title: Timing at peak force may be the hidden target controlled in continuation and synchronization tapping.
abstract: Timing control, such as producing movements at a given rate or synchronizing movements to an external event, has been studied through a finger-tapping task where timing is measured at the initial contact between finger and tapping surface or the point when a key is pressed. However, the point of peak force is after the time registered at the tapping surface and thus is a less obvious but still an important event during finger tapping. Here, we compared the time at initial contact with the time at peak force as participants tapped their finger on a force sensor at a given rate after the metronome was turned off (continuation task) or in synchrony with the metronome (sensorimotor synchronization task). We found that, in the continuation task, timing was comparably accurate between initial contact and peak force. These two timing events also exhibited similar trial-by-trial statistical dependence (i.e., lag-one autocorrelation). However, the central clock variability was lower at the peak force than the initial contact. In the synchronization task, timing control at peak force appeared to be less variable and more accurate than that at initial contact. In addition to lower central clock variability, the mean SE magnitude at peak force (SEP) was around zero while SE at initial contact (SEC) was negative. Although SEC and SEP demonstrated the same trial-by-trial statistical dependence, we found that participants adjusted the time of tapping to correct SEP, but not SEC, toward zero. These results suggest that timing at peak force is a meaningful target of timing control, particularly in synchronization tapping. This result may explain the fact that SE at initial contact is typically negative as widely observed in the preexisting literature.
authors.affiliation: Department of Kinesiology, School of Public Health, University of Maryland, College Park, MD, 20742, USA. duyue@umd.edu.|Applied Mathematics & Statistics, and Scientific Computation Program, University of Maryland, College Park, MD, 20742, USA. duyue@umd.edu.
authors.forename: Yue
authors.identifier: 0000-0002-3865-0805
authors.initials: Y
authors.lastname: Du
authors.affiliation: Department of Kinesiology, School of Public Health, University of Maryland, College Park, MD, 20742, USA.|Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD, 20742, USA.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Clark
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, School of Medicine, University of Maryland, Baltimore, MD, 21201, USA.|Faculty of Health Sciences, University of Southampton, Southampton, Hampshire, SO17 1BJ, UK.
authors.forename: Jill
authors.initials: J
authors.lastname: Whitall
mesh_terms: D000704:Analysis of Variance; D003344:Cortical Synchronization / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D013997:Time Factors; D013998:Time Perception / Q000502:physiology*; D055815:Young Adult
keywords: Continuation tapping; Negative synchronization error; Sensorimotor synchronization; Timing at initial contact; Timing at peak force; Timing variability