May 10, 2012 @ 14:30, Room: Ballroom G
Chair: Olivier Chapuis, Univ Paris-Sud, France
Accurate Measurements of Pointing Performance from In Situ Observations - Paper
Contribution & Benefit: Method for obtaining lab-quality measurements of pointing performance from unobtrusive observations of natural in situ interactions.
Abstract » We present a method for obtaining lab-quality measurements of pointing performance from unobtrusive observations of natural in situ interactions. Specifically, we have developed a set of user-independent classifiers for discriminating between deliberate, targeted mouse pointer movements and those movements that were affected by any extraneous factors. To develop and validate these classifiers, we developed logging software to unobtrusively record pointer trajectories as participants naturally interacted with their computers over the course of several weeks. Each participant also performed a set of pointing tasks in a formal study set-up. For each movement, we computed a set of measures capturing nuances of the trajectory and the speed, acceleration, and jerk profiles. Treating the observations from the formal study as positive examples of deliberate, targeted movements and the in situ observations as unlabeled data with an unknown mix of deliberate and distracted interactions, we used a recent advance in machine learning to develop the classifiers. Our results show that, on four distinct metrics, the data collected in-situ and filtered with our classifiers closely matches the results obtained from the formal experiment.
ACMA General-Purpose Target-Aware Pointing Enhancement Using Pixel-Level Analysis of Graphical Interfaces - Paper
Contribution & Benefit: We present a general-purpose implementation of a target aware pointing technique, functional across an entire desktop.
Abstract » We present a general-purpose implementation of a target aware pointing technique, functional across an entire desktop and independent of application implementations. Specifically, we implement Grossman and Balakrishnan�s Bubble Cursor, the fastest general pointing facilitation technique in the literature. Our implementation obtains the necessary knowledge of interface targets using a combination of pixel-level analysis and social annotation. We discuss the most novel aspects of our implementation, including methods for interactive creation and correction of pixel-level prototypes of interface elements and methods for interactive annotation of how the cursor should select identified elements. We also report on limitations of the Bubble Cursor unearthed by examining our implementation in the complexity of real-world interfaces. We therefore contribute important progress toward real-world deployment of an important family of techniques and shed light on the gap between understanding techniques in controlled settings versus behavior with real-world interfaces.
ACMAssisting Hand Skill Transfer of Tracheal Intubation Using Outer-Covering Haptic Display - Note
Contribution & Benefit: Proposes a novel haptic device. The device can effectively guide human hand motion with significantly lower detection threshold than conventional devices.
Abstract » Various systems for hand tool skill training have been developed in the domain of haptic displays. These systems typically present force to a learner�s palm by directly actuating the tool. However, this approach is sometimes ineffective because learners have difficulty sensing the haptic feedback from the tool when they are holding it tightly. Thus, we propose a different approach (OCHD) that effectively guides the learner�s hand by presenting force to the back of his/her hand as if an instructor is holding it. A preliminary experiment showed that OCHD effectively guides users with less actuator drive force than cases where the tool is directly actuated.
ACMAn Investigation of Fitts' Law in a Multiple-Display Environment - Note
Contribution & Benefit: Experiment showing that Fitts' Law may underestimate difficulty of pointing tasks on multiple-monitor systems. Pertinent for designers trying applying Fitts' Law to interface design for multiple-display environments.
Abstract » We describe the design and analysis of a Fitts' law experiment, conducted in a multiple-display environment (MDE), in which the physical gap between displays and the proximity of targets to the gap systematically varied. Participants achieved decreasing throughput values (a combined measure of movement time and accuracy in a target acquisition task) under increasing gap sizes. Participants likewise performed relatively poorly in tasks involving monitor crossing over all gap conditions, especially so when motion either originates or terminates very close to the gap. Both results could be considered surprising since in either case, the amount of mouse movement needed to successfully execute the task does not change based on physical gap size or a target's proximity to the edge. Fitts' law may underestimate the difficulty of movement tasks in MDEs.
ACMExtending Fitts' Law to Account for the Effects of Movement Direction on 2D Pointing - Paper
Contribution & Benefit: Improves understanding of modeling 2D pointing using Fitts' law, with an intuitive explanation for the new model. Provides practitioners and researchers with guidelines for UI and Fitts task experiment designs.
Abstract » Fitts' law is the most widely applied model in the field of HCI. However, this model and its existing extensions are still limited for 2D pointing task especially when the effects of movement direction (θ) remain in the task. In this paper, we employ the concept of projection to account for the effects of target width (W) and height (H) on movement time so that we seamlessly integrate the four factors, i.e. θ, amplitude (A), W and H, into the new extension of Fitts' law, which can uncover not only the periodicity of the asymmetrical impacts of W and H with the variation of θ but also their interrelation. Carrying out two experiments, we verify that the vertical projection of W and the horizontal projection of H in the line of movement direction can be viewed as the determinants of movement time. Finally, we offer recommendations for 2D pointing experiments and discuss the implications for interface designs.
ACM