Showing papers by "Carnegie Mellon University published in 1991"

Bounded Rationality and Organizational Learning

Abstract: : If organization theory finds it useful to draw upon some of the ideas that have emerged in cognitive psychology, it will be advantageous to borrow also the terminology used in discussing these ideas. Without working toward a higher level of consistency in terminology than prevails in organization theory today, it will be difficult or impossible to cumulate and assemble into a coherent structure the knowledge we are gaining from individual case studies and experiments. We will be continually reinventing wheels. That is a luxury we cannot afford. The happy band of researchers on organization theory is sufficiently small to be kept fully occupied discovering and verifying the theory just once. (Author) (kr)

Connections: New Ways of Working in the Networked Organization

Abstract: From the Publisher: Computer networking is changing the way people work and the way organizations function. "Connections" is an accessible guide to the promise and the pitfalls of this latest phase of the computer revolution.

Psychological Stress and Susceptibility to the Common Cold

Abstract: Background. It is not known whether psychological stress suppresses host resistance to infection. To investigate this issue, we prospectively studied the relation between psychological stress and the frequency of documented clinical colds among subjects intentionally exposed to respiratory viruses. Methods. After completing questionnaires assessing degrees of psychological stress, 394 healthy subjects were given nasal drops containing one of five respiratory viruses (rhinovirus type 2, 9, or 14, respiratory syncytial virus, or coronavirus type 229E), and an additional 26 were given saline nasal drops. The subjects were then quarantined and monitored for the development of evidence of infection and symptoms. Clinical colds were defined as clinical symptoms in the presence of an infection verified by the isolation of virus or by an increase in the virus-specific antibody titer. Results. The rates of both respiratory infection (P<0.005) and clinical colds (P<0.02) increased in a dose-response manner...

Rete: a fast algorithm for the many pattern/many object pattern match problem

Abstract: The Rete Match Algorithm is an efficient method for companng a large collection of patterns to a large collection of objects. It finds all the objects that match each pattern The algorithm was developed for use in production system interpreters, and it has been used for systems containing from a few hundred to more than a thousand patterns and objects. This article presents the algorithm in detail It explains the basic concepts of the algorithm, it describes pattern and object representations that are appropriate for the algorithm, and it describes the operations performed by the pattern matcher.

Reflections of the Environment in Memory

Abstract: Availability of human memories for specific items shows reliable relationships to frequency, recency, and pattern of prior exposures to the item. These relationships have defied a systematic theoretical treatment. A number of environmental sources (New York Times, parental speech, electronic mail) are examined to show that the probability that a memory will be needed also shows reliable relationships to frequency, recency, and pattern of prior exposures. Moreover, the environmental relationships are the same as the memory relationships. It is argued that human memory has the form it does because it is adapted to these environmental relationships. Models for both the environment and human memory are described. Among the memory phenomena addressed are the practice function, the retention function, the effect of spacing of practice, and the relationship between degree of practice and retention.

The Adaptive Nature of Human Categorization.

Abstract: A rational model of human categorization behavior is presented that assumes that categorization reflects the derivation of optimal estimates of the probability of unseen features of objects. A Bayesian analysis is performed of what optimal estimations would be if categories formed a disjoint partitioning of the object space and if features were independently displayed within a category. This Bayesian analysis is placed within an incremental categorization algorithm. The resulting rational model accounts for effects of central tendency of categories, effects of specific instances, learning of linearly nonseparable categories, effects of category labels, extraction of basic level categories, base-rate effects, probability matching in categorization, and trial-by-trial learning functions. Although the rational model considers just I level of categorization, it is shown how predictions can be enhanced by considering higher and lower levels. Considering prediction at the lower, individual level allows integration of this rational analysis of categorization with the earlier rational analysis of memory (Anderson & Milson, 1989). Anderson (1990) presented a rational analysis ot 6 human cognition. The term rational derives from similar "rational-man" analyses in economics. Rational analyses in other fields are sometimes called adaptationist analyses. Basically, they are efforts to explain the behavior in some domain on the assumption that the behavior is optimized with respect to some criteria of adaptive importance. This article begins with a general characterization ofhow one develops a rational theory of a particular cognitive phenomenon. Then I present the basic theory of categorization developed in Anderson (1990) and review the applications from that book. Since the writing of the book, the theory has been greatly extended and applied to many new phenomena. Most of this article describes these new developments and applications.

