Jouni Huotari, Kalle Lyytinen, Marketta Niemelä
We studied the impact of large screens and of two promising visual integration techniques, elision and connecting lines, which can decrease the cognitive efforts of designers to read diagrams. We conducted a laboratory experiment using 84 computer-science students to investigate the impact of these techniques on the accuracy of the subjects' search and recall with entity-relationship diagrams and data flow diagrams. Both vertical and horizontal searches were conducted on a moderately complex information system model that consists of multiple diagrams. We also examined the subjects' spatial visualization abilities as a possible covariant for observed search performance. The visual integration techniques significantly reduced errors in both the search and the recall of diagrams, especially for individuals with low spatial visualization ability.
The results show that paying attention to the visual aspects of diagrams can improve their readability, especially with subjects who have low spatial visualization ability. We believe that the findings are important because issues on dataflow and entity-relationship diagrams can be transferred to any diagramming techniques that share similar features. One promising target is the improvement of Unified Modeling Language (UML), which includes complex relationships between diagrams. For practicing designers, our study suggests several ways in which error rates in design activities can be decreased. They suggest that the use of larger screens is consistently better than the use of small separate diagrams, thus lending support to the use of techniques such as Joint Application Development (JAD). Moreover, the impact of such large screens can be amplified by using advanced visualization techniques. Finally, we should approach the use of 3-D representations with caution in abstract domains until we can create effective ways to map semantics into 3-D space and rendering techniques. Our message to Computer-Aided Software Engineering (CASE) tool vendors is that they should seriously consider providing improved linking and visualization support in CASE tools that help search design repositories through customizable, interactive task windows. The tools should also provide adequate intelligence to automatically arrange large layouts that reduce the number of crossing lines or hide links. Similar integration and dispersion problems also naturally exist in other domains. Therefore, in the end, all users that rely on visual representations in their cognitive tasks would benefit from better tools with advanced visualization techniques.
Overall, this is one of the first experimental studies that evaluates the impact of visual integrations methods, which help IS designers and other stakeholders understand complex graphical specifications. This is surprising given that these representations have been deployed widely for 20 years in IS design tasks. The cognitive foundations of searching information across multiple diagrams and representations are largely unstudied. This experiment is one step toward developing and deploying design tools that address better the cognitive needs of IS designers through more powerful diagram displays.
Case Western Reserve University
University of Jyväskylä
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