Andrew Sears

Split menus: effectively using selection frequency to organize menus

When some items in a menu are selected more frequently than others, as is often the case, designers or individual users may be able to speed performance and improve preference ratings by placing several high-frequency items at the top of the menu. Design guidelines for split menus were developed and applied. Split menus were implemented and tested in two in situ usability studies and a controlled experiment. In the usability studies performance times were reduced by 17 to 58% depending on the site and menus. In the controlled experiment split menus were significantly faster than alphabetic menus and yielded significantly higher subjective preferences. A possible resolution to the continuing debate among cognitive theorists about predicting menu selection times is offered. We conjecture and offer evidence that, at least when selecting items from pull-down menus, a logarithmic model applies to familiar (high-frequency) items, and a linear model to unfamiliar (low-frequency) items.

Investigating Touchscreen Typing: the Effect of Keyboard Size on Typing Speed

Two studies investigated the effect keyboard size has on typing speed and error rates for touchscreen keyboards using the lift-off strategy . A cursor appeared when users touched the screen and a key was selected when they lifted their finger from the screen. Four keyboard sizes were investigated ranging from 24.6 cm to 6.8 cm wide. Results indicate that novices can type approximately 10 words per minute (WPM) on the smallest keyboard and 20 WPM on the largest. Experienced users improved to 21 WPM on the smallest keyboard and 32 WPM on the largest. These results indicate that, although slower, small touchscreen keyboards can be used for limited data entry when the presence of a regular keyboard is not practical. Applications include portable pocket-sized or palmtop computers, messaging systems, and personal information resources. Results also suggest the increased importance of experience on these smaller keyboards. Research directions are suggested.

Heuristic Walkthroughs: Finding the Problems Without the Noise

Inspection-based evaluation techniques are popular because they require less formal training, are quick, can be used throughout the development process, do not require test users, and can result in finding numerous usability problems. A new technique is described that combines the benefits of heuristic evaluations, cognitive walkthroughs, and usability walkthroughs. This technique, a heuristic walkthrough, provide more structure than heuristic evaluations but less than cognitive walkthroughs. The result is an effective task-oriented evaluation technique that is easy to learn and apply. Methods are proposed for comparing the validity, thoroughness, and reliability of evaluation techniques. Finally, heuristic walkthroughs are compared to heuristic evaluations and cognitive walkthroughs in a controlled study. The results indicate that heuristic walkthroughs are more thorough than cognitive walkthroughs and more valid than heuristic evaluations. In other words, heuristic walkthroughs resulted in finding more ...

Capturing the effects of context on human performance in mobile computing systems

Many real world mobile device interactions occur in context-rich environments. However, the majority of empirical studies on mobile computing are conducted in static or idealized conditions, resulting in a deficit of understanding of how changes in context impact users’ abilities to perform effectively. This paper attempts to address the disconnect between the actual use and the evaluation of mobile devices by varying contextual conditions and recording changes in behavior. A study was performed to investigate the specific effects of changes in motion, lighting, and task type on user performance and workload. The results indicate that common contextual variations can lead to dramatic changes in behavior and that interactions between contextual factors are also important to consider.

Layout appropriateness: a metric for evaluating user interface widget layout

Numerous methods for evaluating user interfaces have been investigated to develop a metric that incorporates simple task descriptions which can assist designers in organizing their user interface. The metric, Layout Appropriateness (LA), requires a description of the sequences of actions users perform and how frequently each sequence is used. This task description can either be from observations of an existing system or from a simplified task analysis. The appropriateness of a given layout is computed by weighting the cost of each sequence of actions by how frequently the sequence is performed, which emphasizes frequent methods of accomplishing tasks while incorporating less frequent methods in the design. In addition to providing a comparison of proposed or existing layouts, an LA-optimal layout can be presented to the designer. The designer can compare the LA-optimal and existing layouts or start with the LA-optimal layout and modify it to take additional factors into consideration. >

Improving Touchscreen Keyboards: Design issues and a comparison with other devices

