INFA NT BEHA VIO R AND DEVELO PMENT zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED 19,425-440 (1996) Evid e nc e fo r Ta sk- De p e nd e nt C a te g o riza tio n in Infa nc y zyxwvutsrqponm LISA M. OAKES, JODIE M. PLUMERT, JEFFREY M. LANSINK, AND JENNIFXR D. MERRYMAN The University of Iowa Two experiments compared infants’ attention to the categorical distinction between people and animals in object-examining and sequential-touching tasks. In Experiment 1, lO- and 13-month- old infants distinguished between animals and people in an object-examining task. In this task, infants are familiarized with individual exemplars from one category, and then their response to exemplars from another category is measured. In Experiment 2, 13- and 16-month-old infants, but not lo-month-old infants, attended to the same distinction in a sequential-touching task. In this task, infants are presented with several exemplars from two categories simultaneously, and the order in which they touch those objects is assessed. Evaluation of infants’ touching behavior in Experiment 2 also revealed developmental changes in how they approached this task. The combined results of these two experiments confum the general tre ndre p o rte d in the literature and begin to provide insight into developmental changes that contribute to infants’ ability to apply their categorization skills in different task contexts. categorization objectexamining sequential -touching conceptual development How infants and children form and represent categories has become the subject of extensive research and debate in recent years (e.g., Jones & Smith, 1993; Mandler, 1988, 1993; Quinn & Eimas, 1986; Younger & Cohen, 1985). Much of this research has focused on what categories infants possess, and when they first form these categories. For example, at what age do infants have categories such as dogs (Cohen & Caputo, 1978), trucks (Oakes, Madole, & Cohen, 1991), animals (Mandler & McDonough, 1993), and furniture (Ross, 1980)? Evaluation of the exist- ing literature, however, reveals that infants con- sistently respond to categorical distinctions ear- lier in habituation or familiarization tasks (e.g., Eimas & Quinn, 1994; Mandler & McDonough, 1993; Oakes, 1995) than in sequential-touching This research was supported in part by a University of Iowa Junior Faculty Seed Grant awarded to L.M.O., in addition to services provided to L.M.O. by the Center for Advanced Studies at The University of Iowa. We would like to express our appreciation to Hilary Condon, Amy Crigger, Kathy DeVet, Jason Feehan, Heather Hughes, Tracy Krulik, Erika Landl, Holly Matousek, Kimberly McCreedy, Paula McMaster, Pamela Prellwitz, Matthew Syverson, Donald Tellinghuisen, Peter Thompson, Cheryl Von Ruden, and Wende Wubbena for their help with data collection and coding. We would also like to thank Laraine McDonough for kindly providing the Monte Carlo proba- bilities for Experiment 2. Correspondence and requests for reprints should be sent to Lisa M. Oakes or Jodie M. Plume& Department of Psychology, 11 SSH East, University of Iowa, Iowa City, IA 52242. tasks (Bauer, Dow, & Hertsgaard, 1995; Mandler & Bauer, 1988; Mandler, Bauer, & McDonough, 1991), suggesting that the conclu- sions drawn about categorical responding in infancy depend on the particular task used to assess those abilities. The goal of this investigation was to provide a first step in establishing how features of the task context make it more or less difficult for infants to attend to a particular categorical dis- tinction. Thelen and Smith (1994) argued that we can gain insight into how and why skills change with development by evaluating the contexts in which a particular skill does and does not occur. Clearly, if older infants apply their categorization skills in more contexts than do younger infants, developmental changes in their cognitive abilities must contribute to whether or not they respond categorically in a given task. By evaluating infants’ categorical responding in tasks that differ along particular dimensions, for example a familiarization- dishabituation task and a sequential-touching task, we can determine which of their develop- ing cognitive abilities are relevant to the appli- cation of their categorization skills. Clearly, therefore, perfomzance in different categoriza- tion tasks can inform us about the process of categorization. That is, tasks place differing demands on infants’ cognitive resources, and how infants respond to these demands can inform us about the cognitive skills necessary to use categorization skills. 425