Duet synchronization interventions affect social interactions

Humans' complex behavior, such as speech, music, or dance, requires us to coordinate our actions with external sounds as well as with social partners. The presence of a partner can influence individuals' synchronization, and, in turn, social connection with the partner may depend on the degree of synchronization. We manipulated the synchronization quality in intervention conditions to address the causal relationship between observed temporal synchrony and perceived social interaction. Pairs of musician and nonmusician participants first performed a turn-taking task consisting of alternating which partner tapped their melody in synchrony with a metronome (each tap generated the next tone in the melody). In two intervention conditions, participants attempted to synchronize their melodies simultaneously with their partner, either with normal auditory feedback (normal feedback) or randomly placed delayed feedback on 25% of melodic tones (delayed feedback). After each intervention, the turn-taking condition was repeated, and participants completed a questionnaire about connectedness, relationship, and feeling of synchronization with their partner. Results showed that partners' mean asynchronies were more negative following the delayed feedback intervention. In addition, nonmusician partners' tapping variability was larger following the delayed feedback intervention when they had the delayed feedback intervention first. Ratings of connectedness, relationship, and feeling of synchronization with their partner were reduced for all participants after the delayed feedback Intervention. We modeled participants' synchronization performance in the post-intervention turn-taking conditions using delay-coupling oscillator models. Reductions in synchronization performance after delayed feedback intervention were reflected in reduced coupling strength. These findings suggest that turn-taking synchronization performance and social connectedness are altered following short interventions that disrupt synchronization with a partner.

Social and nonlinear dynamics unite: musical group synchrony

Synchronization, the human tendency to align behaviors in time with others, is necessary for many survival skills. The ability to synchronize actions with rhythmic (predictable) sound patterns is especially well developed in music making. Recent models of synchrony in musical ensembles rely on pairwise comparisons between group members. This pairwise approach to synchrony has hampered theory development, given current findings from social dynamics indicating shifts in members' influence within larger groups. We draw on social theory and nonlinear dynamics to argue that emergent properties and novel roles arise in musical group synchrony that differ from individual or pairwise behaviors. This transformational shift in defining synchrony sheds light on successful outcomes as well as on disruptions that cause negative behavioral outcomes.

Smartphone-derived Virtual Keyboard Dynamics Coupled with Accelerometer Data as a Window into Understanding Brain Health: Smartphone Keyboard and Accelerometer as Window into Brain Health

We examine the feasibility of using accelerometer data exclusively collected during typing on a custom smartphone keyboard to study whether typing dynamics are associated with daily variations in mood and cognition. As part of an ongoing digital mental health study involving mood disorders, we collected data from a well-characterized clinical sample (N = 85) and classified accelerometer data per typing session into orientation (upright vs. not) and motion (active vs. not). The mood disorder group showed lower cognitive performance despite mild symptoms (depression/mania). There were also diurnal pattern differences with respect to cognitive performance: individuals with higher cognitive performance typed faster and were less sensitive to time of day. They also exhibited more well-defined diurnal patterns in smartphone keyboard usage: they engaged with the keyboard more during the day and tapered their usage more at night compared to those with lower cognitive performance, suggesting a healthier usage of their phone.

Does interpersonal liking lead to interpersonal synchrony in musical contexts?

The causal relationship of interpersonal liking affecting interpersonal synchrony is inconsistently documented. This study tests whether (a) interpersonal liking increases both behavioural and perceived synchrony and (b) people will synchronise with an agreeable partner over a competing musical stimulus. We had college students (N = 25) shake an egg-shaker with an agreeable or disagreeable confederate without music, with music, and with specific instruction to synchronise. Participants reported liking the agreeable confederate more than the disagreeable confederate and rated their relationship more positively; however, both behavioural and perceived synchrony were unaffected by the agreeableness of the confederate. Thus, we failed to replicate previous findings in an auditory only context. Furthermore, participants who believed they were more synchronised with the confederate liked the confederate more and felt more like a team, but the degree of behavioural synchrony was unrelated to these social perceptions. Perception of synchrony appears to be more important for social bonding than behavioural synchrony.

