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Young infants have an impressive knowledge of material objects. They appreciate that distinct objects cannot occupy the same space at the same time, are internally cohesive units that maintain their boundaries, and exist continuously in space and time. We report a surprising limit to this body of understanding: Although 8-month-olds responded to the “magical” disappearance of an object as an unexpected event, they did not so respond to a magical appearance. These results suggest that infants' understanding of objects differs from adult cognition in important respects. We discuss four possible ways in which this finding can be reconciled with evidence that infants appreciate the spatiotemporal continuity of objects.

Adults value scarce objects, such as rare precious stones and limited edition items. This valuation may derive from an understanding of market forces and sociological considerations, but it may also be related to more basic cognitive and motivational processes. The present studies addressed these possibilities by investigating the development and cross-cultural prevalence of a preference for scarce objects. Children (N = 366) from Israel and Taiwan, ranging from 4 to 11 years of age, were given a choice between a scarce and an abundant reward. We found that whereas a preference for the scarce appeared among Israelis by age 7, it never appeared among the Taiwanese. These findings indicate that a scarcity preference emerges already at age 7, but only among children living in a culture that emphasizes self-individuality. These findings are discussed in light of cultural accounts of the development of self-motivations.

Extensive previous research has focused on the development of children's conceptual organization and its effects on children's veridical memory. The present research investigated whether the structure of children's category knowledge also affected their false memories using categorical lists in the DRM paradigm, a listlearning method commonly used in false memory research. In Experiment 1, the effects of graded category structure were examined with both third and sixth graders by accessing false memories for unstudied critical items of differing output dominance in category production. In Experiment 2, the effects of hierarchical category structure were examined with third graders by manipulating the hierarchical level of studied list items (basic or subordinate) and unstudied critical items (superordinate, basic, or subordinate). The results show that by age 10, the graded and hierarchical structure is present in children's conceptual organization and affects formation of false memories. Theoretical implications of the present findings are discussed.Key words: category structure, false memory, list learning paradigm, memory developmentThe organization of concepts has long been an important topic in the research of human mind: it is thought to underlie several important cognitive functions that humans constantly engage in daily lives, such as classification and memory. In consequence, acquisition of an adult-like conceptual organization became a major focus in research of cognitive development.Extensive earlier literature suggested that children's conceptual organization underwent a shift in focus from thematic/complementary relations (e.g., dog grouped with leash) to taxonomic/similarity relations (e.g., dog grouped with cat) based on their responses in sorting objects on a table into groups (e.g., Annett, 1959;Inhelder & Piaget, 1964;Vygotsky, 1962). Some researchers hence proposed that early in development, children's knowledge was organized in terms of schematic or script-based relationships derived from perceptual-motor experiences and real-world scenes and events (e.g., Denney, 1974;Nelson, 1974), and later beyond about age 8 and through adulthood, This research was supported by Grant NSC90-2413-H-194-022 from National Science Council of Taiwan, R.O.C. to W.-C. C. The authors thank Yuh-Shiow Lee for valuable discussions on this work; an anonymous reviewer for helpful comments on an earlier version of this article; Tian-yoong Cheng for assistance with data processing; the children for their participation; and the staff of the elementary schools for assistance with testing arrangements.