How much does a shared name make things similar? Part 1. Linguistic labels and the development of similarity judgment.

Most theoretical proposals considering effects of language on similarity assume that labels affect similarity in a qualitative all-or-nothing manner. This article proposes another theoretical alternative--a model of the label as a discrete attribute of an object. According to this model, the relative weight of labels decreases with the child's age. Predictions derived from the model were tested in 3 experiments. In these experiments, children aged 6-12 years were presented with triads of schematic faces and were asked to make similarity judgments. Similarity of faces within the triads was manipulated via systematic variation of distinct facial features. It was found that (a) labels contribute to similarity judgment in a quantifiable manner, (b) labels' weight decreased with age, and (c) effects of labels are likely to stem from the cross-modality of labels. These results are discussed in relation to theories of development of categorization.