www.frontiersin.org February 2011 | Volume 2 | Article 15 | 1 ORIGINAL RESEARCH ARTICLE published: 09 February 2011 doi: 10.3389/fpsyg.2011.00015 Manipulating objects and telling words: a study on concrete and abstract words acquisition Anna M. Borghi 1,2 *, Andrea Flumini 1 , Felice Cimatti 3 , Davide Marocco 4 and Claudia Scorolli 1 * 1 Department of Psychology, University of Bologna, Bologna, Italy 2 Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy 3 Department of Philosophy, University of Calabria, Arcavacata di Rende, Italy 4 School of Computing and Mathematics, University of Plymouth, Plymouth, UK Four experiments (E1–E2–E3–E4) investigated whether different acquisition modalities lead to the emergence of differences typically found between concrete and abstract words, as argued by the words as tools (WAT) proposal. To mimic the acquisition of concrete and abstract concepts, participants either manipulated novel objects or observed groups of objects interacting in novel ways (Training 1). In TEST 1 participants decided whether two elements belonged to the same category. Later they read the category labels (Training 2); labels could be accompanied by an explanation of their meaning. Then participants observed previously seen exemplars and other elements, and were asked which of them could be named with a given label (TEST 2). Across the experiments, it was more difficult to form abstract than concrete categories (TEST 1); even when adding labels, abstract words remained more difficult than concrete words (TEST 2). TEST 3 differed across the experiments. In E1 participants performed a feature production task. Crucially, the associations produced with the novel words reflected the pattern evoked by existing concrete and abstract words, as the first evoked more perceptual properties. In E2–E3–E4,TEST 3 consisted of a color verification task with manual/verbal (keyboard–microphone) responses. Results showed the microphone use to have an advantage over keyboard use for abstract words, especially in the explanation condition. This supports WAT: due to their acquisition modality, concrete words evoke more manual information; abstract words elicit more verbal information. This advantage was not present when linguistic information contrasted with perceptual one. Implications for theories and computational models of language grounding are discussed. Keywords: categorization, concepts, embodied cognition, grounded cognition, language grounding, language acquisition Edited by: Diane Pecher, Erasmus University Rotterdam, Netherlands Reviewed by: Domenico Parisi, The National Research Council, Italy Manuel De Vega, University of La Laguna, Spain *Correspondence: Anna M. Borghi and Claudia Scorolli, Department of Psychology, University of Bologna, Viale Berti Pichat 5, 40100 Bologna, Italy. e-mail: annamaria.borghi@unibo.it; claudia.scorolli2@unibo.it that this distinction captures some aspects of word meaning, and that it is important to understand how the process of abstraction occurs, from single instances to categories at different levels of abstraction. In particular, explaining the ways in which abstract words are represented constitutes a major challenge for embod- ied and grounded views of cognition, as well as for embodied computational models and robotics. The problem abstract words pose for embodied and grounded theories is clearly synthesized by Barsalou (2008, p. 634) as follows: “Abstract concepts pose a classic challenge for grounded cognition. How can theories that focus on modal simulations explain concepts that do not appear modal?” We will first clarify why explaining abstract concepts is a crucial challenge for embodied cognition, and later clarify its importance for research in robotics. According to the standard propositional view (e.g., Fodor, 1998), the representation of both concrete and abstract concepts is abstract, symbolic, and amodal. In contrast, according to stand- ard embodied accounts (e.g., Barsalou, 1999) both concrete and abstract concepts are grounded in perception and action systems, and therefore are modal. Notice that both standard propositional and embodied accounts evoke a single kind of representation, either amodal or modal, for both concrete and abstract concepts. INTRODUCTION How do children acquire abstract words? This paper presents a study on novel categories focusing on what differs in the acquisi- tion of concrete and abstract words. One standard way of dif- ferentiating between concrete and abstract words is to refer to their perceivability. Concrete words refer to entities that can be perceived through the senses. Abstract words refer to entities more detached from physical experience (Paivio et al., 1986; Crystal, 1995; Barsalou et al., 2003). However, the distinction between con- crete and abstract words cannot be conceived of as a dichotomy (Wiemer-Hastings et al., 2001). For example, words referring to social roles (e.g., “physician”) might be more abstract than words referring to single objects (e.g., “bottle”), but less abstract than purely definitional words (e.g., “odd number”) (Keil, 1989). In addition, words referring to emotions probably require special classification (Altarriba et al., 1999). Further, basic and subordinate words, such as “cat” and “Siamese cat,” referring to single entities, can be seen as more concrete than superordinate words, such as “animal,” that refer to sets of entities that differ in shape and other perceptual characteristics (e.g., Borghi et al., 2005). To summarize, the distinction between concrete and abstract words is not clear- cut, and should be intended as a continuum. However, we believe