Sensorimotor synchronization with adaptively timed sequences

Most studies of human sensorimotor synchronization require participants to coordinate actions with computer-controlled event sequences that are unresponsive to their behavior. In the present research, the computer was programmed to carry out phase and/or period correction in response to asynchronies between taps and tones, and thereby to modulate adaptively the timing of the auditory sequence that human participants were synchronizing with, as a human partner might do. In five experiments the computer's error correction parameters were varied over a wide range, including "uncooperative" settings that a human synchronization partner could not (or would not normally) adopt. Musically trained participants were able to maintain synchrony in all these situations, but their behavior varied systematically as a function of the computer's parameter settings. Computer simulations were conducted to infer the human participants' error correction parameters from statistical properties of their behavior (means, standard deviations, auto- and cross-correlations). The results suggest that participants maintained a fixed gain of phase correction as long as the computer was cooperative, but changed their error correction strategies adaptively when faced with an uncooperative computer.     

Sensorimotor synchronization: Motor responses to pseudoregular auditory patterns

Musically trained and untrained subjects (N=30) were asked to synchronize their finger tapping with stimuli in auditory patterns. Each pattern comprised six successive tonal stimuli of the same duration, the first of which was accented by a different frequency. The duration of interstimulus onset intervals (ISIs) gradually increased or decreased in constant steps toward the end of the patterns. Four values of such steps were used in different trials: 20, 30, 45, and 60 msec. Various time-control mechanisms are hypothesized as being simultaneously responsible for subjects’ incorrect reproduction of the internal temporal ratios of the stimulus patterns. The mechanism of assimilation (of a central tendency) led subjects to enforce a regular (isochronous) structure on the patterns. The influence of other time-control mechanisms (distinction, subjective expression of an accent, sequential transfer) was expressed mainly in differences between intertap onset intervals (ITIs) and the corresponding ISIs at the beginning of the patterns. The duration of the first two ITIs was in the majority of the trials in an inverse ratio to the ratio of the respective ISIs. The distortions resulting from the timing mechanisms concerned were more pronounced in the performance of nonmusicians than in that of musicians.     

Sensorimotor synchronization: Motor responses to regular auditory patterns

Subjects (N = 32) were asked to synchronize a motor response with tones in auditory patterns. These patterns were created from six tones and six intertone intervals of equal duration. The pitch of the first tone differed from the others. It was found that subjects used three types of timing in their motor response: (1) the first intertone interval was prolonged and the second interval was shortened, (2) the second intertone interval was prolonged and the first interval was shortened, and/or (3) the first interval and the second interval were of approximately the same length. The prolongation of the fifth interval was observed during all three types of timing. The results are explained using the concept of suprasegmental control of timing, which explains a prolongation of intervals at critical control point of the patterns. The occurrence of three different strategies of timing is discussed in connection with similar principles in musical performance.     

Sensorimotor synchronization: A review of the tapping literature

Sensorimotor synchronization (SMS), the rhythmic coordination of perception and action, occurs in many contexts, but most conspicuously in music performance and dance. In the laboratory, it is most often studied in the form of finger tapping to a sequence of auditory stimuli. This review summarizes theories and empirical findings obtained with the tapping task. Its eight sections deal with the role of intention, rate limits, the negative mean asynchrony, variability, models of error correction, perturbation studies, neural correlates of SMS, and SMS in musical contexts. The central theoretical issue is considered to be how best to characterize the perceptual information and the internal processes that enable people to achieve and maintain SMS. Recent research suggests that SMS is controlled jointly by two error correction processes (phase correction and period correction) that differ in their degrees of cognitive control and may be associated with different brain circuits. They exemplify the general distinction between subconscious mechanisms of action regulation and conscious processes involved in perceptual judgment and action planning.     

Sensorimotor synchronization: motor responses to regular auditory patterns.

Subjects (N = 32) were asked to synchronize a motor response with tones in auditory patterns. These patterns were created from six tones and six intertone intervals of equal duration. The pitch of the first tone differed from the others. It was found that subjects used three types of timing in their motor response: (1) the first intertone interval was prolonged and the second interval was shortened, (2) the second intertone interval was prolonged and the first interval was shortened, and/or (3) the first interval and the second interval were of approximately the same length. The prolongation of the fifth interval was observed during all three types of timing. The results are explained using the concept of suprasegmental control of timing, which explains a prolongation of intervals at critical control point of the patterns. The occurrence of three different strategies of timing is discussed in connection with similar principles in musical performance.     

Sensorimotor synchronization: the impact of temporally displaced auditory feedback

When subjects are asked to tap in synchrony to a regular sequence of stimulus events (e.g., clicks), performance is not perfect in that, usually, an anticipation of the tap is observed. The present study examines the influence of temporally displaced auditory feedback on the size of this anticipatory error. Whereas earlier studies have shown that this asynchrony exhibits a linear increase in size as a function of an increasing delay in such additional auditory feedback, this study compared the impact of shifting feedback forward in time (i.e., feedback presented before the tap) with that of delayed auditory feedback. Results showed that the impact of feedback displacement on the amount of asynchrony differed for positive and negative displacements. Delayed feedback led to an increase in asynchrony, whereas negative displacements had (almost) no effect. This finding is related to a model assuming that the various feedback components arising from the tap (tactile, kinesthetic, auditory) are integrated to form one central representation, and that the timing of this central representation arises from a linear combination of the components involved.     

