User-interruption in human-computer interaction (HCI) is an increasingly important problem. Many of the useful advances in intelligent and multitasking computer systems have the significant side effect of greatly increasing user-interruption. This previously innocuous HCI problem has become critical to the successful function of many kinds of modern computer systems. Unfortunately, no HCI design guidelines exist for solving this problem. In fact, theoretical tools do not yet exist for investigating the HCI problem of user-interruption in a comprehensive and generalizable way. This report asserts that a single unifying definition of user-interruption and the accompanying practical taxonomy would be useful theoretical tools for driving effective investigation of this crucial HCI problem. These theoretical tools are constructed here. A comprehensive analysis is conducted through the existing literature. Theoretical constructs from several relevant but diverse fields are identified and discussed. A unifying definition of user-interruption is synthesized. This new definition is supported with an array of postulates, assertions, and a taxonomy of human interruption to facilitate its practical application.

The "cocktail party effect"---the ability to focus one's listening attention on a single talker among a cacophony of conversations and background noise---has been recognized for some time. This specialized listening ability may be because of characteristics of the human speech production system, the auditory system, or high-level perceptual and language processing. This paper investigates the literature on what is known about the effect, from the original technical descriptions through current research in the areas of auditory streams and spatial display systems. The underlying goal of the paper is to analyze the components of this effect to uncover relevant attributes of the speech production and perception chain that could be exploited in future speech communication systems. The motivation is to build a system that can simultaneously present multiple streams of speech information such that a user can focus on one stream, yet easily shift attention to the others. A set of speech appli...

This article argues that (a) ego, or self, is an organization of knowledge, (b) ego is characterized by cognitive biases strikingly analogous to totalitarian information-control strategies, and (c) these totalitarian-ego biases junction to preserve organization in cognitive structures. Ego's cognitive biases are egocentricity (self as the focus of knowledge), "beneffectance" (perception of responsibility for desired, but not undesired, outcomes), and cognitive conservatism (resistance to cognitive change). In addition to being pervasively evident in recent studies of normal human cognition, these three biases are found in actively functioning, higher level organizations of knowledge, perhaps best exemplified by theoretical paradigms in science. The thesis that egocentricity, beneffectance, and

We present an empirical study investigating collaborative and individual decision-making about data using two different information visualization systems. Based on previous research, one system is considered more transparent than the other in terms of visual representation and functionality. We found that people who worked in groups were more correct in their answers for objective questions, based on searching a large dataset. These results held for the more transparent system, but not the less transparent system. In a second task, groups were more accurate in their results for a free data discovery task. Again, these results held for the more transparent system only. Subjects using this system also produced results that were higher in complexity but judged lower in importance. Groups and individuals did not differ. We suggest that given the right visualization system, groups do better than individuals in finding more accurate results, but not necessarily increased or more meaningful results.

Researchers have proposed building auditory interfaces that make use of the "cocktail party effect" -- the human's ability to selectively attend to a single talker or stream of audio among a cacophony of others -- to reduce the amount of time required to listen [Arons 1992, Cohen 1992, Mullins 1993]. The premise is that by presenting multiple streams of audio simultaneously, the user will be able to focus on one, yet overhear interesting information in another and easily switch attention. In this study, subjects listen to multiple channels of audio and perform two tasks simultaneously -- listening comprehension and target monitoring. While listening to one passage of speech, the subject must identify target words in one or two other passages played simultaneously. The results showed that the subject's performance, both listening comprehension and target monitoring, decreased significantly as the number of simultaneous audio channels increased.

We present an empirical study in which we investigated group vs. individual performance with collaborative information visualization environments (CIVEs), the effects of system transparency on users' performance and the effects of different collaborative settings on CIVE usage. Subjects searched for findings with CIVEs, working either alone, in a collocated dyad using a shared electronic whiteboard, or in a remote dyad using application sharing. Groups answered more questions correctly and took less time with the more transparent CIVE than groups using the less transparent CIVE. We interpret our results to mean that groups have better self-corrective abilities when the system is transparent. We present a stage model to explain the collaborative process of using CIVEs, which accounts for task type, collaborative setting, and system transparency.

