I've been advised that if a 'title' attribute expands upon what's present in a control's visible text, it should include all information in the visible text, because the screenreader may read the title instead of the visible text. To clarify exactly how this works, are any of the following points true (for must screenreaders)?
If a label is associated with an input field using the 'for' attribute, and the input field's title attribute is set, then the screenreader will read only the title attribute and ignore the label text.
If a control with its own text, such as a button, is provided with both visible text and a title attribute, then only the title attribute will be read.
The screenreader will ignore visible text for button controls, even if the developer neglected to provide the title attribute for that particular control (the most extreme possibility).