Sensorimotor synchronization: neurophysiological markers of the asynchrony in a finger-tapping task

Psychological Research - Sensorimotor synchronization (SMS) is a form of referential behavior in which an action is coordinated with a predictable external stimulus. The neural bases of the...     

Sensorimotor synchronization during gait is altered by the addition of variability to an external cue

Sensorimotor synchronization has been used in the rehabilitation of gait, yet much remains unknown regarding the optimal use of this technique. The purpose of this study was to test the hypothesis that adding small amounts of variability to the motion of a vertically oscillating treadmill would affect the behavior of healthy walkers. Sixteen young adults walked on a treadmill and pneumatically actuated platform for one control trial (no oscillation) and eight trials in which the walking surface oscillated in the vertical direction under different conditions of variability. During the oscillation trials, the mean frequency of oscillation was equal to the preferred step frequency of the participant, but each individual cycle period was allowed to vary within a pre-determined range from 0% (no variability) to ±25% (high variability) of the mean cycle period. The amount of variance of each cycle period within each condition was drawn randomly from a white noise generator. Synchronization was improved when a small amount of noise was added to the platform motion but synchronization significantly decreased at higher levels of noise. Coefficient of variation of stride duration was relatively unchanged at lower levels of variability, but increased significantly at higher levels of variability. Statistical persistence of stride duration was significantly reduced during all trials with vertical oscillation relative to normal walking, but was not significantly altered by variability in the treadmill oscillation. These results suggest that the addition of a small amount of random variability to the cycle period of an oscillator may enhance sensorimotor synchronization of gait to an external signal. These data may have implications for the use of synchronization in a therapeutic setting.     

Effect of harmonic relatedness on the detection of temporal asynchronies

Speeded intonation judgments of a target chord are facilitated when the chord is preceded by a harmonically related prime chord. The present study extends harmonic priming to temporal asynchrony judgments. In both tasks, the normative target chords (consonant, synchronous) are processed more quickly and accurately after a harmonically related prime than after a harmonically unrelated prime. However, the influence of harmonic context on sensitivity (d') differs between the two tasks: d' was higher in the related context for intonation judgments but was higher in the unrelated context for asynchrony judgments. A neural net model of tonal knowledge activation provides an explanatory framework for both the facilitation in the related contexts and the sensitivity differences between the tasks.     

Effet de l’action motrice sur les asynchronies perceptives

In agreement with the hypothesis of differential treatment of the intrinsic (color, shape, category…) and extrinsic (position, orientation…) visual characteristics along the ventral and dorsal pathways of the visual system (Milner & Goodale, 1995), the study of temporal order judgment (TOJ) of the variation of two visual attributes highlighted the perceptual asynchrony even though these changes occur synchronously. In this context, we investigated the role of action in the perception of perceptual asynchrony, especially the effect of a reaching movement on the TOJ of position and color changes of a target occurring at different times of movement execution. In the absence of voluntary action, the point of subjective simultaneity (PSS) shows that the color changes must occurr 46.6 ms before the change of position to give rise to a synchronous perception of these two changes. Performing a reaching movement reduced significantly the PSS (12.4 ms), but only if the changes occur near movement end-point. If changes occur during movement execution, the PSS (40.2 ms) was not different from that obtained in the perceptual condition. These results suggest that endogenous signals associated with voluntary motor action contribute to the reduction of perceptual asynchrony in relation to the goal of the action. We discuss the possibility that, in the context of the action, the motor system contributes to the binding of objects sensory attributes as well as to the sense of agency.     

Musical duplex perception: perception of figurally good chords with subliminal distinguishing tones.

In a variant of duplex perception with speech, phoneme perception is maintained when distinguishing components are presented below intensities required for separate detection, forming the basis for the claim that a phonetic module takes precedence over nonspeech processing. This finding is replicated with music chords (C major and minor) created by mixing a piano fifth with a sinusoidal distinguishing tone (E or E flat). Individual threshold intensities for detecting E or E flat in the context of the fixed piano tones are established. Chord discrimination thresholds defined by distinguishing tone intensity were determined. Experiment 2 verified masked detection thresholds and subliminal chord identification for experienced musicians. Accurate chord perception was maintained at distinguishing tone intensities nearly 20 dB below the threshold for separate detection. Speech and music findings are argued to demonstrate general perceptual principles.     