A Novel Approach to Clustering Accelerometer Data for Application in Passive Predictions of Changes in Depression Severity

The treatment of mood disorders, which can become a lifelong process, varies widely in efficacy between individuals. Most options to monitor mood rely on subjective self-reports and clinical visits, which can be burdensome and may not portray an accurate representation of what the individual is experiencing. A passive method to monitor mood could be a useful tool for those with these disorders. Some previously proposed models utilized sensors from smartphones and wearables, such as the accelerometer. This study examined a novel approach of processing accelerometer data collected from smartphones only while participants of the open-science branch of the BiAffect study were typing. The data were modeled by von Mises-Fisher distributions and weighted networks to identify clusters relating to different typing positions unique for each participant. Longitudinal features were derived from the clustered data and used in machine learning models to predict clinically relevant changes in depression from clinical and typing measures. Model accuracy was approximately 95%, with 97% area under the ROC curve (AUC). The accelerometer features outperformed the vast majority of clinical and typing features, which suggested that this new approach to analyzing accelerometer data could contribute towards unobtrusive detection of changes in depression severity without the need for clinical input.

Associations between smartphone keystroke dynamics and cognition in MS

Objective

Examine the associations between smartphone keystroke dynamics and cognitive functioning among persons with multiple sclerosis (MS).

Methods

Sixteen persons with MS with no self-reported upper extremity or typing difficulties and 10 healthy controls (HCs) completed six weeks of remote monitoring of their keystroke dynamics (i.e., how they typed on their smartphone keyboards). They also completed a comprehensive neuropsychological assessment and symptom ratings about fatigue, depression, and anxiety at baseline.

Results

A total of 1,335,787 keystrokes were collected, which were part of 30,968 typing sessions. The MS group typed slower (P < .001) and more variably (P = .032) than the HC group. Faster typing speed was associated with better performance on measures of processing speed (P = .016), attention (P = .022), and executive functioning (cognitive flexibility: P = .029; behavioral inhibition: P = .002; verbal fluency: P = .039), as well as less severe impact from fatigue (P < .001) and less severe anxiety symptoms (P = .007). Those with better cognitive functioning and less severe symptoms showed a stronger correlation between the use of backspace and autocorrection events (P < .001).

Conclusion

Typing speed may be sensitive to cognitive functions subserved by the frontal-subcortical brain circuits. Individuals with better cognitive functioning and less severe symptoms may be better at monitoring their typing errors. Keystroke dynamics have the potential to be used as an unobtrusive remote monitoring method for real-life cognitive functioning among persons with MS, which may improve the detection of relapses, evaluate treatment efficacy, and track disability progression.

Social Interaction and Rate Effects in Models of Musical Synchronization

Important individual differences are observed in people’s abilities to synchronize their body movements with regular auditory rhythms. We investigate whether synchronizing with a regular auditory cue is affected by each person’s spontaneous production rate (SPR) and by hearing a partner’s synchronization in a social context. Musically trained and untrained participants synchronized their tapping with an auditory cue presented at different rates (their own SPR or their partner’s SPR) and in a Solo or Joint (turn-taking) condition. Linear and nonlinear oscillator models were fit to participants’ mean asynchronies (signed timing differences between the cued onsets and taps). In Joint turn-taking, participants’ synchrony was increased when the auditory signal was cued at the participant’s own SPR, compared with their partner’s SPR; in contrast, synchronization did not differ across rates in the Solo condition. Asynchronies in the Joint task became larger as the difference between partners’ spontaneous rates increased; the increased asynchronies were driven by the faster partner who did not slow down to match the rate of their slower partner. Nonlinear delay-coupled models (with time delay, coupling strength, and intrinsic frequency) outperformed linear models (intrinsic frequency only) in accounting for tappers’ synchronization adjustments. The nonlinear model’s coupling value increased for musically trained participants, relative to untrained participants. Overall, these findings suggest that both intrinsic differences in partners’ spontaneous rates and the social turn-taking context contribute to the range of synchrony in the general population. Delay-coupled models are capable of capturing the wide range of individual differences in auditory-motor synchronization.

