Abstract: L L. Jacoby's "process dissociation procedure" was used to quantitatively estimate the contributions of conscious and unconscious additive operations to performance on a forced choice task. The results showed:1.Sometimes subjects chose a target figure Which was the operational result and the choices were at a significantly above-baseline level, even if in the exclusion test condition, which undoubtedly provided a strong evidence for the existence of unconscious additive operations.2. Although LoP and PC influenced the estimation of value C, value U was left unchanged, which demonstrated that both LoP and PC were the important factors that could separate conscious and unconscious additive operations.

Key words: process dissociation procedure, forced choice testing method, additive operation, level of processing, peripheral cue