We found a matchYour institution may have access to this item. Find your institution then sign in to continue.TitleFive plus two equals yellow.AuthorsDixon MJ; Smilek D; Cudahy C; Merikle PMPublicationNature, 2000, Vol 406, Issue 6794, p365ISSN0028-0836Publication typearticleDOI10.1038/35019148