visitors using magnifiers have different access needs than screen reader users

[tonyfast]

visitors using magnifiers have different access needs than screen reader users. we ran into this consideration because we added the ability to create text really big for low vision users. the layout became suspect when we did that. so what design consideration are there for magnification users?

typically, digital content is constrained horizontally leaving the vertical scroll as a degree of freedom for position. sighted viewers consume this high density information in parallel, or all-at-once, by physically adjusting their posture, moving their head, and scrolling vertically. this is a distinctly different physical activity compared to magnifier users who hold their position fixed while moving low information density content through their viewport. karl dahlke references these concerns for screen readers and braille displays, However, a blind user cannot assimilate this data at a glance, and separate the wheat from the chaff.. in magnifier mode, horizontal scroll becomes a critical design axis to consider because we can't rely on a constrained viewport.

the impulse of sense data is different for screen readers and magnifiers. respectively, one is audible and the other is visual. despite these difference, both technologies present low density serial input modes. they require us to consider information density as another critical design axis; we are looking for something not too dense or fluffy, but just right. developer and designer karl dahlke recommends a design space that distributes responsibility to authors and application developers to consider that:

Output is measured and conserved like a precious commodity as it passes through the narrow channel of speech or braille.

designing for magnifiers appends the now channel of low vision to this concern. design considerations for magnifiers:

• viewports that don't consider horizontal scrolling require magnifier visitors to track back and forth across the width of the screen. this experience can be nauseating and difficult to process for those with low literacies. should we use lone single lines?
• don't use columns
• how do dialog effect the magnifier experience?
• test magnifier with big text
• authoring recommendations

At the end of the day the visual accessibility of a page is determined by the author more than the browser. The more content that he or she tries to squeeze onto a single page the harder it is going to be for many people with low vision to access.

Magnification of Web Pages

 

• How to make your site accessible for screen magnifiers
• How to Make Your Website Accessible to People Who Use a Screen Magnifier
• Magnification of Web Pages