Centralizing Bias and the Vibrotactile Funneling Illusion on the Forehead

This paper provides a novel psychophysical investigation of head-mounted vibrotactile interfaces for sensory augmentation. A 1-by-7 headband vibrotactile display was used to provide stimuli on each participant's forehead. Experiment I investigated the ability to identify the location of a vibrotactile stimulus presented to a single tactor in the display; results indicated that localization error is uniform but biased towards the forehead midline. In Experiment II, two tactors were activated simultaneously, and participants were asked to indicate whether they experienced one or two stimulus locations. Participants reported the funneling illusion-experiencing one stimulus when two tactors were activated-mainly for the shortest inter-tactor difference. We discuss the significance of these results for the design of head-mounted vibrotactile displays and in relation to research on localization and funneling on different body surfaces.