The role of individual differences and metaphor in hypermedia navigation

Research and practice within interaction design are often based on the assumption that computer interfaces are understood through metaphorical reasoning, in that they communicate abstract information by depicting) a concrete object or situation from which the abstractions can be inferred. Within hypertext systems, metaphors are used to assist in navigating, or locating information, by providing a familiar frame of reference. This research is concerned with the psychological processes underlying the utilisation of interface metaphors. It aims to examine the value of prior knowledge and spatial properties of metaphor source domains in supporting hypertext navigation tasks, and how these relate to task and user characteristics. These issues are investigated through a series of eight studies. The first three studies examine constructs and measurements of individual differences (cognitive style, experience, confidence, and visuospatial ability). The remaining ones are experiments measuring the direct effects metaphor spatiality and familiarity, and interactions between metaphor and: task phase (search and retrieval); hyperlink structure; and exposure type (active and passive). Performance and behaviour is measured in terms of length and structure of navigation patterns, accuracy of mental representations, and self-reported disorientation. The experimental tasks are carried out using simple hypertext structures representing the different metaphors. The results show that type of metaphor does affect performance and behaviour on a general level. It is found that the familiarity of a metaphor source domain is of great importance for users’ ability to form mental representations of a hypertext structure. Furthermore, the influence of metaphor is greatest when it is based on a prototypical domain. The influence of metaphor on performance and behaviour is stronger than that of individual differences among users. From a theoretical point of view, the findings indicate that the extent to which users benefit from interface metaphors is predominantly based on top-down processing. Users are relying more on schematic representations of prior knowledge than on immediate perceptual information. From a practical point of view, this research implies that fewer geometric or spatial constraints may be applied when choosing appropriate source domains for interface metaphors. It also suggests that when provided with a familiar source domain, individual cognitive abilities are of less importance than what has been proposed within previous user-centred design literature.