues with video content. Use with caution.
Supplying video content in text format is a basic accessibility requirement. It will also help users who might not have headphones, good reception or data.
Your transcripts and captions need to be readable, so follow all the readability guidelines. For example, do not present them in block capital letters. And make sure your transcripts are accessible for screen reading and text to speech software,
You should also:
consider including sign-language translation in your video,
consider providing audio descriptions of what is happening in the video, the soundtrack may not communicate everything,
provide alt text descriptions for GIFs on social media.
Video content, like other images, distracts users, as it is eye-catching. This will make it harder for users to focus on other content on the page. This focus-pull could make it harder to comprehend other page content accurately, especially if users already have cognitive challenges or are multi-tasking. Put important information which is not part of the video content on a different page, or re-consider including a video at all.
Flashing images, or apparently flashing images, like fireworks or gunfire simulation, could cause death if they trigger a photoepileptic seizure. Avoid completely.
Moving visual content can also trigger, migraines, nausea, dizziness and anxiety. Accessibility expert Sheri Byrne-Haber has some useful practical advice on video content that suits motion-sensitive users.
Consider that visually rich video content, which contains many different objects, scenes and people, has more potential to trigger unconscious associations or memories. Aim to keep video content simple.
Again, ask yourself is video format really the best way of communicating to meet user needs for this information?
This causes usability issues for users. The World Content Accessibility Guidelines say you must include user controls to stop, pause and hide the video if it does autoplay.
These are recommendations from Scope, a UK disability equality charity, for the best video conferencing apps and software for accessibility.
Video and streaming media, Nielson Norman Group, 1999.
Talking-head video is boring online, Nielson Norman Group, 2005.
Video usability, Nielson Norman Group, 2014.
Accessibility and motion, Sheri Byrne-Haber, 2019.
A11y project video tips, Emma Patricious, 2013.
We invite you to share further usability studies and academic papers in the comments section of this page.
Usability evidence collected: April 2020
Wiki page published: 1 May 2020