From Paper to Computer Screen

Human Information-Processing and User Interface Design

Else Nygren

Nygren, E., 1996. From paper to computer screen. Human information processing and user interface design. Acta Univ. Ups., Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 188.31 pp. Uppsala. ISBN 91-554-3699-4.

Abstract

How should data be presented on a computer screen so that the average search time for extracting relevant information is minimized? This question is of central interest, especially when designing user interfaces for computer support systems for frequent professional use.

In three field studies of information use in work situations, it was observed that experienced users had learned a repertoire of skills that was used in the task of extracting information from a display. One such skill was to recognize variations in figural patterns in the displays that were correlated to variations in the content. Recognition of such patterns reduced the need for ordinary reading and resulted in fast and efficient visual interpretation.

To investigate these observations in a controlled laboratory setting, an experimental environment was constructed. In a series of five experiments, the average search time was assessed as a function of presentation format. The test subjects were allowed to train to achieve skilled performance. They were considered skilled when no further decline in search time could be observed. We found that the subjects, regardless of instruction, learned to recognize feature patterns, figural patterns, probability patterns, positional patterns and combinations of these. The search time was significantly less than in the corresponding control conditions in which the informational content was the same but no patterns were present in the displays.

Based on the results of the five experiments, a mathematical model for prediction of the required search time for a certain class of display layouts was formulated. The model was validated by application to 41 display layouts described in the literature. Comparison of predicted and observed search time data showed that the model explained 94% of the variance. The model was used to analyze the relative efficiency of different principles for presenting information on a display. The results indicate that the most effective design principles are those that use the peripheral visual system to limit search space; feature highlights, informative patterns and positional constancy. Less effective principles are those that require extensive use of the foveal visual system, especially multiple groups of horizontally aligned items.

The guidelines for design, predicted by the model, have been used in the design of prototypical user interfaces for reading medical records from a computer screen, and for the design of an information system for car manufacturing.

Summary

HTML ()
Else Nygren, CMD, Uppsala University, Lägerhyddvägen 18, S-752 37 Uppsala, Sweden