The ability to discriminate the ordinal information embedded in magnitude-based sequences has been shown in 4-month-old infants, both for numerical and size-based sequences. At this early age, however, this ability is confined to increasing sequences, with infants failing to extract and represent decreasing order. Here we investigate whether the ability to represent order extends to duration-based sequences in 4-month-old infants, and whether it also shows the asymmetry signature previously observed for number and size. Infants were tested in an order discrimination task in which they were habituated to either increasing or decreasing variations in temporal duration, and were then tested with novel sequences composed of new temporal items whose durations varied following the familiar and the novel orders in alternation. Across three experiments, we manipulated the duration of the single temporal items and therefore of the whole sequences, which resulted in imposing more or less constraints on infants' working memory, or general processing capacities. Results showed that infants failed at discriminating the ordinal direction in temporal sequences when the sequences had an overall long duration (Experiment 1), but succeeded when the duration of the sequences was shortened (Experiments 2 and 3). Moreover, there was no sign of the asymmetry signature previously reported for number and size, as successful discrimination was present for infants habituated to both increasing and decreasing sequences. These results suggest that sensitivity to temporal order is present very early in development, and that its functional properties are not shared with other magnitude dimensions, such as size and number.

中文翻译：

---

4个月大婴儿按时间顺序区分序数关系。

在4个月大的婴儿中，对于基于数字和基于大小的序列，已经显示出区分嵌入在基于幅度的序列中的序数信息的能力。然而，在这个很小的年龄，这种能力仅限于序列增加，而婴儿无法提取并代表降序。在这里，我们研究了代表顺序的能力是否扩展到4个月大婴儿中基于持续时间的序列，以及它是否还显示了先前观察到的数量和大小的不对称特征。在有序歧视任务中对婴儿进行了测试，使他们习惯于增加或减少时间持续时间的变化，然后用由新的时间项目组成的新序列进行测试，这些新的时间项目的持续时间根据熟悉的和新颖的顺序而变化。在三个实验中，我们操纵了单个时间项的持续时间，因此也操纵了整个序列的持续时间，这导致对婴儿的工作记忆或一般加工能力施加或多或少的约束。结果表明，当序列的总体持续时间较长时，婴儿无法区分时间序列中的顺序方向（实验1），但是当序列的持续时间缩短时，婴儿则能够成功（实验2和3）。而且，以前没有报道过数量和大小不对称的迹象，因为对习惯于递增和递减序列的婴儿存在成功的区分。这些结果表明，对时间顺序的敏感性在开发的早期就已经存在，并且其功能特性并未与其他量纲维度共享，