Nava Elena, Rinaldi Luca, Bulf Hermann, Macchi Cassia Viola
Department of Psychology, University of Milan-Bicocca, 20126 Milan, Italy.
Department of Psychology, University of Milan-Bicocca, 20126 Milan, Italy; NeuroMi-Milan Center for Neuroscience.
J Exp Child Psychol. 2017 Sep;161:161-177. doi: 10.1016/j.jecp.2017.04.012. Epub 2017 May 18.
There has been compelling evidence favoring the idea that human adults similarly represent number and time along a horizontal mental number line (MNL) and mental time line (MTL), respectively. Yet, analogies drawn between the MNL and MTL have been challenged by recent studies suggesting that adults' representations of number and time arise from different spatial frames of reference; whereas the MNL relies on both hand-centered and object-centered coordinates, the MTL appears to be exclusively anchored on object-centered coordinates. To directly test this possibility, here we explored the extent to which visual feedback and proprioceptive feedback affect children's performance in a Number Comparison task (Experiment 1) and a Time Comparison task (Experiment 2), in which participants needed to associate a lateralized key with numerical and temporal words, respectively. Children (5- and 6-year-olds) performed the task with their hands either uncrossed or crossed over the body midline (i.e., manipulation of proprioceptive feedback) and with either visual control over their hands allowed or precluded under blindfolds (i.e., manipulation of visual feedback). Results showed that children were facilitated in associating smaller/larger numbers with the left/right side of the external space, but only when hands were uncrossed and visual feedback was available. On the contrary, blindfolding and crossing their hands over the midline did not affect spatial time mapping, with 6-year-olds showing facilitation in associating words referring to the past/future with the left/right side of the external space irrespective of visual and proprioceptive feedback. This same effect was also present in 5-year-olds despite their difficulty in performing the Time Comparison task. Together, these findings show, for the first time, that-just like adults-young children (a) map temporal events onto space in a rightward direction as they do for numbers and (b) anchor their spatial representation of time and numbers to different spatial frames of reference.
有令人信服的证据支持这样一种观点，即成年人类似地分别沿着水平心理数字线（MNL）和心理时间线（MTL）来表征数字和时间。然而，MNL和MTL之间的类比受到了最近研究的挑战，这些研究表明，成年人对数字和时间的表征源自不同的空间参照系；MNL依赖于以手为中心和以物体为中心的坐标，而MTL似乎完全以物体为中心的坐标为锚定。为了直接检验这种可能性，我们在此探究了视觉反馈和本体感觉反馈在多大程度上影响儿童在数字比较任务（实验1）和时间比较任务（实验2）中的表现，在这些任务中，参与者需要分别将一个侧向化的按键与数字和时间词汇相关联。儿童（5岁和6岁）在执行任务时，双手要么不交叉，要么交叉于身体中线之上（即本体感觉反馈的操控），并且要么允许他们对双手进行视觉控制，要么在蒙上眼睛的情况下排除这种控制（即视觉反馈的操控）。结果表明，儿童在将较小/较大数字与外部空间的左侧/右侧相关联时会得到促进，但仅当双手不交叉且有视觉反馈时才会如此。相反，蒙上眼睛以及双手交叉于中线之上并不影响空间时间映射，6岁儿童在将指代过去/未来的词汇与外部空间的左侧/右侧相关联时表现出促进作用，而不论视觉和本体感觉反馈如何。尽管5岁儿童在执行时间比较任务时有困难，但这种相同的效应在他们身上也存在。总之，这些发现首次表明，与成年人一样，幼儿（a）像对数字那样将时间事件向右映射到空间中，并且（b）将他们对时间和数字的空间表征锚定到不同的空间参照系上。
