【正文】 er, their attractiveness and the user?s behaviour, all need to be considered. As such, the design of products or interactive systems should take three levels of processing into account: – visceral design, which refers primarily to the initial impact of products and systems due to their appearance。), the magentas (280176。) yellow (60176。), and three in the other (180176。) and grey (3176。), blue (220176。). Two of the blues are in one cluster (200176。). The orangereds (0– 40176。. This allowed us to define 18 values for hue (., 18 colours), to which we added white, black and three nuances of grey (see Fig. 3). In this way, we were able to create 23 homepages. Participants accessed these pages by logging onto the experimental site, which provided them with the homepages and allowed them to answer questions (see 167。).We then point out the relationships between aesthetic feelings and users? judgments (167。 3 – behavioural design, which is about the experience of using a product or system (the “l(fā)ook and feel” ) and which contributes to its usability。, 340176。) and blue (180176。, 240176。). The judgments expressed by the users and designers about these selected colours (see Fig. 5) were pared by means of Mann– Whitney tests (between users and designers), and of Friedman ANOVAs (within colours for users and for designers) followed by nonparametric pairwise parisons (Wilcoxon paired sample test). The mean scores given to homepage colours by the professional designers were lower than those given by the users for the green (Mann– Whitney test, U = , p .01), the blue (U = , p .01), and the magenta (U = , p .001), and higher for the grey (U = , p .01). The difference was not significant for the orange (U = 683, p .10). The analysis of user data revealed a main effect of colour, Friedman chi2(4) = , p .001. Blue was preferred to all other colours (all z = .001). By contrast, grey was significantly less appreciated than all the other colours (all z .01), except for green (marginal significance。), green (120176。 and 40176。, 4176。 “Experimental material”). As the 23 resulting versions of this homepage differed only in respect of colour, there was no confounding influence of Webpage structure or balance. In addition, we wished to determine whether the status of participants had an impact on the colours they judged to be therefore distinguished between two kinds of participants: Website users and designers. According to Norman [1], the designer?s model and the user?s model are broadly dissimilar due to differences in background and experience. These differences help to explain the difficulties encountered by users when they try to use a newly designed system. However, in the case of judgments about colours, it is surely possible to argue that preferences mainly depend on the feelings that colours convey, and these may be similar regardless of the participants? status. However, although we expected some of the preferences expressed by Website designers and users to be consensual, the former might also regard colours conveying an “ambiance” of novelty as appealing, as designers try to e up with products that are creative and therefore different from existing ones [9,62]. In contrast, users would favour external consistency and would thus prefer colours that matched the ones they were used to seeing in the Websites they visited. Therefore, it should be possible to identify colours that were preferred by both designers and users, as well as colours that were preferred solely by designers or by users. Experimental material In order to identify participants? preferences across a broad spectrum of colours, 23 versions of the same Web homepage weredeveloped by using Photoshop software (see examples in Fig. 1). This homepage was the first page of an informational site called “PsychAix”, which is intended to provide information about university courses and leisure activities to prospective students applying to a French university (cf. study 2 for details). When designing the different versions of the homepage, we took into account the fact that colours can be defined with regard to three dimensions: hue, value and chroma (see Fig. 2). As our study was about colour preferences, value and chroma were controlled, and only hue differed from one homepage to another. To select the colours of our homepages, we created pages with a constant physical difference in hue of 20176。 – determining whether some colours favour Website visitors? navigation and cognitive processes. To this end, we carried out two experimental studies. The first one investigated the preferences expressed by designers and users when they were shown Website homepages in 23 different colours. The second one analyzed how the use of three different colours (selected on the basis of the results from the first study) in Website design influenced interactions between visitors and three different versions of the same Website. We argued that the role of colours is essential not only when accessing a site and navigating it, but also after the actual interaction has e to an end and users exploit the information they have just obtained from the site. Before describing these studies, we present their theoretical framework, in order to underline both the importance of perceptual and aesthetic features (., colours) in terms of the affects or emotions they convey, and their influence on users?interactions with systems. 2 Emotions, aesthetics and colours For years, researchers showed little or no interest in the possible links between emotion and cognition, and between usability and users? emotions and aesthetic feelings. Only recently have they sought to draw these different threads together. We therefore begin by briefly characterizing emotions and their relationship with cognition, as well as their implications for product design (