Experiments in hearing

Recent advances in touch screen technology have increased the prevalence of touch screens and have prompted a wave of new touch screen-based devices. However, touch screens are still largely inaccessible to blind users, who must adopt error-prone compensatory strategies to use them or find accessible alternatives. This inaccessibility is due to interaction techniques that require the user to visually locate objects on the screen. To address this problem, we introduce Slide Rule, a set of audio-based multi-touch interaction techniques that enable blind users to access touch screen applications. We describe the design of Slide Rule, our interaction techniques, and a user study in which 10 blind people used Slide Rule and a button-based Pocket PC screen reader. Results show that Slide Rule was significantly faster than the button-based system, and was preferred by 7 of 10 users. However, users made more errors when using Slide Rule than when using the more familiar button-based system.

Slide rule: making mobile touch screens accessible to blind people using multi-touch interaction techniques

Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems 参加報告

Despite growing awareness of the accessibility issues surrounding touch screen use by blind people, designers still face challenges when creating accessible touch screen interfaces. One major stumbling block is a lack of understanding about how blind people actually use touch screens. We conducted two user studies that compared how blind people and sighted people use touch screen gestures. First, we conducted a gesture elicitation study in which 10 blind and 10 sighted people invented gestures to perform common computing tasks on a tablet PC. We found that blind people have different gesture preferences than sighted people, including preferences for edge-based gestures and gestures that involve tapping virtual keys on a keyboard. Second, we conducted a performance study in which the same participants performed a set of reference gestures. We found significant differences in the speed, size, and shape of gestures performed by blind people versus those performed by sighted people. Our results suggest new design guidelines for accessible touch screen interfaces.

https://faculty.washington.edu/wobbrock/pubs/chi-11.05.pdf

Usable gestures for blind people: understanding preference and performance

April 24-29, 2004 Vienna, Austria

Chi 2004

A prototype of friction-based horizontally rotating fingertip stimulator was used to investigate emotional experiences and behavioral responses to haptic stimulation. The rotation style of 12 different stimuli was varied by burst length (i.e., 20, 50, 100 ms), continuity (i.e., continuous and discontinuous), and direction (e.g., forward and backward). Using these stimuli 528 stimulus pairs were presented to 12 subjects who were to distinguish if stimuli in each pair were the same or different. Then they rated the stimuli using four scales measuring the pleasantness, arousal, approachability, and dominance qualities of the 12 stimuli. The results showed that continuous forward-backward rotating stimuli were rated as significantly more unpleasant, arousing, avoidable, and dominating than other types of stimulations (e.g., discontinuous forward rotation). The reaction times to these stimuli were significantly faster than reaction times to discontinuous forward and backward rotating stimuli. The results clearly suggest that even simple haptic stimulation can carry emotional information. The results can be utilized when making use of haptics in human-technology interaction.

Emotional and behavioral responses to haptic stimulation

This paper describes the development of a new technique for touchscreen interaction, based on a single gesture-driven adaptive software button. The button is intended to substitute the software keyboard, and provides text-entry functionality. Input is accomplished through recognition of finger gestures that is comprised of movement towards the eight basic directions in any position. The target user group of such an interaction technique is primarily blind people who could benefit significantly. The adaptability of the button provides complementary help and follows the style of interaction in a natural way. The analysis of the results, collected from twelve blindfolded subjects, revealed an encouraging tendency. During blind manipulation on touch screen, three of the subjects achieved a maximal typing speed of about 12 wpm after five trials. This suggests that the technique developed is reliable and robust enough to be possibly applied to diverse application platforms, including personal device assistants.

Adaptive blind interaction technique for touchscreens

Virtual keyboards used by physically impaired users for text entry usually display all characters simultaneously on the screen. Applications where saving physical space is critical, however, require another approach. A common option is grouping several symbols under one key and employing a hierarchical selection mechanism. We present an alternative technique (Symbol Creator) based on assembling characters using segments that resemble basic elements of Latin cursive. This technique was empirically evaluated along with another technique developed as an eye-gaze analogue to mobile phones’ multi-tap system. In terms of accuracy and entry speed, both techniques performed equally well. Subjectively, however, Symbol Creator was the preferred method, since it was perceived as being more fun to use and less frustrating than the other technique. These findings suggest that designers of text entry systems for disabled users should not stick to menu tree-based systems – there are also other solutions to on-screen space saving problem.

Symbol Creator: An Alternative Eye-based Text Entry Technique with Low Demand for Screen Space.

The aim of this work is to present a novel stylus with embedded vibro-tactile actuator and an empirical pilot study on nonvisual feedback cues, tactile and sound, used when a graphical trail is inspected. The study showed that tactile feedback took less time than sound feedback to complete the task. In addition, participants preferred tactile feedback to sound during blind inspection of a trail. These results can be used for further development of novel diagrammatic tools and pen-based input techniques especially for physically challenged users.

Non-visual feedback cues for pen computing

A new device, the Braille Slate Talker, is introduced. An ordinary hand held device (a PDA) is used with a fixed layout plastic guide placed over the touch screen to allow Braille input. Contracted Braille is converted to text by a table-driven state machine. Programs are written in Java language to provide full hardware and software platform independence. Future network applications will use Sun’s Jini technology.

Grigori Evreinov

Papers

Emotional and behavioral responses to haptic stimulation

Adaptive blind interaction technique for touchscreens

Symbol Creator: An Alternative Eye-based Text Entry Technique with Low Demand for Screen Space.

Non-visual feedback cues for pen computing

Java-Powered Braille Slate Talker