Are We in Time? How Predictive Coding and Dynamical Systems Explain Musical Synchrony

Humans tend to anticipate events when they synchronize their actions with sound (such as when they clap to music), which has puzzled scientists for decades. What accounts for this anticipation? We review two theoretical mechanisms for synchrony: predictive coding and dynamical systems. Both theories are grounded in neural activation patterns, but there are important distinctions. We contrast their assumptions, their computations, and their musical applications to anticipatory synchronization.

Naturalistic smartphone keyboard typing reflects processing speed and executive function

OBJECTIVE

The increase in smartphone usage has enabled the possibility of more accessible ways to conduct neuropsychological evaluations. The objective of this study was to determine the feasibility of using smartphone typing dynamics with mood scores to supplement cognitive assessment through trail making tests.

METHODS

Using a custom-built keyboard, naturalistic keypress dynamics were unobtrusively recorded in individuals with bipolar disorder (n = 11) and nonbipolar controls (n = 8) on an Android smartphone. Keypresses were matched to digital trail making tests part B (dTMT-B) administered daily in two periods and weekly mood assessments. Following comparison of dTMT-Bs to the pencil-and-paper equivalent, longitudinal mixed-effects models were used to analyze daily dTMT-B performance as a function of typing and mood.

RESULTS

Comparison of the first dTMT-B to paper TMT-B showed adequate reliability (intraclass correlations = 0.74). In our model, we observed that participants who typed slower took longer to complete dTMT-B (b = 0.189, p < .001). This trend was also seen in individual fluctuations in typing speed and dTMT-B performance (b = 0.032, p = .004). Moreover, participants who were more depressed completed the dTMT-B slower than less depressed participants (b = 0.189, p < .001). A practice effect was observed for the dTMT-Bs.

CONCLUSION

Typing speed in combination with depression scores has the potential to infer aspects of cognition (visual attention, processing speed, and task switching) in people's natural environment to complement formal in-person neuropsychological assessments that commonly include the trail making test.

Behavioral and Neural Dynamics of Interpersonal Synchrony Between Performing Musicians: A Wireless EEG Hyperscanning Study

Interpersonal synchrony refers to the temporal coordination of actions between individuals and is a common feature of social behaviors, from team sport to ensemble music performance. Interpersonal synchrony of many rhythmic (periodic) behaviors displays dynamics of coupled biological oscillators. The current study addresses oscillatory dynamics on the levels of brain and behavior between music duet partners performing at spontaneous (uncued) rates. Wireless EEG was measured from N = 20 pairs of pianists as they performed a melody first in Solo performance (at their spontaneous rate of performance), and then in Duet performances at each partner's spontaneous rate. Influences of partners' spontaneous rates on interpersonal synchrony were assessed by correlating differences in partners' spontaneous rates of Solo performance with Duet tone onset asynchronies. Coupling between partners' neural oscillations was assessed by correlating amplitude envelope fluctuations of cortical oscillations at the Duet performance frequency between observed partners and between surrogate (re-paired) partners, who performed the same melody but at different times. Duet synchronization was influenced by partners' spontaneous rates in Solo performance. The size and direction of the difference in partners' spontaneous rates were mirrored in the size and direction of the Duet asynchronies. Moreover, observed Duet partners showed greater inter-brain correlations of oscillatory amplitude fluctuations than did surrogate partners, suggesting that performing in synchrony with a musical partner is reflected in coupled cortical dynamics at the performance frequency. The current study provides evidence that dynamics of oscillator coupling are reflected in both behavioral and neural measures of temporal coordination during musical joint action.

