Comparison Dimensions and Similarity: Addressing Individual Heterogeneity

How many comparison dimensions do individuals consider when they are asked to make similarity judgments? I addressed individual heterogeneity in the number of comparison dimensions with data from a laboratory experiment. I used multidimensional scaling to estimate the number of dimensions on the individual level. I found that the number of dimensions varies across subjects and that the mean number of dimensions in real data is significantly lower than the mean number of dimensions in randomly simulated data. Moreover, I found that the number of dimensions is correlated with judgment time and with propensity to make nonmonotonic judgments. However, there is no direct relationship between the number of dimensions considered by participants and their perception of the average similarity between stimuli. In summary, I found evidence that indicates analytical similarity judgment based on a relatively low number of dimensions.