How Social Identity Shapes Concept Expansion

11:00 - 12:30

Toward a Unified View of Categorization: Linking Cognitive Mechanisms and Social Consequences

Room: HSZ - N3

Chair/s:

Rebecca Albrecht, Florian Seitz

Categorization processes are fundamental to how humans structure, interpret, and interact with the world. They shape individual perception as well as higher-level judgments and decisions, and at the societal level play a key role in stereotyping, prejudice, and group formation. Yet, research on perceptual and social categorization has largely proceeded along separate tracks. Whereas perceptual research has aimed to identify domain-general mechanisms underlying individual categorization, social research has aimed to uncover the broader implications of categorization for group dynamics. Integrative approaches that bridge perceptual and social categorization remain rare.

Differences in research goals are mirrored by differences in methodology. Perceptual research typically relies on simplified, abstract tasks that maximize internal validity and support formal modeling, often at the expense of external validity. Social research, in turn, embeds categorization in realistic contexts that reflect lived experience and intergroup relations, but at the cost of making it harder to isolate and formalize the underlying processes. Recent methodological advances—from richer behavioral paradigms to automated theory discovery using ML/AI—create novel opportunities to combine the strengths of both traditions. These developments make it increasingly possible to study categorization in contexts that are both controlled and ecologically valid, paving the way for genuine integration of perceptual and social research.

This symposium is structured around three complementary steps in building this bridge. The first examines computational models of categorization and asks what predictions they offer for understanding social categorization. The second starts from the opposite direction, considering how phenomena of social categorization and judgment can be explained within computational frameworks. The third takes a meta-perspective, highlighting how recent methodological advances—ranging from large-scale experimentation to theory-driven simulations and formal model comparison—create new opportunities for linking the two traditions. Together, these perspectives show how research on categorization can move beyond separate traditions by uniting mechanistic explanations with social consequences and aligning methodological control with ecological relevance, paving the way toward a unified theory of categorization.

Submission 461

How Social Identity Shapes Concept Expansion

SymposiumTalk-01

Presented by: Rebecca Albrecht

Rebecca Albrecht ¹, Mikhail S. Spektor ^{2, 3}, Gaël Le Mens ^{4, 5, 6}

¹ University of Freiburg, Germany

² University of Warwick, United Kingdom

³ VinUniversity, Vietnam

⁴ UPF–Barcelona School of Management, Spain

⁵ Barcelona School of Economics, Spain

⁶ Universitat Pompeu Fabra, Spain

How people draw category boundaries shapes not only perception but also social judgment, influencing who is included or excluded from a group. Prevalence-induced concept change captures this adaptive process: when one category becomes rarer, people broaden it to include previously excluded items. In perceptual domains, this adaptation is typically symmetric–boundaries shift in either direction depending on which category becomes rare. In social categorization, however, categories carry evaluative meaning, and these meanings may constrain or bias category expansion.

The present study examines whether adaptive boundary shifts depend on group membership. In two experimental sessions (at least two weeks apart), participants begin the first session by self-selecting into one of two abstract social groups representing two ends of a one-dimensional attribute. In each session, group identity is then reinforced through a three-way public-goods game. Subsequently, participants complete a binary categorization task in which stimuli vary gradually between the two social-group prototypes. After completing a first block of uniformly distributed stimuli, category prevalence is manipulated within participants across the two experimental sessions: either the in-group or the out-group becomes rare (order counter-balanced across participants).

If categorization shifts are governed purely by the stimuli, boundary shifts should occur symmetrically. In contrast, we hypothesize that people resist expanding their in-group concept while being readily willing to expand the concept of the out-group. Examining such asymmetries will help clarify how the evaluative meaning of social categories interacts with domain-general adaptation processes and may inform a process-level account of how flexible categorization mechanisms shape social categorization.

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