Negative affect and alcohol craving in trauma-exposed young adult drinkers

BACKGROUND

Clinical research indicates that successful posttraumatic stress disorder (PTSD) treatment does not lead to improvements in alcohol use outcomes in comorbid PTSD and alcohol use disorder (AUD). Emerging theory suggests that treating PTSD may not disrupt an association between negative affect and alcohol craving, which underlies negative reinforcement drinking. The goal of the current study was to determine the respective influences of PTSD symptoms, coping motives, and negative affect on trauma and alcohol cue reactivity to inform theoretical models of co-occurring PTSD and AUD.

METHODS

The sample consisted of 189 young adults (50.3% women; 49.2% current PTSD; 84.0% current AUD) who endorsed interpersonal trauma (e.g., sexual/physical assault) and current weekly alcohol use. Participants completed a trauma and alcohol cue reactivity assessment, in which subjective (e.g., craving, affect) and physiological (i.e., salivation) measures were recorded in response to 4 narrative (i.e., personalized trauma or standard neutral) and in vivo beverage (i.e., personalized alcohol or water) cue combinations.

RESULTS

Forward-fitted linear mixed-effects (LME) models confirmed that trauma cue-elicited craving was elevated among those high but not low in PTSD symptoms, consistent with prior research and theory. Trauma cue-elicited craving was fully explained by increases in negative affect, with no evidence of a direct effect of trauma cue on craving. PTSD symptoms moderated an association between trauma cue and negative affect (but not negative affect and craving), and coping motives for alcohol moderated an association between negative affect and craving (but not trauma cue and negative affect).

CONCLUSIONS

This study provides novel laboratory evidence for the respective contributions of negative affect, PTSD symptoms, and coping motives on alcohol craving in trauma-exposed drinkers. It offers a methodological framework in which to evaluate novel strategies that aim to disrupt negative reinforcement drinking in individuals with co-occurring PTSD and AUD.

Effects of mood and aging on keystroke dynamics metadata and their diurnal patterns in a large open-science sample: A BiAffect iOS study

OBJECTIVE

Ubiquitous technologies can be leveraged to construct ecologically relevant metrics that complement traditional psychological assessments. This study aims to determine the feasibility of smartphone-derived real-world keyboard metadata to serve as digital biomarkers of mood.

MATERIALS AND METHODS

BiAffect, a real-world observation study based on a freely available iPhone app, allowed the unobtrusive collection of typing metadata through a custom virtual keyboard that replaces the default keyboard. User demographics and self-reports for depression severity (Patient Health Questionnaire-8) were also collected. Using >14 million keypresses from 250 users who reported demographic information and a subset of 147 users who additionally completed at least 1 Patient Health Questionnaire, we employed hierarchical growth curve mixed-effects models to capture the effects of mood, demographics, and time of day on keyboard metadata.

RESULTS

We analyzed 86 541 typing sessions associated with a total of 543 Patient Health Questionnaires. Results showed that more severe depression relates to more variable typing speed (P < .001), shorter session duration (P < .001), and lower accuracy (P < .05). Additionally, typing speed and variability exhibit a diurnal pattern, being fastest and least variable at midday. Older users exhibit slower and more variable typing, as well as more pronounced slowing in the evening. The effects of aging and time of day did not impact the relationship of mood to typing variables and were recapitulated in the 250-user group.

CONCLUSIONS

Keystroke dynamics, unobtrusively collected in the real world, are significantly associated with mood despite diurnal patterns and effects of age, and thus could serve as a foundation for constructing digital biomarkers.

Individuals with schizophrenia display behaviour inconsistent with learned social impressions during a gambling task

