The effects of perceptual similarity and category membership on early word-referent identification q Natalia Arias-Trejo * , Kim Plunkett * Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK article info Article history: Received 14 December 2008 Revised 1 October 2009 Keywords: Word-referent identification Category competition Perceptual competition Basic-level categories Global categories Preferential looking abstract We investigated the impact of perceptual and categorical related- ness between a target and a distracter object on early referent identification in infants and adults. In an intermodal preferential looking (IPL) task, participants looked at a target object paired with a distracter object that could be perceptually similar or dissimilar and drawn from the same or different global category. The propor- tion of target looking measures revealed that infants and adults were sensitive to the interplay between category membership and perceptual similarity. Online latency measures demonstrated an advantage for perceptually dissimilar items regardless of their categorical status, indicating that different IPL measures index dif- ferent processes during target identification. Results suggest that perceptual similarity and category membership of the objects lead to competition effects in word recognition and referent identifica- tion in both adults and infants and that lexical categorization and nonlinguistic categorization processes are closely related during infancy. Ó 2010 Elsevier Inc. All rights reserved. Introduction Do infants use words to refer to objects that are perceptually similar, or are their usages con- strained by knowledge of the categories to which the objects belong? Of course, both of these ques- tions can be answered in the affirmative because objects that belong to the same category are often perceptually similar (Huttenlocher & Smiley, 1987; Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976). However, objects that are perceptually similar need not be in the same category (e.g., bird 0022-0965/$ - see front matter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jecp.2009.10.002 q The research reported in this article was supported by a grant from the Leverhulme Trust to Kim Plunkett. * Corresponding authors. E-mail addresses: nariast@unam.mx (N. Arias-Trejo), kim.plunkett@psy.ox.ac.uk (K. Plunkett). Journal of Experimental Child Psychology 105 (2010) 63–80 Contents lists available at ScienceDirect Journal of Experimental Child Psychology journal homepage: www.elsevier.com/locate/jecp