Mark H. Chignell

Virtual reality for palmtop computers

We are exploring how virtual reahty theories can be applied toward palmtop computers. In our prototype, called the Chameleon, a small 4-inch hand-held monitor acts as a palmtop computer with the capabihties of a Silicon graphics workstation. A 6D input device and a response button are attached to tbe small monitor to detect user gestures and input selections for issuing commands. An experiment was conducted to evaluate our design and to see how well depth could be perceived in the small screen compared to a large 21-inch screen, and the extent to which movement of the small display (in a palmtop virtual reality condition) could improve depth perception, Results show that with very little training, perception of depth in the palmtop virtual reality condition is about as good as corresponding depth perception in a large (but static) display. Variations to the initial design are also discussed, along with issues to be explored in future research, Our research suggests that palmtop virtual reality may support effective navigation and search and retrieval, in rich and portable information spaces.

Earpod: eyes-free menu selection using touch input and reactive audio feedback

We present the design and evaluation of earPod: an eyes-free menu technique using touch input and reactive auditory feedback. Studies comparing earPod with an iPod-like visual menu technique on reasonably-sized static menus indicate that they are comparable in accuracy. In terms of efficiency (speed), earPod is initially slower, but outperforms the visual technique within 30 minutes of practice. Our results indicate that earPod is potentially a reasonable eyes-free menu technique for general use, and is a particularly exciting technique for use in mobile device interfaces.

Mental workload dynamics in adaptive interface design

In examining the role of time in mental workload, the authors present a different perspective from which to view the problem of assessment. Mental workload is plotted in three dimensions, whose axes represent effective time for action, perceived distance from desired goal state, level of effort required to achieve the time-constrained goal. This representation allows the generation of isodynamic workload contours that incorporate the factors of operator skill and equifinality of effort. An adaptive interface for dynamic task reallocation is described that uses this form of assessment to reconcile the joint aims of stable operator loading and acceptable primary task performance by the total system. >

Mobile text entry: relationship between walking speed and text input task difficulty

The effect of key size on text entry on a handheld device while walking and standing was examined in order to answer the following questions: 1) Will the additional workload of walking amplify the effect of input difficulty? and 2) Can walking speed be used as a secondary task measure of mental workload during mobile text entry? 13 participants (7 males and 6 females) input well known sayings (sentences) in English into a handheld device in each of four size conditions, with the text input box ranging in width between 2 and 5 millimetres (mm). Text input speed increased with larger size of text box up to a size of 3mm, and text input speed was faster when standing (vs. walking). The effect of size did not depend on whether participants were walking or standing. Errors were significantly higher for the 2mm size condition but did not vary for the wider sizes, while subjective ease of input increased with increasing input box width, only crossing the midpoint of the rating scale (i.e., more easy than difficult) at an input box width of 3mm. Based on these results it is recommended that a minimum text input box width of 3mm be used for handheld text input. Walking speed during text entry in this study was relatively low (with a mean of 1.77 km/h) but width of text input box had no additional effect on walking speed over and above the general slowing caused by text entry. Thus the answers to both of the main questions posed in this study were in the negative, although the fact that people had to enter text slowed walking speed by a fixed amount (independent of level of input difficulty) that varied between individuals. Implications for measuring workload in mobile text entry tasks are discussed.

Adaptive control in human-machine systems

Publisher Summary This chapter discusses contemporary advances in the understanding of adaptive control as applied to systems that include the cooperative action of a machine and its operator. The key component of an adaptive interface is a reasoning process that selects a task allocation policy that changes the loading on the human in such a way as to improve overall system performance. This process must have access to both overall system goals (a model of the task) and information about what the person and machine components of the system are capable of accomplishing (person and system models). As an initial foundation, it is recognized in the chapter that the prosthetics that can surround individuals and augment their capabilities allow human operators to traverse the traditional boundary constraints imposed by the environment. A different approach is advocated where a hierarchical model of the task is built in terms of procedural and knowledge-based components. The human–machine interaction is a view of the task as a knowledge system that requires combined human–machine intelligence along with an interface that permits and controls joint human–machine reasoning. The chapter describes some developments in the understanding of human-adaptive response and the way by which such adaptive capability may be replicated in human–machine systems.

