Handbook of Human-Computer Interaction || Mental Models in Human-Computer Interaction11This chapter appeared in its entirety and is reprinted from Mental Models in Human Computer Interaction: Research Issues about What the User of Software Knows, J.M. Carroll and J.R. Olson, Editors,-The report of the workshop on software human factors: Users mental models, Nancy Anderson, chair, sponsored by the Committee on Human Factors, Commission on Behavioral and Social Sciences and Education, National Research Council, published by the National Academy Press, 1987