How Specific is the Shape Bias? Gil Diesendruck and Paul Bloom Children tend to extend object names on the basis of sameness of shape, rather than size, color, or materialFa tendency that has been dubbed the ‘‘shape bias.’’ Is the shape bias the result of well-learned associations between words and objects? Or does it exist because of a general belief that shape is a good indicator of object category membership? The present three studies addressed this debate by exploring whether the shape bias is specific to naming. In Study 1, 3-year-olds showed the shape bias both when asked to extend a novel name and when asked to select an object of the same kind as a target object. Study 2 found the same shape bias when children were asked to generalize properties relevant to category membership. Study 3 replicated the findings from Study 1 with 2-year-olds. These findings suggest that the shape bias derives from children’s beliefs about object kinds and is not the product of associative learning. The surrealist painter Rene Magritte’s most famous work is a realistic picture of a pipe, floating above the heading ‘‘Ceci n’est pas une pipe’’FThis is not a pipe. Magritte was making a statement about the relationship between representation and reality, and about the illusory nature of art: One should not confuse a picture of a pipe with an actual pipe. But when you first look at this work, there is a jolt because the sentence seems so obviously false. Of course it is a pipeFit looks exactly like a pipe, and it would certainly be called a pipe. Magritte’s picture illustrates, and mocks, our strong tendency to name things based on their appearance and, in particular, their shapes. This tendency is what Landau, Smith, and Jones (1988) have called the shape bias. What is the nature of this bias? One propo- salFdubbed attentional-learning account by Smith (1999)Fis that there is a direct link between names, and specifically count nouns, and shape. This link exists because children are exposed to many count nouns (words that appear in contexts such as ‘‘This is a X’’) denoting objects that are similar in shape (objects such as chairs and balls). As a result, children learn that count nouns tend to refer to objects of the same shape and, more generally, that an object’s shape determines the name it gets (see also, Smith, Jones, & Landau, 1996). In support of this account, several studies have found that when taught a new noun for a new object, 3- to 4-year-olds show a strong tendency to extend the name to other objects that are similar in shape to the target object, not to objects similar in color, size, or texture. They do not show such a preference for shape when simply asked to ‘‘pick another one that goes with this’’ (Jones, Smith, & Landau, 1991; Landau et al., 1988). Furthermore, there is a positive correlation between the number of count nouns in children’s vocabulary that define categories based on shape and the strength of children’s shape bias (Samuelson & Smith, 1999). An alternative proposalFdubbed shape-as-cue by Bloom (2000)Fis that the relationship between count nouns and same-shaped objects is not due to a direct association. It instead exists because children believe that count nouns refer to object kinds, and that shape is a reliable cue to the kind to which an object belongs or, in the case of a picture, the kind that is being represented (see also, Bloom & Markson, 1998; Gelman & Diesendruck, 1999; Soja, Carey, & Spelke, 1992). Consistent with a shape-as-cue account, a number of findings have shown that from an early age, children seem to have a notion of object kind. For instance, 1-year-olds seem to understand that count nouns, but not proper names, extend to kinds (Hall, Lee, & Be ´langer, 2001; Katz, Baker, & Macnamara, 1974), and 14- to 18-month-olds induce properties of r 2003 by the Society for Research in Child Development, Inc. All rights reserved. 0009-3920/2003/7401-0012 Gil Diesendruck, Department of Psychology, Bar-Ilan Univer- sity; Paul Bloom, Department of Psychology, Yale University. This research was supported by a grant from the Israel Foundations Trustees (Special Fund for Post-Doctoral Research Grants) to the first author. A version of this paper was presented at the Biennial Meeting of the Society for Research Child Develop- ment, Minneapolis, MN, April 2001. We thank the supervisors, teachers, parents, and children from the following day-care centers for participating in the studies: Wizo-Stern, Wizo-Ganei Tikva, Gan Havatzelet, Gan Bar Yehuda, and Gan Yael, all in the Kiriat Ono area, as well as Gan Rimon in Ramat Gan. We are grateful to Ayelet Elron, Lital Dofet, and Gabriella Glass for their help with data collection. Correspondence concerning this article should be addressed to Gil Diesendruck, Department of Psychology, Bar-Ilan University, Ramat-Gan 52900, Israel. Electronic mail may be sent to dieseng@mail.biu.ac.il. Child Development, January/February 2003, Volume 74, Number 1, Pages 168–178