The specific objectives are: a) to determine the degree of objective correlations between cues necessary for subjects to detect reliably that the cues are correlated; b) to determine the degree of difference between objective correlations between cues necessary for subjects to discriminate reliably between those correlations; c) to gather some information concerning useful methods of presenting correlated cues; and d) to gather some validation data on a simple method of measuring subjective correlation. The experiments will employ the methodology of contemporary psychophysics, specifically the yes-no and forced choice methods of TSD. The results of this primarily methodological research are expected to be of especial interest to investigators doing MCPL research.