Effects of Pressure and Vibration Stimuli on the Usability of Human-Machine Systems

Abstract

Users’ information processing during human-machine interaction can be supported by redundant or additional tactile information, especially in situations of visual information overload or impaired visual perception. The present work is meant to describe basic thoughts on tactile semantics, the development of a variable tactile belt with 8 actuator units as well as first results of comparative studies of pressure and vibration stimuli, separately and in addition to visual perception. The examinations were conducted with 25 subjects. Spatial recognition rate and response time were recorded for pressure, vibration and visual stimuli presentation as well as all combinations of these. For purely tactile perception (pressure and vibration) reduced recognition rates occur at the sides of the waist, decreasing to approximately 80 %. Response times for discrete presentation of information via pressure or vibration were longer than for visual presentation but shorter response times of the visual presentation could almost be achieved purely tactile by the combination of pressure and vibration. The significantly shortest response times were detected for the combinations of visual + pressure + vibration and visual + pressure, revealing the potential of pressure stimuli for human-machine interaction. According to the 8 presented directions around the body, the shortest response times for tactile stimuli were detected for the actuator unit on the back. Furthermore, the article deals with subjects’ estimations about their performances, distribution of input errors as well as different stimuli durations. The findings confirm expected advantages of visual-tactile information presentation in human-machine systems. Visual perception leads to high accuracy while additional tactile stimuli reduce response times. Especially pressure stimuli seem to have slight advantages compared to vibration stimuli in terms of response times. The combination of pressure and vibration stimuli even leads to response times similar to visual presentation. As a conclusion, the potential of pressure stimuli could be shown to enhance future design of visual-tactile interfaces. In the long term, guidelines for tactile semantics are supposed to be derived.