The W3C’s Web Accessibility Initiative has some good resources that specifically address Web usability / accessibility, but the same principles can be applied to design in general. This document outlines the “POUR” principles of WCAG (Web Content Accessibility Guidelines) related to web accessibility - much of which can apply to scenarios where a user has needs related to cognition, attention, and timing.

We have seen that the WCAG principles can be challenging to implement. To address this, our Infusion project has the Preferences Framework which assists content creators create more flexible content, and allows users customize the presentation. You can see a demo here: http://build.fluidproject.org/infusion/demos/prefsFramework/. The Simplify Content, Contrast modes, and the Text-to-Speech features may be useful for cognitive needs.

Other possible useful resources:

Learner Needs and Preferences - The Inclusive Learning Design Handbook
Cognitive Disabilities - WebAIM
Design for Adaptability and Flexibility - Inclusive Design Guide

Thinking beyond the standards and best practices, the needs of each person will vary from case to case. Given that each person and their context is unique, one can anticipate that providing multiple options and features would be important. For example:

Automatic saving of sessions so a user can leave and resume where they left off
Content simplification (remove ads, remove sidebars, etc.)
Options for controlling time restrictions (i.e. ability to disable inactivity logout timers, extend response durations for tests, etc.)
Thoughtful use of colour, layout, and dynamic content (like system notifications)
etc.

Other resources

Designing interfaces to meet the needs of users with cognitive disabilities - Dana Ayotte, Inclusive Design Research Centre
"Designing for ADHD: in search of guidelines" - Lorna McKnight, ChiCI Group, University of Central Lancashire
"Cognitive Disabilities and the Web" - Heather Mariger, National Centre on Disabilities and Access to Education

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