Perceptual and Cognitive Enhancement with an Adaptive Timing Partner: Electrophysiological Responses to Pitch Change

(ProQuest: . denotes formula omitted.)When two people play music together, they need to control the timing of their own actions while also adjusting their actions in response to those of the other (Nowicki, Prinz, Grosjean, Repp, & Keller, 2013; Wing, Endo, Bradbury, & Vorberg, 2014). Having a partner who adapts can be satisfying. Patients playing a percussion instrument with a music therapist who entrains to them may gain a sense of freedom in expressing their emotion and feel empowered by the experience (Bensimon, Amir, & Wolf, 2008; Winkelman, 2003). In many species, individuals synchronize their movements together, such as birds that fly in formation, fish that swim in schools, and fireflies that flash at the same time (Buck, 1935, 1937, 1988; Partridge, 1982; Weimerskirch, Martin, Clerquin, Alexandre, & Jiraskova, 2001). More rare, but found in humans and a few vocal learning species, is the ability to synchronize movement to a predictable auditory stimulus, such as the beat in music (Patel & Iversen, 2014; Patel, Iversen, Bregman, & Schulz, 2009; Schachner, Brady, Pepperberg, & Hauser, 2009; Trainor, 2015). This ability is referred to as sensorimotor synchronization (SMS) and is defined as "the coordination of rhythmic movement with an external rhythm" (Repp & Su, 2013). In a typical musical performance, the underlying beat or tempo produced is not completely steady, with deviations arising from several sources, such as internal time-keeping errors (Torre & Delignieres, 2008; Wing & Kristofferson, 1973a, 1973b), and deliberate deviations for expressive purposes (James, Michel, Britz, Vuilleumier, & Hauert, 2012; Rankin, Large, & Fink, 2009; Repp, 1992). Thus, for two or more people to play music together in synchrony, it necessarily involves mutual adjustments of phase alignment and tempo (period) to achieve SMS.The study of interpersonal synchrony is particularly important because empirical evidence indicates that synchronous movement promotes a sense of group affiliation. For example, walking or singing in synchrony with others increases cooperation, trust, and ratings of likability among participants (Hove & Risen, 2009; Kirschner & Tomasello, 2010; Valdesolo, Ouyang, & DeSteno, 2010; Wiltermuth & Heath, 2009). Synchronous movement to music even leads to enhanced prosocial instrumental helping in infants (Cirelli, Einarson, & Trainor, 2014; Cirelli & Trainor, 2015). Cirelli, Wan, and Trainor (2014) bounced 14-month-old infants to music facing an experimenter who bounced in synchrony with the infant, or in antiphase (but at the same tempo), or at a different tempo from the infant. After this experience, infants were more likely to help the experimenter by retrieving "accidentally" dropped items needed to complete a task if they had bounced at the same tempo as the experimenter (either in phase or antiphase) compared with if they bounced at a different tempo, whether faster or slower. Of interest to the authors, this increase in helping after synchronous bouncing is targeted to the bouncing partner and not to neutral strangers (Cirelli, Wan, et al., 2014), although it does apply to friends of the synchronous bouncing partner (Cirelli & Trainor, 2015). It has been proposed that three core cognitive-motor skills are needed for people to engage in real-time interpersonal coordination-( a) propensity to synchronize movements, (b) ability to use anticipatory mechanisms during SMS, and (c) ability to divide attention (reviewed by Keller, Novembre, & Hove, 2014), reviewed in more detail below. In the present study, we investigate perceptual/cognitive consequences of playing with an adaptive partner. In particular, during a difficult SMS task, we expect that an adaptive virtual partner that adjusts its onset times so as to place its upcoming tones closer to the expectations of a musically untrained partner will reduce resource demands for that untrained partner compared with a virtual partner that does not adjust, leading to enhanced perceptual and cognitive processing of the music. …