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Aminat Adebiyi, Shadi Bohlool, Mort Arditti, James D Weiland; Tactile output as a method for communicating with the visually impaired in mobility.. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4144.
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© ARVO (1962-2015); The Authors (2016-present)
This study evaluated the ability of blind subjects to navigate complex routes when guided with vibrotactile commands.
The tactile feedback system consists of six vibration motors that are attached to individual points on a subject’s upper torso through a vest. The motors are connected to a push-button microcontroller system that delivers commands to the subject when the researcher presses a button that activates the corresponding motor(s). Eight navigational commands are encoded into the six-motor array, including, ‘forward’, ‘veer left’, ‘approaching left turn’, ‘turn left’, ‘veer right’, ‘approaching right turn’, turn right’ and ‘stop’. For example, ‘approaching left turn’ is coded as a single pulse of a motor, whereas ‘turn left’ is coded as two pulses of the same motor. Ten low-vision subjects were recruited from the Braille Institute, Los Angeles. Wearing the tactile feedback system, subjects were guided through indoor and outdoor courses. As a control, the subject navigated the same course using a cane for guidance. Appropriate response to commands, time to complete a trial, and reaction time were measured. Subjects were also given an exit survey that measured the usability of the feedback system. A parallel LED-array allowed alignment of a given command to video footage recorded for each trial.
Using tactile commands, subjects displayed responses consistent with 82.46% of commands and an average reaction time of 1.46 seconds. Subjects also completed routes faster than with their cane alone (p = 0.04). When using the device, subjects complained that encoding multiple commands on a single motor affected their ability to successfully comply with commands, probably stemming from a cognitive dissonance effect. They also preferred that the motors were placed closer to their skin. The device was rated 76% usable with subjects enthusiastic for its use as a street crossing guide.
The tactile feedback system shows promise as an alternative to verbal-assist devices as means of communicating important information to users for mobility. However, optimal motor positioning and command encoding need to be investigated further to maximize its benefit.
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