Brain and Cognition 76 (2011) 26–36 Contents lists available at ScienceDirect Brain and Cognition journal homepage: www.elsevier.com/locate/b&c Motor execution affects action prediction ⇑ Anne Springer a,b, , Simone Brandstädter a, Roman Liepelt a,c, Teresa Birngruber a, Martin Giese d, Franz Mechsner e, Wolfgang Prinz a a Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany b University of Potsdam, Exzellenzbereich Kognitionswissenschaften, Department of Sport and Exercise Psychology, Potsdam, Germany c Westfälische Wilhelms University, Department of Psychology, Junior Group ‘Neurocognition of Joint Action’, Münster, Germany d Hertie-Institute for Clinical Brain Research and Centre for Integrative Neuroscience, University Clinic Tübingen, Tübingen, Germany e Northumbria University, Newcastle upon Tyne, UK article info abstract Article history: Previous studies provided evidence of the claim that the prediction of occluded action involves real-time Accepted 15 March 2011 simulation. We report two experiments that aimed to study how real-time simulation is affected by Available online 8 April 2011 simultaneous action execution under conditions of full, partial or no overlap between observed and exe- cuted actions. This overlap was analysed by comparing the body sides and the movement kinematics Keywords: involved in the observed and the executed action. While performing actions, participants observed Action prediction point-light (PL) actions that were interrupted by an occluder, followed by a test pose. The task was to Internal simulation judge whether the test pose depicted a continuation of the occluded action in the same depth angle. Motor execution Using a paradigm proposed by Graf et al., we independently manipulated the duration of the occluder Common coding Perception-action-link and the temporal advance of the test pose relative to occlusion onset (occluder time and pose time, respectively). This paradigm allows the assessment of real-time simulation, based on prediction perfor- mance across different occluder time/pose time combinations (i.e., improved task performance with decreasing time distance between occluder time and pose time is taken to reflect real-time simulation). The PL actor could be perceived as from the front or back, as indicated by task instructions. In Experiment 1 (front view instructions), evidence of action simulation was obtained for partial overlap (i.e., observed and performed action corresponded either in body side or movement kinematics), but not for full or no overlap conditions. The same pattern was obtained in Experiment 2 (back view instructions), ruling out a spatial compatibility explanation for the real-time pattern observed. Our results suggest that motor pro- cesses affect action prediction and real-time simulation. The strength of their impact varies as a function of the overlap between observed and executed actions. Ó 2011 Elsevier Inc. All rights reserved. 1. Introduction (Hamilton, Wolpert, & Frith, 2004; Zwickel, Grosjean, & Prinz, 2007). On the other hand, movement execution was faster when Human mirror neuron research has indicated that perceiving an go-stimuli displayed the to-be-executed movements (Brass, action activates similar cortical networks as executing the same ac- Bekkering, & Prinz, 2001; Craighero, Bello, Fadiga, & Rizzolatti, tion (Gallese, Fadiga, Fogassi, & Rizzolatti, 1996; for a review see 2002), and the variance of executed movements was increased Iacoboni & Dapretto, 2006). This corresponds to the notion that while observing a different movement relative to the same move- perception and action share common representational codes ment (Kilner, Paulignan, & Blakemore, 2003). (Hommel, Müsseler, Aschersleben, & Prinz, 2001; Prinz, 1990, The relationship between perception and action has been de- 1997). Numerous behavioral studies have supported this notion scribed in terms of ‘representational overlap’ (e.g., Dinstein, Hasson, by showing that action execution affects action observation and Rubin, & Heeger, 2007; Marconi, Pecchioli, Koch, & Caltagirone, vice versa (for a review see Schütz-Bosbach & Prinz, 2007). For in- 2007). According to the theory of event coding (TEC), codes of per- stance, visual motions were detected less efficiently when they ceived events and planned actions share a common representational went in the same direction as concurrently performed actions domain. As a consequence, perceptual codes and action codes may prime each other on the basis of their representational overlap in this domain (Hommel et al., 2001). For instance, during different motor ⇑ Corresponding author at: University of Potsdam, Exzellenzbereich Kognitions- wissenschaften, Department of Sport and Exercise Psychology, Am Neuen