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Nazzi, T., & Gopnik, A. (2001). Linguistic and cognitive abilities in infancy: When does language become a tool for categorization? Cognition, 80, B11-B20. Purpose The purpose of the present study was to explore infants’ use of naming to categorize objects. Specifically, infants’ use of naming to form new categories was studied. It has been well established that obvious cues such as color and shape and non-obvious cues such as functional attributes and causal properties are used in infancy and early childhood to categorize. Few previous studies examined the effect of naming to form new categories. For example, Waxman & Markow (1995) found that naming enhanced 13-month-old infants’ object categorization. In this study, infants heard labels for familiar objects. Their categorization performance in the label condition was better than in the no-label condition, indicating that naming focused infants’ attention. Because familiar objects were used, this study was unable to identify whether infants were able to form new object categories based upon naming alone. Other studies have also shown that infants may be able to use naming to enhance categorization of familiar objects. The present study was designed to examine whether infants are able to categorize visually non-identical novel objects based upon novel names. Experimental Work 16-month-old and 20-month-old infants were tested in the present study. There were two “blocks” per testing session in which six triads of small objects were used. All of the testing objects were unfamiliar to the infants. The first block of testing consisted of three trials in which the infants saw a pair of identical objects and a third object that differed in size, shape, and color. The experimenter did not explicitly label the objects in the first part of the experiment. After the infants were introduced to the objects and allowed to play with them, the experimenter held one of the paired objects and asked the infant to give him the object that went with the one in his hand. The second block of testing consisted of three trials in which the infants saw three different objects. These objects were explicitly labeled. Two were labeled identically while the other was given a different name. Again, the infants were asked to give the experimenter the object that belonged with the one in his hand (which was one member of the named, visually non-identical pair). Also, a vocabulary measurement was taken. The infants behaved similarly in the first part of the experiment. Both the 16-month-old and 20-month-old infants selected the second object of the visual pair significantly more often than chance. This suggests that both 16-month-old and 20-month old infants are able to use obvious visual cues to categorize. The infants behaved differently during the naming condition. 20-month-old infants selected the second object of the named, non-identical pair more often than 16-month-old infants. The 16-month-olds responded at chance levels, while the 20-month-olds responded significantly above chance. This suggests that only the 20-month-old infants were able to use naming as a tool for categorization. Results from the vocabulary test indicated that the 20-month-olds had significantly larger vocabularies than the 16-month-olds. There was a significant correlation between naming performance and productive vocabulary size indicating that naming performance and productive vocabulary size increase in a related way. Conclusions Both 16-month old and 20-month-old infants use obvious visual cues to group objects together. The 20-month-olds also performed at above chance levels in the naming task. The 16-month-olds, however, only performed at chance levels in the naming task. Because the older infants both had larger productive vocabularies and were “successful” at the naming task, the authors link the development of naming-based categorization skills and increases in productive vocabulary. Points for Discussion During the naming trials, the identically labeled objects were named one right after the other. Why wasn’t labeling order counterbalanced? Could that have made a difference? Did you notice the example objects the authors gave (silvery, metal doorknob vs. yellow, wood trapezoid vs. gray, plastic bar)? Would it be fair if the doorknob and bar were the identically named pair? They both have similar colors and more similar textures than the wooden trapezoid. Could there possibly have been an effect of similarity in the named pair that maybe only the 20-month-olds were savvy enough to pick up? The authors discuss alternate explanations regarding why the 16-month-old infants were unsuccessful in the naming task. Why did they not (and not have to) rule out the plausible explanations concerning task demands? How strong of a role do you think language plays in categorization? For children? For us? |
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