Lovibond, P. F., & Shanks, D. R. (2002). The role of awareness in Pavlovian conditioning: Empirical evidence and theoretical implications. Journal of Experimental Psychology-Animal Behavior Processes, 28(1), 3-26.

This article reviews research over the past decade concerning the relationship between Pavlovian conditioning and conscious awareness. The review covers autonomic conditioning, conditioning with subliminal stimuli, eyeblink conditioning, conditioning in amnesia, evaluative conditioning, and conditioning under anesthesia. The bulk of the evidence is consistent with the position that awareness is necessary but not sufficient for conditioned performance, although studies suggestive of conditioning without awareness are identified as worthy of further investigation. Many studies have used inadequate measures of awareness, and strategies for increasing validity and sensitivity are discussed. It is concluded that conditioning may depend on the operation of a propositional system associated with consciousness rather than a separate, lower level system.

Manns, J. R., Clark, R. E., & Squire, L. R. (2002). Standard delay eyeblink classical conditioning is independent of awareness. Journal of Experimental Psychology-Animal Behavior Processes, 28(1), 32-37.

P. F. Lovibond and D. R. Shanks (2002) suggested that all forms of classical conditioning depend on awareness of the stimulus contingencies. This article considers the available data for eyeblink classical conditioning, including data from 2 studies (R. E. Clark, J. R. Matins, & L. R. Squire, 200 1; J. R. Manns, R. E. Clark, & L. R. Squire, 2001) that were completed too recently to have been considered in their review. In addition, in response to questions raised by P. F. Lovibond and D. R. Shanks, 2 new analyses of data are presented from studies published previously. The available data from humans and experimental animals provide strong evidence that delay eyeblink classical conditioning (but not trace eyeblink classical conditioning) can be acquired and retained independently of the forebrain and independently of awareness. This conclusion applies to standard conditioning paradigms; for example, to single-cue delay conditioning when a tone is used as the conditioned stimulus (CS) and to differential delay conditioning when the positive and negative conditioned stimuli (CS+ and CS-) are a tone and white noise.