AbstractÐThis paper examines and proposes an approach to writing software specifications, based on research in systems theory, cognitive psychology, and human-machine interaction. The goal is to provide specifications that support human problem solving and the tasks that humans must perform in software development and evolution. A type of specification, called intent specifications, is constructed upon this underlying foundation. Index TermsÐRequirements, requirements specification, safety-critical software, software evolution, human-centered specifications, means-ends hierarchy, cognitive engineering.

Web page loading speed continues to vex users, even as broadband adoption continues to increase. Several studies have addressed delays both in the context of web sites as well as interactive corporate systems, and a wide range of “rules of thumb ” have been recommended. Some studies conclude that response times should be allowed to grow to no greater than 2 seconds while other studies caution on delays of 12 seconds or more. One of the strongest conclusions had been that complex tasks seemed to allow longer response times. This study examined delay times of 0, 2, 4, 6, 8, 10, and 12 seconds using 196 undergraduate students in an experiment. The subjects were randomly assigned a constant delay time and were asked to complete 9 search tasks, exploring a familiar and an unfamiliar site. Plots of the dependent variables performance, attitudes, and behavioral intentions, along those delays, suggested the use of non-linear regression, and the explained variance was in the neighborhood of 2%, 5%, and 7%, respectively. Focusing only on the familiar site, explained variance in attitudes and behavioral intentions grew to about 16%. A sensitivity analysis implies that decreases in

Web page loading speed continues to vex users, even as broadband adoption continues to increase. Several studies have addressed delays both in the context of web sites as well as interactive corporate systems, and a wide range of “rules of thumb ” have been recommended. Some studies conclude that response times should be allowed to grow to no greater than 2 seconds while other studies caution on delays of 12 seconds or more. One of the strongest conclusions had been that complex tasks seemed to allow longer response times. This study examined delay times of 0, 2, 4, 6, 8, 10, and 12 seconds using 196 undergraduate students in an experiment. The subjects were randomly assigned a constant delay time and were asked to complete 9 search tasks, exploring a familiar and an unfamiliar site. Plots of the dependent variables performance, attitudes, and behavioral intentions, along those delays, suggested the use of non-linear regression, and the explained variance was in the neighborhood of 2%, 5%, and 7%, respectively. Focusing only on the familiar site, explained variance in attitudes and behavioral intentions grew to about 16%. A sensitivity analysis implies that decreases in

J; plants has been faced with complex human factors problems. In conventional control rooms the arrangement of meters, recorders,and control keys on the control desk, and the choice of properly designed knobs and dials are the chief objectives for human factors con;-; i dera t Ion • The advent of computer-control led display systems with the variety

this paper describes some of the unique features of SpecTRM that differentiate it from other system engineering tools and environments.