Tesla Model 3: Impact of Vertical Segmentation on Visual Search Time

Automotive industries are implementing high-end technology with minimalistic design and advancing rapidly. Tesla Model 3 is among those automobiles replaced physical knobs with fully functional touchscreen screens to enhance the minimal interior aesthetic. All the in-vehicle touchscreen interaction requires visual attention allocation between driving and touchscreen interaction resulting in drivers' divided attention posing a hazard or risk to the driver's safety. This research aims to assess the impact of the vertical grid design of the Tesla Model 3 infotainment system on visual search time while multitasking. For comparison, a horizontal grid design was prototyped to see the difference in visual search time between vertical and horizontal grid designs. Task success rate, the number of incorrect searches, reaction time for search, and subjective measures were considered to assess the dimension of efficiency and satisfaction. Eleven novice participants performed visual search tasks and answered follow-up questions based upon the task experience. Visual search task was designed using Psycho-Py and to collect real-time data Pavlovia.org online platform was used to run the experiment. Each trial in the visual search tasks starts with a red color fixation cross presented on a grey background lasting on-screen for 500 milliseconds. This fixation cross was followed by an on-road driving video that contains a question presented on the top-center of the video display. An image of the infotainment system appears at the bottom right corner of the screen at different time stamps lasting for 2 seconds. When a participant presses the right or left key based on the response, the video automatically terminates. This is followed by a two-response window, one after the other; the first response window where the participant must type the visual searched target answer asked during the video. In the second response window, the participant must typecast the total number of cars counted. A fixation cross appears again for 500 milliseconds indicating to participants that the subsequent trial will begin after this. After task completion, follow-up questions were asked. The purpose of asking follow-up questions was to understand the frustrations and difficulty experienced by the participants while searching target on the infotainment screen. A mixture of quantitative and qualitative data was gathered to assess the goals of efficiency and satisfaction. The result indicates that task success rate or target miss rate, and incorrect task response are high in the vertical grid design of the Tesla Model 3 infotainment system. Visual search time for vertical grid conditions was significantly higher than the NHTSA guideline. The results showed that the horizontal grid design strategy leads to a better target visual search user experience. The study concludes that the Tesla Model 3 infotainment system lacks discoverability, goal-based design, affordance, visual momentum, mode awareness, and consistency with the user's mental model. A robust design is required to achieve the crucial information search without leading the driver to a high risk of causing adverse consequences due to interface design. This research was conducted and submitted to the faculty of the graduate program in Human Factors/ Ergonomics for the partial fulfillment of the requirements for the Degree Master of Science.Keywords: visual attention, NHTSA guideline, discoverability, affordance, visual momentum, mode awareness, mental model