This paper provides an overview of developments in a dual processing theory of automatic and controlled processing that began with the empirical and theoretical work described by Schneider and Shiffrin (1977) and Shiffrin and Schneider (1977) over a quarter century ago. A review of relevant empirical findings suggests that there is a set of core behavioral phenomena reflecting differences between controlled and automatic processing that must be addressed by a successful theory. These phenomena relate to: consistency in training, serial versus parallel processing, level of effort, robustness to stressors, degree of control, effects on long-term memory, and priority encoding. We detail a computational model of controlled processing, CAP2, that accounts for these phenomena as emergent properties of an underlying hybrid computational architecture. The model employs a large network of distributed data modules that can categorize, buffer, associate, and prioritize information. Each module is a connectionist network with input and output layers, and each module communicates with a central Control System by outputting priority and activity report signals, and by receiving control signals. The Control System is composed of five processors including a Goal Processor, an Attention Controller, an Activity Monitor, an Episodic Store, and a Gating & Report Relay. The transition from controlled to automatic processing

The meaning people assign to physical sensations can have profound implications for their physical and psychological health. A predominant research question in somatic interpretation asks if it is more adaptive to distract one's attention away from a potentially unpleasant sensation or to focus one's attention on it. This question, however, has yielded equivocal answers. Many apparent ambiguities in this research can be traced to a failure to distinguish the content of a person's attention from its mere direction or degree. A model of somatic interpretation is discussed, incorporating not only perceptual focus but also the attributions, goals, coping strategies, and prior hypotheses of the perceiver, thus delineating the psychobiological conditions under which various attentional strategies should be adaptive. In contrast to the prevailing concern with when and why somatic distraction doesn't "work, " this conceptual analysis also considers when and why somatic attention does. Theoretical and methodological issues are discussed, as is the potential utility of somatic attention in cardiac rehabilitation and multiple sclerosis. He shivered repeatedly as he lay looking out through the wooden arch at the reeking, dripping damp outside, which seemed on the point of passing over into snow. It was strange that with all that

This paper addresses the problems of (1) representing natural shapes such as mountains, trees and clouds, and (2) computing such a description from image data. In order to solve these problems we must be able to relate natural surfaces to their images; this requires a good model of natural surface shapes. Fractal functions are good a choice for modeling natural surfaces because (1) many physical processes produce a fractal surface shape, (2) fractals are widely used as a graphics tool for generating naturallooking shapes, and (3) a survey of natural imagery has shown that the 3-D fractal surface model, transformed by the image formation process, furnishes an accurate description of both textured and shaded image regions. This characterization of image regions has been shown to be stable over transformations of scale and linear transforms of intensity. Much work has been accomplished that is relevant to computing 3-D information from the image data, and the computation of a 3-D fractal-based representation from actual image data has been demonstrated using an image of a mountain. This example shows the potential of a fractal-based representation for efficiently computing good 3-D representations of natural shapes, including such seemingly-difficult cases as mountains, clumps of leaves and clouds. I

Like traditional classroom instruction, distributed learning derives from passive training paradigms. Just as studentcentered classroom teaching methods have been applied over several decades of classroom instruction, interactive approaches have been encouraged for distributed learning. While implementation of multimedia-based training features may appear to produce active learning, sophisticated use of multimedia features alone does not necessarily enhance learning. This paper describes the application of cognitive science principles to enhance learning in a studentcentered, distributed learning environment. The basis of the application of cognitive principles is the innovative use of multimedia technology to implement interaction elements that support scenario-based training. These simple multimedia interactions are used to support new concepts and later combined with other interaction elements to create more complex, integrated practical exercises. This technology-based approach may be applied in a variety of training and education contexts, but is especially well suited for training of equipment operators and maintainers. Based on classroom training material developed by the US Army for operation and maintenance of wireless logistics communications equipment, the Pacific Northwest National Laboratory designed and developed an interactive, student-centered distributed-learning application for Combat Service Support Automated Information Systems