User adaptation in user-system-interaction

Abstract

1 The assumption that users act as if their behaviour is controlled by a self-regulatory system (Carver and Scheier, 1998) is applied to user-system interaction. The self-regulatory system is specified as a feedback control mechanism consisting of monitoring, evaluation and action adjustment mechanisms. Two experiments were carried out to test whether perception processes take care of monitoring, and whether evaluation, based on a comparison of the results of monitoring with reference values, gives an indicator of the adequacy of the interaction. In these experiments a typical system property, time-delay, was manipulated. In a first experiment, the relationship between the estimated task duration and the actual time-totask-completion were studied. These findings were replicated in a second experiment. The consistent findings support the idea that perception processes, interpreted as a monitoring mechanism, can keep track of physical task-time. A monotonic, positive relationship was found between the time-to-task-completion and the user satisfaction, which supports the assumption that objective efficiency influences the evaluation of interaction. A linear relationship between the estimated duration and user satisfaction indicates that the monitoring mechanism transforms physical signals into a format that can be used in the evaluation process. An increased variability in time-delay negatively influenced user satisfaction. In the second experiment the variability of time-delay is investigated further by offering specific patterns of variations of time-delay to the participants. With the same variability, some patterns received higher satisfaction scores, indicating that patterns influence satisfaction by changing the internal reference frame of the evaluation mechanism. 1 Part of this research has been published as Fischer and Blommaert, 2001.