There are many books that provide 'guidelines' for designing interfaces - some tell you how and when to use different colours and typefaces, how to format columns and tables, and how to make your designs aesthetically appealing. This is not one of those books.
Although they provide a valuable service, and sometimes also try to explain why they are providing the advice that they do, guidelines are intended to be prescriptive - telling you what you should do for each part of an interface. You can follow all of the advice that they provide for every individual part of your interface, and still find that you produce a design that is not 'easy to use'. Books of guidelines cannot tell you how to decide for yourself whether an interface will be usable, nor how to identify the problematic parts of the design so that you can improve them. That is what this Guide tries to do.
It will introduce you to some psychological ideas about perception and cognition - the processes by which people see objects in the world, recognise them, search between them, and use them to reach their goals. The techniques this Guide teaches you will let you decide how difficult it will be for people to group objects together, to tell objects apart, to search for objects, and to switch their attention from one part of the display to another. You don't need to be a psychologist to read this Guide, but when you have read it, you should be able to use these ideas to analyse your interface designs.
May, J. & Barnard, P.J. (1997) Modelling multimodal Interaction: A theory-based technique for design analysis and support. In S. Howard, J. Hammond & G. Lindegaard (eds) Human-Computer Interaction INTERACT '97. Chapman & Hall: London. pp 667-668.
Jørgensen, A. & May, J. (1997) Evaluation of a Theory-Based Display Guide. In Proceedings of HCI International 97.
prepared by Jon May on October 9th 1997