Applying spindex auditory cues while driving and performing a secondary search task

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Gable, Thomas Matthew
Walker, Bruce N.
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This thesis investigated the impact of applying “spindex” text to speech (TTS) auditory cues in a long-list searching task on a cell phone while driving as compared to a visuals-only interface. Previous research has found that when using advanced auditory cues (i.e., spindex), both participants’ visual dwell time off the road and subjective workload is lower than when using visuals-only displays. The current study expanded on previous research by investigating the impact of these cues through two factors of distraction – workload and willingness to engage – as well as investigating the use of the Visual Auditory Cognitive and Psychomotor (VACP) predictive workload scale. Previously investigated workload measures of visual behaviors, subjective workload, primary and secondary task performance, and preferences were supplemented with additional measures via physiological detection and VACP as a predictive measure of workload. The newly added factor of willingness to engage was investigated via the inclusion of two different driving difficulties (hard or easy), by modifying the roadway type (city or highway). Results support previous findings of lower workload when novice users employ the spindex-TTS cues compared to visuals-only as seen through increased dwell time on the driving task, less glance frequency off the driving task, lower subjective demand, and higher perceived performance, but no conclusive results were seen in regards to willingness to engage. In addition, the patterns of workload predictions from the VACP measure matched well with data collected during the experiment. These results and their implications for the application of spindex-TTS cues as well as the future measurement of willingness to engage and use of the VACP scale as a predictor of workload are discussed.
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