Neuropsychologia 147 (2020) 107579 Available online 3 August 2020 0028-3932/© 2020 Elsevier Ltd. All rights reserved. Schizotypy and individual differences in peripersonal space plasticity F. Ferroni a, * , M. Ardizzi a , F. Ferri b , A. Tesanovic a , N. Langiulli a , M. Tonna c , C. Marchesi a , V. Gallese a, d a Department of Medicine and Surgery, Unit of Neuroscience, University of Parma, Parma, Italy b Department of Neuroscience, Imaging and Clinical Science, University G. D’Annunzio, Chieti, Italy c Department of Mental Health, Local Health Service, Parma, Italy d Berlin School of Mind and Brain, Humboldt-Universit¨ at zu Berlin, Germany A R T I C L E INFO Keywords: Action Observation Peripersonal space Schizotypy Tool-use ABSTRACT The space surrounding our body, defned as peripersonal space (PPS), is dynamically shaped by our motor ex- periences. For instance, PPS extends after using a tool to reach far objects. Several studies have demonstrated how PPS size varies across people, depending on different individual characteristics, including schizotypy. Coherently, narrower PPS boundaries have been reported among high schizotypal individuals and schizophrenia patients. However, little is known about the relationship between PPS plasticity and personality traits like schizotypy. To this purpose, the present study has investigated the individual PPS plasticity, after two different motor trainings, along the schizotypal continuum. Specifcally, PPS plasticity was tested after using a tool (Experiment 1) and after the mere observation of another person using the same tool (Experiment 2). Indeed, previous evidence has shown that tool-use observation infuences visual distance judgments, extending the representation of PPS. To date, however, there is no study investigating whether observation of tools action could also affect multisensory PPS tasks. Experiment 1 has shown that PPS boundaries extended after using the tool; on the other hand, Experiment 2 has revealed the absence of PPS expansion. Moreover, greater PPS expansion emerged in the relatively-low schizotypal group than in the relatively-high one, regardless of the type of motor training performed. The absence of PPS modulation after the observation task is discussed in relation to recent fndings showing that intentional action and/or the goal of the action represent potentially crucial elements to trigger PPS plasticity. Finally, these new results extend previous evidence underlining a potential general functional alteration of PPS with the increase of schizotypal level. 1. Introduction In everyday life, we regularly interact with, orient to, and reach objects. Most of these interactions occur within a limited portion of space immediately surrounding our body, defned as Peripersonal Space (PPS) (Rizzolatti et al., 1981). Neurophysiological studies on monkeys have provided empirical evidence of bimodal and trimodal neurons located in the ventral premotor cortex and in the posterior parietal cortex with tactile receptive felds centred on specifc body parts and visual and/or auditory receptive felds anchored to the tactile ones (Rizzolatti et al., 1997). Additionally, neuroimaging studies (Brozzoli et al., 2011, 2012b; 2013; Ferri et al., 2015a; Makin et al., 2007; Sereno and Huang, 2006) have suggested the existence of a similar PPS repre- sentation in humans, relying on the activity of multisensory parietal and premotor regions. From what stated above, it follows that PPS is a multisensory space where tactile and proprioceptive information con- cerning specifc body parts, and visual inputs related to the environment are integrated (Gross and Graziano, 1995; Rizzolatti et al., 1997; for a review, see Serino, 2019). Nevertheless, since in our environment we interact not only with objects but also with other individuals, another specifc space sector is described and mapped. This space sector, i.e. the distance between ourselves and other people, is commonly called Interpersonal Space (IPS). In this regard, it has been demonstrated that both PPS and IPS are plastic and can be modifed by social and non-social interactions (e.g., Teneggi et al., 2013). Moreover, a recent study (Patan´ e et al., 2017) has demonstrated that these two space rep- resentations can be dissociated, showing that PPS has a putative role for the guidance of interpersonal motor interactions (e.g., Ambrosini and Costantini, 2013; Brozzoli et al., 2014) while IPS is more dependent upon socio-emotional factors (e.g., Sommer, 2002; Tajadura-Jim´ enez * Corresponding author. Via Volturno, 39/E, 43121, Parma, Italy. E-mail address: francesca.ferroni1@unipr.it (F. Ferroni). Contents lists available at ScienceDirect Neuropsychologia journal homepage: http://www.elsevier.com/locate/neuropsychologia https://doi.org/10.1016/j.neuropsychologia.2020.107579 Received 4 May 2020; Received in revised form 30 July 2020; Accepted 31 July 2020