Understanding Users' Perceived Difficulty of Multi-Touch Gesture Articulation

Abstract

International audienceWe show that users are consistent in their assessments of the articulation difficulty of multi-touch gestures, even under the many degrees of freedom afforded by multi-touch input, such as (1) various number of fingers touching the surface, (2) various number of strokes that structure the gesture shape, and (3) single-handed and bimanual input. To understand more about perceived difficulty, we characterize gesture articulations captured under these conditions with geometric and kinematic descriptors computed on a dataset of 7,200 samples of 30 distinct gesture types collected from 18 participants. We correlate the values of the objective descriptors with users' subjective assessments of articulation difficulty and report path length, production time, and gesture size as the highest correlators (max Pearson's r=.95). We also report new findings about multi-touch gesture input, e.g., gestures produced with more fingers are larger in size and take more time to produce than single-touch gestures; bimanual articulations are not only faster than single- handed input, but they are also longer in path length, present more strokes, and result in gesture shapes that are deformed horizontally by 35% in average. We use our findings to outline a number of 14 guidelines to assist multi-touch gesture set design, recognizer development, and inform gesture-to-function mappings through the prism of the user-perceived difficulty of gesture articulation

Exploring Visually Impaired People's Gesture Preferences for Smartphones

“…Therefore, we confirmed previous results that the longer the gesture the more difficult it is perceived to be [17]. …”

“…These results are consistent with previous studies, both for sighted [17] and visually impaired people [10]. Regarding prior knowledge of gestures, although 26 participants said they had used some kind of mobile touchscreen, only half of them already knew the most popular gestures: swipe left and swipe up.…”

“…Concerning the goodness of touch-based gestures, Yosra et al carried out a study to better understand perceived difficulty of multi-touch gesture articulation [17]. They found a significant impact of finger count, stroke count and synchronicity on participants' perceived difficulty.…”

Gesture Heatmaps

“…Researchers have also looked at people's perceptions about gesture commands in order to identify perceptually-similar classes [19,22,30,31]. For example, Long et al [19] investigated the visual similarity of pen gestures and derived a computable model for perceptual similarity using gesture features, such as curviness, that correlated R 2 =.56 with user-reported similarity.…”

“…Vatavu et al [31] found that subjects were highly consistent in estimating the execution difficulty of single-stroke gestures, leading to two estimation rules based on production time that approximated absolute and relative perceived difficulty with 75% and 90% accuracy, respectively. Recently, Rekik et al [22] extended the study to include multi-stroke gestures. Subjects were also consistent in their perception of gesture scale (e.g., large versus small gestures), which is predictable with 90% accuracy using a rule based on the area size of the gesture bounding box [30].…”