Specifying gestures by example

Abstract: Gesture-Based interfaces offer an alternative to traditional keyboard, menu, and direct manipulation interfaces. The ability to specify objects, an operation, and additional parameters with a single intuitive gesture appeals to both novice and experienced users. Unfortunately, gesture-based interfaces have not been extensively researched, partly because they are difficult to create. This paper describes GRANDMA, a toolkit for rapidly adding gestures to direct manipulation interfaces. The trainable single-stroke gesture recognizer used by GRANDMA is also described.

Stress and infectious disease in humans.

Abstract: This article reviews research on the role of stress in infectious disease as measured either by illness behaviors (symptoms and use of health services) or by verified pathology. Substantial evidence was found for an association between stress and increased illness behavior, and less convincing but provocative evidence was found for a similar association between stress and infectious pathology. Introverts, isolates, and persons lacking social skills may also be at increased risk for both illness behaviors and pathology. Psychobiological models of how stress could influence the onset and progression of infectious disease and a psychological model of how stress could influence illness behaviors are proposed.

A Theory of Group Stability

Abstract: Some groups endure longer, are more stable, and are better able than other groups to incorporate new members or ideas without losing their distinctiveness. I present a simple model of individual behavior based on the thesis that interaction leads to shared knowledge and that relative shared knowlege leads to interaction. Using this model I examine the structural and cultural bases of group stability. Groups that are stable in the short run do not necessarily retain their distinctiveness in the long run as new members enter or new ideas are discovered. A Theory of Group Stability Consider two hypothetical high-tech consulting companies -Fairview and Taliesin -that specialize in designing medical information systems. Over the years, both companies have gained considerable expertise. Despite these similarities, however, the companies are quite different. Fairview was founded by six men, all graduates of BL Tech with degrees in business. The current members of the company get along well -they frequently hold Monday evening meetings and tend to have a unified perspective on how to develop systems. Taliesin resulted from a chance meeting in an airport between a computer science major and a business major interested in health care. Taliesin currently employs 12 men and women, who graduated from different universities and who represent a variety of disciplines. As at Fairview, the Taliesin employees get along well. Even so, they spend less time together than do Fairview employees, and often split into subgroups to handle multiple clients. Fairview and Taliesin thus represent very different sociocultural configurations: Fairview is small, socially undifferentiated, and culturally homogeneous; Taliesin is large, socially differentiated, and culturally heterogeneous. Because of increasing requests by clients, both companies are considering moving into the area of limited medical expert systems. Such a move may require hiring at least one new person. Will the addition of a new member or new information destabilize these groups? What are the structural and cultural bases for group stability? For example, what types of groups are the most stable? What types of groups are least affected by the addition of new members? What types of groups are least affected by expansion of the group's knowledge base? Various theories attempt to explain why some groups endure longer than others. These explanations usually suggest that favorable contexts are necessary for group stability, particularly when memberships change and new technologies and ideas emerge, and that highly differentiated contexts produce multiple groups. Such contexts frequently are characterized in terms of their environmental (Aldrich 1979; Hannan and Freeman 1977), institutional (Blau 1967; Collins 1975; Etzioni 1964; Sills 1957; Simmel [1908] 1955), ritual (Durkheim [1912] 1954; Goffman 1959; Mead [1934]1962), or functional (Aberle, Cohen, Davis, Leng, and Sutton 1950; Mack 1967; Parsons 1949, 1951) characteristics, but rarely in terms as simple as "who knows what." Although these explanations tend to assume that groups members learn, interact, and communicate, the precise mechanisms underlying such processes are underspecified and the power of these fundamental "cognitive" mechanisms in producing and maintaining groups are ignored. In contrast to these context-dependent themes, I