Investigations of Hypesthesia: Using Anesthetics to Explore Relationships between Consciousness, Learning, and Memory

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 (e.g., Caseley-Rondi, 1996) 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.     

And one more for the road: Commentary on the Special Issue on alcohol and eyewitness memory

Studies examining the influence of alcohol intoxication have reported mixed findings on whether it impairs eyewitness memory. Although the studies in this Special Issue investigated different questions and tested different variables, the findings of these studies collectively provide insight into mechanisms and methodological issues that may explain the ambiguous findings of alcohol intoxication and eyewitness memory. In this commentary, we first describe the experimental studies of this Special Issue. We then discuss four mechanisms that could underlie those mixed findings (alcohol myopia, disinhibition, hypervigilance, and metacognitive processes at retrieval). Last, we address methodological issues that may have contributed to those ambiguous findings (i.e., alcohol intoxication levels, automatic processing of stimuli, sensitivity of dependent variables, and possible interactions with arousal) and provide suggestions for future research to address these issues.     

Postoperative Cognitive Dysfunction Versus Complaints: A Discrepancy in Long-Term Findings

This review describes the discrepancy in findings between postoperative cognitive performance and postoperative cognitive complaints long time after an operation under general anesthesia. Shortly (from 6 hr to 1 week) after an operation a decline in cognitive performance is reported in most studies. However, long time (from 3 weeks to 1–2 years) after an operation this is rarely found although some patients are still reporting cognitive complaints. In general this kind of research is suffering from severe methodological problems (use of insensitive tests, lack of control groups, lack of parallel tests, different definitions of cognitive decline). However, these problems cannot totally explain the discrepancy in findings in the long term. Thus, there are patients who have persistent cognitive complaints long time after an operation, that cannot be measured with cognitive tests. More psychological factors such as fixation on short-term cognitive dysfunction, mood, coping style, and personality are possible explanations for these cognitive complaints in the long term. As a consequence, these factors should be a topic in future research elucidating the persistence of these cognitive complaints long time after an operation under general anesthesia.     

Adults also have difficulty recalling one instance of a repeated event

Some forms of abuse, such as domestic violence, tend to occur repeatedly. Although memory for repeated events has received considerable empirical attention, most of this research has used a child sample. Experiments that have examined adult repeated‐event memory tend to use vastly different methodological paradigms to that used for children. To investigate whether the same pattern of findings emerge with young adults, we adapted the methodological paradigm used in child repeated‐event experiments. In this experiment, 41 undergraduate students experienced one, or multiple similar events. All participants were then interviewed about the same event. Participants who had experienced a single‐event were more likely to report correct details than those who had experienced a repeated event. Repeated‐event participants were more likely to report general details. These results have implications for the methodological paradigm which is used to examine adult memory for a recurring event.     

Problem Solving and Suicidal Behavior

Research on suicidal behavior falls into two main areas: studies that aim to identify demographic and social risk factors, and studies that aim to investigate the psychological processes mediating suicidal behavior. Within the latter approach, impaired problem-solving ability has been found to be an important variable. This paper reviews recent research focusing on problem-solving deficits and their relation to suicidal behavior and considers some of the methodological problems that arise. These findings are discussed in terms of active versus passive problem solving, state or trait factors, and the psychological processes underlying problem solving. Suggestions for further research are made, focusing on the links between suicidal behavior, problem solving, and autobiographical memory.     

Frontal-Lobe Involvement in Spatial Memory: Evidence from PET,fMRI, and Lesion Studies

Many studies have identified the prefrontal cortex as the brain area that is critical for spatial memory, both in humans and in other primates. Other studies, however, have failed to establish this relation. Therefore, the aim of this paper was to review the literature regarding the role of the human prefrontal lobe in spatial memory. This was done by examining the evidence obtained from neuropsychological patients and from studies using brain-imaging techniques (PET and fMRI). Evidence supporting the notion that the prefrontal cortex is extensively involved in spatial working memory was found. The majority of these studies, however, suggests that frontal-lobe involvement is not related to the type of material that is being processed (e.g., spatial vs. nonspatial), but to process-specific functions, such as encoding and retrieval. Theoretically, these functions could be linked to the central executive within Baddeley's working-memory model, or to recent theories that emphasize the various processes that play a role in working memory. Also, methodological issues were discussed. Further research is needed to enhance our understanding of the precise interaction of domain-specific and general processes.     

