Perceptual Simulation in Conceptual Combination: Evidence from Property Generation
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Author's personal copy Acta Psychologica 132 (2009) 173–189 Contents lists available at ScienceDirect Acta Psychologica journal homepage: www.elsevier.com/locate/actpsy Perceptual simulation in conceptual combination: Evidence from property generation Ling-ling Wu a, Lawrence W. Barsalou b,* a Department of Information Management, National Taiwan University, Taiwan b Department of Psychology, Emory University, Atlanta, GA 30322, USA article info abstract In three experiments, participants received nouns or noun phrases for objects and verbally generated Available online 18 March 2009 their properties (‘‘feature listing”). Several sources of evidence indicated that participants constructed perceptual simulations to generate properties for the noun phrases during conceptual combination. First, PsycINFO classification: the production of object properties for noun phrases depended on occlusion, with unoccluded properties 2340 being generated more often than occluded properties. Because a perceptual variable affected conceptual combination, perceptual simulations appeared central to combining the concepts for modifiers and head Keywords: nouns. Second, neutral participants produced the same distributions of properties as participants Perceptual simulation instructed to describe images, suggesting that the conceptual representations used by neutral partici- Conceptual combination Property generation pants were similar to the mental images used by imagery participants. Furthermore, the property distri- Feature listing butions for neutral and imagery participants differed from those for participants instructed to produce Situated cognition word associations. Third, participants produced large amounts of information about background situa- Concepts and categories tions associated with the object cues, suggesting that the simulations used to generate properties were Knowledge situated. The experiments ruled out alternative explanations that simulation effects occur only for famil- Mental imagery iar noun phrases associated with perceptual memories and that rules associated with modifiers produce occlusion effects. A process model of the property generation task grounded in simulation mechanisms is presented. The possibility of integrating the simulation account of conceptual combination with tradi- tional accounts and well-established findings is explored. Ó 2009 Elsevier B.V. All rights reserved. 1. Introduction number of concepts, humans can construct an infinite number of new concepts productively whose meanings are systematically re- Conceptual combination is a fundamental process in human lated to one another. Although major arguments exist about the cognition. Besides knowing thousands of individual concepts, peo- mechanisms responsible for this ability—as described next—there ple can combine these concepts into an infinite number of more is no doubt that humans have a powerful ability to combine complex concepts. Conceptual combination is found throughout concepts. higher cognition. During the perception of a novel scene, concepts According to traditional theories of cognition, conceptual com- that categorize scene components are combined to interpret the bination results from combining amodal symbols in predicate-cal- novel configuration of entities and events perceived. During lan- culus-like representations (e.g., Barsalou, 1992; Fodor, 1975; Fodor guage production, speakers combine concepts as they conceptual- & Pylyshyn, 1988; Pylyshyn, 1984; Smith, Osherson, Rips, & Keane, ize what to convey in an utterance. In turn, listeners combine 1988). Consider combining concepts for blue and house to repre- concepts for words in sentences to conceptualize what speakers sent the meaning of the noun phrase, ‘‘blue house.”1 According to are saying. During thought, agents combine concepts as they solve traditional theories, house is a predicate-like structure (often re- problems, reason, and make decisions. Although non-humans may ferred to as a ‘‘frame” or ‘‘schema”) that contains many arguments, have some ability to combine concepts (e.g., when perceiving novel each taking multiple values (e.g., arguments such as color, size, and scenes), humans appear qualitatively superior. location). To represent the meaning of ‘‘blue house,” a symbol for In a classic paper, Fodor and Pylyshyn (1988) argued that con- the value blue becomes bound to the color argument in the predicate ceptual combination is a signature ability of humans. Using a finite structure for house, creating the expression, house (color = blue, size = ?, location = ?, ...). Thus, standard theories assume that * Corresponding author. Tel.: +404 727 4338. E-mail address: [email protected] (L.W. Barsalou). 