Mikael Goldstein

Non-keyboard QWERTY touch typing: a portable input interface for the mobile user

Using traditional mobile input devices results in decreasedeffectiveness and efficiency. To improve usability issues aportable Non-Keyboard QWERTY touch-typing paradigm that supportsthe mobile touch-typing user is presented and investigated. Itrequires negligible training time. Pressure sensors strapped to thefingertips of gloves detect which finger is depressed. A languagemodel based on lexical and syntactic knowledge transforms thedepressed finger stroke sequence into real words and sentences.Different mobile input QWERTY paradigms (miniaturised, floating andNon-Keyboard) have been compared with full-size QWERTY. Among themobile input paradigms, the Non-Keyboard fared significantlybetter, both regarding character error rate and subjectiveratings.

The Media Equation Does Not Always Apply: People are not Polite Towards Small Computers

Abstract: The Media Equation asserts that people treat and behave towards computers in much the same way as towards other people, for example regarding politeness. We report the results of a study investigating the validity of the Media Equation for PDAs and smart phones. Twenty-five users each performed seven tasks with one of four PDAs or a smart phone. None of the users had any prior experience with a PDA. Contrary to the postulations of the Media Equation, the number of “likes” decreased and number of “dislikes” increased in the computer present condition. Previous objective performance when interacting with a palm computer appears to account for subjective attitudes much more than computer absence/presence. It appears that degree of politeness might be performance-level dependent but this has to be reinvestigated before more firm conclusions can be drawn.

Eye Movement Study of Reading on a Mobile Device Using the Page and RSVP Text Presentation Formats

We present findings from a balanced repeated-measurement evaluation where 16 subjects read texts of similar length and difficulty using the traditional Page and the dynamic Rapid Serial Visual Presentation (RSVP) format on a mobile device. Apart from monitoring reading speed, comprehension, and NASA-TLX task load, we also devised a system that enabled us to keep track of subjects eye movements. The results indicate no significant differences in reading speed or comprehension, but for task load, RSVP increased the Temporal task load factor. However, the most striking differences were found in the eye movement recordings. RSVP was found to decrease the overall number of eye movements significantly. But, RSVP was also found to significantly increase the number of regressions, although it decreased the number of saccades. These findings contradict common claims and their implications for the improvement of readability on mobile devices are discussed.

Productivity prediction by extrapolation: Using workload memory as a predictor of target performance

In order to assess if productivity based on extrapolated data is a good predictor of longer texts, an experimental study was conducted. Two full-sized text input devices for touch typing and two miniaturized for tapping were used, all featuing QWERTY layout, in a repeated measurement design. Twenty subjects were exposed to both a task within the limit of working memory (nine words) and four running memory tasks (approx. 275 words). For miniaturized tapping keyboards, extrapolated data significantly underestimated both entry speed (uncorrected wpm, up to 17%) and character error rate (up to 61%) whereas it significantly overestimated ratio of correct words (up to 62%) of running memory tasks. Further, error-corrected entry speed was significantly overestimated up to a factor of 2.7. Results based on extrapolated productivity metrics must therefore be interpreted with caution. Running memory tasks with text length of more than 32 words is needed to assess productivity of text input devices if tapping is used.

Icon size as a function of display screen

As wireless and mobile computing advances, user interface designers are faced with the challenge of designing an interface for miniaturized devices that may be capable of performing Windows applications. The present study attempted to define the optimal icon size for small display with a psychophysical approach -- the method of adjustment. Participants were asked to adjust the icon size in descending and ascending order to satisfy the operational criteria of (1) adjusting the icon to its smallest size, and (2) maintaining recognition of the icon image. Three display areas, 40x40 ram, 120x70 turn and 180x100 mm were used. Results from this study show that icon ≈5.0 mm may be recommended for displays with limited area.

Visualising data using the ActionMapper: a proposed interactive event logger for user interface evaluation

The proposed ActionMapper tool extends previous work on the generic KeystrokeMapper tool to provide an efficient method of logging and visualising a novice users interaction with a dynamic interface. For any specified task the ActionMapper could generate a graphic representation of both the designers conceptual model (represented by an Optimum path) and an indication of the users mental model (represented by the actual path navigated by the user). In this study, the results from two usability experiments have been analysed using the KeystrokeMapper concept. From this a refined version of the tool, referred to as ActionMapper, is outlined. It is argued that the future implementation of the ActionMapper concept as a computer-based tool, which includes the automatic analysis and visualisation of numerous usability metrics, will substantially enhance the evaluation process. By adding event recording functionality in a prototype for a small handheld device, effective usability evaluations could also be conducted in a mobile context.