This article was downloaded by: [Knoblich, Gunther] On: 1 November 2008 Access details: Access Details: [subscription number 905025113] Publisher Psychology Press Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Social Neuroscience Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t741771143 Action co-representation: The joint SNARC effect Silke Atmaca a; Natalie Sebanz b; Wolfgang Prinz c; Günther Knoblich b a Rutgers, The New Jersey State University, Newark, NJ, USA b University of Birmingham, UK c Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany First Published on: 30 January 2008 To cite this Article Atmaca, Silke, Sebanz, Natalie, Prinz, Wolfgang and Knoblich, Günther(2008)'Action co-representation: The joint SNARC effect',Social Neuroscience,3:3,410 — 420 To link to this Article: DOI: 10.1080/17470910801900908 URL: http://dx.doi.org/10.1080/17470910801900908 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. 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SOCIAL NEUROSCIENCE, 2008, 3 (3Á4), 410Á420 Action co-representation: The joint SNARC effect Silke Atmaca Rutgers, The New Jersey State University, Newark, NJ, USA Natalie Sebanz University of Birmingham, UK Wolfgang Prinz Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany Gu¨ nther Knoblich University of Birmingham, UK Traditionally, communication has been defined as the intentional exchange of symbolic information between individuals. In contrast, the mirror system provides a basis for nonsymbolic and nonintentional information exchange between individuals. We believe that understanding the role of the mirror system in joint action has the potential to serve as a bridge between these two domains. The present study investigates one crucial component of joint action: the ability to represent others’ potential actions in the same way as one’s own in the absence of perceptual evidence. In two experiments a joint spatial numerical association of response codes (SNARC) effect is demonstrated, providing further evidence that individuals form functionally equivalent representations of their own and others’ potential actions. It is shown that numerical (symbolic) stimuli that are mapped onto a spatially arranged internal representation (a mental number line) can activate a co-represented action in the same way as spatial stimuli. This generalizes previous results on co-representation. We discuss the role of the mirror system in co-representation as a basis for shared intentionality and communication. Downloaded By: [Knoblich, Gunther] At: 09:11 1 November 2008 INTRODUCTION a sender and a receiver? Obviously, employing this sort of classical engineering definition of At first glance, the idea that the mirror system communication creates a seemingly unbridgeable (Gallese, Keysers, & Rizzolatti, 2004; Rizzolatti divide between action perception and commu- & Craighero, 2004) supports communication nication. seems like a long shot. How can a system that However, if one accepts a wider definition of resonates with others’ actions (Di Pellegrino, communication that allows for nonsymbolic and Fadiga, Fogassi, Gallese, & Rizzolatti, 1992; nonintentional information exchange, the mirror Gallese, Fadiga, Fogassi, & Rizzolatti, 1996), system presents itself as a potentially powerful perceptions (Keysers et al., 2004), and emotions device in the service of communication and other (Goldman & Sripada, 2005), support the inten- forms of social interaction. It can be regarded as a tional exchange of symbolic information between basic link between sender and receiver (Rizzolatti Correspondence should be addressed to: Gu¨ nther Knoblich, School of Psychology, Behavioural Brain Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. E-mail: [email protected] We thank Irmgard Hagen, Jana Hiller, and, in particular, Veronika Ga¨rtner for their help in collecting the data. Silke Atmaca would like to thank Stefan Krauss for helpful advice. # 2008 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business www.psypress.com/socialneuroscience DOI:10.1080/17470910801900908 THE JOINT SNARC EFFECT 411 & Arbib, 1998) that provides procedural, percep- provide the means to jointly attend to the same tual, and emotional common ground between objects and events (cf. Tomasello, 2000), to individuals (Sebanz, Bekkering, & Knoblich, effectively perform different parts of a task 2006). If observing you perform an action is (Sebanz, Knoblich, & Prinz, 2005; Sebanz et al., similar to performing it myself (e.g., Grezes, 2006), and to coordinate the timing of actions Armony, Rowe, & Passingham, 2003), if seeing (Knoblich & Jordan, 2003). you being touched is similar to being touched As a first step towards understanding how the myself (e.g., Keysers et al., 2004), and if perceiv- mirror system supports joint action, we focus on ing your pain is similar to being in pain myself the question of whether and how individuals (e.g., Singer et al., 2004), there is an interpersonal represent each other’s actions when performing link between us that requires neither symbols nor different parts of a task together. If the mirror the intention to communicate. system gets recruited during joint action, co- How can we build on the mirror system to actors should represent their own and others’ arrive at more sophisticated (symbolic, inten- actions in a functionally equivalent way. Theore- tional) forms of communication that entail com- tical frameworks extending ideomotor theory mon, conventionalized knowledge (Clark, 1996) (Greenwald, 1970; James, 1890), in particular and shared intentionality (Barresi & Moore, common coding theory (Hommel et al., 2001; 1996)? One possibility is to claim that the Jeannerod, 1999; Prinz, 1997), have long postu- mirroring principle is gradually extended from lated such a functional equivalence. The com- concrete content to more abstract content. For mon coding theory postulates that the same example, Arbib (2005) proposed a progression representations are involved in action production from the mirroring of instrumental action to hand and action observation. The mirror system can gestures and, ultimately, to speech (Galantucci, be regarded as the neural implementation of this Fowler, & Turvey, 2006; Liberman & Whalen, functional principle. 2000). While this proposal focuses on changes in In line with the common coding principle, prior content that can be shared interpersonally, it research has shown that observing somebody else cannot explain the evolution of shared intention- concurrently performing the same action as ality (Tomasello, Carpenter, Call, Behne, & Moll, oneself results in facilitation, whereas observing 2005). How is it that people can represent a joint somebody else concurrently performing the op- task, represent their role in performing a task posite action interferes with performing the together, and coordinate their actions to achieve a action (Brass, Bekkering, & Prinz, 2001; Kilner, shared goal? This seems to be a further critical Paulignan, & Blakemore, 2003; Stuermer, Ascher- component boosting social interaction and com- sleben, & Prinz, 2000). Less is known about how munication (cf. Galantucci, 2005). In fact, there actors influence each other’s performance when would not be much use for communication but for acting in turns, which is prototypical of many Downloaded By: [Knoblich, Gunther] At: 09:11 1 November 2008 the need to successfully engage in joint action types of joint action. When taking turns, one does (Clark, 1996). not perceive competing (or facilitating) informa- We believe that understanding how the mirror tion about the other while acting oneself. Rather, system is recruited in the service of joint action influences of the other’s actions are expected only may provide a crucial link between implicit, if they are part of one’s own task representation. nonsymbolic, and nonintentional information ex- In other words, if facilitation or interference change achieved through mirroring, and explicit, occurs in the absence of action observation, one symbolic, and intentional information exchange can conclude that coactors represent not only that characterizes discourse (cf. Garrod & Pick- their own, but also the other’s potential actions. ering, 2004). The advantage of calling both In an earlier study (Sebanz, Knoblich and ‘‘communication’’ is to leave open the possibility Prinz, 2003), we demonstrated such effects using that more sophisticated forms of communication a variant of a spatial compatibility (Simon) task still recruit basic