INTERACTING WITH COMPUTERS

Effect of age on human-computer-interface control via neck electromyography
Hands GL and Stepp CE
The purpose of this study was to determine the effect of age on visuomotor tracking using submental and anterior neck surface electromyography (sEMG) to assess feasibility of computer control via neck musculature, which allows people with little remaining motor function to interact with computers. Thirty-two healthy adults participated: sixteen younger adults aged 18 - 29 years and sixteen older adults aged 69 - 85 years. Participants modulated sEMG to achieve targets presented at different amplitudes using real-time visual feedback. Root-mean-squared (RMS) error was used to quantify tracking performance. RMS error was increased for older adults relative to younger adults. Older adults demonstrated more RMS error than younger adults as a function of increasing target amplitude. The differential effects of age found on static tracking performance in anterior neck musculature suggest more difficult translation of human-computer-interfaces controlled using anterior neck musculature for static tasks to older populations.
Querying Event Sequences by Exact Match or Similarity Search: Design and Empirical Evaluation
Wongsuphasawat K, Plaisant C, Taieb-Maimon M and Shneiderman B
Specifying event sequence queries is challenging even for skilled computer professionals familiar with SQL. Most graphical user interfaces for database search use an exact match approach, which is often effective, but near misses may also be of interest. We describe a new similarity search interface, in which users specify a query by simply placing events on a blank timeline and retrieve a similarity-ranked list of results. Behind this user interface is a new similarity measure for event sequences which the users can customize by four decision criteria, enabling them to adjust the impact of missing, extra, or swapped events or the impact of time shifts. We describe a use case with Electronic Health Records based on our ongoing collaboration with hospital physicians. A controlled experiment with 18 participants compared exact match and similarity search interfaces. We report on the advantages and disadvantages of each interface and suggest a hybrid interface combining the best of both.
The impact of progress indicators on task completion
Conrad FG, Couper MP, Tourangeau R and Peytchev A
A near ubiquitous feature of user interfaces is feedback on task completion or progress indicators such as the graphical bar that grows as more of the task is completed. The presumed benefit is that users will be more likely to complete the task if they see they are making progress but it is also possible that feedback indicating slow progress may sometimes discourage users from completing the task. This paper describes two experiments that evaluate the impact of progress indicators on the completion of on-line questionnaires. In the first experiment, progress was displayed at different speeds throughout the questionnaire. If the early feedback indicated slow progress, abandonment rates were higher and users' subjective experience more negative than if the early feedback indicated faster progress. In the second experiment, intermittent feedback seemed to minimize the costs of discouraging feedback while preserving the benefits of encouraging feedback. Overall, the results suggest that when progress seems to outpace users' expectations, feedback can improve their experience though not necessarily their completion rates; when progress seems to lag behind what users expect, feedback degrades their experience and lowers completion rates.
Response to a Relational Agent by Hospital Patients with Depressive Symptoms
Bickmore TW, Mitchell SE, Jack BW, Paasche-Orlow MK, Pfeifer LM and Odonnell J
Depression affects approximately 15% of the US population, and is recognized as an important risk factor for poor outcomes among patients with various illnesses. Automated health education and behavior change programs have the potential to help address many of the shortcomings in health care. However, the role of these systems in the care of patients with depression has been insufficiently examined. In the current study, we sought to evaluate how hospitalized medical patients would respond to a computer animated conversational agent that has been developed to provide information in an empathic fashion about a patient's hospital discharge plan. In particular, we sought to examine how patients who have a high level of depressive symptoms respond to this system. Therapeutic alliance-the trust and belief that a patient and provider have in working together to achieve a desired therapeutic outcome- was used as the primary outcome measure, since it has been shown to be important in predicting outcomes across a wide range of health problems, including depression. In an evaluation of 139 hospital patients who interacted with the agent at the time of discharge, all patients, regardless of depressive symptoms, rated the agent very high on measures of satisfaction and ease of use, and most preferred receiving their discharge information from the agent compared to their doctors or nurses in the hospital. In addition, we found that patients with symptoms indicative of major depression rated the agent significantly higher on therapeutic alliance compared to patients who did not have major depressive symptoms. We conclude that empathic agents represent a promising technology for patient assessment, education and counseling for those most in need of comfort and caring in the inpatient setting.
Visualizing Set Concordance with Permutation Matrices and Fan Diagrams
Kim B, Lee B and Seo J
Scientific problem solving often involves concordance (or discordance) analysis among the result sets from different approaches. For example, different scientific analysis methods with the same samples often lead to different or even conflicting conclusions. To reach a more judicious conclusion, it is crucial to consider different perspectives by checking concordance among those result sets by different methods. In this paper, we present an interactive visualization tool called ConSet, where users can effectively examine relationships among multiple sets at once. ConSet provides an overview using an improved permutation matrix to enable users to easily identify relationships among sets with a large number of elements. Not only do we use a standard Venn diagram, we also introduce a new diagram called Fan diagram that allows users to compare two or three sets without any inconsistencies that may exist in Venn diagrams. A qualitative user study was conducted to evaluate how our tool works in comparison with a traditional set visualization tool based on a Venn diagram. We observed that ConSet enabled users to complete more tasks with fewer errors than the traditional interface did and most users preferred ConSet.
How should Fitts' Law be applied to human-computer interaction?
Gillan DJ, Holden K, Adam S, Rudisill M and Magee L
The paper challenges the notion that any Fitts' Law model can be applied generally to human-computer interaction, and proposes instead that applying Fitts' Law requires knowledge of the users' sequence of movements, direction of movement, and typical movement amplitudes as well as target sizes. Two experiments examined a text selection task with sequences of controlled movements (point-click and point-drag). For the point-click sequence, a Fitts' Law model that used the diagonal across the text object in the direction of pointing (rather than the horizontal extent of the text object) as the target size provided the best fit for the pointing time data, whereas for the point-drag sequence, a Fitts' Law model that used the vertical size of the text object as the target size gave the best fit. Dragging times were fitted well by Fitts' Law models that used either the vertical or horizontal size of the terminal character in the text object. Additional results of note were that pointing in the point-click sequence was consistently faster than in the point-drag sequence, and that pointing in either sequence was consistently faster than dragging. The discussion centres around the need to define task characteristics before applying Fitts' Law to an interface design or analysis, analyses of pointing and of dragging, and implications for interface design.
A Virtual Reality Platform for Analyzing Remote Archaeological Sites
Cassidy B, Sim G, Wayne Robinson D and Gandy D
This paper describes a Virtual Reality (VR) prototype developed to help archaeologists and other stakeholders explore and analyse archaeological data in a more immersive context. We describe a VR reconstruction of Pleito Cave, a fragile world class rock-art site with accessibility limitation. Key stakeholders are identified and a prototype is described that provides a VR platform for visualizing and interacting with complex archaeological data (gathered from techniques such as decorrelation stretch and X-ray fluorescence) virtually 'in , in a way that would not be possible at the real site. The prototype allows multiple remote users to interact with the cave together remotely providing opportunities for collaborative interpretation and analysis of archaeological data. We also present a survey-based evaluation in which both archaeologists and Native American stakeholders indicate positive responses for measures of both engagement and value.