Neuroscience Letters 492 (2011) 89–93 Contents lists available at ScienceDirect Neuroscience Letters journal homepage: www.elsevier.com/locate/neulet Sensory-motor interference abolishes repetition priming for observed actions, but not for action-related verbs Marianna Busiello a,b,∗ , Marcello Costantini a,b , Gaspare Galati c,d , Giorgia Committeri a,b a Laboratory of Neuropsychology and Cognitive Neuroscience, Department of Neuroscience and Imaging, G. d’Annunzio University, Chieti, Italy b Institute for Advanced Biomedical Technologies – ITAB, G. d’Annunzio Foundation University, Chieti, Italy c Department of Psychology, Sapienza University, Roma, Italy d Laboratory of Neuropsychology, Foundation Santa Lucia, Roma, Italy article info Article history: Received 1 December 2010 Received in revised form 10 January 2011 Accepted 24 January 2011 Keywords: Mirror mechanism Action recognition Repetition priming Action goal abstract Several studies on humans have shown a recruitment of the sensory-motor system in the perception of action-related visual and verbal material, suggesting that actions are represented through sensory-motor processes. To date, these studies have not disentangled whether such a recruitment is epiphenomenal or necessary to action representation. Here we took advantage of repetition priming as a tool to investigate the cognitive representation of actions, and systematically looked whether a concurrent motor or verbal task had a detrimental effect on this representation. In a first experiment participants discriminated images depicting meaningless and meaningful actions, while performing either a concurrent sensory- motor or an articulatory suppression task. Images were classified as depicting a repeated or a new action, relative to the previous image in the trial series. We found a facilitation by repetition priming, that was unaffected by the articulatory task but was completely abolished by the sensory-motor task. In a second experiment, we investigated whether the sensory-motor system is also causally involved in processing action-related verbs. In this experiment actions were presented as written infinitive verbs rather than as images. The facilitation by repetition priming was again unaffected by the concurrent articulatory task, while the sensory-motor concurrent task, although reducing the facilitation, did not abolish it. Our data provide evidence that the sensory-motor system is differentially involved during visual processing of actions and during processing of action-related verbs. Results are discussed within the theoretical frame of embodied cognition. © 2011 Elsevier Ireland Ltd. All rights reserved. Converging evidence suggests that perception and action planning are coded in a common representational medium [20,26,27]. For instance, behavioural studies have shown that action obser- vation and action execution interact with each other. Brass and colleagues [4] instructed participants to execute finger move- ments in response to observed compatible and incompatible finger movements, and found a reaction time advantage for compatible trials. Similarly, Kilner and colleagues [23] showed an increased variance in arm movement execution when observing a human model executing a qualitatively different, rather than the same arm movement. This interference effect disappeared when partic- ipants watched a robot executing both the same and different arm movements, suggesting that the interference on motor control is due to the simultaneous activation of a neural network processing ∗ Corresponding author at: Department of Neuroscience and Imaging, University of Chieti, Via dei Vestini 33, 66013 Chieti, Italy. Tel.: +39 0871 3556910; fax: +39 0871 3556930. E-mail address: m.busiello@unich.it (M. Busiello). both movement execution and the observation of the movement performed by a conspecific. This neural network would be based on the activity of mirror neurons [32]. These neurons respond when the monkey performs an object-directed action or while perceiving the same action per- formed by someone else [9,13,15,35,36]. Neuroimaging studies suggest that mirror mechanisms do exist also in humans, by show- ing that motor planning areas are activated when humans simply observe actions of others [5,7]. But why does the brain re-enact observed actions? Several pos- sible functions of such simulation have been proposed, like the facilitation of overt imitation [22], the understanding of action in motor terms [31], and the understanding of others’ intentions [3,11,21]. Most important for the present study, it has been pro- posed that the mirror system is the neurophysiological counterpart of the cognitive representation of actions [34] (see for a different view: [24]). Such a cognitive representation seems to be activated not only when observing actions, but also when reading or listening to action-related verbal material. Indeed, functional brain imaging 0304-3940/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2011.01.063