Interaction of Taxonomic and Contextual Knowledge in Categorization of Cross-Classified Instances

Interaction of Taxonomic and Contextual Knowledge in Categorization of Cross-Classified Instances Nadya Y. Vasilyeva (vasilyeva.n@neu.edu) Department of Psychology, Northeastern University, 125 NI Huntington Ave, Boston, MA 02115-5000 USA John D. Coley (j.coley@neu.edu) Department of Psychology, Northeastern University, 125 NI Huntington Ave, Boston, MA 02115-5000 USA Tara M. Muratore (muratore.t@neu.edu) Department of Psychology, Northeastern University, 125 NI Huntington Ave, Boston, MA 02115-5000 USA Abstract Murphy, 1999) and that accessing taxonomic knowledge may inhibit access to contextual knowledge (Macrae, Bodenhausen & Milne, 1995; Vitkin, Coley & Feigin, 2005). However, cognitive scientists are increasingly acknowledging the important role of contextual categories in both organizing knowledge and guiding reasoning (e.g., Lin & Murphy, 2001; Lopez, Atran, Coley, Medin & Smith, 1997; Medin, Lynch, Coley & Atran, 1997; Murphy, 2001; Ross & Murphy, 1999; Shafto & Coley, 2003). This highlights the importance of understanding cross- classification and its implications for conceptual structure and reasoning. In previous studies taxonomic and contextual categories have typically been considered independently to contrast their representation, accessibility, and use (e.g., Ross & Murphy, 1999). As a result, we still know relatively little about how these kinds of conceptual systems interact. In this study we examine how simultaneous membership in multiple categories influences detection of relationships between entities in the complex real-world domain of folk biology. One possibility is that taxonomic and contextual conceptual systems are relatively independent, and that accessing one kind of category has little effect on the other. Alternatively, multiple cross-cutting conceptual systems might interact symmetrically to facilitate or inhibit each other. In line with a spreading activation view of semantic memory (e.g., Collins and Quillian, 1969), accessing one kind of category information could facilitate the accessibility of semantically related knowledge about other conceptual systems an object belonged to. In contrast, accessing one kind of category information might serve to inhibit accessibility of other kinds of knowledge. Empirical support for this prediction comes from a study by Macrae, Bodenhausen and Milne (1995) who primed participants with either an ethnic (Chinese) or gender (female) stereotype, then exposed them to a cross-classified stimulus (a video of a Chinese woman reading a book). On a subsequent lexical decision task participants were faster to This study examined the interplay of taxonomic and contextual knowledge in cross-classification by assessing the interaction of taxonomic and ecological knowledge in folk biology. Stimuli were pairs of animal species in which the presence or absence of taxonomic and ecological relations was manipulated orthogonally. Participants judged whether each pair was related taxonomically and ecologically; we measures speed and accuracy. Presence of taxonomic relations facilitated ecological judgments for ecologically related pairs, and hindered judgments for unrelated pairs. In contrast, although ecological relations hindered taxonomic judgments for taxonomically unrelated pairs, they failed to facilitate judgments for taxonomically related pairs. These results underscore the interactive nature of different conceptual systems for cross-classified categories and suggest a disproportionally strong influence of taxonomic categories. Keywords: Multiple categories; cross-cutting categorization; taxonomic knowledge; ecological categories; contextual categories; folkbiology. Complex real-world knowledge is usually multidimensional. Most things fall into multiple categories, and multiple kinds of category systems. For example, although ducks and roadrunners are birds and otters and coyotes are mammals, these species can also be cross-classified as pond animals and desert animals. Two broad kinds of categories that seem to recur across domains are taxonomic categories, wherein common membership stems from shared intrinsic properties of the members themselves, and contextual categories (also known as thematic or relational categories), wherein common membership stems from shared extrinsic properties including causal relations and spatio-temporal co- occurrence. Traditionally, taxonomic categories have been assumed to provide the mainstay of conceptual structure (e.g. Rosch, 1978; Smith & Medin, 1981; Murphy, 2002). Past research suggests that taxonomic categories may be more accessible than contextual categories (Ross &