INFANT BEHAVIOR AND DEVELOPMENT 20 (3), 1997, pp. 405-416 ISSN 0163-6383 Copyright 0 1997 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA A BLEX Pub lishing C o rp o ra tio n All rig hts o f re p ro d uc tio n in o ny fo rm re se rve d . zyxwvutsrqp Perseverative Reaching in Infancy: The Roles of Hidden Toys and Motor History in the AB task zyxwvutsrqponmlkjihgfed YUKOMUNAKATA University of Denver Two experiments tested the roles of hidden toys and motor history in the AB task with l&month- old infants. In Experiment 1 (N = 24), infants were tested in lid and toy versions of the task, each comprised of A and B trials. No toys were ever hidden in the lid condition. On all A trials, an exper- imenter directed infants’ attention to one of two lids (the A lid) and allowed infants to reach fol- lowing a 5-s delay. On B trials in the lid condition, the experimenter directed infants’ attention to the other, B lid. On B trials in the toy condition, the experimenter directed infants’ attention to a toy that was then hidden underneath the B lid. Following a 5-s delay, infants reached persevera- tively to A-producing the AB error-in the lid condition (replicating Smith, McLin, Titzer, & Thelen, 1995). but not in the toy condition. In Experiment 2 (N= 24), infants were tested in similar lid and toy versions of the task, except that on all A trials the experimenter directed attention to a toy that was then hidden underneath the A lid. Infants produced AB errors across lid and toy con- ditions. Contrary to Smith et al.% (1995) claims, these findings indicate that infants distinguish hidden toys from lids alone in the AB task. The presence of hidden toys on A trials and on B trials, not simply infants’ motor history, influences production of the AB error. AB e rra r p e rse ve ra tio n m o to r histo ry infa nt memory object concept What do infants know about hidden objects, and when do they know it? After decades of empiri- cal work on these questions, researchers give widely disparate answers. This disparity is based largely on disagreements about how to interpret infant behavior. Although many inno- vative techniques have been designed to test what infants know about hidden objects, these techniques often appear to be outnumbered by challenges to what the techniques actually mea- sure. For example, the visual habituation tech- nique has provided a wealth of data taken as evidence for an object concept in very young infants (Baillargeon, 1993; Spelke, Breinlinger, Macomber, & Jacobson, 1992; Wynn, 1992; Xu & Carey, 1996). However, multiple alternative interpretations of the data do not rely on an object concept (e.g., Bogartz, 1995; Fischer & Bidell, 1991; Munakata, in press; Munakata, McClelland, Johnson, & Siegler, in press; Thelen & Smith, 1994). These challenges to the visual habituation paradigm allow for a range of perspectives on infant knowledge of hidden objects. Direct all correspondence to: Yuko Munakata, who is now at the Department of Psychology, University of Denver 2 155 South Race St., Denver. CO 80208 <munakato@kote.psy. du.edu> The task of specifying what a given tech- nique measures is thus of central importance. The current paper addresses a recent challenge to the AB task as a measure of object knowledge in infants, and provides empirical support for the relevance of hidden objects to performance in this task. In the AB task, devised by Piaget (1954), infants watch an experimenter hide an object in one location (A). Typically, infants are allowed to retrieve the hidden object after a short delay, and this procedure is repeated some number of times. Infants then watch the experimenter hide the object in a new location (B). When they are allowed to reach after a short delay, infants often show the AB error, reaching perseveratively back to A rather than to the new hiding location at B. Wellman, Cross, and Bartsch (1986) con- ducted a meta-analysis indicating four factors that influence the production of AB errors: par- ticipants’ ages and the length of delays (e.g., Diamond, 1985), number of hiding locations (e.g., Cummings & Bjork, 1983a; 1983b), and distinctiveness of hiding locations (e.g., Brem- ner, 1978). The striking and robust AB finding and the influences upon it have been the basis for many theories of object permanence (e.g., Butterworth, 1977; Cummings & Bjork, 1983b; Diamond, 1985; Gratch, Appel, Evans, 405