Martins Maurício D, Bergmann Zoe, Leonova Elena, Bianco Roberta, Sammler Daniela, Villringer Arno
SCAN-Unit, Department of Cognition, Emotion, and Methods in Psychology, Faculty of Psychology, University of Vienna.
Max Planck Institute for Human Cognitive and Brain Sciences.
Cogn Sci. 2025 Sep;49(9):e70108. doi: 10.1111/cogs.70108.
Recursive hierarchical embedding allows humans to generate multiple hierarchical levels using simple rules. We can acquire recursion from exposure to linguistic and visual examples, but only develop the ability to understand "multiple-level" structures like "[[second] red] ball]" after mastering "same-level" conjunctions like "[second] and [red] ball." Whether we can also learn recursion in motor production remains unexplored. Here, we tested 40 adults' ability to learn and generate sequences of finger movements using "multiple-level" recursion and "same-level" iteration rules (like linguistic conjunction). Rule order was counterbalanced. First, they learned the generative rules (without explicit rule instructions or feedback) by executing examples of motor sequences based on visual cues displayed on the screen (learning). Second, participants were asked to discriminate between correct and incorrect motor sequences beyond those to which they were previously exposed (discrimination). Finally, they were asked to use the rules to generate new hierarchical levels consistent with the previously given (generation). We repeated the procedure (all three phases) on 2 days, allowing for a night of sleep. We found that most participants could discriminate correct/incorrect sequences based on recursive rules and use recursive rules to generate new hierarchical levels in motor sequences, but mostly on the second day of testing, and when they had acquired iterative before recursive rules. This aligns with previous literature on vision and language and with literature showing that sleep is necessary to generate abstract knowledge of motor sequences. Lastly, we found that the ability to discriminate well-formed motor sequences using recursion was insufficient for motor generativity.
递归层次嵌入使人类能够使用简单规则生成多个层次级别。我们可以通过接触语言和视觉示例来习得递归，但只有在掌握了诸如“[第二个]和[红色]球”这样的“同级”连词之后，才会发展出理解像“[[第二个]红色]球”这样的“多层次”结构的能力。我们是否也能在运动产生中学习递归仍未得到探索。在这里，我们测试了40名成年人使用“多层次”递归和“同级”迭代规则（如语言连词）学习和生成手指运动序列的能力。规则顺序是平衡的。首先，他们通过根据屏幕上显示的视觉线索执行运动序列示例来学习生成规则（无明确规则指令或反馈）（学习阶段）。其次，要求参与者区分他们之前接触过的运动序列之外的正确和不正确的运动序列（辨别阶段）。最后，要求他们使用这些规则生成与之前给定的一致的新层次级别（生成阶段）。我们在两天内重复了这个过程（所有三个阶段），中间有一晚的睡眠。我们发现，大多数参与者能够根据递归规则区分正确/不正确的序列，并使用递归规则在运动序列中生成新的层次级别，但大多是在测试的第二天，并且是在他们先习得迭代规则再习得递归规则的情况下。这与之前关于视觉和语言的文献以及表明睡眠对于生成运动序列的抽象知识是必要的文献一致。最后，我们发现使用递归辨别结构良好的运动序列的能力对于运动生成来说是不够的。
