How infant-directed actions enhance infants’ attention, learning, and exploration

When teaching infants new actions, parents tend to modify their movements. Infants prefer these infant-directed actions (IDAs) over adult-directed actions and learn well from them. Yet, it remains unclear how parents’ action modulations capture infants’ attention. Typically, making movements larger than usual is thought to draw attention. Recent findings, however, suggest that parents might exploit movement variability to highlight actions. We hypothesized that variability in movement amplitude rather than higher amplitude is capturing infants’ attention during IDAs. Using EEG, we measured 15-month-olds’ brain activity while they were observing action demonstrations with normal, high, or variable amplitude movements. Infants’ theta power (4-5Hz) in fronto-central channels was compared between conditions. Frontal theta was significantly higher, indicating stronger attentional engagement, in the variable compared to the other conditions. Computational modelling showed that infants’ frontal theta power was predicted best by how surprising each movement was. Thus, surprise induced by variability in movements rather than large movements alone engages infants’ attention during IDAs. Infants with higher theta power for variable movements were more likely to perform actions successfully and to explore objects novel in the context of the given goal. This highlights the brain mechanisms by which IDAs enhance infants’ attention, learning, and exploration.

在教导婴儿学习新动作时，家长往往会调整自身的动作模式。相较于成人导向动作，婴儿更偏爱这类婴儿导向动作 (infant-directed actions, IDAs)，并能从中高效习得动作技能。然而，目前学界尚未明确家长的动作调整是如何吸引婴儿注意力的。传统观点认为，动作幅度大于常规水平通常能够有效吸引注意力。但近期研究结果显示，家长或许会利用动作变异性来凸显动作本身。本研究提出假设：在婴儿导向动作中，吸引婴儿注意力的是动作幅度的变异性，而非更大的动作幅度。本研究采用脑电图 (electroencephalogram, EEG) 技术，记录了15个月大婴儿观察三类动作演示时的脑活动，这三类动作分别为常规幅度动作、大幅度动作以及变幅动作。研究人员对比了各实验条件下婴儿额中央通道的θ波功率 (4-5Hz)。相较于其他实验条件，变幅动作组的婴儿额叶θ波功率显著更高，这表明其注意力投入程度更强。计算建模结果显示，婴儿的额叶θ波功率的最佳预测因子为每个动作引发的惊讶程度。由此可见，在婴儿导向动作中，吸引婴儿注意力的是动作变异性所引发的惊讶感，而非单纯的大动作幅度。对变幅动作表现出更高θ波功率的婴儿，更易成功完成目标动作，并会在给定目标的情境下探索新颖客体。该研究揭示了婴儿导向动作提升婴儿注意力、学习能力与探索行为的脑机制。