The theory of Gestalt was proposed in the nineteenth century to explain and predict the way that people perceptually group visual elements, and it has been used to develop guidelines for designing visual computer interfaces. In this thesis we seek to extend the use of Gestalt principles to the design of haptic and visual-haptic displays. The thesis begins with a survey of Gestalt research into visual, auditory and haptic perception. From this survey the five most commonly found principles are identified as figure-ground, continuation, closure, similarity and proximity. This thesis examines the proposition that these five principles can be applied to the design of haptic interfaces. Four experiments investigate whether Gestalt principles of figure-ground, continuation, closure, similarity and proximity are applicable in the same way when people group elements either through their visual (by colour) or haptic (by texture) sense. The results indicate significant correspondence between visual and haptic grouping. A set of haptic design guidelines for haptic displays are developed from the experiments. This allows us to use the Gestalt principles to organise a Gestalt-Taxonomy of specific guidelines for designing haptic displays. The Gestalt-Taxonomy has been used to develop new haptic design guidelines for information displays.