Sensorimotor synchronization: a review of recent research (2006-2012).

Sensorimotor synchronization (SMS) is the coordination of rhythmic movement with an external rhythm, ranging from finger tapping in time with a metronome to musical ensemble performance. An earlier review (Repp, 2005) covered tapping studies; two additional reviews (Repp, 2006a, b) focused on music performance and on rate limits of SMS, respectively. The present article supplements and extends these earlier reviews by surveying more recent research in what appears to be a burgeoning field.

Synchronization with competing visual and auditory rhythms: bouncing ball meets metronome.

Synchronization of finger taps with periodically flashing visual stimuli is known to be much more variable than synchronization with an auditory metronome. When one of these rhythms is the synchronization target and the other serves as a distracter at various temporal offsets, strong auditory dominance is observed. However, it has recently been shown that visuomotor synchronization improves substantially with moving stimuli such as a continuously bouncing ball.

A general linear framework for the comparison and evaluation of models of sensorimotor synchronization.

Sensorimotor synchronization (SMS), the temporal coordination of a rhythmic movement with an external rhythm, has been studied most often in tasks that require tapping along with a metronome. Models of SMS use information about the timing of preceding stimuli and responses to predict when the next response will be made. This article compares the theoretical structure and empirical predictions of four two-parameter models proposed in the literature: Michon (Timing in temporal tracking, Van Gorcum, Assen, 1967), Hary and Moore (Br J Math Stat Psychol 40:109-124, 1987b), Mates (Biol Cybern 70:463-473, 1994a; Biol Cybern 70:475-484, 1994b), and Schulze et al.

Quantifying phase correction in sensorimotor synchronization: empirical comparison of three paradigms.

Tapping in synchrony with a metronome requires phase error correction, a process often described by a single-parameter autoregressive model. The parameter (α) is a measure of sensorimotor coupling strength. This study compares α estimates obtained from three experimental paradigms: synchronization with (1) a perfectly regular metronome (RM), (2) a perturbed metronome containing phase shifts (PS), and (3) an "adaptively timed" metronome (AT).

Anticipatory phase correction in sensorimotor synchronization.

Studies of phase correction in sensorimotor synchronization often introduce timing perturbations that are unpredictable with regard to direction, magnitude, and position in the stimulus sequence. If participants knew any or all of these parameters in advance, would they be able to anticipate perturbations and thus regain synchrony more quickly? In Experiment 1, we asked musically trained participants to tap in synchrony with short isochronous tone sequences containing a phase shift (PS) of -100, -40, 40, or 100 ms and provided advance information about its direction, position, or both (but not about its magnitude). The first two conditions had little effect, but in the third condition participants shifted their tap in anticipation of the PS, though only by about ±40 ms on average.

Detecting perturbations in polyrhythms: effects of complexity and attentional strategies.

Jones et al. in Journal of Experimental Psychology Human Perception and Performance 21:293-307, 1995, showed that a temporal perturbation is easier to detect in a 3:2 polyrhythm than in a single-stream isochronous baseline condition if the two isochronous pulse streams forming the polyrhythm are perceptually integrated: integration creates shorter inter-onset interval (IOI) durations that facilitate perturbation detection. The present study examined whether this benefit of integration outweighs the potential costs imposed by the greater IOI heterogeneity and memory demands of more complex polyrhythms.

No temporal binding of action consequences to actions in a rhythmic context.

Temporal binding (TB) refers to a subjective contraction of the time that elapses between an action and a delayed sensory consequence of it. The TB effect has been demonstrated primarily in tasks in which a key press triggers a tone after a short delay and in which participants judge the timing of one or both of these events relative to a visual reference (e.g.

Tapping in synchrony with a perturbed metronome: the phase correction response to small and large phase shifts as a function of tempo.

When tapping is paced by an auditory sequence containing small phase shift (PS) perturbations, the phase correction response (PCR) of the tap following a PS increases with the baseline interonset interval (IOI), leading eventually to overcorrection (B. H. Repp, 2008).

Measuring perceptual centers using the phase correction response.

The perceptual center (P-center) is fundamental to the timing of heterogeneous event sequences, including music and speech. Unfortunately, there is currently no comprehensive and reliable model of P-centers in acoustic events, so P-centers must instead be measured empirically. This study reviews existing measurement methods and evaluates two methods in detail-the rhythm adjustment method and a new method based on the phase correction response (PCR) in a synchronous tapping task.

Comfortable synchronization of cyclic drawing movements with a metronome.

Continuous circle drawing is considered a paragon of emergent timing, whereas the timing of finger tapping is said to be event-based. Synchronization with a metronome, however, must to some extent be event-based for both types of movement. Because the target events in the movement trajectory are more poorly defined in circle drawing than in tapping, circle drawing shows more variable asynchronies with a metronome than does tapping.

Temporal evolution of the phase correction response in synchronization of taps with perturbed two-interval rhythms.

Human sensorimotor synchronization is flexible but subject to temporal constraints. Previous research has shown that musicians tend to lose synchrony with target tones in an isochronous sequence when the sequence rate exceeds 8-10 Hz, presumably because phase correction ceases to function. The present study investigated directly the time required for an immediate phase correction response (PCR).

Altered sense of agency in schizophrenia and the putative psychotic prodrome.

The mechanisms underlying distortions in sense of agency, i.e. the experience of controlling one's own actions and their consequences, in schizophrenia are not fully understood and have barely been investigated in patients classified as being in a putative psychotic prodrome.

A filled duration illusion in music: Effects of metrical subdivision on the perception and production of beat tempo.

