Visual vs. Cognitive Disabilities
http://www.webaim.org/techniques/articles/vis_vs_cog

Bohman, Paul, Shane Anderson and Sachin Pavithran
WebAIM
2003

Abstract:

Graphics are not directly accessible to people who are blind, yet graphics can be beneficial (in some cases necessary) to individuals with cognitive disabilities. Are these two disability types at odds with each other? How can Web developers reconcile the needs of these two very different audiences? Read more about the apparent conflicting interests in our feature article.