present a "constructural" perspective that is spare and highly general (see also Carley 1986a, 1986b, 1990, forthcoming a, forthcoming c) . According to this perspective, social change and stability result from changes in the distribution of knowledge as individuals interact and acquire and disseminate information. Constructuralism can be viewed as a modification of structural symbolic interactionism (Stryker 1980) in which knowledge mediates interaction and language, or it can be viewed as a modification of social differentiation theory (Blau 1977) in which knowledge mediates social dimensions (e.g., religion, sex, and age) and interaction. According to both theories, groups can be defined by shared social, demographic, or sociocultural features -e.g., Catholic boys age 13. According to the constructural perspective, each position on a social dimension is associated with a particular body of knowledge that is acquired by individuals with that characteristic -e.g., Catholics learn the tenets of Catholicism, the order of the mass, the holy days of obligation, and so forth. It is the wealth and uniqueness of the information associated with that dimension, not the dimension per se, that determines behavior. Constructural theory derives group characteristics and behavior from the characteristics and behaviors of individual group members that, in turn, are generated by processes relating individual knowledge to individual behavior. Three axioms capture this relationship: (1) individuals are continuously engaged in acquiring and communicating information; (2) what individuals know influences their choices of interaction partners; and (3) an individual's behavior is a function of his or her current knowledge. According to the constructural perspective, groups form and endure because of discrepancies in who knows what. Groups typically are in flux simply because members are continually acquiring new information and communicating it to each other. A group is perfectly stable only when no new information enters the group and everyone in the group knows everything that anyone else in the group knows. From this perspective, neither institutional nor motivational factors are necessary for group stability, nor is a differentiated environment or a differentiated set of institutional or motivational factors necessary for distinct groups. Rather, these factors may serve as secondary forces modifying the impact of the primary force -interaction and the exchange of information. To the extent that institutions are forms of knowledge (Berger and Luckman 1966), this perspective suggests that the distribution of knowledge across the population corresponds to the distribution of institutions and that perfect stability signals the effective demise of institutions because individuals, by knowing everything, are effectively members of all institutions. Institutions can maintain their identity, stability, and cultural distinctiveness by preventing the flow of information. Differences in the information possessed by individuals may arise for many reasons, e.g., because they were born at different places or at different times. Demography, geography, and innovation permit information to be distributed unequally across the population. Regardless of the sources of these discrepancies, at any point societies can be characterized in terms of their social structure, culture (distribution of information), population, number of groups, size of groups, and total amount of information. According to the constructural perspective, this sociocultural configuration changes as individuals interact, communicate, and adapt to new information. The initial sociocultural configuration and the processes of information exchange will determine whether groups endure and whether these groups, when confronted with new members or new ideas, will be able to reconstruct, i.e., adopt new members or ideas without losing their uniqueness as a group. I develop a simple dynamic simulation model of the interaction shared knowledge cycle in which individuals interact, communicate, and adapt to new information. (The Appendix presents an outline of the simulation program.) A more detailed technical description of the model is presented in Carley (1990).) Despite its simplicity, important and complex social behaviors emerge, many of which are consistent with existent empirical data. I use the model to explore group stability and endurance in one-group and two-group societies in which there is no change in group membership and no new ideas. I then examine the ability of these groups to assimilate a new member or idea without losing their uniqueness as a group. Finally, I discuss the model's scope, some important extensions to the model, and the role of simulation in this type of analysis.

