Vol.:(0123456789) 1 3 Psychological Research https://doi.org/10.1007/s00426-018-1074-8 ORIGINAL ARTICLE Efects of pitch and tempo of auditory rhythms on spontaneous movement entrainment and stabilisation Manuel Varlet 1  · Rohan Williams 1  · Peter E. Keller 1 Received: 11 January 2018 / Accepted: 9 August 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Human movements spontaneously entrain to auditory rhythms, which can help to stabilise movements in time and space. The properties of auditory rhythms supporting the occurrence of this phenomenon, however, remain largely unclear. Here, we investigate in two experiments the efects of pitch and tempo on spontaneous movement entrainment and stabilisation. We examined spontaneous entrainment of hand-held pendulum swinging in time with low-pitched (100 Hz) and high-pitched (1600 Hz) metronomes to test whether low pitch favours movement entrainment and stabilisation. To investigate whether stimulation and movement tempi moderate these efects of pitch, we manipulated (1) participants’ preferred movement tempo by varying pendulum mechanical constraints (Experiment 1) and (2) stimulation tempo, which was either equal to, or slightly slower or faster (± 10%) than the participant’s preferred movement tempo (Experiment 2). The results showed that participants’ movements spontaneously entrained to auditory rhythms, and that this efect was stronger with low-pitched rhythms independently of stimulation and movement tempi. Results also indicated that auditory rhythms can lead to increased movement amplitude and stabilisation of movement tempo and amplitude, particularly when low-pitched. However, stabili- sation efects were found to depend on intrinsic movement variability. Auditory rhythms decreased movement variability of individuals with higher intrinsic variability but increased movement variability of individuals with lower intrinsic variability. These fndings provide new insights into factors that infuence auditory–motor entrainment and how they may be optimised to enhance movement efciency. Introduction People spontaneously move in synchrony with audi- tory rhythms, musical rhythms in particular. Such audi- tory–motor entrainment happens intentionally but also often spontaneously (Burger, Thompson, Luck, Saarikallio, & Toiviainen, 2014; Demos, Chafn, Begosh, Daniels, & Marsh, 2012; Néda, Ravasz, Brechet, Vicsek, & Barabási, 2000; Nozaradan, Petretz, & Keller, 2016; Phillips-Silver, Aktipis, & Bryant, 2010; Repp, 2005; Repp & Su, 2013; Torre, Varlet, & Marmelat, 2013; Van Dyck et al., 2015). The tendency for auditory rhythms to make us move has opened a window to understanding links between auditory and motor processes in the brain. This form of entrainment has also received interest in clinical contexts, as it can be used to stimulate and modulate the motor system of patients with movement disorders simply by presenting auditory rhythms (Hove & Keller, 2015; Malcom, Massie, & Thaut, 2009; McIntosh, Brown, Rice, & Thaut, 1997; Thaut et al., 1996; Thaut, McIntosh, & Rice, 1997). Auditory–motor entrainment can thus help to improve the locomotion of patients with Parkinson’s disease or stroke, for instance, by stabilising movements in time and space. However, not all auditory rhythms induce movement entrainment and stabi- lisation equally. In fact, it remains unclear which properties of auditory rhythms facilitate spontaneous motor entrain- ment. Here, we investigate in two experiments the mecha- nisms underlying spontaneous auditory–motor entrainment and movement stabilisation, and more specifcally, the role played by the pitch and tempo of auditory rhythms. Auditory rhythms induce movements and attract pro- duced movements towards synchrony in a variety of contexts (Burger et al., 2014; Demos et al., 2012; Keller & Rieger, 2009; Peckel, Pozzo, & Bigand et al., 2014; Van Dyck et al., 2015). Underlying these efects, previous research has revealed shared functions and neural substrates between * Manuel Varlet M.Varlet@westernsydney.edu.au 1 The MARCS Institute for Brain, Behaviour and Development, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia