Correlations for timing consistency among tapping and drawing tasks: evidence against a single timing process for motor control.

Three experiments were conducted to examine whether timing processes can be shared by continuous tapping and drawing tasks. In all 3 experiments, temporal precision in tapping was not related to temporal precision in continuous drawing. There were modest correlations among the tapping tasks, and there were significant correlations among the drawing tasks. In Experiment 3, the function relating timing variance to the square of the observed movement duration for tapping was different from that for drawing. The conclusions drawn were that timing is not an ability to be shared by a variety of tasks but instead that the temporal qualities of skilled movement are the result of the specific processes necessary to produce a trajectory. These results are consistent with the idea that timing is an emergent property of movement.     

Force and timing variability in rhythmic unimanual tapping

In 3 experiments the interdependencies between timing and force production in unimanual paced and self-paced rhythmic tapping tasks were examined as participants (N = 6 in each experiment) tapped (a) to 1 of 3 target periods (333 ms, 500 ms, and 1,000 ms), while they simultaneously produced a constant peak force (PF) over a 50-s trial; (b) to produce 1 of 3 target forces (5, 10, and 15 N) at their preferred frequency, while keeping their rhythm as invariant as possible; and (c) to all combinations of target force and period. The results showed that (a) magnitudes of force and period were largely independent; (b) variability in timing increased proportionally with tapping period, and the variability in force increased with peak force; (c) force variability decreased at faster tapping rates; and (d) timing variability decreased with increasing force levels. (e) Analysis of tap-to-tap variability revealed adjustments over sequences of taps and an acceleration in the tapping rate in unpaced conditions. The interdependencies of force and time are discussed with respect to the challenges they provide for an oscillator-based account.     

Frequency dependence of rhythm in periodic tapping

Cross-correlation between successive stresses and time intervals in periodic tapping was analyzed at 15 different frequencies. Three types of rhythmic pattern of stress and timing in the sequencing of taps were identified in their intrinsic regions of frequency above 2.7 Hz. The tapping sequences were temporally grouped into units of two taps in which relatively stressed taps at the top (type I) or end (type II) of the group were preceded or followed, respectively, by the longer time intervals, while type III was a rhythm with 4 meters. These three types transformed to each other reversibly with shift of the frequencies in a way such as ←(f1)^→ type I←(f2)^→ type II←(f3)^→ type III, where critical frequencies were f1 = 2.7, f2 = 4.0 and f3 = 5.0 Hz. The changes of the rhythmic type with the frequencies are discussed in terms of phase transition in which structures of rhythm are reorganized in order to maintain stable control of sequential tapping in each of the three frequency regions.     

Dissociation of explicit and implicit timing in repetitive tapping and drawing movements

Four experiments explored the hypothesis that temporal processes may be represented and controlled explicitly or implicitly. Tasks hypothesized to require explicit timing were duration discrimination, tapping, and intermittent circle drawing. In contrast, it was hypothesized that timing control during continuous circle drawing does not rely on an explicit temporal representation; rather, temporal control is an emergent property of other control processes (i.e., timing is controlled implicitly). Temporal consistency on the tapping and intermittent drawing tasks was related, and performance on both of these tasks was correlated with temporal acuity on an auditory duration discrimination task. However, timing variability of these 3 tasks was not correlated with timing variability of continuous circle drawing. These results support the hypothesized distinction between explicit and implicit temporal representations.     

Asymmetric control of force and symmetric control of timing in bimanual finger tapping

An experiment was conducted to examine the control of force and timing in bimanual finger tapping. Participants were trained to produce both unimanual (left or right hand) and bimanual finger-tapping sequences with a peak force of 200 g and an intertap interval (ITI) of 400 ms. During practice, visual force feedback was provided pertaining to the hand performing the unimanual tapping sequences and to either the dominant or the nondominant hand in the bimanual tapping sequences. After practice, the participants produced the learned unimanual and bimanual tapping sequences in the absence of feedback. In those trials the force produced by the dominant (right) hand was significantly larger than that produced by the nondominant (left) hand, in the absence of a significant difference between the ITIs produced by both hands. Furthermore, after unilateral feedback had been provided of the force produced by the nondominant hand, the force output of the dominant hand was significantly more variable than that of the nondominant hand. In contrast, after feedback had been provided of the force produced by the dominant hand, the variability of the force outputs of the two hands did not differ significantly. These results were discussed in the light of both neurophysiological and anatomical findings, and were interpreted to imply that the control of timing (in bimanual tasks) may be more tightly coupled in the motor system than the control of force.     

Weber (slope) analyses of timing variability in tapping and drawing tasks

Timing variability in continuous drawing tasks has not been found to be correlated with timing variability in repetitive finger tapping in recent studies (S. D. Robertson et al., 1999; H. N. Zelaznik, R. M. C. Spencer, & R. B. Ivry, 2002). Furthermore, the central component of timing variability, as measured by the slope of the timing variance versus the square of the timed interval, differed for tapping and drawing tasks. On the basis of those results, the authors posited that timing in tapping is explicit and as such uses a central representation of the interval to be timed, whereas timing in drawing tasks is implicit, that is, the temporal component is an emergent property of the trajectory produced. The authors examined that hypothesis in the present study by determining the linear relationship between timing variance and squared duration for tapping, circle-drawing, and line-drawing tasks. Participants (N = 50) performed 1 of 5 tasks: finger tapping, line drawing in the x dimension, line drawing in the y dimension, continuous circle drawing timed in the x dimension, or continuous circle drawing timed in the y dimension. The slopes differed significantly between finger tapping, line drawing, and circle drawing, suggesting separable sources of timing variability. The slopes of the 2 circle-drawing tasks did not differ from one another, nor did the slopes of the 2 line-drawing tasks differ significantly, suggesting a shared timing process within those tasks. Those results are evidence of a high degree of specificity in timing processes.     

Variability in the timing of responses during repetitive tapping with alternate hands

Summary This paper addresses the question of whether a simple two-stage account of variability in timing developed for single-hand repetitive tapping is applicable to regular tapping with the hands in alternation. The task required key presses at a steady rate, previously set by a periodic auditory signal. On separate blocks of trials four subjects used the index finger of the left hand or of the right hand at intervals of 200, 400, and 800 ms or alternated between the hands at intervals of 100, 200, or 400 ms. For each subject the variability of the between-hand intervals in the 200- and 400-ms alternate-hand conditions was greater than the variability of the same interval in the single-hand conditions. In the 100-ms alternate-hand condition correlations between adjacent (between-hand) intervals were reliably less then –.5. These results are inconsistent with the simple two-stage model, and two variants are shown to provide a better qualitative fit to at least some aspects of the data.     

Correlations between intelligence and components of serial timing variability

Psychometric intelligence correlates with reaction time in elementary cognitive tasks, as well as with performance in time discrimination and judgment tasks. It has remained unclear, however, to what extent these correlations are due to top–down mechanisms, such as attention, and bottom–up mechanisms, i.e. basic neural properties that influence both temporal accuracy and cognitive processes. Here, we assessed correlations between intelligence (Raven SPM Plus) and performance in isochronous serial interval production, a simple, automatic timing task where participants first make movements in synchrony with an isochronous sequence of sounds and then continue with self-paced production to produce a sequence of intervals with the same inter-onset interval (IOI). The target IOI varied across trials. A number of different measures of timing variability were considered, all negatively correlated with intelligence. Across all stimulus IOIs, local interval-to-interval variability correlated more strongly with intelligence than drift, i.e. gradual changes in response IOI. The strongest correlations with intelligence were found for IOIs between 400 and 900 ms, rather than above 1 s, which is typically considered a lower limit for cognitive timing. Furthermore, poor trials, i.e. trials arguably most affected by lapses in attention, did not predict intelligence better than the most accurate trials. We discuss these results in relation to the human timing literature, and argue that they support a bottom–up model of the relation between temporal variability of neural activity and intelligence.     

Statistical analysis for finger tapping with a periodic external stimulus

In this paper we outline an experiment in which seven subjects attempted to tap in synchrony with a pacing stimulus with the interstimulus interval that varied in a cycle (T,T+dT,T, T-dT) repeating every fourth interval, where T represents an unexpected step change of an interstimulus interval. Conditions included three levels of T= (400, 500, and 600 msec.) with four levels of dT= 1, 3, 5, and 7% of T). The statistical analysis indicated that small changes in T lead to rapid matching of the interresponse intervals to the new interstimulus intervals even when the variation in the input is not apparent to subjects.     

Bimanual finger tapping: effects of frequency and auditory information on timing consistency and coordination

The authors' goal in this study was to probe the basis for an earlier, unexpected finding that preferred-frequency finger tapping tends to have higher frequencies and to be less stable for in-phase than for antiphase tasks. In follow-up experiments, 3 protocols were employed: a preferred-frequency replication in both coordination modes, a metronome-driven matching of the preferred frequencies to each of the coordination modes, and a frequency scaling of both modes. The original findings were affirmed for preferred frequency. Tapping to a metronome had a differential effect on in-phase and antiphase: A more stable coupling across frequencies was exhibited during in-phase. Under frequency scaling, the antiphase pattern decomposed at lower frequencies than did in-phase, but no phase transitions were observed. The loss of stable coordination in both modes was attended by sudden increases in frequency differences between fingers and by phase wandering. The emergence of those effects is discussed in light of asymmetric modifications to the Haken-Kelso-Bunz model (H. Haken, J. A. S. Kelso, & H. Bunz, 1985) and the task constraints of tapping.     

Timing variability in circle drawing and tapping: probing the relationship between event and emergent timing

R. Ivry, R. M. Spencer, H. N. Zelaznik, and J. Diedrichsen (2002) have proposed a distinction between timed movements in which a temporal representation is part of the task goal (event timing) and those in which timing properties are emergent. The issue addressed in the present experiment was how timing in conditions conducive to emergent timing becomes established. According to what the authors term the transformation hypothesis, timing initially requires an event-based representation when the temporal goal is defined externally (e.g., by a metronome), but over the first few movement cycles, control processes become established that allow timing to become emergent. Different groups of participants (N = 84) executed either 1 timed interval, 4 timed intervals, or 2 timed intervals separated by a pause. They produced the intervals by either circle drawing, a task associated with emergent timing, or tapping, a task associated with event timing. Analyses of movement variability suggested that similar timing processes were used in the 2 tasks only during the 1st interval. Those results are consistent with the transformation hypothesis and lead to the inference that the transition from event-based control to emergent timing can occur rapidly during continuous movements.     

Timing and aging: slowing of fastest regular tapping rate with preserved timing error detection and correction

This study assessed motor limits of regular tapping, timing error detection, and correction in 60 participants aged from 19 to 98 years. Rate limitations on motor production were estimated from the average inter-tap interval when tapping as fast as possible for 30 s. Timing error detection required participants to judge whether a sound sequence presented at a slow, intermediate, or fast speed contained an irregularity because of phase shift. This was performed with or without synchronizing to the sounds. On the basis of the just-detectable positive phase shift (JND), participants synchronized with sequences containing phase shifts that were subliminal, just detectable or supraliminal. On average, JNDs were 9% of the inter-onset interval and by and large were not affected by synchronization tapping. Speed of error correction was estimated from the number of tones to return within 20% of the preshift synchronization error. Consistent with previous findings of motor slowing with aging, the fastest inter-tap interval increased with age. However, there was no age-related decline in JNDs or speed of error correction, both of which reflect predictive abilities for intervals within the motor repertoire of human adults. These results point towards intact timing error processing up to an advanced age. In assessing timing abilities in the brain of older adults, it is important to differentiate between motor slowing and its impact on rhythmic behavior (e.g., walking pace) from anticipatory mechanisms ('what to expect when') and how these are used to adjust the timing of actions ('what to do when').     

