General anesthesia provides an alternative to typical laboratory paradigms for investigating implicit learning. We assess the evidence that a simple type of learning—priming—can occur without consciousness. Although priming has been shown to be a small but persistent phenomenon in surgical patients there is reason to question whether it occurs implicitly due to problems in detecting awareness using typical clinical signs. This paper reviews the published studies on priming during anesthesia that have included a measure of awareness or of anesthetic depth. (...) We conclude that perceptual priming, but not conceptual priming, takes place in the absence of conscious awareness. (shrink)

This paper discusses the ways in which anesthetic agents can be used to investigate the role of awareness in learning and memory. It reviews research into learning during light, subclinical anesthesia, termedhypesthesia.This research suggests that the effects of anesthetics on implicit and explicit memory are roughly comparable, although implicit memory for simple stimuli may resist the effects of very low doses of anesthetic. In addition, this paper reports experimental data demonstrating that long-term retention of information is prevented by doses of (...) anesthetic that are low enough to permit awareness and even short-term memory of auditory stimuli. Overall, these findings are consistent with the hypothesis that frontal lobe function is particularly sensitive to anesthetics. They raise theoretical and practical questions about the necessity of consciousness for learning and about interpretation of the evidence for learning during surgery under general anesthesia. (shrink)

The elaborated intrusion (EI) theory of desire (Kavanagh, Andrade, & May, 2005) attributes the motivational force of cravings to cognitive elaboration, including imagery, of apparently spontaneous thoughts that intrude into awareness. We report a questionnaire study in which respondents rated a craving for food or drink. Questionnaire items derived from EI theory formed a single factor alongside factors for anticipated reward/relief, resistance, and opportunity. In a multiple regression predicting strength of craving, the first three factors accounted for 36% of the (...) variance. Opportunity did not enter the model. In a second study, the difference between individuals' strong and weak cravings to take part in a sporting activity was shown to be related to visual, auditory, and general imagery, and to anticipated reward or relief from engaging in the activity. Implications for treatment of craving-related disorders are discussed in the light of these results and of other research indicating that interference with imagery can reduce the strength of craving. (shrink)

In this book, experienced researchers in the field address the question: Will the model survive these challenges?

This paper explores the changes in cognitive function which occur as someone "loses consciousness" under anesthesia. Seven volunteers attempted a categorization task and a within-list recognition test while inhaling air, 0.2% isoflurane, and 0.4% isoflurane. In general, performance on these tests declined as the dose of anesthetic was increased and returned to baseline after 10 min of breathing air. A measure of auditory evoked responding termed "coherent frequency" showed parallel changes. At 0.2% isoflurane, subjects could still identify and respond to (...) category exemplars but showed impaired short-term memory function. Electrical stimulation at 0.4% isoflurane, intended to mimic the arousing effects of surgery, had a small, beneficial effect on performance. A mean of 63% of category exemplars was identified at this stage, but recognition memory for those exemplars was at chance on recovery. There was no evidence for learning of words presented at 0.8% isoflurane. (shrink)

Anesthesia research has focused on showing learning in the absence of awareness for good practical reasons. Crucially, continued learning during otherwise clinically adequate anesthesia may affect patients’ well-being on recovery. Theoretically, preserved perceptual priming during anesthesia offers a useful starting point for consciousness research by determining the limits of memory function during minimal consciousness. The big question for consciousness research is not to demonstrate absolutely unconscious processing, but rather to map out the cognitive and neurobiological processes that enable conscious experience (...) itself. (shrink)