Knowledge-based search tactics for an intelligent intermediary system

Research on the nature of knowledge-based systems for bibliographic information retrieval is summarized. Knowledge-based search tactics are then considered in terms of their role in the functioning of a semantically based search system for bibliographic information retrieval, EP-X. This system uses such tactics to actively assist users in defining or refining their topics of interest. It does so by applying these tactics to a knowledge base describing topics in a particular domain and to a database describing the contents of individual documents in terms of these topics. This paper, then, focuses on the two central concepts behind EP-X: semantically based search and knowledge-based search tactics.

Empathic tutoring software agents using real-time eye tracking

This paper describes an empathic software agent (ESA) interface using eye movement information to facilitate empathy-relevant reasoning and behavior. Eye movement tracking is used to monitor users attention and interests, and to personalize the agent behaviors. The system reacts to user eye information in real-time, recording eye gaze and pupil dilation data during the learning process. Based on these measures, the ESA infers the focus of attention and motivational status of the learner and responds accordingly with affective (display of emotion) and instructional behaviors. In addition to describing the design and implementation of empathic software agents, this paper will report on some preliminary usability test results concerning how users respond to the empathic functions that are provided.

Identifying communities in blogs: roles for social network analysis and survey instruments

We examine the problem of identifying, measuring and evaluating communities in blogs. In our approach, we use sense of community (McMillan and Chavis, 1986) and centrality measures derived from social network analysis. We then describe a method for identifying communities in blogs using both sense of community measurement and Social Network Analysis (SNA). We apply this framework to a blog on Canadian independent music. Hypotheses are developed concerning the specific structural properties of social networks formed by blogging relationships and how those properties are related to the sense of community experienced by the participants (authors and readers of the blogs). Finally, we discuss the implications for blog implementation and use.

Discriminating meta-search: a framework for evaluation

There was a proliferation of electronic information sources and search engines in the 1990s. Many of these information sources became available through the ubiquitous interface of the Web browser. Diverse information sources became accessible to information professionals and casual end users alike. Much of the information was also hyperlinked, so that information could be explored by browsing as well as searching. While vast amounts of information were now just a few keystrokes and mouseclicks away, as the choices multiplied, so did the complexity of choosing where and how to look for the electronic information. Much of the complexity in information exploration at the turn of the twenty-first century arose because there was no common cataloguing and control system across the various electronic information sources. In addition, the many search engines available diAered widely in terms of their domain coverage, query methods and eAciency. Meta-search engines were developed to improve search performance by querying multiple search engines at once. In principle, meta-search engines could greatly simplify the search for electronic information by selecting a subset of first-level search engines and digital libraries to submit a query to based on the characteristics of the user, the query/topic, and the search strategy. This selection would be guided by diagnostic knowledge about which of the first-level search engines works best under what circumstances. Programmatic research is required to develop this diagnostic knowledge about first-level search engine performance. This paper introduces an evaluative framework for this type of research and illustrates its use in two experiments. The experimental results obtained are used to characterize some properties of leading search engines (as of 1998). Significant interactions were observed between search engine and two other factors (time of day and Web domain). These findings supplement those of earlier studies, providing preliminary information about the complex relationship between search engine functionality and performance in diAerent contexts. While the specific results obtained represent a time-dependent Information Processing and Management 35 (1999) 337‐362

Further evidence for priming in perceptual matching: Temporal, not spatial, separation enhances the fast-same effect

Sequential (vs. simultaneous) presentation of two letters in a physical-identity matching task enhanced the fast-same effect, but did not reduce the preponderance of false-“different” errors or the effect of visual similarity. Thus, the sequential enhancement of the fast-same effect involves an increased efficiency in encoding (d’) owing to letter repetition, as Proctor claimed, rather than a criterion shift (β), and it involves the visual code rather than the name code. The increased efficiency in detecting sameness with sequential presentation might result from spatial separation (e.g., reduced lateral interference and self-termination), though, rather than temporal separation (e.g., priming), However, such spatial factors as letter size and interletter spacing had no consistent effect on the speed advantage forsame pairs, and it was concluded that temporal, not spatial, separation enhances the fast-same effect on sequential trials, Consistent with the response-competition model (Eriksen, O’Hara, & Eriksen), responses were slower and more errorful to similar than to dissimilardifferent pairs, and were equally fast to dissimilar andsame pairs on simultaneous trials.