About

Eugene Johnsen is an Emeritus Faculty member in the Department of Mathematics at the University of California, Santa Barbara. His specialization includes combinatorial mathematics, matrix theory, mathematical sociology, and social network theory. He is associated with the Department of Mathematics at UCSB, located in South Hall, Room 6607, and has an office hours schedule from Monday to Friday, 9-12 and 1-4. His contact information includes an email address (johnsen@math.ucsb.edu), a phone number (805-893-5808), and a fax number (805-893-2385). His work focuses on mathematical areas that intersect with social sciences, emphasizing the structural and theoretical aspects of social networks and combinatorial structures.

Research topics

• Mathematics
• Psychology
• Social psychology
• Combinatorics
• Computer science

Selected publications

• Status, Networks, and Opinion Change: An Experimental Investigation

  Social Psychology Quarterly · 2017-04-27 · 10 citations

  articleSenior author

  This study evaluates two prominent sociological theories of interpersonal influence: status characteristics theory and social influence network theory. In application to status settings, we test social influence network theory and its established measurement model as well as a recent “modular integration” that operationalizes social influence network theory’s central constructs by incorporating assumptions from status characteristics theory. The two formulations are systematically examined within an open interaction experiment where groups of two, three, and four participants discussed their initial opinions and formed final opinions on two separate issues. Participants were randomly assigned to status positions, which status characteristics theory emphasizes as normative foundations of influence in small task-oriented groups. Analyses of group-level and individual-level opinion change support social influence network theory as it has been used in the past and suggest that status characteristics theory shows promise in modeling the influence networks that drive opinion change at the individual level.

  PublisherDOI

• Two steps to obfuscation

  Social Networks · 2014-05-13

  preprintOpen accessSenior author
  PublisherOA PDFDOI

• Social Influence Network Theory: A Sociological Examination of Small Group Dynamics

  2014-02-20 · 190 citations

  bookOpen accessSenior author

  Social influence network theory presents a mathematical formalization of the social process of attitude changes that unfolds in a social network of interpersonal influences. This book brings the theory to bear on lines of research in the domain of small group dynamics concerned with changes of group members' positions on an issue, including the formation of consensus and of settled disagreement, via endogenous interpersonal influences, in which group members are responding to the displayed positions of the members of the group. Social influence network theory advances a dynamic social cognition mechanism, in which individuals are weighing and combining their own and others' positions on an issue in the revision of their own positions. The influence network construct of the theory is the social structure of the endogenous interpersonal influences that are involved in this mechanism. With this theory, the authors seek to lay the foundation for a better formal integration of classical and current lines of work on small groups in psychological and sociological social psychology

  PublisherOA PDFDOI

• The Smallest Group

  Cambridge University Press eBooks · 2011-04-18

  book-chapterSenior author

  In this chapter, we analyze the process of interpersonal influence on attitudes in isolated dyads. Dyadic relationships are usually part of larger networks of interpersonal relationships. Although most relationships are not isolated, there are instances of dyads whose members are isolated on particular issues that do not involve the influences of other persons. Here, our theoretical focus is on the influence systems of such isolated dyads, the smallest groups in which interpersonal influence may occur.

  PublisherDOI

• Models of Group Decision-Making

  Cambridge University Press eBooks · 2011-04-18 · 3 citations

  book-chapterSenior author

  A group decision occurs when group members select or settle upon one option from a set of alternatives and collectively consider that option to be the choice of the group (Brandstatter, Davis, and Stocker-Kreichgauer 1982; Castellan 1993; Levine and Moreland 1990, 1998; Moscovici and Doise 1994; Witte and Davis 1996). Social influence network theory has an important bearing on how groups make decisions, because it presents an account of how interpersonal influences produce the agreements that are the foundation of many group decisions. In this chapter, we describe how our theory is related to several lines of formal work on group decision-making in which a decision scheme or normative procedure is invoked to reach a group decision.