Many studies of social perception and judgement have required individuals to make evaluations of social parameters based on static presentations of social stimuli. In the current study, we assessed whether individuals with a schizophrenia spectrum disorder and community controls differed in their judgements of others based on a series of computerized encounters designed to simulate impression formation over time. Twenty-eight community controls and 29 individuals with a schizophrenia spectrum disorder completed 25 gambling interactions with three different computer partners. After interacting with each partner, subjects rated how much they liked, trusted, and would like to play again with each partner. Results indicated that while individuals with schizophrenia rated the three partners differently (evaluating partners who returned more money higher than partners who returned less money), they did not adjust their gambling strategies with the different partners. Community controls adjusted the amount of money they gambled with the different partners, gambling more with partners that returned more money and gambling less with partners who returned less money, despite not rating the neutral and positive partners significantly differently from one another. These results suggest differences in behavioural strategies and social evaluation practices between community controls and individuals with schizophrenia. PRACTITIONER POINTS: Schizophrenia (SZ) and community control (CC) participants evaluate virtual partners on a gambling task in accordance with their behaviour (e.g., positive > neutral > negative in terms of trustworthiness, how much they liked them, and the likelihood that they would play with that individual again). Individuals with schizophrenia gambled equally with neutral, negative, and positive partner. Individuals with schizophrenia demonstrate an intact ability to form social impressions based on others' behaviour. However, subsequent behaviour does not parallel the formed impression (i.e., changing their gambling amount so that they are betting less money with a virtual partner they know is untrustworthy).

Time to Throw in the Towel? No Evidence for Automatic Conceptual Metaphor Access in Idiom Processing

The goal of the current research was to determine if conceptual metaphors are activated when people read idioms within a text. Participants read passages that included idioms that were consistent (blow your top) or inconsistent (bite his head off) with an underlying conceptual metaphor (ANGER IS HEATED FLUID IN A CONTAINER) followed by target words that were related (heat) or unrelated (lead) to the conceptual metaphor. Reading time (Experiment 1) or lexical decision time (Experiment 2) for the target words were measured. We found no evidence supporting conceptual metaphor activation. Target word reading times were unaffected by whether they were related or unrelated to underlying conceptual metaphors. Lexical decision times were facilitated for related target words in both the consistent and inconsistent idiom conditions. We suggest that the conceptual (target) domain, not a specific underlying conceptual metaphor, facilitates processing of related target words.

Staying Together: A Bidirectional Delay-Coupled Approach to Joint Action

To understand how individuals adapt to and anticipate each other in joint tasks, we employ a bidirectional delay-coupled dynamical system that allows for mutual adaptation and anticipation. In delay-coupled systems, anticipation is achieved when one system compares its own time-delayed behavior, which implicitly includes past information about the other system's behavior, with the other system's instantaneous behavior. Applied to joint music performance, the model allows each system to adapt its behavior to the dynamics of the other. Model predictions of asynchrony between two simultaneously produced musical voices were compared with duet pianists' behavior; each partner performed one voice while auditory feedback perturbations occurred at unpredictable times during live performance. As the model predicted, when auditory feedback from one musical voice was removed, the asynchrony changed: The pianist's voice that was removed anticipated (preceded) the actions of their partner. When the auditory feedback returned and both musicians could hear each other, they rapidly returned to baseline levels of asynchrony. To understand how the pianists anticipated each other, their performances were fitted by the model to examine change in model parameters (coupling strength, time-delay). When auditory feedback for one or both voices was removed, the fits showed the expected decrease in coupling strength and time-delay between the systems. When feedback about the voice(s) returned, the coupling strength and time-delay returned to baseline. These findings support the idea that when people perform actions together, they do so as a coupled bidirectional anticipatory system.

Amplitude envelope correlations measure synchronous cortical oscillations in performing musicians

A major question facing cognitive neuroscience is measurement of interbrain synchrony between individuals performing joint actions. We describe the application of a novel method for measuring musicians' interbrain synchrony: amplitude envelope correlations (AECs). Amplitude envelopes (AEs) reflect energy fluctuations in cortical oscillations over time; AE correlations measure the degree to which two envelope fluctuations are temporally correlated, such as cortical oscillations arising from two individuals performing a joint action. Wireless electroencephalography was recorded from two pianists performing a musical duet; an analysis pipeline is described for computing AEs of cortical oscillations at the duet performance frequency (number of tones produced per second) to test whether these oscillations reflect the temporal dynamics of partners' performances. The pianists' AE correlations were compared with correlations based on a distribution of AEs simulated from white noise signals using the same methods. The AE method was also applied to the temporal characteristics of the pianists' performances, to show that the observed pair's AEs reflect the temporal dynamics of their performance. AE correlations offer a promising approach for assessing interbrain correspondences in cortical activity associated with performing joint tasks.

