As originally proposed by Kenneth Deffenbacher, the optimality hypothesis states that the likelihood of obtaining statistically reliable positive correlations of witness confidence and accuracy varies directly with the degree of optimality of information-processing conditions present for the witness at stimulus encoding, [Page 531]during memory storage (retention interval), and at memory test. The more nearly ideal the processing conditions are for witnesses, the more they should be able to track accurately the adequacy of their memory performance in overtly expressed confidence ratings. The context in which the optimality hypothesis was proposed is discussed next.

By the end of the first decade of the modern resurgence of interest in conducting research concerned with the psychology of testimony, several dozen studies had accumulated wherein both witness accuracy and confidence ...