Michael E Atwood

A process model for water jug problems

Abstract We develop and evaluate a model for the water jug task in which a subject is required to find a sequence of moves (pouring operations) which produce a specified amount of water in each jug. Experiment 1 was designed to evaluate the meansends, move selection heuristics that are assumed by the model. Experiment 2 tested the models predictions concerning those aspects of the water jug task that determine problem difficulty. A three stage process model incorporating GPS-like, means-ends heuristics and assumptions concerning the utilization of short- and long-term memory was able to account for differences across problems as well as details of the performance of subjects solving a given problem. We conclude that a GPS-like model that only selects one move at a time (no forward planning of move sequences or setting up of subgoals) can provide a good account of solution behavior in the water jug task.

A Process Model for Missionaries--Cannibals and Other River-Crossing Problems.

Abstract We extend a model originally developed by Atwood and Polson (1976) for the water jug task to four isomorphs of the Missionaries-Cannibals problem. Our results show that variation in cover story produced no differences in number of legal moves to solution, but caused large differences in illegal moves. A three-stage process model incorporating means-ends heuristics, assumptions about the utilization of memory, and an illegal move-detection process is able to account for both legal and illegal move data from all four versions of the problem.

Further explorations with a process model for water jug problems.

Subjects performed a water jug task in which the object was to find a sequence of pouring operations that would produce a specified amount of water in each jug. A model for this task is presented and evaluated. The model makes strong assumptions concerning lack of planning in the water jug task. In addition, alternative models incorporating planning assumptions were considered. Alternative models were evaluated in two experiments. All experimental conditions were successfully simulated by making reasonable and well-motivated parameter changes in our model, which assumes no planning. Further, several classes of models incorporating planning assumptions were shown to be inconsistent with the observed results.

Man-Computer Interface Design Guidance: State of the Art*

A major literature survey investigated the state of the art in human factors in computer systems. The survey was concerned both with the status of human factors research in the area of user-computer interaction and with the current state of user-computer interaction technology and practices. The principal goal of the study was to determine the feasibility of human factors guidelines for interactive computer systems, and to investigate their possible form and content. Thus, the study addressed both the state of the art in the field and the information needs and problem-solving behavior of interactive system designers, since these personnel would be the primary users of guidelines. It is concluded that insufficient data exist for the development of a “quantitative reference handbook” in this area, and that that form of presentation may not be appropriate anyway. On the other hand, a “human factors design guide” – which discusses issues, alternatives, and methods in the context of the design process – appears both feasible and needed.

Paper simulation techniques in user requirements analysis for interactive computer systems

This paper describes the use of a technique called “paper simulation” in the analysis of user requirements for interactive computer systems. In a paper simulation, the user solves problems with the aid of a “computer”, as in normal man-in-the-loop simulation. In this procedure, though, the computer does not exist, but is simulated by the experimenters. This allows simulated problem solving early in the design effort, and allows the properties and degree of structure of the system and its dialogue to be varied. The technique, and a method of analyzing the results, are illustrated with examples from a recent paper simulation exercise involving a Space Shuttle flight design task.