Human Development and Family Studies, The Pennsylvania State University, Brandywine Campus, Media, PA 19063, USA.
J Exp Child Psychol. 2012 Nov;113(3):322-36. doi: 10.1016/j.jecp.2012.07.005. Epub 2012 Aug 26.
Accurate representation of a changing environment requires individuation-the ability to determine how many numerically distinct objects are present in a scene. Much research has characterized early individuation abilities by identifying which object features infants can use to individuate throughout development. However, despite the fact that without memory featural individuation would be impossible, little is known about how memory constrains object individuation. Here, we investigated infants' ability to individuate multiple objects at once and asked whether individuation performance changes as a function of memory load. In three experiments, 18-month-old infants saw one, two, or three objects hidden and always saw the correct number of objects retrieved. On some trials, one or more of these objects surreptitiously switched identity prior to retrieval. We asked whether infants would use this identity mismatch to individuate and, hence, continue searching for the missing object(s). We found that infants were less likely to individuate objects as memory load grew, but that infants individuated more successfully when the featural contrast between the hidden and retrieved objects increased. These results suggest that remembering more objects may result in a loss of representational precision, thereby decreasing the likelihood of successful individuation. We close by discussing possible links between our results and findings from adult working memory.
准确地描述不断变化的环境需要个体化能力——即确定场景中存在多少数量上不同的物体的能力。许多研究通过确定婴儿在整个发展过程中可以使用哪些物体特征来区分个体，从而描述了早期的个体化能力。然而，尽管没有记忆，特征个体化是不可能的，但人们对记忆如何限制物体个体化知之甚少。在这里，我们研究了婴儿同时区分多个物体的能力，并询问个体识别表现是否随记忆负荷而变化。在三个实验中，18 个月大的婴儿看到一个、两个或三个物体被隐藏，并总是看到正确数量的物体被取回。在一些试验中，一个或多个这些物体在取回之前偷偷地改变了身份。我们询问婴儿是否会利用这种身份不匹配来区分物体，从而继续寻找丢失的物体。我们发现，随着记忆负荷的增加，婴儿区分物体的可能性降低，但当隐藏和取回的物体之间的特征对比增加时，婴儿的区分就更成功。这些结果表明，记住更多的物体可能会导致表示精度的损失，从而降低成功个体化的可能性。最后，我们讨论了我们的结果与成人工作记忆研究结果之间的可能联系。
