The rapid advances in information retrieval, especially with visualisation-oriented user interface design, highlight the need for an understanding of the interplay between cognitive abilities of users and the design of visual user interfaces. In this study, we focus on two aspects of memory abilities of users in attempts to reveal their roles in facilitating information-seeking tasks. In particular, we study the relationships between associative memory and the use of a spatial user interface, and the relationship between visual memory and the same user interface. The design of the spatial user interface draws upon information visualisation techniques in order to highlight the strongest semantic relations in the search space. Two retrieval tasks were performed. While associative memory was strongly correlated with the first task, visual memory was negatively correlated with the second task. Both correlations were statistically significant. Implications for user interface design and suggestions for further empirical studies are also discussed.