Synchronizing MIDI and wireless EEG measurements during natural piano performance

Although music performance has been widely studied in the behavioural sciences, less work has addressed the underlying neural mechanisms, perhaps due to technical difficulties in acquiring high-quality neural data during tasks requiring natural motion. The advent of wireless electroencephalography (EEG) presents a solution to this problem by allowing for neural measurement with minimal motion artefacts. In the current study, we provide the first validation of a mobile wireless EEG system for capturing the neural dynamics associated with piano performance. First, we propose a novel method for synchronously recording music performance and wireless mobile EEG. Second, we provide results of several timing tests that characterize the timing accuracy of our system. Finally, we report EEG time domain and frequency domain results from N=40 pianists demonstrating that wireless EEG data capture the unique temporal signatures of musicians' performances with fine-grained precision and accuracy. Taken together, we demonstrate that mobile wireless EEG can be used to measure the neural dynamics of piano performance with minimal motion constraints. This opens many new possibilities for investigating the brain mechanisms underlying music performance.

The state of social and personality science: Rotten to the core, not so bad, getting better, or getting worse?

The scientific quality of social and personality psychology has been debated at great length in recent years. Despite research on the prevalence of Questionable Research Practices (QRPs) and the replicability of particular findings, the impact of the current discussion on research practices is unknown. The current studies examine whether and how practices have changed, if at all, over the last 10 years. In Study 1, we surveyed 1,166 social and personality psychologists about how the current debate has affected their perceptions of their own and the field's research practices. In Study 2, we coded the research practices and critical test statistics from social and personality psychology articles published in 2003-2004 and 2013-2014. Together, these studies suggest that (a) perceptions of the current state of the field are more pessimistic than optimistic; (b) the discussion has increased researchers' intentions to avoid QRPs and adopt proposed best practices, (c) the estimated replicability of research published in 2003-2004 may not be as bad as many feared, and (d) research published in 2013-2014 shows some improvement over research published in 2003-2004, a result that suggests the field is evolving in a positive direction. (PsycINFO Database Record

The Unresponsive Partner: Roles of Social Status, Auditory Feedback, and Animacy in Coordination of Joint Music Performance

We examined temporal synchronization in joint music performance to determine how social status, auditory feedback, and animacy influence interpersonal coordination. A partner’s coordination can be bidirectional (partners adapt to the actions of one another) or unidirectional (one partner adapts). According to the dynamical systems framework, bidirectional coordination should be the optimal (preferred) state during live performance. To test this, 24 skilled pianists each performed with a confederate while their coordination was measured by the asynchrony in their tone onsets. To promote social balance, half of the participants were told the confederate was a fellow participant – an equal social status. To promote social imbalance, the other half was told the confederate was an experimenter – an unequal social status. In all conditions, the confederate’s arm and finger movements were occluded from the participant’s view to allow manipulation of animacy of the confederate’s performances (live or recorded). Unbeknownst to the participants, half of the confederate’s performances were replaced with pre-recordings, forcing the participant into unidirectional coordination during performance. The other half of the confederate’s performances were live, which permitted bidirectional coordination between performers. In a final manipulation, both performers heard the auditory feedback from one or both of the performers’ parts removed at unpredictable times to disrupt their performance. Consistently larger asynchronies were observed in performances of unidirectional (recorded) than bidirectional (live) performances across all conditions. Participants who were told the confederate was an experimenter reported their synchrony as more successful than when the partner was introduced as a fellow participant. Finally, asynchronies increased as auditory feedback was removed; removal of the confederate’s part hurt coordination more than removal of the participant’s part in live performances. Consistent with the assumption that bidirectional coupling yields optimal coordination, an unresponsive partner requires the other member to do all the adapting for the pair to stay together.