Kinesthetic Compensation for Sensorimotor Rearrangements

ABSTRACT

The authors report a new sensorimotor phenomenon in which participants use hand-sensed kinesthetic information to compensate for rotational sensorimotor rearrangements. This compensation benefits from conscious awareness and is related to hand posture. The technique can reduce control inefficiency with some misalignments by as much as 64%. The results support Y. Guiard's (1987) Guiard, Y. 1987. Asymmetric division of labor in human skilled bimanual action. Journal of Motor Behavior, 19: 486–517. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar] suggestion that in bimanual tasks one hand provides an operational frame of reference for the other hand as in a closed kinematic chain. Results with right-handed participants show that the right and left hands are equally effective at providing such a cue. A constant-angular-targeting-error model, similar to that used for hand movements by H. Cunningham and I. Vardi (1990) and for walking by S. K. Rushton, J. M. Harris, M. R. Lloyd, and J. P. Wann (1998), is used to model the trajectories of targeting hand movements demonstrating the phenomenon. The model provides a natural parameter of the error.     

Sensorimotor coordination generates extended agency

When we synchronize finger tapping with a visual metronome, we experience a strikingly robust phenomenon of extended agency known as Spizzo’s effect. This effect is the compelling sense that we are controlling the metronome. The effect arises even though the agent knows that the metronome operates autonomously. We propose that the extended agency here established over metronome pulses results from sensorimotor coordination. To test this hypothesis, we operationalize sensorimotor coordination in terms of the correlation structures in series of asynchronies or reaction times from two finger-tapping tasks. Analyses reveal that, whereas correlation structures vary across individuals and show a systematic drift towards nonstationarity with increasing metronome frequency conditions, the presence of correlation structure is co-extensive with Spizzo’s effect. We interpret this result as supporting the view that extended agency relies on sensorimotor coordination. Sensorimotor coordination, we suggest, may induce the effect by integrating the perception of visual pulses and the agency over tapping into a synesthetic experience.     

Discrete cortical regions associated with the musical beauty of major and minor chords

Previous research has demonstrated that the degree of aesthetic pleasure a person experiences correlates with the activation of reward functions in the brain. However, it is unclear whether different affective qualities and the perceptions of beauty that they evoke correspond to specific areas of brain activation. Major and minor musical keys induce two types of affective qualities--bright/happy and dark/sad--that both evoke aesthetic pleasure. In the present study, we used positron emission tomography to demonstrate that the two musical keys (major and minor) activate distinct brain areas. Minor consonant chords perceived as beautiful strongly activated the right striatum, which has been assumed to play an important role in reward and emotion processing, whereas major consonant chords perceived as beautiful induced significant activity in the left middle temporal gyrus, which is believed to be related to coherent and orderly information processing. These results suggest that major and minor keys, both of which are perceived as beautiful, are processed differently in the brain.     

Reaction time and musical expectancy: priming of chords

The cognitive processes underlying musical expectation were explored by measuring reaction time in a priming paradigm. Subjects made a speeded true/false decision about a target chord following a prime chord to which it was either closely or distantly related harmonically. Using a major/minor decision task in Experiment 1, we found that major targets were identified faster, and with fewer errors, when they were related than when unrelated. An apparent absence (and possible reversal) of this effect for minor targets can be attributed to the prime's biasing effect on the target's stability. In Experiments 2 and 3 we tested this hypothesis by employing an in-tune/out-of-tune decision for major and minor targets separately. Both major and minor in-tune targets were identified faster when related than when unrelated. We outline a spreading activation model which consists of a network of harmonic relations. Priming results from the indirect activation of chord nodes linked through the network.     

Staying offbeat: Sensorimotor syncopation with structured and unstructured auditory sequences

Three experiments investigated whether adding metric (higher-order, periodic) structure to tone sequences stabilizes syncopated finger tapping. Participants tapped in antiphase with metronomic tone sequences in which accents—produced by sounding two tones simultaneously—occurred regularly every two, three, or four tones (metric), occurred unpredictably (irregular), occurred on every tone (heavy beat), or were absent (light beat). Tap timing variability, although commensurate with metric and light beat sequences, was lower with metric than with heavy beat and irregular sequences even when the instructions specified using metric grouping in all conditions. Higher-order periodic fluctuations (delays) in tap timing—found only in metric conditions—were associated with low overall tap timing variability, suggesting that a regularly applied, meter-based phase-resetting mechanism stabilizes syncopation.

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Sensorimotor expectations and the visual field

Sensorimotor expectations concern how visual experience covaries with bodily movement. Sensorimotor theorists argue from such expectations to the conclusion that the phenomenology of vision is constitutively embodied: objects within the visual field are experienced as 3-D because sensorimotor expectations partially constitute our experience of such objects. Critics argue that there are (at least) two ways to block the above inference: to explain how we visually experience objects as 3-D, one may appeal to such non-bodily factors as (1) expectations about movements of objects, not the perceiver, or to (2) the role of mental imagery in visual experience. But instead of using sensorimotor expectations to explain how objects are experienced within the visual field, we can instead use them to explain our experience of the visual field itself and, in particular, our experience of its limits; that is, our ever-present visual sense of there being more to see, beyond what’s currently within the visual field. Crucially, this inference from sensorimotor expectations to the constitutive embodiment of visual phenomenology is not threatened by the above two challenges. I thus present here a sensorimotor theory of the phenomenology of the visual field, that is, our experience of our visual fields as such.