The Effect of Labels on Categorization: Is Attention to Relevant Features a Good Index of Infants' Category Learning? - eScholarship

The Effect of Labels on Categorization: Is Attention to Relevant Features A Good Index of Infants’ Category Learning? Catherine A. Best (best.140@osu.edu) Department of Psychology and the Center for Cognitive Science, The Ohio State University 208G Ohio Stadium East, 1961 Tuttle Park Place, Columbus, OH 43210, USA Christopher W. Robinson (robinson.777@osu.edu) Department of Psychology, The Ohio State University 208F Ohio Stadium East, 1961 Tuttle Park Place, Columbus, OH 43210, USA Vladimir M. Sloutsky (sloutsky.1@osu.edu) Department of Psychology and the Center for Cognitive Science, The Ohio State University 208D Ohio Stadium East, 1961 Tuttle Park Place, Columbus, OH 43210, USA Abstract Shifting attention to category relevant features has been demonstrated in adults to be a successful strategy for categorizing novel objects. The current experiment was aimed at exploring whether infants would use a similar strategy for category learning when objects were presented with and without labels. Using an eye tracker, 6- to 8-month-old infants were familiarized and tested with a novel visual category where only half of the features were relevant for category membership. There was some evidence that infants learned the target category only when objects were not labeled. Furthermore, infants who learned the target category did not appear to optimize their attention to the category relevant features. In addition, contrary to some theoretical accounts, there was no evidence that labels facilitated categorization by highlighting category relevant features. Keywords: Categorization; Attention; Language; Infants Introduction Categorization, the ability to treat discriminable items as similar, is a critical skill for making sense of the visual world. One strategy for successful categorization of new information is to optimize attention to features that may predict category membership and away from features that may not predict category membership. Selectively attending to category relevant information while ignoring category irrelevant information has been demonstrated by human adults and non-human animals (e.g., Dixon, Ruppel, Pratt, & De Rosa, 2009; Mackintosh, 1965). Adults tested in a categorization task with an eye tracker demonstrated attention optimization when they attended selectively to the relevant features of a category during learning trials (Hoffman & Rehder, 2010). It is less clear, however, whether infants have the ability to optimize their attention in a similar way as adults. Some research suggests that infants would be less likely to engage in selective attention due to an immature prefrontal cortex, which is responsible for executive functions such as selective attention (e.g., Posner & Petersen, 1990). Sloutsky (2010) further argues that because the prefrontal cortex matures later in the course of development, infants (who are known to categorize visual input) ought to learn categories through means other than selectivity. Therefore, the assumption that infants, like adults, should optimize their attention to relevant features over the course of learning may not be plausible based solely on the prematurity of the prefrontal cortex. However, there is research suggesting that linguistic labels may help infants shift attention to relevant features during categorization by focusing infants’ attention on perceptual features that are shared by members of a category. If labels can direct attention to commonalities among category members, then infants should optimize their attention to relevant features over time. Previous research demonstrates that infants ranging from 3 to 12 months are often better at learning visual categories when objects are associated with labels than when the same visual stimuli are associated with nonlinguistic sounds (Balaban & Waxman, 1997; Fulkerson & Waxman, 2007; Robinson & Sloutsky, 2007; Ferry, Hespos, & Waxman, 2010). However, labels have also been shown to attenuate infants’ learning of visual categories when performance was compared to learning of unlabeled objects presented in silence (Robinson & Sloutsky, 2007). What underlying mechanisms can account for the facilitative effects of labels on infants’ categorization? It has been argued that labels facilitate categorization by highlighting the commonalities among labeled entities (Fulkerson & Waxman, 2007; Waxman, 2003) and that labeling objects directs attention to perceptual properties that will aid successful categorization (Waxman, 2004). In contrast, some researchers argue that infants have difficulty processing multimodal information, with labels often attenuating visual processing early in development (Robinson & Sloutsky, 2007; Sloutsky & Robinson, 2008). Therefore by this account, labels should have no facilitative effect above a silent condition and may even overshadow infants’ visual processing. One limitation of previous research is that the mechanisms underlying the effects of labels on categorization are often inferred by examining infants’ novelty preference at test, rather than directly testing how labels affect attention in the course of category learning.