Recurrent Model of Group Biases 1 A Recurrent Connectionist Model of Group Biases

Major biases and stereotypes in group judgments are reviewed and modeled from a recurrent connectionist perspective. These biases are in the areas of group impression formation (illusory correlation), group differentiation (accentuation), stereotype change (dispersed versus concentrated distribution of inconsistent information), and group homogeneity. All these phenomena are illustrated with well-known experiments, and simulated with an auto-associative network architecture with linear activation update and delta learning algorithm for adjusting the connection weights. All the biases were successfully reproduced in the simulations. The discussion centers on how the particular simulation specifications compare to other models of group biases and how they may be used to develop novel hypotheses for testing the connectionist modeling approach and, more generally, for improving theorizing in the field of social biases and stereotype change. Recurrent Model of Group Biases 3 Petite, attractive, intelligent, WSF, 30, fond of music, theatre, books, travel, seeks warm, affectionate, fun-loving man to share life’s pleasures with view to lasting relationship. Send photograph. Please no biochemists. (Personal ad, New York Review of books, cited in Barrow, 1992, p.2) The ability to learn about groups and their characteristics is crucial to the way people make sense of their social world. Nevertheless, quite a number of studies have indicated that people can have great trouble learning associations between groups and their attributes and often perceive associations that do not exists. It is generally assumed that these shortcomings or biases are partly responsible for group stereotyping and minority discrimination. Among the most prominent of these group biases are illusory correlation — the perception of a correlation between a group and some characteristics that do not exist (Hamilton & Gifford, 1976; Hamilton & Rose, 1980), accentuation — making a distinction between groups beyond actual differences (Tajfel & Wilkes, 1963; Eiser, 1971), subtyping — the rejection of stereotype-inconsistent information concentrated in a few group members (Hewstone, 1994), and outgroup homogeneity — the perception of outgroups as more homogeneous and stereotypical than the ingroup (Linville, Fisher & Salovey, 1989; Messick & Mackie, 1989). It is thus of crucial importance to psychologists to understand how these biases are created and how they can be eliminated (Hewstone, 1994). However, many empirical reports on the occurrence of group biases were explained by appeals to what often appear to be rather ad-hoc hypotheses and assumptions. Moreover, the field of group perception has developed largely independent from other important areas in cognition at large and social cognition in particular, including domains such as person perception, impression formation, attribution and attitudes (Hamilton & Sherman, 1996). There have been some recent attempts, however, to provide a common theory of group judgments and shortcomings under the heading of exemplar-based models (Smith, 1991, Fiedler, 1996) or a tensor-product connectionist network (Kashima, Woolcock & Kashima, 2000). The goal of the present paper is to build further on these initial proposals and to present a connectionist model that potentially can explain a wider range of group biases than these earlier attempts. Moreover, the proposed Recurrent Model of Group Biases 4 model has already been fruitfully applied to other areas in memory and cognition (for a classic example, see McClelland & Rumelhart, 1996, p. 170), including the domain of social cognition (Van Overwalle, Labiouse & French, 2001; see also Read & Montoya, 1999; Smith & DeCoster, 1998; Van Overwalle & Jordens, 2002), where it has been applied to encompass and integrate earlier algebraic models of impression formation (Anderson, 1981), causal attribution (Cheng & Novick, 1992) and attitude formation (Ajzen, 1991). Our basic claim is that a connectionist account of group biases does not require special processing of information as many theories in social cognition posit (e.g., Hamilton & Gifford, 1976; Hastie, 1980). Rather, general information processing characteristics captured in general-purpose connectionist models lead to these biases. What are the characteristics that accomplish this? First, connectionist models exhibit emergent properties such as the ability to extract prototypes from a number of exemplars (prototype extraction), to recognize exemplars based on the observation of incomplete features (pattern completion), to generalize knowledge about features to similar exemplars (generalization), to adjust to multiple constraints from the external environment (constraint satisfaction), and to lose stored knowledge only partially after damage (graceful degradation). All of these properties have been extensively reviewed in Smith (1996) and Rumelhart & McClelland (1986). It is clear that these characteristics are potentially useful for any account of group stereotyping. In addition, connectionist models assume that the development of internal representations and the processing of these representations are done in parallel by simple and highly interconnected units, contrary to traditional models where the processing is inherently sequential. As a result, these systems have no need for a central executive, which eliminates the requirement of previous theories of explicit (central) processing of relevant information. Consequently, biases in information processes are, in principle, due to implicit and automatic mechanisms without explicit conscious reasoning. Of course, this does not preclude people’s being aware of the outcome of these preconscious processes. Second, connectionist networks are not fixed models but are able to learn over time, usually by means of a simple learning algorithm that progressively modifies the strength of the Recurrent Model of Group Biases 5 connections between the units making up the network. The fact that most traditional models in psychology are incapable of learning is a significant restriction. Interestingly, the ability to learn incrementally can put connectionist models in agreement with developmental and evolutionary pressures. This implies that group biases emerge from general processes that are otherwise quite adaptive. Third, connectionist networks have a degree of neurologically plausibility that is generally absent in previous approaches to integration and storage of group information (Anderson, 1981; Ajzen, 1991). While it is true that connectionist models are highly simplified versions of real neurological circuitry and processing, it is commonly assumed that they reveal a number of emergent processing properties that real human brains also exhibit. One of these emergent properties is the integration of long-term memory (i.e., connection weights), short-term memory (i.e., internal activation) and outside information (i.e., external activation). There is no clear separation between memory and processing as there is in traditional models. Even if biological constraints are not strictly adhered to in connectionist models of group prejudice, interest in the biological implementation of social cognitive mechanisms has indeed started to emerge (Adolphs & Damasio, 2001; Allison, Puce & McCarthy, 2000; Ito & Cacioppo, 2001; Cacioppo, Berntson, Sheridan & McClintock, 2000; Ochsner & Lieberman, 2001; Phelps, O’Connor, Cunningham, Funayama, Gatenby, Gore & Banaji, 2000) and parallel the increasing attention paid to neurophysiological determinants of social behavior. This article is organized as follows: First, we will describe the proposed connectionist model in some detail, giving the precise architecture, the general learning algorithm and the specific details of how the model processes information. In addition, a number of other less well-known emergent properties of this type of network will be discussed. We will then present a series of simulations, using the same network architecture applied to a number of important biases in group judgments, including illusory correlation, accentuation, stereotype change and homogeneity. Our review of empirical phenomena in the field is not meant to be exhaustive, but is rather designed to illustrate how connectionist principles can be used to shed light on the processes underlying group judgments. Recurrent Model of Group Biases 6 While the emphasis of the present article is on the use of a particular connectionist model to explain a wide variety of group biases, previous applications of connectionist modeling to social psychology (Smith & DeCoster, 1998; Read & Montoya, 1999; Van Overwalle, 1998; Van Overwalle, Labiouse & French, 2001) are also mentioned. In addition, we will perform a comparison of different models. Finally, we will discuss the limitations of the proposed connectionist approach and discuss areas where further theoretical developments are under way or are needed. Ultimately, what we would like to accomplish in this paper is to create a greater awareness that connectionist principles could potentially underlie diverse shortcomings in group judgments, as a natural consequence of the basic processing mechanisms in these adaptive cognitive systems.