Multimedia Accessibility

Images and graphics enhance content appeal and comprehension, but they must be accessible to users with visual or cognitive disabilities. Alternative text (alt text) provides a textual description that screen readers can convey to users who cannot see images.

Alt text serves multiple purposes beyond accessibility. It appears when images fail to load due to connection issues or broken links, ensuring users still understand the content. Search engines also use alt text to better index and categorize web pages, improving SEO performance.

Alt text can be presented in two ways:

• Within the alt attribute of the <img> element
• Within a visible image caption or on a separate page

Focus on describing the image's purpose and function rather than its visual details. Only mention colors or visual elements when they're essential to understanding the content's meaning.^[1]

Not all images have meaningful content. Decorative elements like abstract patterns, background textures, or spacer graphics enhance visual appeal without conveying essential information. For such purely aesthetic images, use empty (null) alt attributes instead of descriptive text.

Adding a null alt attribute (alt="") explicitly tells screen readers and other assistive technologies to skip the image. This prevents unnecessary interruptions in the user experience for people relying on text-to-speech tools. Without null attributes, assistive technology might attempt to interpret or announce decorative images, creating confusion and diminishing usability.

Determining whether an image is decorative requires careful consideration. Ask yourself: "If this image were removed, would the user miss any important information?" If the answer is no, a null alt attribute is appropriate. This thoughtful approach helps create cleaner, more efficient experiences for all users, particularly those with cognitive or visual disabilities.

When images contain text, the simplest and most effective approach is to use that exact text as the alt attribute. For instance, a logo with the word "Dropbox" should have an alt attribute stating "Dropbox logo." This direct approach ensures screen reader users receive the same information as sighted users.

Screen reading technologies rely on these alt attributes to verbally describe images to people with visual impairments. The alt text creates a verbal equivalent of the visual content, maintaining information parity across different ways of experiencing your product. Additionally, search engines use these text descriptions when indexing your site, improving your content's discoverability and SEO performance.

Keep your alt text concise and focused on the essential message. Avoid redundant phrases like "picture of" or "image of" since screen readers already announce the element as an image. This streamlined approach creates a more efficient and less frustrating experience for users relying on assistive technology.

Automatically playing videos and audio files creates accessibility barriers for many users. This practice is particularly problematic for people with vestibular disorders or seizure disabilities, as sudden movement and sound can trigger discomfort or even medical episodes.

Always give users control over when multimedia content begins playing. Place media controls prominently at the beginning of the content or at the top of the page, making them easy to find and operate. These controls should be keyboard accessible and clearly labeled to ensure all users can interact with them regardless of how they navigate your site.

Media players need comprehensive, accessible controls that work for all users. At minimum, include options to pause, play, stop, rewind, adjust volume, mute, and toggle captions.^[2]

These controls should be clearly visible and usable with both mouse and keyboard. They should also have sufficient size, contrast, and clear labeling. Consider keyboard shortcuts for common functions and ensure that controls work with assistive technologies like screen readers.

Remember that these controls benefit everyone, not just users with disabilities, as they allow all people to customize their experience according to their preferences and environment.

Captions refer to text versions of the speech. Furthermore, captions not only provide the dialogue but also identify the speaker and incorporate sound effects for a more realistic environment. They allow users who experience hearing loss or have cognitive and learning disabilities to reach the audio or video content without constraints.

However, captions benefit all users, not just those with disabilities. When people start learning a new language, captions are like crutches — they assist and support users when watching a movie or educational channel.

These are also useful when users can't hear the audio due to noisy environments (like a crowded bar or subway) or if they don't want to disturb others (like a library).^[3]

Web animations in videos, GIFs, PNGs, SVGs, and JavaScript can create engaging user experiences. However, strobing or flashing elements create serious accessibility barriers, causing eye strain for many and potentially triggering seizures in people with photosensitive epilepsy.

Flashing content can be harmful even at low frequencies — some individuals experience symptoms at less than 3 Hz (flashes per second). Similarly, patterns with more than 5 light-dark stripe pairs can provoke seizures regardless of orientation. Color choices also matter significantly, with red flashing being particularly problematic for people with photosensitive seizure disorders.

If your design absolutely requires flashing content, never expose users to it without warning. Implement clear opt-in mechanisms with explicit warnings about potential risks.^[4] Better yet, consider alternative design approaches that achieve similar engagement without relying on potentially harmful visual effects.

Use specialized testing tools like the Photosensitive Epilepsy Analysis Tool (PEAT) or the Harding Test to evaluate animations before implementation.

Transcripts convert audio content into text format, making information accessible to everyone. They are essential for people with hearing disabilities who cannot access audio information through listening alone. Transcripts provide a complete text alternative that can be read at any pace.

Users benefit from transcripts in various scenarios beyond accessibility requirements. People learning a language can read along while listening to improve comprehension. Those in noisy environments or situations where playing audio isn't possible can still access the content. Transcripts also help users who process written information more effectively than spoken words.

You have flexibility in how you present transcripts. You can place them directly on the same page as the audio content for immediate access or provide them on a separate page with a clear link.^[5] Whichever method you choose, ensure the transcript is easily discoverable and properly formatted for readability.

Icons serve as visual shorthand for actions and concepts in digital interfaces. When thoughtfully implemented, they enhance navigation and improve the overall user experience by providing visual cues that reinforce textual information.

The most effective icons pair with clear text labels rather than standing alone. This combination prevents ambiguity and supports users with diverse needs. People with cognitive disabilities benefit from the dual coding of information, while those with partial vision impairments can use icon shapes as additional navigational landmarks even when they can't see fine details.

Choose icons that follow established conventions whenever possible. A magnifying glass for search, a house for home, or a shopping cart for checkout are widely recognized patterns. Consistent, familiar icons reduce cognitive load and create more intuitive experiences for all users, particularly benefiting those with learning disabilities who may struggle with abstract or novel representations.

Swipe gestures are often designed to follow a left-to-right or right-to-left motion. But if a gesture only works from one edge, like swiping from the left to open a menu, it may feel awkward or even unreachable for left-handed users holding a phone in their left hand. This friction adds up when gestures are tied to essential actions like navigation or content discovery.

To make gestures more accessible, avoid relying on single-direction swipes for key features. If an action is tied to an edge, ensure it can be triggered from either side or provide an alternate way to access it. This approach supports both hand preferences and improves usability for people with limited mobility or range of motion.

A few more considerations:

• Check edge-based gestures: Test actions like opening menus or dismissing screens—do they work for both swipe directions?
• Provide tap alternatives: Ensure all gestures have a visible, touchable equivalent on screen.