The impact of sleep deprivation on visual perspective taking GA  ETANE DELIENS 1,2,3, * , HENRYK BUKOWSKI 4, *, HICHEM SLAMA 3 , ANDREW SURTEES 5,6 , AXEL CLEEREMANS 2 , DANA SAMSON 5 and PHILIPPE PEIGNEUX 3 1 Autism in Context: Theory and Experience (ACTE), Center of Research in Linguistics (LaDisco), Universit e libre de Bruxelles, Brussels, Belgium; 2 Consciousness, Cognition and Computation at CRCN (CO3), Center for Research in Cognition and Neurosciences and UNI–ULB Neurosciences Institute, Universit e libre de Bruxelles, Brussels, Belgium; 3 Neuropsychology and Functional Neuroimaging Research Group at CRCN (UR2NF), Center for Research in Cognition and Neurosciences and UNI –ULB Neurosciences Institute, Universit e libre de Bruxelles, Brussels, Belgium; 4 Social, Cognitive and Affective Neuroscience Unit (SCAN), Department of Basic Psychological Research and Research Methods, University of Vienna, Vienna, Austria; 5 Psychological Sciences Research Institute, Universit e catholique de Louvain, Louvain-La- Neuve, Belgium; 6 School of Psychology, University of Birmingham, Birmingham, UK Keywords cognitive empathy, executive functions, mentalizing, Visual perspective taking Correspondence Ga etane Deliens, Autism in Context: Theory and Experience (ACTE), Center of Research in Linguistics (LaDisco), Universit e libre de Bruxelles, Avenue F.D. Roosevelt, 50, B-1050 Brussels, Belgium. Tel.: +32(0)26506033; fax: +32(0)26502209; e-mail: Gaetane.Deliens@ulb.ac.be *These authors contributed equally to this study. Accepted in revised form 18 July 2017; received 22 January 2017 DOI: 10.1111/jsr.12595 SUMMARY Total sleep deprivation (TSD) is known to alter cognitive processes. Surprisingly little attention has been paid to its impact on social cognition. Here, we investigated whether TSD alters levels-1 and -2 visual perspective-taking abilities, i.e. the capacity to infer (a) what can be seen and (b) how it is seen from another person’s visual perspective, respectively. Participants completed levels-1 and -2 visual perspective- taking tasks after a night of sleep and after a night of TSD. In these tasks, participants had to take their own (self trials) or someone else’s (other trials) visual perspective in trials where both perspectives were either the same (consistent trials) or different (inconsistent trials). An instruction preceding each trial indicated the perspective to take (i.e. the relevant perspective). Results show that TSD globally deteriorates social perfor- mance. In the level-1 task, TSD affects the selection of relevant over irrelevant perspectives. In the level-2 task, the effect of TSD cannot be unequivocally explained. This implies that visual perspective taking should be viewed as partially state-dependent, rather than a wholly static trait-like characteristic. INTRODUCTION Sleep loss is a recognized societal issue, known to impact markedly upon a wide range of cognitive functions (Basner et al., 2013). Surprisingly, however, perspective taking has received scant attention, despite the fact that we need to place ourselves regularly in another person’s shoes to achieve successful social interactions. The negative effect of sleep debt on emotional empathy (i.e. emotional perspective taking) has been evidenced in some studies (e.g. Bellini et al., 2002; Guadagni et al., 2014), but the interplay between sleep and the cognitive side of perspective taking remains unexplored. The only study that investigated the impact of sleep loss on cognitive perspective-taking reported slower reaction time on a sarcasm detection task after a night of total sleep deprivation (TSD) than after a whole night of sleep (Deliens et al., 2015a). This effect was not fully explainable by generalized cognitive slowing after TSD. However, proper completion of a sarcasm detection task depends upon working memory integrity, to keep in mind the context in which sarcasm may be detected and a series of paralinguistic cues such as the speaker’s facial expression and prosody. As TSD can affect working memory negatively (for a meta-analysis see Lim and Dinges, 2008), this adverse effect may have partially driven the observed effects on sarcasm detection. In the present study, we assessed the impact of TSD on visual perspective taking (VPT). VPT allows inferring what can or cannot be seen by another person (i.e. a level-1 perspective), and how it is seen by that person (i.e. a level-2 perspective) (Flavell et al., 1981). The ability to infer another person’s visual experience is a pivotal source of information for managing social interactions. For instance, it allows inferring: (i) knowledge and beliefs of others about the nearby environment, (ii) which objects they prefer or (iii) whether they see us or pay attention to us. Congruently, VPT performance correlates with self-reported perspective-taking habits (Bukowski and Samson, 2017; Mattan et al., 2016). Crucially, ª 2017 European Sleep Research Society 175 J Sleep Res. (2018) 27, 175–183 Sleep deprivation and sleep reduction