TOWARDS REAL-TIME GOMS - A MODEL OF EXPERT BEHAVIOR IN A HIGHLY INTERACTIVE TASK

We present an analysis of an expert performing a highly interactive co mputer task. The analysis uses GOMS models, specifying the Goals, Oper ators, Methods, and Selection rules used by the expert. Two models are presented, one with function-level1 operators which perform high-leve l functions in the domain, and one with keystroke-level operators whic h describe hand movements. For a segment of behaviour in which the exp ert accomplished about 30 functions in about 30 s, the function-level model predicted the observed behaviour well, while the keystroke-level model predicted only about half of the observed hand movements. These results, including the discrepancy between the models, are discussed.