Redundant alt text is announced twice
Aliases: double announcement · duplicate alt · icon plus text
What it is
A button that already says “Download,” with an icon whose alt is also “Download,” is announced “Download Download.” A photograph whose caption is copied into alt sends the same sentence through the speech stream twice. Redundancy is not “too long.” It is the same sentence on two channels. In that structure the icon should be hidden as decoration and the visible words should be the only name.
Why it happens
Name computation concatenates, and readers also speak adjacent nodes in source order. Once visible text already bears the name, an image node that supplies the same string produces a double in the linear stream. What people hear is not emphasis; it is a glitch, and they are more likely to skip the control.
This is the inverse of “a short alt cannot finish a complex figure”: the information is already on the visible layer, and the image adds no new fact. It sits next to “hide pure decoration,” but the motive differs — the graphic may still help sighted scanning, yet it is a duplicate for AT. An aria-label that repeats the visible words, or a matching title, stacks a third copy. When a figcaption exists, copying it into alt is one of the usual doubles.
Studying it
Listen to every icon control and inspect Name in the accessibility tree; mark consecutive repeated words. Compare empty-alt icons, same-copy alts, and a second aria-label.
Independent variables: whether the icon exposes the same name as the visible text, presence of a figcaption. Dependent variables: double-announcement count, skips of that control, whether the computed name becomes “Download Download button.”
Automation almost never sees semantic duplication; someone has to listen. Readers differ on “image + caption”; test at least one desktop and one mobile stack.
Where it stops holding
If the image adds a fact the adjacent words omit (a defect visible in the photo, an instrument model the caption skips), alt should add that increment, not recopy the caption. An icon button with no visible words must keep a name; removing it yields a nameless control. A link that wraps only an image uses alt as the link name — not redundancy. Two side-by-side images that say different things each get their own text.
Applying it
- Icon plus visible words:
alt=""oraria-hiddenon the icon; leave the visible sentence as the name. - Photographs with a caption: empty alt, or only the fact the caption lacks — do not copy the caption.
- Do not stack an
aria-label/titlethat matches the visible words. - Verify: walk buttons, cards, and figures with a reader. Any two identical words in a row: delete the copy on the image. In the accessibility tree, Name should equal the on-screen sentence once, not twice.