Frequency plot for the first response in a 4-item list, as a function of the stimulus rank in each of the psychophysical dimensions during Experimental Phase 1. In each plot, responses falling between the dashed lines are correct responses, and all others are incorrect. Responses falling between the dotted lines are those that are ranked first according to the distractor dimension. In Experimental Phase 1, subjects consistent restricted most of their responses to within the black dashed lines, but nevertheless displayed some interference from the distractor dimension