or each participant. Using these data the probabilities of every possible pair of images being grouped together were calculated. The groups of images consistently reported by the participants were identified using a principle components analysis (PCA) of the probabilities associated with each pairing (N=2,346). PCA was used as a data reduction technique to generate variables (components) explaining variance in the probability of images being grouped together (affinity). To ease interpretation, theresults were limited to the first two components and graphed. Figure 1 displays the final scatter plot graph of each image using the values of the first two components (factor loadings) as measures of affinity.