Memory for Unconsciously Perceived Events: Evidence from Anesthetized Patients

Studies investigating memory for events during anesthesia show a confusing pattern of positive and negative results. To establish whether there are any consistent patterns of findings across studies, we conducted a meta-analysis of the data from 2517 patients in 44 studies. The meta-analysis included two measures of the effects of positive suggestions on postoperative recovery: (a) the duration of postoperative hospitalization and (b) the amount of morphine administered via patient-controlled anesthesia, as well as two measures of memory for specific information presented during anesthesia: (c) direct tests and (d) indirect tests. The meta-analysis indicated that positive suggestions presented during anesthesia have little or no effect on postoperative recovery. On the other hand, the meta-analysis showed that specific information is remembered following surgery, as long as testing is not delayed longer than 36 h. Studies of memory for events during anesthesia provide a useful avenue for exploring unconscious cognition.     

Similarities and differences between traumatic and emotional memories: review and directions for future research

The authors review theory and empirical research on the characteristics of memories for traumatic versus emotional events, with the goal of bringing together the cognitive and clinical perspectives on this issue. They consider the most important approaches to the study of traumatic and emotional memory and summarize the results of recent studies that have compared autobiographical recollections of traumatic and nontraumatic emotional experiences (positive and negative), either in nonclinical or clinical samples. Overall, findings from the current empirical literature are inconsistent. Although some researchers have found that traumatic memories are retrieved differently than are emotional memories, others have demonstrated that the phenomenological characteristics of these memory types are highly similar. The authors discuss methodological issues that could help researchers to interpret the inconsistencies found in the empirical findings. Last, they suggest possible directions for future research that may advance researchers' knowledge of memory, trauma, and emotion.     

The effect of midazolam on implicit memory tests

Substantial empirical evidence exists suggesting that there are distinct forms of explicit and implicit memory. However, methodological problems have hampered attempts to identify the nature of the information processing underlying these forms of memory. These problems include the contamination of performance on implicit memory tests by explicit memory processes, as well as a host of difficulties inherent in correlational approaches that involve amnesiac subjects. In this paper we attempt to explore whether midazolam, a benzodiazepine used in surgical anesthesia, might be useful for studying implicit memory. Specifically, we attempt to determine whether midazolam produces selective effects on explicit, as opposed to implicit, memory. We focus on midazolam because of prior studies demonstrating that benzodiazepines do not affect implicit memory and because its rapid pharmacokinetics ensure that sedative effects are minimized when testing occurs at relatively short retention intervals. The results of an experiment using free recall, fragment completion and perceptual identification tests suggest that midazolam diminishes memory in implicit and explicit memory tests, although the diminution is proportionally larger in explicit memory. These results constrain the inferences that may be drawn when midazolam is used to explore implicit memory.     

Effects and mechanisms of working memory training: a review

Can cognitive abilities such as reasoning be improved through working memory training? This question is still highly controversial, with prior studies providing contradictory findings. The lack of theory-driven, systematic approaches and (occasionally serious) methodological shortcomings complicates this debate even more. This review suggests two general mechanisms mediating transfer effects that are (or are not) observed after working memory training: enhanced working memory capacity, enabling people to hold more items in working memory than before training, or enhanced efficiency using the working memory capacity available (e.g., using chunking strategies to remember more items correctly). We then highlight multiple factors that could influence these mechanisms of transfer and thus the success of training interventions. These factors include (1) the nature of the training regime (i.e., intensity, duration, and adaptivity of the training tasks) and, with it, the magnitude of improvements during training, and (2) individual differences in age, cognitive abilities, biological factors, and motivational and personality factors. Finally, we summarize the findings revealed by existing training studies for each of these factors, and thereby present a roadmap for accumulating further empirical evidence regarding the efficacy of working memory training in a systematic way.     

Episodic remembering creates access to involuntary conscious memory: Demonstrating involuntary recall on a voluntary recall task

The idea that involuntary memory retrieval might occur during voluntary memory retrieval can be traced back to Ebbinghaus (1885/1964). However, methodological challenges have stood in the way of testing this idea. Recent diary studies of naturally occurring involuntary memories have provided insights into how this idea could be tested (Berntsen, 1998; Mace, 2005b, 2006). These studies have shown that the contents of an involuntary memory sometimes trigger additional involuntary memories, a process called chaining. It was hypothesised that chaining should also occur on autobiographical memory tasks, and this was tested in the present study by asking participants in an autobiographical memory task to report the presence of involuntary memories while they were performing the task. The results showed that involuntary memories did occur when participants were recalling the past. The results also showed involuntary memories dissociating from voluntary memories on two independent measures, thereby enhancing the credibility of the results.     