Palais 10, cognitive tasks (i.e., motor imagery; movement observation), the D-14469 Potsdam, Germany. cortical representations of a target muscle and a functionally related E-mail address: [email protected] (A. Springer). muscle were enhanced within a single task and across different 0278-2626/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.bandc.2011.03.007 A. Springer et al. / Brain and Cognition 76 (2011) 26–36 27 tasks, indicating a topographical and functional overlap of motor 100; 700/400) and lowest at a distance of ±600 ms (100/700 cortical representations (Marconi et al., 2007). and 700/100). Representational overlap may be used for anticipating others’ Indeed, previous results (Graf et al., 2007; Springer & Prinz, action by mapping those actions onto one’s own motor repertoire 2010) showed that performance was best when occluder time (Gallese, 2005; Jeannerod, 2001). Humans seem to run internal and pose time corresponded and decreased with increasing time sensorimotor simulations when predicting the future course of distance, supporting the notion that action prediction involves observed actions (see Sebanz & Knoblich, 2009; Wilson & internal real-time processes. This notion corresponds to the view Knoblich, 2005, for reviews). Flanagan and Johansson (2003) that sensorimotor simulations enable the extrapolation of future showed that eye movements during action observation were pre- actions (Grush, 2004; Thornton & Knoblich, 2006). Efficient body dictive rather than reactive, and Kilner, Vargas, Duval, Blakemore, control requires the estimation of one’s own body state prior to and Sirigu (2004) found that motor-related brain activity movement execution, which is based on internal forward occurred prior to observing a predictable movement. Further- models. These forward models predict the sensory consequences more, increased premotor activation was found when observers of movements in real time by relying on motor commands (i.e., predicted the future course of partly invisible action sequences efference copies) (Wolpert & Flanagan, 2001). They may also be (Stadler et al., in press), indicating that internal simulation is used applied when predicting the actions observed in another for action prediction. individual (Blakemore & Frith, 2005; Kilner, Friston, & Frith, 2007). 1.1. The present research To test our assumption that the processes involved in an ac- tion prediction task pertain to a motor representational format, Although motor representations of observed actions may be we adapted the paradigm by Graf et al. (2007) by adding a con- involved in predicting these actions, this issue has not directly current motor execution task. While watching arm movements been investigated. The present study aimed to test the impact of a point-light (PL) figure, the participants executed arm move- of motor processes on action prediction. Based on studies show- ments synchronized in time to the PL movements (see Fig. 1). ing a close link between perception and action (Brass et al., We used three different conditions. In the ‘full overlap’ condition, 2001; Craighero et al., 2002; Hamilton et al., 2004; Kilner et al., both the executed actions and the observed actions were fully 2003, 2004; Liepelt, von Cramon, & Brass, 2008; Stadler et al., congruent and involved the same anatomical body side and the in press; Zwickel et al., 2007), we suggest that motor processes same movement pattern. In contrast, in the ‘partial overlap’ con- are involved in internal action simulation. More specifically, the dition, executed and observed actions differed either in the ana- degree of a representational overlap between executed and ob- tomical body side used or in the exact movement pattern served movements (i.e., the degree to which they share common involved. In the ‘no overlap’ condition, observed and executed ac- representational features) should modulate the degree to which tions were fully incongruent, involving different anatomical body simulation processes are recruited during an action prediction sides and different movement patterns (as specified below). As task (Hommel et al., 2001). the two dimensions – which we refer to as ‘body side’ and ‘move- We examined how motor execution affects the performance in ment pattern’, respectively – varied independently, this design al- a visual action prediction task that is considered to reflect internal lowed us to systematically test how the degree of a action simulation. We used a paradigm by Graf et al. (2007), who representational overlap between executed and observed actions presented videos of a point-light (PL) actor performing familiar ac- affects internal action simulation (indicated by a monotonic dis- tions that were briefly occluded and then