Internal Timing Mechanism Characteristics Of Rhythm Complexity Influencing The Timing Accuracy Of Sequential Movements In Auditory-Motor Entrainment

The effectiveness execution of sequential movements requires the individual to complete the precise coordination and execution of a series of sub-actions in a relative short time duration.The temporal accuracy of sub-actions is an important feature of sequential movements as well as an essential factor for individuals to complete movements(e.g.,writing and throwing)effectively.Auditory-motor entrainment provides a reliable and accurate method of external conditioning and intervention.However,the performance of sequential movements during auditory-motor entrainment is controversial due to its rhythm complexity and the internal timing mechanisms.The role of auditory-motor entrainment on the temporal accuracy of unskilled sequential movements has not been systematically explored in the previous literature,and the role of rhythm complexity and individual internal timing strategies – the beat-based timing strategy and the duration-based timing strategy,is still unclear.How individuals match sequence movements to auditory rhythmic stimuli through different functional timing mechanisms is an important basis for explaining auditory-motor system interactions and facilitating coordinated processing of auditory-motor entrainment.The present experimental study was conducted on the timing accuracy of sequential movements in auditory-motor entrainment under different rhythm complexities.Study 1 tested the timing accuracy improvement of sequential movements under different rhythm complexity conditions.Experiment 1 manipulated rhythm complexity(number of non-integer ratios in a rhythmic sequence)and used a multi-target fingertapping task that added rhythm predefinition of sequential tapping guided by auditory rhythmic stimuli prior to the synchronization-continuation paradigm.The temporal accuracy and the sustained effect(the degree of temporal accuracy improvement)in different dimensions were examined in 30 healthy young adult non-musician participants in four rhythm conditions(simple rhythm,mixed rhythm,complex rhythm C1 and C2)and two pitch types of the auditory stimuli presentation.Experiment 2analyzed the temporal accuracy and the sustained effect of auditory-motor entrainment in 32 non-musician participants with predefined isochronous sequential tapping,and manipulated path complexity by changing the order of tapping targets,in order to distinguish the role of movement velocity and rhythm complexity in auditory entrainment.Experiment 3 distinguished the role of two forms of auditory-motor entrainment by comparing the sequential tapping initiation time of 20 non-musician participants after passive perception versus active action synchronization.Study 2,based on Study 1,further investigated the error correction characteristics underlying different rhythm complexities,explored the matching mechanism characteristics auditory stimuli and sub-action in the internal timing mechanism,and further explained the correlation between the timing accuracy improvement of sequential movements and rhythm complexity.Experiment 4 assessed the association between temporal accuracy and the size and direction of perturbations in 19 non-musician participants’ sequential tapping with different temporal complexities,and used perturbation stimuli of different sizes and directions to test the temporal information referencing of error correction predictions.Experiment 5 examined differences in error correction prediction temporal scales across rhythm complexity,and the active inhibitions of 32 non-musician participants were tested using a stop-signal task.Based on the results of Study 1,Study3 explored the robustness of auditory-motor entrainment on sequential movement timing accuracy in a social evaluation scenario.Experiment 6 set a social evaluation scenario and examined the temporal accuracy and sustained effect of 21 non-musicians’ sequential tapping in a similar task of Experiment 1 in the social evaluation scenario,and the difference with the performance alone scenario.The results showed that:(1)in Experiment 1,the sequential tapping with four temporal complexities sustained different dimensions of temporal accuracy improvement through auditory-motor synchronization;the sustained effect of ratio accuracy was better for complex rhythms and mixed rhythm than for simple rhythm;the sustained effect in ratio accuracy was not significant for simple and mixed rhythms;the interval accuracy was significantly improved for simple and mixed rhythms,but the interval accuracy of complex rhythms was not significantly different before and after synchronization.(2)In Experiment 2,there was no significant effect of path complexity on the sustained effect of auditory entrainment,and no significant effect of pitch type was found in the temporal accuracy and the sustained effect.(3)In Experiment 3,the sequential tapping initiation was faster in the active action synchronization condition than in the passive perception condition.(4)In Experiment 4,the stable synchronized sequential tapping was shifted by the perturbations,the simple and mixed rhythm sequential tapping were shifted by the preorder perturbation direction in low phase perturbations,and the subsequent tapping of complex rhythm was shifted by the by the preorder perturbation direction in high phase perturbations;the interval reproduction in the mixed and complex rhythm was shifted by low and high period perturbations.(5)In Experiment 5,the active inhibition difference was found in mixed and complex rhythms,and the active inhibition on the target position connected an integer interval and a non-integer ratio interval was lower than the target position connected a noninteger and an integer interval,thus the time scale of prediction might be caused the interval shift.In Experiment 6,the temporal accuracy of predefined sequential tapping with different temporal complexities was improved by auditory-motor entrainment in the social evaluation scenario,and the sustained effect was not significantly different from the performance alone scenario.Also,there was no significant effect of pitch type on the sustained effect.In conclusion,(1)the integer-ratio rhythmic sequential tapping sustained interval accuracy improvement from auditory-motor entrainment,and the non-integer-ratio rhythmic sequential tapping sustained ratio accuracy improvement.The dimensionality of timing accuracy improvement was related to rhythm complexity and the internal timing strategies.(2)Integer-ratio rhythmic error correction prediction tended to use phase correction,while non-integer-ratio rhythmic error correction prediction tended to use period correction.The difference in active inhibition was related to integer-ratio and non-integer-ratio interval conversion.(3)Auditory-motor entrainment is robust in social evaluation context.(4)Absolute frequency pitch variation is not an essential factor in auditory-motor entrainment.