Investigating the Effect of Encumbrance on Gaze- and Touch-based Target Acquisition on Handheld Mobile Devices

TL;DR

This study examines how carrying objects affects gaze and touch input performance on mobile devices, revealing that gaze remains stable under encumbrance and is preferred when users are burdened, informing future mobile interface design.

Contribution

It provides novel insights into the impact of encumbrance on gaze and touch input performance, highlighting the robustness of gaze input under real-world conditions.

Findings

Gaze input performance remains consistent regardless of encumbrance.

Participants prefer gaze input when encumbered, and touch when unencumbered.

Touch generally outperforms gaze in raw performance metrics.

Abstract

The potential of using gaze as an input modality in the mobile context is growing. While users often encumber themselves by carrying objects and using mobile devices while walking, the impact of encumbrance on gaze input performance remains unexplored. To investigate this, we conducted a user study (N=24) to evaluate the effect of encumbrance on the performance of 1) Gaze using Dwell time (with/without visual feedback), 2) GazeTouch (with/without visual feedback), and 3) One- or two-hand touch input. While Touch generally performed better, Gaze, especially with feedback, showed a consistent performance regardless of whether participants were encumbered or unencumbered. Participants' preferences for input modalities varied with encumbrance: they preferred Gaze when encumbered, and touch when unencumbered. Our findings enhance understanding of the effect of encumbrance on gaze input and contribute towards selecting appropriate input modalities in future mobile user interfaces to account for situational impairments.