This study replicates and extends previous findings suggesting that metrical subdivision slows the perceived beat tempo (Repp, 2008). Here, musically trained participants produced the subdivisions themselves and were found to speed up, thus compensating for the perceived slowing. This was shown in a synchronization-continuation paradigm (Experiment 1) and in a reproduction task (Experiment 2a).

Perception-production relationships and phase correction in synchronization with two-interval rhythms.

Two experiments investigated the effects of interval duration ratio on perception of local timing perturbations, accuracy of rhythm production, and phase correction in musicians listening to or tapping in synchrony with cyclically repeated auditory two-interval rhythms. Ratios ranged from simple (1:2) to complex (7:11, 5:13), and from small (5:13 = 0.38) to large (6:7 = 0.

Do metrical accents create illusory phenomenal accents?

In music that is perceived as metrically structured, events coinciding with the main beat are called metrically accented. Are these accents purely cognitive, or do they perhaps represent illusory increases in perceived loudness or duration, caused by heightened attention to main beats? In four separate tasks, musicians tried to detect a small actual increase or decrease in the loudness or duration of a single note in melodies comprising 12 notes. Musical notation prescribed a meter (6/8) implying a main beat coinciding with every third note.

Simultaneous event-based and emergent timing: synchronization, continuation, and phase correction.

It has been claimed that rhythmic tapping and circle drawing represent fundamentally different timing processes (event-based and emergent, respectively) and also that circle drawing is difficult to synchronize with a metronome and exhibits little phase correction. In the present study, musically trained participants tapped with their left hands, drew circles with their right (dominant) hands, and also performed both tasks simultaneously. In Experiment 1, they synchronized with a metronome and then continued on their own, whereas in Experiment 2, they synchronized with a metronome containing phase perturbations.

Sensorimotor synchronization and perception of timing: effects of music training and task experience.

To assess individual differences in basic synchronization skills and in perceptual sensitivity to timing deviations, brief tests made up of isochronous auditory sequences containing phase shifts or tempo changes were administered to 31 college students (most of them with little or no music training) and nine highly trained musicians (graduate students of music performance). Musicians showed smaller asynchronies, lower tapping variability, and greater perceptual sensitivity than college students, on average. They also showed faster phase correction following a tempo change in the pacing sequence.

Self versus other in piano performance: detectability of timing perturbations depends on personal playing style.

Differences between recorded repetitions of one's own movements are detected more readily than are differences between repetitions of others' movements, suggesting improved visual discrimination due to heightened resonance in the observer's action system and/or relatively accurate internal action simulation (Daprati et al. in Conscious Cogn 16:178-188, 2007). In Experiment 1, we attempted to replicate this finding in the auditory modality.

Context sensitivity and invariance in perception of octave-ambiguous tones.

Three experiments investigated the influence of unambiguous (UA) context tones on the perception of octave-ambiguous (OA) tones. In Experiment 1, pairs of OA tones spanning a tritone interval were preceded by pairs of UA tones instantiating a rising or falling interval between the same pitch classes. Despite the inherent ambiguity of OA tritone pairs, most participants showed little or no priming when judging the OA tritone as rising or falling.

Top-down control of rhythm perception modulates early auditory responses.

Our perceptions are shaped by both extrinsic stimuli and intrinsic interpretation. The perceptual experience of a simple rhythm, for example, depends upon its metrical interpretation (where one hears the beat). Such interpretation can be altered at will, providing a model to study the interaction of endogenous and exogenous influences in the cognitive organization of perception.

Rhythmic sensorimotor coordination is resistant but not immune to auditory stream segregation.

In a recent study of musicians' sensorimotor synchronization with auditory sequences composed either of beat and subdivision tones differing in pitch or of beat tones only, Repp (2009) found that the phase correction response (PCR) to perturbed beats was inhibited by the presence of subdivisions regardless of whether beats and subdivisions formed integrated or segregated perceptual streams. The present study used a different paradigm in which perturbed subdivisions triggered the PCR. At the slower of two sequence tempi, the PCR was equally large in integrated and segregated conditions, but at the faster tempo stream segregation reduced the PCR substantially.

Performed or observed keyboard actions affect pianists' judgements of relative pitch.

Action can affect visual perception if the action's expected sensory effects resemble a concurrent unstable or deviant event. To determine whether action can also change auditory perception, participants were required to play pairs of octave-ambiguous tones by pressing successive keys on a piano or computer keyboard and to judge whether each pitch interval was rising or falling. Both pianists and nonpianist musicians gave significantly more "rising" responses when the order of key presses was left-to-right than when it was right-to-left, in accord with the pitch mapping of the piano.

Inferring agency from sound.

In three experiments we investigated how people determine whether or not they are in control of sounds they hear. The sounds were either triggered by participants' taps or controlled by a computer. The task was to distinguish between self-control and external control during active tapping, and during passive listening to a playback of the sounds recorded during the active condition.

Flexibility of temporal expectations for triple subdivision of a beat.

When tapping in synchrony with an isochronous sequence of beats, participants respond automatically to an unexpectedly early or late beat by shifting their next tap; this is termed the phase correction response (PCR). A PCR has also been observed in response to unexpected perturbations of metrical subdivisions of a beat, which suggests that participants have temporal expectancies for subdivisions to occur at particular time points. It has been demonstrated that a latent temporal expectancy at 1/2 of the inter-beat interval (IBI) exists even in the absence of explicit duple subdivision in previous IBIs of a sequence.

Segregated in perception, integrated for action: immunity of rhythmic sensorimotor coordination to auditory stream segregation.

Auditory stream segregation can occur when tones of different pitch (A, B) are repeated cyclically: The larger the pitch separation and the faster the tempo, the more likely perception of two separate streams is to occur. The present study assessed stream segregation in perceptual and sensorimotor tasks, using identical ABBABB ..