The equalization phenomenon: status effects in computer-mediated and face-to-face decision-making groups

Abstract: New computer-based communications technologies make possible new or expanded forms of group work. Although earlier researchers suggest that scant social information in these technologies might cause status equalization in groups, no experimental test of this phenomenon has been made. In a laboratory experiment, we compared face-to-face communication with electronic mail in decision-making groups whose members differed in social status. We examined status in two ways: by varying the external status of group members, and by varying the decision task to manipulate expertise. When the groups made decisions in face-to-face meetings, the high-status member dominated discussions with the three low-status members. Also, the high-status member more often was a "first advocate" in the face-to-face discussions, and first advocates were more influential than later advocates. These status inequalities in face-to-face decision making were pronounced just when the high-status member's expertise was relevant to the decision task. When the same groups made comparable decisions using electronic mail, status and expertise inequalities in participation were reduced. A striking and unexpected result was that "first" advocacy was shared by high-and low-status members in discussions using electronic mail. This behavior resulted in increased equality of influence across status and expertise. We discuss the implications of these results for research and for design of new communication technologies.

An Algorithm for Fast Recovery of Sparse Causal Graphs

Abstract: Previous asymptotically correct algorithms for recovering causal structure from sample probabilities have been limited even in sparse causal graphs to a few variables. We describe an asymptotically...

Efficient training of artificial neural networks for autonomous navigation

Abstract: The ALVINN (Autonomous Land Vehicle In a Neural Network) project addresses the problem of training artificial neural networks in real time to perform difficult perception tasks. ALVINN is a backpropagation network designed to drive the CMU Navlab, a modified Chevy van. This paper describes the training techniques that allow ALVINN to learn in under 5 minutes to autonomously control the Navlab by watching the reactions of a human driver. Using these techniques, ALVINN has been trained to drive in a variety of circumstances including single-lane paved and unpaved roads, and multilane lined and unlined roads, at speeds of up to 20 miles per hour.

Surface reflection: physical and geometrical perspectives

Abstract: Reflectance models based on physical optics and geometrical optics are studied. Specifically, the authors consider the Beckmann-Spizzichino (physical optics) model and the Torrance-Sparrow (geometrical optics) model. These two models were chosen because they have been reported to fit experimental data well. Each model is described in detail, and the conditions that determine the validity of the model are clearly stated. By studying reflectance curves predicted by the two models, the authors propose a reflectance framework comprising three components: the diffuse lobe, the specular lobe, and the specular spike. The effects of surface roughness on the three primary components are analyzed in detail. >

A computational model of semantic memory impairment: modality specificity and emergent category specificity.

Abstract: It is demonstrated how a modality-specific semantic memory system can account for category-specific impairments after brain damage. In Experiment 1, the hypothesis that visual and functional knowledge play different roles in the representation of living things and nonliving things is tested and confirmed. A parallel distributed processing model of semantic memory in which knowledge is subdivided by modality into visual and functional components is described. In Experiment 2, the model is lesioned, and it is confirmed that damage to visual semantics primarily impairs knowledge of living things, and damage to functional semantics primarily impairs knowledge of nonliving things. In Experiment 3, it is demonstrated that the model accounts naturally for a finding that had appeared problematic for a modality-specific architecture, namely, impaired retrieval of functional knowledge about living things. Finally, in Experiment 4, it is shown how the model can account for a recent observation of impaired knowledge of living things only when knowledge is probed verbally.

A random polynomial-time algorithm for approximating the volume of convex bodies

Abstract: A randomized polynomial-time algorithm for approximating the volume of a convex body K in n-dimensional Euclidean space is presented. The proof of correctness of the algorithm relies on recent theory of rapidly mixing Markov chains and isoperimetric inequalities to show that a certain random walk can be used to sample nearly uniformly from within K.

