6. Discussion
Our investigation on three work design elements of user interfaces in CPPS let to results according to our expectations. The factors tend to have different effects on the response variables. While there are just no or very small effects caused by “assistance” and “illustration”, we received more noticeable effects due to the “feedback” factor. We assume that this outcome can be explained by the setup of the experiment.
First, the participants spent the majority of the time working on the scheduling problem on the task page. Since the illustration was on the previous page (task description page), the participants did not look at them intensely. Consequently, the “illustration” design element did not result in a significant effect on both the work performance and work perception. This explanation approach could be confirmed by remarks of the participants after the experiments. Further, the “assistance” element could have been affected by error messages on the task page. The participants received error messages when placing job parts wrongly on the scheduling chart (e.g. on already occupied machines, wrong machines, etc.). This way, they always got another type of assistance even if the investigated “assistance” factor was turned off.
