INDUCING PROCEDURES INTERACTIVELY ADVENTURES WITH METAMOUSE

Abstract

Direct manipulation interfaces have greatly extended the class of casual computer users and encouraged them to conceptualize the system through metaphors. They have not, however, successfully incorporated facilities for end-user programming without breaking out of the direct manipulation paridigm. This thesis supports the contention that "teaching" provides an appropriate metaphor for programming in such an environment. It presents a system for inducing procedures that enables users of a graphics editor to teach it routine tasks by working through example traces. A central problem in the design is to meet the requirements for instructibility without imposing excessive demands on the teacher. A key component of the system is its teaching metaphor, a graphical apprentice called Metamouse. Metamouse is the target of the teacher's demonstrations. It is an eager learner designed to encourage constructive methods, clarify ambiguous situations, reduce errors and extraneous activity, and discourage free variation in teaching. Its behaviour is expected to be understood by users at a metaphorical, intentional level rather than from a precise specification. Metamouse has been fully designed but not yet fully implemented. However, a pilot system has induced procedures with variables, generalized actions, conditional branches and loops. Its ability to reduce errors and extraneous activity by prediction, and to identify underspecification, has been demonstrated. Tests showed that the metaphor is easily understood. Consequently the thesis argues that it is feasible for a system to induce procedures interactively from casual users. This significantly broadens the scope of application of machine learning techniques and opens new areas of research in knowledge acquisition. It facilitates the investigation of intelligent user interfaces and, last but not least, benefits the many users of interactive graphics systems.