Abstract The study explored touchscreen keyboards using high precision touch-screen strategies. Phase one evaluated three possible monitor positions: 30°, 45°, and 75° from horizontal. Results indicate that the 75° angle, approximately the standard monitor position, resulted in more fatigue and lower preference ratings. Phase two collected touch bias and key size data for the 30° angle. Subjects consistently touched below targets, and touched to the left of targets on either side of the screen. Using these data, a touchscreen keyboard was designed. Phase three compared this keyboard with a mouse-activated keyboard, and the standard QWERTY keyboard for typing relatively short strings of 6,19, and 44 characters. Results indicate that users can type approximately 25 words/minute (wpm) with the touchscreen keyboard, compared to 17 wpm using the mouse, and 58 wpm when using the keyboard. Possible improvements to touchscreen keyboards are suggested.

An empirical comparison of use-in-motion evaluation scenarios for mobile computing devices

There is a clear need for evaluation methods that are specifically suited to mobile device evaluation, largely due to the vast differences between traditional desktop computing and mobile computing. One difference of particular interest that needs to be accounted for is that mobile computing devices are frequently used while the user is in motion, in contrast to desktop computing. This study aims to validate the appropriateness of two evaluation methods that vary in representativeness of mobility, one that uses a treadmill to simulate motion and another that uses a controlled walking scenario.The results lead to preliminary guidelines based on study objectives for researchers wishing to use more appropriate evaluation methodologies for empirical, data-driven mobile computing studies. The guidelines indicate that using a treadmill for mobile evaluation can yield representative performance measures,whereas a controlled walking scenario is more likely to adequately simulate the atual user experience.

Touchscreen Interfaces for Alphanumeric Data Entry

Touchscreens have been demonstrated as useful for many applications. Although a traditional mechanical keyboard is the device of choice when entering alphanumeric data, it may not be optimal when only limited data must be entered, or when the keyboard layout, character set, or size may be changed. A series of experiments has demonstrated the usability of touchscreen keyboards. The first study indicated that users who type 58 wpm on a traditional keyboard can type 25 wpm using a touchscreen and that the traditional monitor position is suboptimal for touchscreen use. A second study reported on typing rates for keyboards of various sizes (from 6.8 to 24.6 cm wide). Novices typed approximately 10 wpm on the smallest and 20 wpm on the largest of the keyboards. Users experienced with touchscreen keyboards typed 21 wpm on the smallest and 32 wpm on the largest. We then report on a recent study done with more representative users and more difficult tasks. Thirteen cashiers were recruited for this study and were required to complete ten trials in which they typed names and addresses with punctuation. Results indicate that the users improved rapidly from 9.5 wpm on the first trial to 13.8 wpm on the last trial, reaching their fastest performance after only 25 minutes. Although custom interfaces will be preferred for special types of data (e.g. telephone numbers, times, dates, colors) there will always be situations when limited quantities of text must be entered. In these situations a touchscreen keyboard can be used.

AIDE: a step toward metric-based interface development tools

Automating any part of the user interface design and evaluation process can help reduce development costs. This paper presents a metric-based tool called AIDE (semi-Automated Interface Designer and Evaluator) which assists designers in creating and evaluating layouts for a given set of interface controls. AIDE is an initial attempt to demonstrate the potential of incorporating metrics into user interface development tools, Analyzing the interfaces produced using AIDE provides encouraging feedback about the potential of this technique.

Internet delay effects: how users perceive quality, organization, and ease of use of information

In this paper we report the results of an investigation designed to determine the effects of Internet delays on users perceptions of ease of locating information, organization of information, quality of information, and navigation problems. The results demonstrated user sensitivity to delays. As expected, for text-and-graphics documents, shorter delays provoked more favorable responses. However, for text-only documents, the shorter the delay, the less favorably a document was viewed. The results indicated that users may prefer multi-media web sites but are unwilling to tolerate the substantial network delays often associated with delivering graphics, video, animation, and audio.