Evaluating the Visual Syntax of UML: An Analysis of the Cognitive Effectiveness of the UMLFamily of Diagrams

Daniel Moody, Jos van Hillegersberg

    Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

    81 Citations (Scopus)


    UML is a visual language. However surprisingly, there has been very little attention in either research or practice to the visual notations used in UML. Both academic analyses and official revisions to the standard have focused almost exclusively on semantic issues, with little debate about the visual syntax. We believe this is a major oversight and that as a result, UML’s visual development is lagging behind its semantic development. The lack of attention to visual aspects is surprising given that the form of visual representations is known to have an equal if not greater effect on understanding and problem solving performance than their content. The UML visual notations were developed in a bottom-up manner, by reusing and synthesising existing notations, with choice of graphical conventions based on expert consensus. We argue that this is an inappropriate basis for making visual representation decisions and they should be based on theory and empirical evidence about cognitive effectiveness. This paper evaluates the visual syntax of UML using a set of evidence-based principles for designing cognitively effective visual notations. The analysis reveals some serious design flaws in the UML visual notations together with practical recommendations for fixing them.
    Original languageEnglish
    Title of host publicationSoftware Language Engineering
    Subtitle of host publicationFirst International Conference, SLE 2008, Toulouse, France, September 29-30, 2008. Revised Selected Papers
    EditorsDragan Gašević, Ralf Lämmel, Eric van Wyk
    Place of PublicationBerlin, Heidelberg
    ISBN (Electronic)978-3-642-00434-6
    ISBN (Print)978-3-642-00433-9
    Publication statusPublished - 2009
    Event1st International Conference on Software Language Engineering, SLE 2008 - Toulouse, France
    Duration: 29 Sep 200830 Sep 2008
    Conference number: 1

    Publication series

    NameLecture Notes in Computer Science
    ISSN (Print)0302-9743
    ISSN (Electronic)1611-3349


    Conference1st International Conference on Software Language Engineering, SLE 2008
    Abbreviated titleSLE
    Internet address


    • Unify modelling language
    • Class diagram
    • Visual variable
    • Graphic complexity
    • Redundant ode

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