Elderly people seem to encounter more problems than people from other age groups do, when using consumer electronics products and their accompanying manuals. This may be due to the absence of some kinds of information. In this study the effects of the absence of different information types in instructions on action performance were explored for different age groups. Younger (aged 20–30 y.) and elderly (aged 60–70 y.) participants installed a VCR with the help of the manual, while working aloud. The absence of goal information, consequence information and identification information in the instructions proved to have a negative effect on task performance, especially for the elderly participants. When one of these information types was missing in the instructions, the elderly performed more actions incorrectly than when the information was stated explicitly.

The quality of technical documents often depends on the way in which spatial information is expressed. The coherent processing of installation procedures, route directions, maintenance instructions, and many other technical documents often implies the construction of an almost literal mental space within which instructions have to be executed. Visuals are certainly a powerful tool in expressing instructive space, but text remains indispensable and even dominant. The article focuses on verbal spatial expressions in instructions in which text and visuals are combined. The first part provides the reader with an overview of the problems associated with putting the instructive space into language, In the second part, we report the setup and results of an experiment in which the preference for two basic types of spatial expressions is investigated: user-oriented descriptions (e.g., pull the handle to the right) versus functional descriptions (e.g., push the start switch toward the tone button). The results show an overall preference for producing functional descriptions, but also a higher degree of acceptability for user-oriented descriptions if the user-oriented perspective is explicitly expressed in text.

This article discusses the adequacy of two modes of presenting information on a computer screen, i.e., the alternating screen presentation in which information is presented “screen by screen” and the simultaneous screen presentation that shows different sources of information simultaneously on the same screen. Using a simultaneous or an alternating screen presentation, subjects had to perform short writing tasks, half of which required the use of one on-line document, the other half required two documents. The subjects' task performance as well as their appreciation of the task and the presentation mode were measured. The results show that performance and appreciation data do not run parallel. While all subjects clearly prefer a simultaneous mode of presenting information on the screen, performance data are much more varied and less clear cut: when reading, subjects performed significantly better in the alternating mode; when producing a text, subjects slightly benefited from simultaneous screens.