In two experiments, we systematically examined the reliance on visual (external shape and features) and verbal (origins and internal structure) information in isolation, and together in the identification of animals and machines by 3-, 4-, and 5-year-olds, and adults. Experiment 1 examined the use of visual and verbal information independently in a visual classification task, a verbal classification task, and an induction task. Experiment 2 examined the relative weighting of visual and verbal information in an induction task and a categorization task. The three most important findings from Experiment 1 were that (a) children and adults can use either visual or verbal information to distinguish animals from machines; (b) all age groups classified items with mixed visual information as machines, a tendency that increased with age; and (c) with age, children became increasingly able to induce non-obvious properties, especially the non-obvious properties of machines. The findings from Experiment 2 indicate that the youngest and oldest participants relied on both visual and verbal information in the identification of animals and machines in categorization and induction tasks. Five-year-olds, however, relied only on visual information. As in Experiment 1, we observed a tendency to judge items with contrasting information as machines, suggesting that individuals utilize a more strict definition (both visually and verbally) for the category of animals. We discuss the implication of these results with respect to developmental differences in the use of perceptual and conceptual information across the ontological distinction between artifacts and natural kinds.
Bibliographical noteFunding Information:
This work was conducted while Karen Freeman held a NICHD traineeship (HD07151). The research was supported by a grant from the McKnight Foundation to M. Sera. We thank the children and parents who participated in this study, and Martha Tanquist, Jaime Gathje, and Milissa Tilton for their assistance with data collection. A portion of this work was presented at the Biennial Conference for Human Development in Atlanta, Georgia in 1992 and at the Biennial Meeting of the Society for Research in Child Development in New Orleans, Louisiana in 1993. Karen Freeman is now at The University of Cambridge.