David Large, University of Nottingham
Interface designers often group semantically or functionally related content together and use visual grouping cues, such as delineating or segregating clusters of objects, to communicate the semantic structure. Such techniques have been shown to reduce visual search time and improve interface learning and usability in a sedentary context. We explore whether similar grouping techniques influence visual demand when interacting with an in-vehicle touchscreen HMI while driving. Sixteen participants were asked to repeatedly locate and select target icons from within an array of 36 items, arranged in a 6×6 matrix, while driving in a simulator. Test interfaces comprised 1, 3, 4, 6 and 9 groups, containing 36, 12, 9, 6 and 4 items, respectively, with items clustered using either perceptual cues (delineation between groups) or cognitive association (based on common, culturally-relevant groupings, such as animals, musical instruments, food etc.), or a combination of both: the order of presentation was counterbalanced between participants to avoid learning effects.