Reader Arran T, Rao Vaisnavi M, Christakou Anastasia, Holmes Nicholas P
Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Centre for Integrative Neuroscience and Neurodynamics, School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK.
Atten Percept Psychophys. 2018 Nov;80(8):2069-2083. doi: 10.3758/s13414-018-1582-z.
The dual-route model of imitation suggests that meaningful and meaningless actions are processed through either an indirect or a direct route, respectively. Evidence indicates that the direct route is more cognitively demanding since it relies on mapping visuospatial properties of the observed action on to a performed one. These cognitive demands might negatively influence reaction time and accuracy for actions performed following a meaningless action under time constraints. However, how meaningful and meaningless action imitation processing is reflected in movement kinematics is not yet clear. We wanted to confirm whether meaningless action performance incurs a reaction time cost, whether the cost is reflected in kinematics, and, more generally, to examine kinematic markers of emblematic meaningful and meaningless action imitation. We examined participants' reaction time and wrist movements when they imitated emblematic meaningful or matched meaningless gestures in either blocks of the same action type or mixed blocks. Meaningless actions were associated with a greater correction period at the end of the movement, possibly reflecting a strategy designed to ensure accurate completion for less familiar actions under time constraints. Furthermore, in mixed blocks, trials following meaningless actions had a significantly increased reaction time, supporting previous claims that route selection for action imitation may be stimulus-driven. However, there was only convincing evidence for this effect with an interval of ~2,948ms, but not ~3,573ms or ~2,553ms, between movements. Future work motion-tracking the entire hand to assess imitation accuracy, and more closely examining the influence of duration between movements, may help to explain these effects.
模仿的双路径模型表明，有意义和无意义的动作分别通过间接或直接路径进行处理。有证据表明，直接路径对认知的要求更高，因为它依赖于将观察到的动作的视觉空间属性映射到执行的动作上。在时间限制下，这些认知需求可能会对在无意义动作之后执行的动作的反应时间和准确性产生负面影响。然而，有意义和无意义动作模仿处理在运动运动学中如何体现尚不清楚。我们想确认无意义动作的执行是否会导致反应时间成本增加，这种成本是否在运动学中有所体现，更普遍地说，是要研究标志性有意义和无意义动作模仿的运动学标记。我们研究了参与者在模仿标志性有意义或匹配无意义手势时的反应时间和手腕运动，这些手势分别处于相同动作类型的组块或混合组块中。无意义动作在动作结束时与更长的校正期相关，这可能反映了一种策略，旨在确保在时间限制下不太熟悉的动作能够准确完成。此外，在混合组块中，无意义动作之后的试验反应时间显著增加，这支持了之前的观点，即动作模仿的路径选择可能是由刺激驱动的。然而，只有在动作之间间隔约2948毫秒时有令人信服的证据证明这种效应，而在间隔约3573毫秒或2553毫秒时则没有。未来的工作可以通过对手部进行全运动跟踪来评估模仿准确性，并更仔细地研究动作之间持续时间的影响，这可能有助于解释这些效应。
