The spatial arrangement method of measuring similarity can capture high-dimensional, semantic structures

AbstractDespite its centrality to cognition, similarity is expensive to measure, spurring development of techniques like the Spatial Arrangement Method (SpAM), wherein participants place items on a 2-dimensional plane such that proximity reflects similarity. While SpAM hastens similarity measurement, its suitability for higher-dimensional stimuli is unknown. In Study 1, we collected SpAM data for eight different categories composed of 20-30 words each. Participant-aggregated SpAM distances correlated strongly (r=.71) with pairwise similarity judgments, although below SpAM and pairwise judgment split-half reliabilities (r’s>.9), and cross-validation with multidimensional scaling fits at increasing dimensionalities suggested that aggregated SpAM data favored higher dimensional solutions for 7 of the 8 categories. In study 2, we showed that SpAM can recover the Big Five factor space of personality traits, and that cross-validation favors a four- or five-dimension solution on this dataset. We conclude that SpAM is an accurate and reliable method of measuring similarity for high-dimensional items.

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