In view of the difficulties in evaluating computer pointing devices across different tasks within dynamic and complex systems, new performance measures are needed. This paper proposes seven new accuracy measures to elicit (sometimes subtle) differences among devices in precision pointing tasks. The measures are target re-entry, task axis crossing, movement direction change, orthogonal direction change, movement variability, movement error, and movement offset. Unlike movement time, error rate, and throughput, which are based on a single measurement per trial, the new measures capture aspects of movement behaviour during a trial. The theoretical basis and computational techniques for the measures are described, with examples given. An evaluation with four pointing devices was conducted to validate the measures. A causal relationship to pointing device efficiency (viz. throughput) was found, as was an ability to discriminate among devices in situations where differences did not otherwise appear. Implications for pointing device research are discussed.

We present the design, implementation, and informal evaluation of tactile interfaces for small touch screens used in mobile devices. We embedded a tactile apparatus in a Sony PDA touch screen and enhanced its basic GUI elements with tactile feedback. Instead of observing the response of interface controls, users can feel it with their fingers as they press the screen. In informal evaluations, tactile feedback was greeted with enthusiasm. We believe that tactile feedback will become the next step in touch screen interface design and a standard feature of future mobile devices.

We present a study investigating the use of vibrotactile feedback for touch-screen keyboards on PDAs. Such keyboards are hard to use when mobile as keys are very small. We conducted a laboratory study comparing standard buttons to ones with tactile feedback added. Results showed that with tactile feedback users entered significantly more text, made fewer errors and corrected more of the errors they did make. We ran the study again with users seated on an underground train to see if the positive effects transferred to realistic use. There were fewer beneficial effects, with only the number of errors corrected significantly improved by the tactile feedback. However, we found strong subjective feedback in favour of the tactile display. The results suggest that tactile feedback has a key role to play in improving interactions with touch screens.

This paper first presents an empirical study involving selection of isolated expanding targets, with the goal of determining how to predictively model performance. Various factors, such as the time at which expansion occurs, are varied to investigate their influence on performance

This paper examines how multimodal feedback assists small-target acquisition in graphical user interfaces. All combinations of three feedback modes are analysed: non-speech audio; tactile; and pseudo-haptic ‘sticky’ feedback. The tactile conditions used stimulation through vibration (rather than force-feedback), and the sticky conditions were implemented by dynamically reconfiguring mouse control-display gain as the cursor entered the target. Results show that for small, discretely located targets all feedback modes reduce targeting times, with stickiness providing substantial improvements. Furthermore, stickiness and tactile appear to combine well. However, the results of a more ecologically oriented menu-selection task show the need for caution, revealing that excessive feedback can damage interaction though ‘noise’ that interferes with the acquisition of neighbouring targets.

In this paper we investigate the use of a uni-pressure and dual-pressure augmented mouse. With a pressure augmented mouse users can simultaneously control cursor positions as well as multiple levels of discrete selection modes for common desktop application tasks. Two or more independent pressure sensors can be mounted onto several locations on the body of the mouse. To highlight the design potential of a pressure augmented mouse we conducted a multi-part study. In the first part we identified the number of maximum discrete levels controllable with a uni-pressure augmented mouse, the most appropriate locations for installing pressure sensors on the mouse, and the design of new interaction techniques to support selection with pressure-based input. In a follow-up design we introduced an additional sensor and two different types of selection techniques to control a larger number of discrete levels with two pressure sensors. Our results show that users can comfortably control up to 64 modes with a dual-pressure augmented mouse. We discuss the findings of our results in the context of several desktop interaction techniques and identify several design recommendations. Author Keywords Input device, mouse, interaction technique, pressure-based interaction. ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI):

We evaluate two systems for automatically generating personalized interfaces adapted to the individual motor capabilities of users with motor impairments. The first system, SUPPLE, adapts to users ’ capabilities indirectly by first using the ARNAULD preference elicitation engine to model a user’s preferences regarding how he or she likes the interfaces to be created. The second system, SUPPLE++, models a user’s motor abilities directly from a set of one-time motor performance tests. In a study comparing these approaches to baseline interfaces, participants with motor impairments were 26.4 % faster using ability-based user interfaces generated by SUPPLE++. They also made 73 % fewer errors, strongly preferred those interfaces to the manufacturers’ defaults, and found them more efficient, easier to use, and much less physically tiring. These findings indicate that rather than requiring some users with motor impairments to adapt themselves to software using separate assistive technologies, software can now adapt itself to the capabilities of its users.

Although a number of studies have reported that force feedback gravity wells can improve performance in “pointand-click” tasks, there have been few studies addressing issues surrounding the use of gravity wells for multiple onscreen targets. This paper investigates the performance of users, both with and without motion-impairments, in a “point-and-click ” task when an undesired haptic distractor is present. The importance of distractor location is studied explicitly. Results showed that gravity wells can still improve times and error rates, even on occasions when the cursor is pulled into a distractor. The greatest improvement is seen for the most impaired users. In addition to traditional measures such as time and errors, performance is studied in terms of measures of cursor movement along a path. Two cursor measures, angular distribution and temporal components, are proposed and their ability to explain performance differences is explored.

Abstract. This paper seeks to establish the quantitative effects of providing force feedback on user performance in human computer interaction. A reciprocal tapping test is employed in conjunction with Fitts ' law in order to establish a measure of human performance in a simple target selection task. The test was performed using a PHANToM haptic interface, under conditions with and without the provision of force feedback. It was found that providing force feedback significantly improved subjects ' movement times, but had no effect on the rate of information processing (IP) as defined by Fitts ' law. However, it was shown that for conditions of ballistic movement (corresponding to a low task difficulty (ID)), there was a highly significant improvement in IP for the condition with force feedback, but no improvement when force feedback was not employed. This was deemed due to the fact that for the non-haptic condition no force cues were available, therefore the user had to rely on visual cues, hence, ballistic movement was not possible. 1.

Abstract not found