The distinction between tapping and circle drawing with and without tactile feedback: an examination of the sources of timing variance

An internal clock-like process has been implicated in the control of rhythmic movements performed for short (250-2,000 ms) time scales. However, in the past decade, it has been claimed that a clock-like central timing mechanism is not required for smooth cyclical movements. The distinguishing characteristic delineating clock-like (event) from non-clock-like (emergent) timing is thought to be the kinematic differences between tapping (discrete-like) and circle drawing (smooth). In the archetypal event-timed task (tapping), presence of perceptual events is confounded with the discrete kinematics of movement (table contact). Recently, it has been suggested that discrete perceptual events help participants synchronize with a metronome. However, whether discrete tactile events directly elicit event timing has yet to be determined. In the present study, we examined whether a tactile event inserted into the circle drawing timing task could elicit event timing in a self-paced (continuation) timing task. For a majority of participants, inserting an event into the circle drawing task elicited timing behaviour consistent with the idea that an internal timekeeper was employed (a correlation of circle drawing with tapping). Additionally, some participants exhibited characteristics of event timing in the typically emergently timed circle drawing task. We conclude that the use of event timing can be influenced by the insertion of perceptual events, and it also exhibits persistence over time and over tasks within certain individuals.     

Coordination of a discrete response with periodic finger tapping: additional experimental aspects for a subtle mechanism

The authors investigated the coordination of periodic right-hand tapping with single stimulus-evoked discrete lefthand taps to check for task interactions and a possible relationship between phase resetting (see tapping literature; e.g., J. Yamanishi, M. Kawato, & R. Suzuki, 1979) and phase entrainment (see tremor literature; e.g., R. J. Elble, C. Higgins, & L. Hughes, 1994). The experimental paradigm employs a dual-task condition as used by K. Yoshino, K. Takagi, T. Nomura, S. Sato, and M. Tonoike (2002), and it includes normal tapping and isometric tapping with the authors recording finger positions and ground contact forces. Four different types of coordination schemes were observed in tapping behavior: marginal tapping interaction (MTI), periodic tap retardation (PTR), periodic tap hastening (PTH), and discrete tap entrainment (DTE); MTI and PTR correspond to the phase-resetting effect for the coordination of periodic tapping with single discrete taps. The novel aspect of the study described in this article includes the impact of the periodic tapping on the discrete tap timing and the hastening of the periodic tapping due to the discrete tap behaviors resulting in a synchronized execution of the two concurrent tapping tasks. All participants showed a dominant tapping behavior, but they all used the other nondominant forms of the four reported coordination schemes in some trials too, which reflects possible constraints of the sensorimotor system in handling two competing tasks.     

The distinction between tapping and circle drawing with and without tactile feedback: An examination of the sources of timing variance

An internal clock-like process has been implicated in the control of rhythmic movements performed for short (250–2,000 ms) time scales. However, in the past decade, it has been claimed that a clock-like central timing mechanism is not required for smooth cyclical movements. The distinguishing characteristic delineating clock-like (event) from non-clock-like (emergent) timing is thought to be the kinematic differences between tapping (discrete-like) and circle drawing (smooth). In the archetypal event-timed task (tapping), presence of perceptual events is confounded with the discrete kinematics of movement (table contact). Recently, it has been suggested that discrete perceptual events help participants synchronize with a metronome. However, whether discrete tactile events directly elicit event timing has yet to be determined. In the present study, we examined whether a tactile event inserted into the circle drawing timing task could elicit event timing in a self-paced (continuation) timing task. For a majority of participants, inserting an event into the circle drawing task elicited timing behaviour consistent with the idea that an internal timekeeper was employed (a correlation of circle drawing with tapping). Additionally, some participants exhibited characteristics of event timing in the typically emergently timed circle drawing task. We conclude that the use of event timing can be influenced by the insertion of perceptual events, and it also exhibits persistence over time and over tasks within certain individuals.     