1 Throughout this article, we use quotes to indicate the word or phrase for a URL: http://userwww.service.emory.edu/~barsalou/ (L.W. Barsalou). concept (e.g., ‘‘house”), and italics to indicate the respective concept (e.g., house). 0001-6918/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.actpsy.2009.02.002 Author's personal copy 174 L.-l. Wu, L.W. Barsalou / Acta Psychologica 132 (2009) 173–189 combining amodal symbols in a psychological predicate calculus plant was coded as a taxonomic category, blades as an entity prop- underlies conceptual combination, and indeed much of cognition. erty, you play on it as a situational property, and makes me feel good Alternative theories exist as well. In response to Fodor and Pyly- as an introspective property. Within these four general categories, shyn’s classic (1988) article, connectionists developed statistical each property was assigned to 1 of 37 hierarchically nested specific approaches for implementing conceptual combination (e.g., Pol- categories. Thus, plant was coded as a superordinate category, lack, 1990; Smolensky, 1990). Although these approaches em- blades as an external component of an entity, you play on it as situ- braced the functional importance of conceptual combination in ational action, and makes me feel good as an evaluative introspec- human cognition, they argued that statistical mechanisms imple- tion. For other applications of this coding scheme, see Cree and ment this functionality instead of predicate-calculus-like mecha- McRae (2003), McRae et al. (2005), and Brainerd, Yang, Reyna, nisms. We, too, assume that statistical structures underlie Howe, and Mills (2008).2 conceptual combination, and that conceptual combination is a In the experiments to follow, application of this coding scheme highly dynamical process (e.g., Barsalou, 2003a, 2005a; Barsalou, to property generation data was used to test three hypotheses Breazeal, & Smith, 2007). associated with the simulation account of conceptual combination: Still another alternative—the one pursued here—is that simula- (1) Occlusion modulates the generation of properties from nouns tion mechanisms in the brain play a central role in implementing and noun phrases, (2) Participants spontaneously use simulations conceptual combination (Barsalou, 1999, 2003a; Barsalou, 2005a, to generate properties, such that the properties they generate are 2008b). According to this account, humans represent individual roughly equivalent to those that participants instructed explicitly concepts with simulations of their referents, which could take to use imagery generate (i.e., instructional equivalence), (3) Partic- the form of exemplars or prototypes. When representing house, ipants situate the simulations that represent nouns and noun for example, people represent houses with multi-modal simula- phrases in the context of settings, events, and mental states. The tions of what the experience of a house is like, including percep- next three sections address these hypotheses in turn. tions of houses, actions taken on houses, and introspections about houses (i.e., emotions and beliefs). To perform conceptual 3. Occlusion modulates property generation during conceptual combination, simulations of individual concepts are combined to combination form larger, more complex simulations (e.g., combining simula- tions of blue and house to simulate blue house). Notably, the simu- Much behavioral research demonstrates that when participants lation account does not assume that holistic bit-map-like images generate mental images in working memory, perceptual variables represent concepts. Instead, this account assumes that the con- such as orientation, position, and size affect processing (e.g., Finke, struct of a simulator enables the symbolic functionality of classic 1989; Kosslyn, 1980; Shepard & Cooper, 1982). Because imagery predicate-calculus-like theories. Essentially, simulators function utilizes representations in perceptual systems, variables that affect as the concepts in classic theories, making it possible to implement perception also affect imagery. Just as it takes longer to scan across argument binding, conceptual combination, propositional inter- 30° of visual angle in the visual field than 10°, it also takes longer to pretation, and inference. This account further assumes that the scan across 30° of a visual image than 10°. The following experi- construction of simulations from simulators is highly dynamical, ments pursue a similar research strategy: If participants construct much in the spirit of connectionist approaches. Thus, the simula- perceptual simulations spontaneously to represent concepts, then tion account embraces all three perspectives: It implements classic perceptual variables should affect conceptual processing, analo- predicate-calculus-like