Eyeblink classical conditioning and awareness revisited

Dual-task performance was assessed in 140 adults during eyeblink classical conditioning (EBCC) and one of several secondary tasks (timed-interval tapping, recognition memory, choice reaction time, video viewing). Four groups received paired-EBCC stimulus presentation, and three groups received explicitly unpaired EBCC stimuli. Although the subjects were not told about the conditioning task, they acquired conditioned responses (CRs) at normal levels. Postsession interviews probed participants' awareness of EBCC stimulus contingencies and production of CRs. Reported awareness of paired-EBCC stimulus contingencies and CR production was not related to actual EBCC performance. Twenty-seven percent of the participants receiving explicitly unpaired stimuli reported a stimulus contingency when none existed. The dissociation between awareness and performance provides additional support for the categorization of simple EBCC as a form of nondeclarative learning.