Episodic remembering creates access to involuntary conscious memory: demonstrating involuntary recall on a voluntary recall task

The idea that involuntary memory retrieval might occur during voluntary memory retrieval can be traced back to Ebbinghaus (1885/1964). However, methodological challenges have stood in the way of testing this idea. Recent diary studies of naturally occurring involuntary memories have provided insights into how this idea could be tested (Berntsen, 1998; Mace, 2005b, 2006). These studies have shown that the contents of an involuntary memory sometimes trigger additional involuntary memories, a process called chaining. It was hypothesised that chaining should also occur on autobiographical memory tasks, and this was tested in the present study by asking participants in an autobiographical memory task to report the presence of involuntary memories while they were performing the task. The results showed that involuntary memories did occur when participants were recalling the past. The results also showed involuntary memories dissociating from voluntary memories on two independent measures, thereby enhancing the credibility of the results.     

Functional Neuroimaging Studies of Cognitive Recovery After Acquired Brain Damage in Adults

The first two decades of cognitive neuroimaging research have provided a constant increase of the knowledge about the neural organization of cognitive processes. Many cognitive functions (e.g.working memory) can now be associated with particular neural structures, and ongoing research promises to clarify this picture further, providing a new mapping between cognitive and neural function. The main goal of this paper is to outline conceptual issues that are particularly important in the context of imaging changes in neural function through recovery process. This review focuses primarily on studies made in stroke and traumatic brain injury patients, but most of the issues raised here are also relevant to studies using other acquired brain damages. Finally, we summarize aset of methodological issues related to functional neuroimaging that are relevant for the study ofneural plasticity and recovery after rehabilitation. Deceased     

Agoraphobia: a critical review of methodology in behavioural treatment research

This review focuses on the methodological status of the literature on behavioural treatment of agoraphobia. Thirty-three studies published between 1963 and 1979 are analysed using a methodological rating scale by which each study is assessed on the extent to which it meets eight basic criteria for outcome research. It is concluded that methodological weaknesses in these reports make questionable any general conclusions about the value of the behavioural treatment of agoraphobia, and recommendations are made concerning possible changes in the future direction of research in this area.     

Information processing during general anesthesia: Evidence for unconscious memory

Memory for words presented during general anesthesia was studied in two experiments. In Experiment 1, surgical patients (n=80) undergoing elective procedures under general anesthesia were presented shortly before and during surgery with words via headphones. At the earliest convenient time after surgery (within 5 h) and 24 h later, memory was tested by asking patients to complete auditorily presented word stems with the first word that came to mind and to leave out words they remembered having heard earlier (exclusion task). Moreover, patients were requested to perform a “yes/no” forcedchoice recognition task to assess recognition memory for both the pre- and intraoperative words. Memory for the material presented during anesthesia was demonstrated immediately after surgery and 24 h later by means of both tasks. In a second similar experiment (n=80), the results were replicated. These findings show that anesthetized patients can process information that was presented intraoperatively.     

A starting point for consciousness research: Reply to Thomas Schmidt

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 (if not absent) 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.     

Contributions of survey research to the understanding of memory

This article reviews the results of survey methodological research that illustrate phenomena of potential interest to investigators of memory, and also reviews psychological research designed to explore some of these phenomena under controlled laboratory conditions. We classify the phenomena reviewed into broad categories of remembering what events occurred, remembering when events occurred, and estimation and reconstruction processes used in reporting recurring events. We delineate the contributions of this research for our understanding of memory phenomena and show where this research has revealed gaps in our existing theories and knowledge. These findings present challenges for future collaboration between cognitive psychologists and survey methodologists.     

How effective is workplace counselling? A review of the research literature

The provision of counselling for work‐related problems has expanded in recent years, as organisations have recognised the value of this approach to staff support. However, there has been relatively little research into the outcomes of workplace counselling, and no systematic reviews have been conducted into the effectiveness of counselling in this setting. This paper presents the results of a preliminary review of evidence in this area. 34 studies of the effectiveness of workplace counselling were identified, of which 16 were sufficiently well designed to be considered as comprising reliable findings. The results of these studies suggest that, in general, workplace counselling is effective for clients for a wide variety of type and severity of presenting problems, employed across a range of different organisational contexts. The paper includes discussion of methodological issues associated with this research, recommendations for further research, and implications for practice.     

Are self reports of memory failure accurate?

Previous research with memory questionnaires has been interpreted as showing that people do not recall their memory failures accurately. The present research consisted of three investigations that examined whether participants' reports of memory failures were corroborated by their spouses. These investigations used a greater variety of statistical and survey methods than were used in previous investigations. The results demonstrated that people are able to recall memory failures more accurately than previous research indicated. These results have important methodological and theoretical implications for basic and applied assumptions about what people know about their memory failures. Copyright © 2005 John Wiley & Sons, Ltd.