Design & Evaluation of Layout-Agnostic Tactile Guides for In-Vehicle Touchscreens

Touchscreens are commonly used to provide access to a wide range of vehicle functions. However, interacting with touchscreens can require more attention than physical controls due to their lack of tactile sensation, potentially causing driver distraction. Prior research has indicated that stencils overlays mounted on a touchscreen can ease these problems. However, the previous stencils studies used holes that were cut to the size and location of underlying interface controls, meaning that they could only be used with a single interface layout, which is unrealistic for typical in-vehicle use. In this paper, we examine the use of layout agnostic stencils that can be used with different user interface layouts, with the aim of reducing visual attention on the touchscreen while driving. We conducted an experiment in which two layout agnostic stencil designs were evaluated in comparison to a normal touchscreen during simulated driving. Contrary to our intention, the new stencil designs increased attentional demands and impaired driving performance compared to the normal touchscreen. To understand the causes of this failure, we developed a framework for understanding low-level human activities while interacting with in-vehicle controls. The framework suggests the need for improved understanding of the acuity of the human proprioceptive target approach and of the human ability to discriminate between tactile objects.