  PublisherDOI

• Expectation States and Affect Control Theory

  Cambridge University Press eBooks · 2011-04-18

  book-chapterSenior author

  In this chapter, we will describe a model in which Y(t) affects W(t) at each time t = 1, 2, …. The Y(t) that is involved in this model is an n × n matrix of group members' attitudes toward each other and themselves. Their Y(t) attitudes determine W(t) along with its coupled A(t); and because these attitudes are subject to interpersonal influence, W(t), together with its coupled A(t), generates a Y(t + 1) matrix of attitudes, and so on. From this process, an equilibrium matrix of attitudes, susceptibilities, and interpersonal influences may be produced in the group. The equilibrium W(∞) and A(∞) that may emerge from this process constitute a stable influence network for the group, conditioned on the matrix of initial interpersonal attitudes Y(1). Here, Y(1), in the form of a matrix of interpersonal attitudes, appears as the core construct in determining a group's influence network. The explanation of the origins of stable influence networks in groups has been a longstanding sociological issue, and this model contributes to the theoretical integration of two lines of inquiry related to it – expectation states theory and affect control theory.

  PublisherDOI

• Minority and Majority Factions

  Cambridge University Press eBooks · 2011-04-18

  book-chapterSenior author

  Few studies on social influence have had the enduring impact of Asch's (1951; 1952; 1956) experiments on the conformity responses of individuals to a fixed unanimous majority. Asch's seminal investigation stimulated numerous studies, including work on the reverse situation – responses of a majority to a fixed minority position on an issue.

  PublisherDOI

• Preface

  Cambridge University Press eBooks · 2011-04-18

  book-chapterSenior author

  Social influence network theory presents a formalization of the social process of attitude changes that unfold in a network of interpersonal influence (Friedkin 1986, 1991, 1998, 1999, 2001; Friedkin and Cook 1990; Friedkin and Johnsen 1990, 1997, 1999, 2002, 2003). In this book, we bring the theory to bear on lines of research in the domain of small group dynamics that are concerned with changes of group members' positions on an issue, including the formation of a consensus and of settled disagreement, via endogenous interpersonal influences, in which group members are responding to the displayed positions of the members of the group. Newcomb (1951) has suggested, and we agree, that the occurrence of endogenous interpersonal influence is among the basic postulates of social psychological theory:

  PublisherDOI

• Group Dynamics: Structural Social Psychology

  Cambridge University Press eBooks · 2011-04-18

  book-chapterSenior author

  In this chapter, we present an overview of the group dynamics tradition that is our substantive focus, and we present our case for the advancement of this tradition via analysis of the attitude change process that unfolds in interpersonal influence networks. The idea that motivates this book is that some of the important lines of work on attitude change in small groups developed by psychologists (e.g., their work on social comparison, minority–majority factions, group polarization and choice shifts, and group decision schemes on attitudes) may be advanced if a social network perspective is brought to bear on them. In addition, we show how certain lines of current work in sociological social psychology may be advanced with our approach. Sociologists are more likely to pursue these advances than psychologists, given the current emphasis in psychology on social cognition. However, as we emphasize, the influence network and process specified by our theory are a social cognition structure and process. Thus, we seek to move the two orientations into closer theoretical proximity and to build a theoretical interface that speaks to both psychological and sociological social psychologists. By attending to the classic foundations of modern social psychology, to the theoretical perspectives, hypotheses, and findings that constituted the group dynamics tradition, we hope to advance current work on small group social structures and social processes. We revisit the classical past, pursuing an agenda of formal unification, in order to reshape perspectives and trigger new research.

  PublisherDOI

• Formal Analysis of Dyadic Influence Systems

  2011-04-18

  otherSenior author
  PublisherDOI

Frequent coauthors

• Noah E. Friedkin

  27 shared

• Peter D. Killworth

  National Oceanography Centre

  15 shared

• Gene A. Shelley

  Centers for Disease Control and Prevention

  14 shared

• Christopher McCarty

  University of Florida

  14 shared

• H. Russell Bernard

  Arizona State University

  14 shared

• Thomas Storer

  5 shared

• Adil Yaqub

  4 shared

• David L. Outcalt

  General Electric (United States)

  4 shared

Labs

• WeBWorKPI