User-hostile systems and patterns of psychophysiological activity

摘要

Psychophysiological measures, which are not contaminated by demand characteristics, are potentially useful for improving systems and for examining psychological processes in human—computer interaction. In this study we report the use of minute-by-minute scored heart-rate (HR) and skinconductance level (SCL) in a 25-subject experiment. Each subject was presented with two simulated bank-transaction tasks, one user-friendly and the other userhostile. To check whether any differences were due simply to sheer difficulty, easy (forward digit-span) and hard (backward digit-span) memory tasks were presented to all subjects. The HR was higher during the computer (problem-solving) tasks than the memory tasks, but was unaffected by task difficulty, whereas SCL was uniquely elevated during the hard (user-hostile) computer task. The HR result is interpreted as reflecting parasympathetic withdrawal, while the SCL result suggests that the user-hostile software produced sympathetic excitation of the sort associated with the fight-or-flight reaction. SCL may serve as a good measure of user-friendliness.