Hello Platonides,
Those should have a title attribute.
On German Wikipedia I see no titleattribute if I specify a caption for an image.
We used to have alt attribute equal to the title, but that was removed for duplicating it and being in fact ignored. Is some screen reader preferring alt over title?
The most often used screen reader JAWS behaves like this: By default it uses the alt tag. The user can change this by altering the setting to “use title” or “use longest” and some other fancy stuff. But this is a global setting, so you don’t really want to force the users to change their setting.
If no alt attribute is set, JAWS could disregard the image. In our case images are always surrounded by links. Having no alt attribute JAWS uses an annoying fall back solution: it speaks the image file name.
We discussed this some weeks ago in the German Wikipedia. The preferred solution would be:
1. If [[File:...|alt=...|...]] is given, use this text for the alt attribute. 2. If no alt text is given, use the text given as the thumb caption. 3. If no alt text or thumb caption exists, use the file name (without px data added, without file extension, without _ for blanks).
I hope that clarified the problem.
Kind regards, Maria