Real-time obstacle avoidance using harmonic potential functions

Abstract: A novel formulation of the artificial potential approach to the obstacle avoidance problem for a mobile robot or a manipulator in a known environment is presented. Previous formulations of artificial potentials for obstacle avoidance have exhibited local minima in a cluttered environment. To build an artificial potential field, the authors use harmonic functions that completely eliminate local minima even for a cluttered environment. The panel method is used to represent arbitrarily shaped obstacles and to derive the potential over the whole space. Based on this potential function, an elegant control strategy for the real-time control of a robot is proposed. Simulation results are presented for a bar-shaped mobile robot and a three-degree-of-freedom planar redundant manipulator. >

Self-Assembly in Synthetic Routes to Molecular Devices. Biological Principles and Chemical Perspectives: A Review

Abstract: This article first provides a concise summary of the concepts, limitations, and paradigms of biological self-assembly processes, then surveys covalent self-assembly processes in the synthesis of 3-dimensional molecules and ordered assemblies

Honeymoons and the Liability of Adolescence: A New Perspective on Duration Dependence in Social and Organizational Relationships

Abstract: Many social relationships face a liability of adolescence; the hazard rate of the relationship ending increases for an initial period and then declines. The pervasiveness of this phenomenon suggests that there may be a common set of underlying factors. We believe that many relationships start with an initial stock of assets, which can take a variety of forms (depending on the context), including favorable prior beliefs, trust, goodwill, financial resources, or psychological commitment. We hypothesize that these assets reduce the risk of the relationship dissolving when the initial outcomes of the relationship are unfavorable, resulting in a honeymoon period. The duration of this honeymoon period is a function of the magnitude of these assets. We survey earlier results and report new analyses. For organizational theory, this model of duration dependence raises problems for Stinchcombe's (1965) liability of newness hypothesis, which is central to much theorizing on the population ecology of organizations. W...

Learning the structure of event sequences.

Abstract: How is complex sequential material acquired, processed, and represented when there is no intention to learn? Two experiments exploring a choice reaction time task are reported. Unknown to Ss, successive stimuli followed a sequence derived from a "noisy" finite-state grammar. After considerable practice (60,000 exposures) with Experiment 1, Ss acquired a complex body of procedural knowledge about the sequential structure of the material. Experiment 2 was an attempt to identify limits on Ss ability to encode the temporal context by using more distant contingencies that spanned irrelevant material. Taken together, the results indicate that Ss become increasingly sensitive to the temporal context set by previous elements of the sequence, up to 3 elements. Responses are also affected by priming effects from recent trials. A connectionist model that incorporates sensitivity to the sequential structure and to priming effects is shown to capture key aspects of both acquisition and processing and to account for the interaction between attention and sequence structure reported by Cohen, Ivry, and Keele (1990).

Value elicitation: Is there anything in there?

Abstract: Eliciting people's values is a central pursuit in many areas of the social sciences, including survey research, attitude research, economics, and behavior decision theory. These disciplines differ considerably in the core assumptions they make about the nature of the values that are available for elicitation. These assumptions lead to very different methodological concerns and interpretations, as well as to different risks of reading too much or too little into people's responses. The analysis here characterizes these assumptions and the research paradigms based on them. It also offers an account of how they arise, rooted in the psychological and sociological contexts within which different researchers function.

On the complexity of VLSI implementations and graph representations of Boolean functions with application to integer multiplication

Abstract: Lower-bound results on Boolean-function complexity under two different models are discussed. The first is an abstraction of tradeoffs between chip area and speed in very-large-scale-integrated (VLSI) circuits. The second is the ordered binary decision diagram (OBDD) representation used as a data structure for symbolically representing and manipulating Boolean functions. The lower bounds demonstrate the fundamental limitations of VLSI as an implementation medium, and that of the OBDD as a data structure. It is shown that the same technique used to prove that any VLSI implementation of a single output Boolean function has area-time complexity AT/sup 2/= Omega (n/sup 2/) also proves that any OBDD representation of the function has Omega (c/sup n/) vertices for some c>1 but that the converse is not true. An integer multiplier for word size n with outputs numbered 0 (least significant) through 2n-1 (most significant) is described. For the Boolean function representing either output i-1 or output 2n-i-1, where 1 >

The microgenetic method. A direct means for studying cognitive development.

