Parallel acquisition of awareness and differential delay eyeblink conditioning

Abstract

There is considerable debate about whether differential delay eyeblink conditioning can be acquired without awareness of the stimulus contingencies. Previous investigations of the relationship between differential-delay eyeblink conditioning and awareness of the stimulus contingencies have assessed awareness after the conditioning session was finished using a post-experimental questionnaire. In two experiments, the point at which contingency awareness developed during the conditioning session was estimated from a button-press measure of expectancy of the unconditioned stimulus (US). In both experiments, knowledge of the stimulus contingencies and acquisition of differential delay eyeblink conditioning developed approximately in parallel. In Experiment 1 it was shown that predicting the US facilitated eyeblink conditioning compared with predicting the eyeblink response. In Experiment 2, a masking task was used that slowed down the emergence of awareness, and it was shown that differential conditioning only occurred in participants who were able to predict the US. The current findings challenge the hypothesis that differential delay eyeblink conditioning is entirely mediated by a functionally and neurally distinct nondeclarative learning system.

Awareness is essential for differential delay eyeblink conditioning with soft-tone but not loud-tone conditioned stimuli

“…Our fi nding that differential DEC with a loud-tone CS did not depend on awareness differs from the results of two recent studies [13,22] with the same loud-tone CS, in which differential DEC was reported to be awareness-dependent.…”

“…Another possible factor is that the pressure of the air-puff in these two studies was higher than that in our study (15 psi [13,22] vs 5 psi). Indeed, some recent studies on animals have shown that TEC is affected more by lesions of the mPFC when a relatively non-aversive airpuff, rather than an aversive periorbital shock, is used as the US [41][42][43] , implying that the intensity of the US may be an important factor affecting the results in differential DEC studies.…”

“…Previous studies [12,[19][20][21] have shown that differential DEC only appears in participants who know the relationship between the CSs and the US, which is consistent with the latter view that DEC is awareness-dependent. Similarly, two recent reports [13,22] also reached the same conclusions. Thus, all these studies in favor of the latter view are opposed to the conclusions of Clark and Squire [11] .…”

“…Lovibond et al [13] used two questionnaires, a long one, based on Clark and Squire (1998) [11] , and a short one, based on the recommendations of Dawson and Reardon (1973) [40] . In addition, Weidemann et al [22] used a button-press measure of expectancy of the US rather than the long questionnaire, whereas the participants in our study were only given the long questionnaire based on Clark and Squire (1998) [11] .…”

The role of contingency awareness in single-cue human eyeblink conditioning

“…Squire (1998, 1999) and Smith et al (2005) interpreted this pattern, together with relevant animal and human neural evidence, to mean that delay eyeblink conditioning is a form of unconscious nondeclarative memory carried out by a subcortical circuit involving the cerebellum and brainstem. By contrast, they argued that the temporal gap in trace conditioning means that it cannot be learned by the nondeclarative system; instead, it is processed by the conscious declarative memory system, which involves the hippocampus and medial temporal lobe.Although the data from Squire's group are striking, the same results have not typically been obtained by other groups, who find, instead, that both delay and trace conditioning are restricted to participants classified as contingency aware (Nelson and Ross 1974;Perry et al 1977;Benish and Grant 1980;Knuttinen et al 2001;Lovibond et al 2011;Weidemann and Antees 2012). In response to these disparate results, Manns et al (2002) have argued that differential eyeblink conditioning, even with a delay procedure, might sometimes require involvement of the declarative hippocampal system.…”