Their colleague Robert Kurzban designed an experiment whose results appeared to support this hypothesis. Using the memory confusion protocol, they presented subjects with pictures of individuals and sentences, allegedly spoken by these individuals, which presented two sides of a debate. The errors that the subjects made in recalling who said what indicated that they sometimes mis-attributed a statement to a speaker of the same race as the "correct" speaker, although they also sometimes mis-attributed a statement to a speaker "on the same side" as the "correct" speaker. In a second run of the experiment, the team also distinguished the "sides" in the debate by clothing of similar colors; and in this case the effect of racial similarity in causing mistakes almost vanished, being replaced by the color of their clothing. In other words, the first group of subjects, with no clues from clothing, used race as a visual guide to guessing who was on which side of the debate; the second group of subjects used the clothing color as their main visual clue, and the effect of race became very small.