Abstract: Progress in understanding cognitive developmental change mechanisms requires methods that yield detailed data about particular changes. The microgenetic method is an approach that can yield such data. It involves (a) observations of individual children throughout the period of the change, (b) a high density of observations relative to the rate of change within that period, and (c) intensive trial-by-trial analyses intended to infer the processes that gave rise to the change. This approach can illuminate both qualitative and quantitative aspects of change, indicate the conditions under which changes occur, and yield otherwise unobtainable information about short-lived transition strategies. The cost in time and effort of such studies is often high, but the value of the information about change can more than justify the cost.

Situation Awareness: A Critical But Ill-Defined Phenomenon

Abstract: Situation awareness has recently gained considerable attention as a performance-related psychological concept. This is especially true in the aviation domain where it is considered an essential prerequisite for the safe operation of the complex dynamic system 'aircraft.' There are concerns, however, that inappropriately designed automatic systems introduced to advanced flight decks may reduce situation awareness and thereby put aviation safety at risk. Situation awareness has thus become a ubiquitous phrase. It's use is most often based on an intuitive understanding; a commonly accepted definition is still missing. To fill this gap, we analyze the cognitive basis of the concept, embedding it in the context of related psychological concepts. On this basis, methodological approaches to the investigation of situation awareness are discussed.

Models of My Life

Abstract: Part I Journey to a 21st birthday: the boy in Wisconsin forests and fields education in Chicago encounter with a scientific revolution - political science at Chicago. Part II The scientist as a young man: a taste of research - the City Managers' Association managing research - Berkeley teaching at Illinois Tech a matter of loyalty building a business school - the Graduate School of Industrial Administration research and science politics mazes without minotaurs roots of artificial intelligence climbing the mountain - artificial intelligence achieved. Part III View from the mountain: exploring the plain personal threads in the warp creating a university environment for cognitive science and A.I. on being argumentative the student troubles the scientist as politician foreign adventures. Part IV Research after 60: from Nobel to now the amateur diplomat in China and the Soviet Union guides for choice. Afterword: the scientist as problem solver.

Components of visual orienting in early infancy: Contingency learning, anticipatory looking, and disengaging

Abstract: Three aspects of the development of visual orienting in infants of 2, 3, and 4 months of age are examined in this paper. These are the age of onset and sequence of development of (1) the ability to readily disengage gaze from a stimulus, (2) the ability to consistently show “anticipatory” eye movements, and (3) the ability to use a central cue to predict the spatial location of a target. Results indicated that only the 4--month-old group was easily able to disengage from an attractive central stimulus to orient toward a simultaneously presented target. The 4--month-old group also showed more than double the percentage of “anticipatory” looks than did the other age groups. Finally, only the 4--month-old group showed significant evidence of being able to acquire the contingent relationship between a central cue and the spatial location (to the right or to the left) of a target. Measures of anticipatory looking and contingency learning were not correlated. These findings are, in general terms, consistent with the predictions of matura-tional accounts of the development of visual orienting.

Organizational Learning Curves: A Method for Investigating Intra-Plant Transfer of Knowledge Acquired Through Learning by Doing

Abstract: This paper illustrates how a learning-curve model can be generalized to investigate potential explanations of organizational learning. The paper examines the hypothesis that knowledge acquired through by learning by doing is embodied in an organization's technology by analyzing the amount of transfer that occurs across shifts within a plant. If knowledge becomes completely embodied in technology, transfer across shifts should be complete since both shifts use the same technology. Methods that can be used for studying intra-plant transfer of knowledge are presented. The methods are illustrated by analyzing data from a plant that began production with one shift and then added a second shift several months into the production program. Three aspects of transfer are analyzed: 1 carry forward of knowledge when the plant makes the transition from one to two shifts, 2 transfer across shifts after both shifts are operating, and 3 transfer across time. Results indicate that substantial, but less than complete, transfer of knowledge occurred when the second shift was introduced. Once both shifts were operating, partial transfer across them occurred. Implications of the results for a theory of organizational learning and practical applications are discussed.