Tapping force encodes metrical aspects of rhythm

Humans possess the ability to extract highly organized perceptual structures from sequences of temporal stimuli. For instance, we can organize specific rhythmical patterns into hierarchical, or metrical, systems. Despite the evidence of a fundamental influence of the motor system in achieving this skill, few studies have attempted to investigate the organization of our motor representation of rhythm. To this aim, we studied - in musicians and non-musicians – the ability to perceive and reproduce different rhythms. In a first experiment participants performed a temporal order-judgment task, for rhythmical sequences presented via auditory or tactile modality. In a second experiment, they were asked to reproduce the same rhythmic sequences, while their tapping force and timing were recorded. We demonstrate that tapping force encodes the metrical aspect of the rhythm, and the strength of the coding correlates with the individual’s perceptual accuracy. We suggest that the similarity between perception and tapping-force organization indicates a common representation of rhythm, shared between the perceptual and motor systems.

人类能够从时序刺激（temporal stimuli）序列中提取高度规整的知觉结构。例如，我们可将特定的节律模式组织为层级化（hierarchical）或节拍式（metrical）的系统。尽管已有研究证实运动系统（motor system）对该能力具有基础性影响，但目前极少有研究尝试探索人类对节律的运动表征的组织方式。为此，我们针对音乐家与非音乐家群体，研究了其感知与复刻不同节律的能力。在第一项实验中，受试者需完成时序判断任务（temporal order-judgment task），实验材料为通过听觉（auditory）或触觉（tactile）通道呈现的节律序列；在第二项实验中，受试者被要求复刻相同的节律序列，同时记录其敲击力度（tapping force）与敲击时序（timing）。本研究发现，敲击力度可编码节律的节拍式层面，且该编码的强度与个体的知觉精度（perceptual accuracy）相关。我们据此提出，知觉加工与敲击力度组织之间的相似性表明，知觉系统（perceptual system）与运动系统共享一套共通的节律表征。