A more common experimental approach investigates the unique effects of archetypal images. An influential study of this type, by Rosen, Smith, Huston, & Gonzalez in 1991, found that people could better remember symbols paired with words representing their archetypal meaning. Using data from the Archive for Research in Archetypal Symbolism and a jury of evaluators, Rosen et al. developed an "Archetypal Symbol Inventory" listing symbols and one-word connotations. Many of these connotations were obscure to laypeople. For example, a picture of a diamond represented "self"; a square represented "Earth". They found that even when subjects did not consciously associate the word with the symbol, they were better able to remember the pairing of the symbol with its chosen word. Brown & Hannigan replicated this result in 2013, and expanded the study slightly to include tests in English and in Spanish of people who spoke both languages.