Efficiency in work behaviour: A design approach for modern tools

The central theme of this book is the improvement of modern work tools, such as personal computers. It is argued that Frederick Taylor's approach, based on 'time and motion' studies, is no longer valid. The psychological processes that regulate human work behaviour are not observable and were therefore not taken into account in Taylor's approach. This point is extra relevant to 'cognitive' work tools which require predominantly cognitive operations.

In this study the validity of the Action Facilitation Approach (AFA) is examined. The AFA is an approach to interface design and consists of (1) a set of principles of human action, that serve as a psychological model of the worker, (2) a set of guidelines, based on these principles of human action, that indicate dimensions of support and (3) a set of interface design recommendations that serves to operationalize each of the support dimensions. It is hypothesized that implementation of these design guidelines will lead to 'action facilitation'. Action facilitation refers to supporting the worker to carry out his task and is operationalized as improvement or maintenance of performance at lower individual costs. This should result in users carrying out their tasks more efficiently.

In the first part of the study the concept of 'psychological efficiency' is discussed and elaborated. Furthermore a rating scale to measure mental effort (Rating Scale Mental Effort), as an operationalization of 'psychological costs', is developed and its psychometric qualities are examined. The scale proves to be a valid and reliable indicator of mental effort and appears to be very sensitive to changes in task load, psychophysiological state of the person, and time-on-task.

In a second study an (experimental) interface evaluation study was carried out, in which two word processors were compared. The results demonstrated that the word processor which was judged to be more in line with the AFA, allowed subjects to complete their task in shorter time and/or with less effort and thus more efficiently. This result is regarded to be supportive evidence with respect to the validity of the AFA.