Role of Attention in the Formation of Illusory Correlations Among Preschoolers

Role of Attention in the Formation of Illusory Correlations Among Preschoolers Corinne A. Bower (corinne.bower@sju.edu) Chris A. Lawson (clawson@sju.edu) Saint Joseph's University Department of Psychology, 5600 City Avenue Philadelphia, PA 19131 USA Abstract A large body of research shows that adults will form illusory correlations in the course of category learning. Surprisingly little research has examined illusory correlations among children. Two experiments examined the formation of the illusory correlation in 3- and 5-year- olds. Experiment 1 provides evidence that these young children will not form illusory correlations in a novel categorization task. Results from experiment 2 indicate that eliciting an attentional shift caused younger children to form an illusory correlation. These results are the first to show that the tendency to form illusory correlations occurs early in development. Furthermore, these results have important implications regarding the mechanisms responsible for illusory correlations. Keywords: cognitive development; illusory correlation; statistical learning Introduction People tend to form categories that adhere to regularities in the environment (Anderson, 1991; Pothos & Bailey, 2009). However, there are occasions in which people form categories that violate regularities in the environment. For instance, the so-called illusory correlation (IC) occurs when infrequent properties are associated with uncommon categories, despite the absence of such a relationship (Chapman, 1967). The present study explores the developmental origins of this apparent categorization bias. Hamilton and Gifford (1976) provided a classic demonstration of the illusory correlation. Participants read descriptions about individuals from either a common (e.g., a novel category with 26 members) or rare category (e.g., a novel category with 13 members). One of two properties was attributed to each individual, such that one property was more frequent than the other, yet both property types were distributed among individuals in both categories at the same proportion (e.g., 18:8 and 9:4). After learning about all 39 individuals participants were asked to attribute either the infrequent or frequent property to each individual. Participants attributed the infrequent behaviors to the rare group at higher rates (48%) than the common group (22%). Thus, participants formed an illusory correlation – they falsely perceived a relationship between the rare property and the rare category even though no such relationship was presented in the evidence. Illusory correlations are interesting because they violate normative models of categorization (Fiedler, 2000). That is, rather than utilizing the correlational structure of the data, people appear to rely on other, less optimal strategies in the course of categorization. Indeed, the phenomenon is related to other forms of base-rate neglect that have been demonstrated in the categorization literature (Kruschke, 1996; Medin & Edelson, 1988). Several mechanisms have been proposed to describe why people form illusory correlations. One view is that illusory correlations are the product of memory processes such as having a stronger memory trace for the common elements in the task (Rothbart, 1981; see also Hintzman, 1986), or heightened memory for the distinct features of the evidence such as rare properties and categories (Hamilton & Gifford, 1976; Mullen & Johnson, 1990). It has also been argued that an illusory correlation is the result of attentional learning mechanisms (Sherman, Kruschke, Sherman, Percy, Petrocelli, & Conrey, 2009). For example, Kruschke (1996; 2003) argued that people fail to attend to base rates in the course of multiple-item categorization due to an attentional shift in the learning phase. From this perspective, a learner first focuses on learning about the common group and common property. After building a representation of the common category, a shift in attention to the rare category elicits the expectation that a different property will be associated with this different category. One way to better understand the mechanisms underlying this phenomenon is to explore the origins of illusory correlations. Surprisingly few studies have examined illusory correlations in children and all of these studies have involved children older than 5 years of age. Primi and Agnoli (2002) tested 6- to 22-year- olds using social and nonsocial stimuli. In their study, participants learned about individuals from a common category (N = 14) and individuals from a rare category (N = 7) each of which was paired with infrequent and frequent properties at the same ratio (e.g., 5:2). After the learning phase 6-year-olds’ attributions of the