The classical mean negative asynchrony in sensorimotor synchronization is not universal in humans. A cross-cultural study.

The present study examines to what extent cultural background determines sensorimotor synchronization in humans. The direct comparison of Indian and French students, without particular experience in music or dance, or sport, was motivated by the hypothesis that musical exposure to different musical styles causes a variation in basic synchronization to sound function. At first rate limits of this capacity was sought, using a parametric design increasing the sound periodic frequency up to synchronization breakdown. No robust effect was found in that respect. However, another unpredicted change of the so-called negative mean asynchrony was found. Negative mean asynchrony is defined as the anticipation of movement with respect to sound, of about 40ms. The negative mean asynchrony simply disappears in Indians' participants. This result is very intriguing as negative mean asynchrony was considered ubiquitous for decades, and an invariant hallmark of human timing function. Revision of theoretical modelling of sensorimotor synchronization may be required to account to the found variation.

Dynamic Systems Approach in Sensorimotor Synchronization: Adaptation to Tempo Step-Change

This paper presents a dynamic systems model of a sensorimotor synchronization (SMS) task. An SMS task typically gives temporally discrete human responses to some temporally discrete stimuli. Here, a dynamic systems modeling approach is applied after converting the discrete events to regularly sampled time signals. To collect data for model parameter fitting, a previously published pilot study was expanded. Three human participants took part in an experiment: to tap a finger on a keyboard, following a metronome which changed tempo in steps. System identification was used to estimate the transfer function that represented the relationship between the stimulus and the step response signals, assuming a separate linear, time-invariant system for each tempo step. Different versions of model complexity were investigated. As a minimum, a second-order linear system with delay, two poles, and one zero was needed to model the most important features of the tempo step response by humans, while an additional third pole could give a somewhat better fit to the response data. The modeling results revealed the behavior of the system in two distinct regimes: tempo steps below and above the conscious awareness of tempo change, i.e., around 12% of the base tempo. For the tempo steps above this value, model parameters were derived as linear functions of step size for the group of three participants. The results were interpreted in the light of known facts from other fields like SMS, psychoacoustics and behavioral neuroscience.

Neural entrainment facilitates duplets: Frequency-tagging differentiates musicians and non-musicians when they tap to the beat

ABSTRACTMotor coordination to an isochronous beat improves when it is subdivided into equal intervals. Here, we study if this subdivision benefit (i) varies with the kind of subdivision, (ii) is enhanced in individuals with formal musical training, and (iii), is an inherent property of neural oscillations. We recorded electroencephalograms of musicians and non-musicians during: (a) listening to an isochronous beat, (b) listening to one of 4 different subdivisions, (c) listening to the beat again, and (d) listening and tapping the beat with the same subdivisions as in (b). We found that tapping consistency and neural entrainment in condition (d) was enhanced in non-musicians for duplets (1:2) compared to the other types of subdivisions. Musicians showed overall better tapping performance and were equally good at tapping together with duplets, triplets (1:3) and quadruplets (1:4), but not with quintuplets (1:5). This group difference was reflected in enhanced neural responses in the triplet and quadruplet conditions. Importantly, for all participants, the neural entrainment to the beat and its first harmonic (i.e. the duplet frequency) increased after listening to each of the subdivisions (c compared to a). Since these subdivisions are harmonics of the beat frequency, the observed preference of the brain to enhance the simplest subdivision level (duplets) may be an inherent property of neural oscillations. In sum, a tapping advantage for simple binary subdivisions is reflected in neural oscillations to harmonics of the beat, and formal training in music can enhance it.Highlights-The neural entrainment to periodic sounds only differs between musicians and non-musicians when they perform a predictive sensorimotor synchronization task.-After listening to a subdivided beat, the frequencies related to the beat and its first harmonic are enhanced in the EEG, likely stabilizing the perception of the beat.-There is a natural advantage for binary structures in sensorimotor synchronization, observed in the tapping of duplets by non-musicians, which can be extended to other subdivisions after extensive musical training.

Neural and Behavioral Evidence for Vibrotactile Beat Perception and Bimodal Enhancement

The ability to synchronize movements to a rhythmic stimulus, referred to as sensorimotor synchronization (SMS), is a behavioral measure of beat perception. Although SMS is generally superior when rhythms are presented in the auditory modality, recent research has demonstrated near-equivalent SMS for vibrotactile presentations of isochronous rhythms [Ammirante, P., Patel, A. D., & Russo, F. A. Synchronizing to auditory and tactile metronomes: A test of the auditory–motor enhancement hypothesis. Psychonomic Bulletin & Review, 23, 1882–1890, 2016]. The current study aimed to replicate and extend this study by incorporating a neural measure of beat perception. Nonmusicians were asked to tap to rhythms or to listen passively while EEG data were collected. Rhythmic complexity (isochronous, nonisochronous) and presentation modality (auditory, vibrotactile, bimodal) were fully crossed. Tapping data were consistent with those observed by Ammirante et al. (2016), revealing near-equivalent SMS for isochronous rhythms across modality conditions and a drop-off in SMS for nonisochronous rhythms, especially in the vibrotactile condition. EEG data revealed a greater degree of neural entrainment for isochronous compared to nonisochronous trials as well as for auditory and bimodal compared to vibrotactile trials. These findings led us to three main conclusions. First, isochronous rhythms lead to higher levels of beat perception than nonisochronous rhythms across modalities. Second, beat perception is generally enhanced for auditory presentations of rhythm but still possible under vibrotactile presentation conditions. Finally, exploratory analysis of neural entrainment at harmonic frequencies suggests that beat perception may be enhanced for bimodal presentations of rhythm.

REPP: A robust cross-platform solution for online sensorimotor synchronization experiments

Sensorimotor synchronization (SMS), the rhythmic coordination of perception and action, is a fundamental human skill that supports many behaviors, from daily repetitive routines to the most complex behavioural coordination, including music and dance (Repp 2005; Repp & Su, 2013). Research on SMS has been mostly conducted in the laboratory using finger tapping paradigms, where participants typically tap with their index finger to a rhythmic sequence of auditory stimuli. However, these experiments require equipment with high temporal fidelity to capture the asynchronies between the time of the tap and the corresponding cue event. Thus, SMS is particularly challenging to study with online research, where variability in participants’ hardware and software can introduce uncontrolled latency and jitter into recordings. Here we present REPP (Rhythm ExPeriment Platform), a novel technology for measuring SMS in online experiments that can work efficiently using the built-in microphone and speakers of standard laptop computers. The audio stimulus (e.g., a metronome or a music excerpt) is played through the speakers and the resulting signal is recorded along with participants’ responses in a single channel. The resulting recording is then analyzed using signal processing techniques to extract and align timing cues with high temporal accuracy. This analysis is fully automated and customizable, enabling researchers to monitor online experiments in real time and to implement a wide variety of SMS paradigms. In this paper, we validate REPP through a series of calibration and behavioural experiments. We demonstrate that our technology achieves high temporal accuracy (latency and jitter within 2 ms on average), high test-retest reliability both in the laboratory (r = .87) and online (r = .80), and high concurrent validity (r = .94). We also suggest methods to ensure high data quality in online SMS experiments using REPP while minimizing recruitment costs. REPP can therefore open new avenues for research on SMS that would be nearly impossible in the laboratory, reducing experimental costs while massively increasing the reach, scalability and speed of data collection.