93 Colour Coding of Information Layers in Computer Displays Darren Van Laar*, Terry Williams*, Ian Umbers t & Steve Smeaton t *Department of Psychology University of Portsmouth Portsmouth PO 1 2ER UNITED KINGDOM vanlaard@psyc.port.ac.uk tComputing Systems and MMI Group Nuclear Electric PLC Barnett Way, Barnwood Gloucester GU 7RS UNITED KINGDOM ABSTRACT A method is reported which enables designers to analyse computer displayed information into a task hierarchy, and then allocate sets of colour codes to reflect this information structure. These sets of colours are derived from principles of cartography and colour science, and give rise to the impression of layers of information, where elements of the display most relevant to the task appears more conspicuous and nearer to the user than less task relevant information. The application of this method to typical control room displays is described. KEYWORDS interface design, cartography, colour coding, colour displays, design 1. INTRODUCTION The nature of good interface design lies in the effective communication of information that is directly relevant to the completion of a user's task. Previous work in cartography has advocated the use of conceptual layers as a means to organise task relevant data elements on a map or display (Wood, 1968). Although such an approach has proved its worth in cartography, much cartographic design pays little attention to principles of colour science and often leads to inadequate map design (Taylor, 1984). More recently, this approach has been applied to computer based air-traffic control displays with good initial results (Reynolds, 1994). Besides maps or schematic representations it may be possible to use colour science based cartographic principles to design alphanumeric, tabular or graphical displays of the type typically found in industrial or emergency control rooms. This paper offers a method of producing hierarchical visual effects on control room computer displays. A set of palettes for producing the perceptual effect of layers of information has been identified, and a method of application developed. 2. AIMS AND OBJECTIVES Nuclear power station control room displays in the UK are predominately monochrome, green on black or yellow on black. A methodology for colour coding using 24-bit colour displays was required by the Nuclear Industry with the following objectives: • To provide the designer with a set of colours with which to code display formats according to current psychological principles and standards governing the perception of colour from emissive displays. • Such colour sets should offer a way of visually emphasizing task relevant information. • The entire set of colours should be dividable into smaller sets that will correspond to a series of information layers allocated by the designer according to task relevance. Human-Computer Interaction: INTERACT'97 S. Howard, J. Hammond & G. Lindgaard (editors) Published by Chapman & Hall ©IFIP 1997