Flexibility of Expressive Timing in Repeated Musical Performances

Performances by soloists in the Western classical tradition are normally highly prepared, yet must sound fresh and spontaneous. How do musicians manage this? We tested the hypothesis that they achieve the necessary spontaneity by varying the musical gestures that express their interpretation of a piece. We examined the tempo arches produced by final slowing at the ends of phrases in performances of J. S. Bach's No. 6 (Prelude) for solo cello (12 performances) and the Italian Concerto (Presto) for solo piano (eight performances). The performances were given by two experienced concert soloists during a short time period (3½ months for the Prelude, 2 weeks for the Presto) after completing their preparations for public performance. We measured the tempo of each bar or half-bar, and the stability of tempo across performances (difference of the tempo of each bar/half bar from each of the other performances). There were phrase arches for both tempo and stability with slower, less stable tempi at beginnings and ends of phrases and faster, more stable tempi mid-phrase. The effects of practice were complex. Tempo decreased overall with practice, while stability increased in some bars and decreased in others. One effect of practice may be to imbue well-learned, automatic motor sequences with freshness and spontaneity through cognitive control at phrase boundaries where slower tempi and decreased stability provide opportunities for slower cognitive processes to modulate rapid automatic motor sequences.

Recording thoughts while memorizing music: a case study

Musicians generally believe that memory differs from one person to the next. As a result, memorizing strategies that could be useful to almost everyone are not widely taught. We describe how an 18-years old piano student (Grade 7, ABRSM), learned to memorize by recording her thoughts, a technique inspired by studies of how experienced soloists memorize. The student, who had previously ignored suggestions that she play from memory, decided to learn to memorize, selecting Schumann’s “Der Dichter Spricht” for this purpose. Rather than explicitly teaching the student how to memorize, the teacher taught her to record her thoughts while playing by marking them on copies of the score, adapting an approach used previously in research with experienced performers. Over a 6½ week period, the student recorded her thoughts during practice (five times) and while performing from memory for the teacher (three times). The student also video-recorded 3 weeks of practice, three performances, and the reconstruction of the piece from memory after a 9½-weeks break. The thoughts that the student reported were prepared during practice, stable over time, and functioned as memory retrieval cues during reconstruction. This suggests that the student memorized in the same way as the more experienced musicians who have been studied previously and that teaching student musicians to record their thoughts may be an effective way to help them memorize. The speed and durability of her memorization surprised the student, inspiring her to perform in public and to use the same technique for new pieces.

Toward a dynamical theory of body movement in musical performance

Musicians sway expressively as they play in ways that seem clearly related to the music, but quantifying the relationship has been difficult. We suggest that a complex systems framework and its accompanying tools for analyzing non-linear dynamical systems can help identify the motor synergies involved. Synergies are temporary assemblies of parts that come together to accomplish specific goals. We assume that the goal of the performer is to convey musical structure and expression to the audience and to other performers. We provide examples of how dynamical systems tools, such as recurrence quantification analysis (RQA), can be used to examine performers' movements and relate them to the musical structure and to the musician's expressive intentions. We show how detrended fluctuation analysis (DFA) can be used to identify synergies and discover how they are affected by the performer's expressive intentions.

Rocking to the beat: effects of music and partner's movements on spontaneous interpersonal coordination

People move to music and coordinate their movements with others spontaneously. Does music enhance spontaneous coordination? We compared the influence of visual information (seeing or not seeing another person) and auditory information (hearing movement or music or hearing no sound) on spontaneous coordination. Pairs of participants were seated side by side in rocking chairs, told a cover story, and asked to rock at a comfortable rate. Both seeing and hearing the other person rock elicited spontaneous coordination, and effects of hearing amplified those of seeing. Coupling with the music was weaker than with the partner, and the music competed with the partner's influence, reducing coordination. Music did, however, function as a kind of social glue: participants who synchronized more with the music felt more connected.