Temporal regularity of tapping by the left and right hands in timed and untimed finger tapping

The temporal characteristics of repetitive finger tapping by the left and right hands were examined in two experiments. In the first experiment, interresponse intervals (IRIs) were recorded while right-handed male subjects tapped in synchrony with an auditory timing pulse (the synchronization phase) and then attempted to maintain the same tapping rate without the timing pulses (the continuation phase). The left and right hands performed separately, at four different rates (interpulse intervals of 250, 500, 750, and 1500 ms). There was no asymmetry of the asynchronies of the timing pulses and the associated responses in the synchronization phase or of the IRIs in either phase, but there was an asymmetry of chronization phase or of the IRIs in either phase, but there was an asymmetry in the temporal dispersion of the responses in both phases. in the second experiment, right-handed males tapped separately with each hand at three different speeds: as quickly as possible, at a fast but steady rate, and at a slow rhythmical rate. The speed asymmetry present when tapping as quickly as possible (with the preferred hand tapping more quickly ) was reduced when tapping at the fast steady rate and was absent when tapping at the slow rhythmical rate. The temporal dispersion of the IRIs produced by the nonpreferred hand was greater than the temporal dispersion of those produced by the preferred hand in all speed conditions. These results show smaller temporal dispersion of tapping by the preferred hand in right-handed males under different conditions, including submaximal speeds at which both hands respond at the same rate. This suggests that the motor system controlling the preferred hand in right-handers had more precise timing of response output than that controlling the nonpreferred hand.     

Impulsivity and paced tapping

The purpose of this study was to test the hypothesis that impulsivity is positively related to both the intraindividual variability and the rate of performance of a paced tapping task. The independent variable in the tapping task were: feedback vs. no feedback; tempo; concurrent cognitive task (counting) vs. no concurrent cognitive task. Three measures of tapping performance were computed: absolute or total error of tapping, tapping rate, and the intraindividual variability of tapping. The results confirm the hypothesis that impulsivity is positively related to rate of paced tapping, although the degree of relationship varied under different experimental conditions within the paced tapping task. Intraindividual variability of tapping was not significantly related to impulsivity, but the results were suggestive of a positive relationship.     

Temporal precision in tapping and circle drawing movements at preferred rates is not correlated: further evidence against timing as a general-purpose ability

Recently, researchers have discovered that individuals who are consistent timers in a tapping task are not necessarily consistent timers when they perform a continuous drawing task. In other words, nonsignificant correlations were found among tapping and drawing movements for timing precision (S. D. Robertson et al., 1999). In the present experiment, the authors investigated whether or not consistency in timing for tapping and drawing was correlated when participants (N = 24) were allowed to move at their preferred rate of movement. There were no significant correlations between tapping and drawing in terms of timing precision. That result lends further support to the notion that timing behavior is specific to the nature of the task, and thus further weakens the idea that timing is a generalized ability that can be imposed on a variety of different types of tasks.     

Lateralized interference in finger tapping: comparisons of rate and variability measures under speed and consistency tapping instructions

Forty right-handed college subjects tapped with and without a verbal task under two instructional conditions (tap as quickly as possible vs. tap as consistently as possible) and two levels of verbal production (silent vs. aloud). The tapping task consisted of the alternate tapping of two keys with the index finger of the left vs. right hands, while the verbal task was anagram solution. Three rate and four variability measures of tapping performance were evaluated in the identification of lateralized interference. The results indicate that reliable lateralized interference, more right-hand than left-hand tapping disruption, was observed only for variability measures under instructions to tap as consistently as possible. Furthermore, only one of these variability measures was sensitive to an increase in lateralized interference produced by verbal production. Because of the limited demonstration of verbal laterality effects with the two-key tapping procedure in this study, conclusions suggest that the simpler manual task of repetitive tapping of one key should be viewed as the method of choice in future dual-task studies.     

Programming precision in repetitive tapping

The present paper reports an experiment using the Fitts' tapping paradigm. It is concerned with a comparison of movement times and accuracy during blind and visual repetitive tapping. A blind condition was used to investigate rapid aiming movements under motor program control, whilst visual aiming was used to assess the role of visual feedback for control purposes. Subjects in the blind conditions were able to replicate the amplitude specifications of the task, whereas effective target width was constant for a set amplitude and did not reflect specified target width. Subjects, furthermore, responded more rapidly when tapping blind. These results are discussed in terms of the magnitude of forces being attempted as a result of performing a set amplitude, and the role of visual feedback.