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PubMed1993

Eliciting cryptomnesia: unconscious plagiarism in a puzzle task.

In three experiments we investigated cryptomnesia (unconscious plagiarism) and source memory using a word-search puzzle task. Subjects first alternated with a "computer partner" in locating words from 4 puzzles. They then attempted to recall their previously generated items as well as to locate additional new words. Substantially more plagiarism was committed in these tasks than was observed in a study by A. S. Brown and D. R. Murphy (1989), in which Ss generated category exemplars. Manipulations of retention interval (Experiment 1) and degree of encoding (Experiments 2a and 2b) reliably influenced plagiarism rates. Source confusions from a modified recognition memory task (Experiment 3) were used as the basis for a unitary relative strength model to explain both source and occurrence (item) forgetting.

Adult↗
PubMed2003

Evaluation of six multinomial models of conscious and unconscious processes with the recall-recognition paradigm.

Six multinomial processing-tree models (W. H. Batchelder & D. M. Riefer, 1999), which include parameters representing conscious and unconscious memory processes, were tested using the recall-recognition paradigm. Data from 2 experiments were fit equally well by 3 of the 6 models. One model recognition was an extension of the generate-recognize model (L. L. Jacoby, 1998), and another was an extension of the non-high-threshold model (D. M. McBride & B. A. Dosher, 1999). The 3rd model was the source evaluation model (D. M. McBride & B. A. Dosher, 1999). Values of the parameters of 2 of these 3 models, excepting the non-high-threshold model, responded to experimental manipulations in accordance with the meaning of the parameters. The equivalence of models with regard to goodness-of-fit tests is discussed as is how experiments can be designed to demonstrate the superiority of one model over another. The potential usefulness of these models in the study of amnesia is considered.

Attention↗
PubMed1998

Imaging unconscious semantic priming.

Visual words that are masked and presented so briefly that they cannot be seen may nevertheless facilitate the subsequent processing of related words, a phenomenon called masked priming. It has been debated whether masked primes can activate cognitive processes without gaining access to consciousness. Here we use a combination of behavioural and brain-imaging techniques to estimate the depth of processing of masked numerical primes. Our results indicate that masked stimuli have a measurable influence on electrical and haemodynamic measures of brain activity. When subjects engage in an overt semantic comparison task with a clearly visible target numeral, measures of covert motor activity indicate that they also unconsciously apply the task instructions to an unseen masked numeral. A stream of perceptual, semantic and motor processes can therefore occur without awareness.

Adult↗
PubMed2001

Sudden unconsciousness during a lesser occipital nerve block in a patient with the occipital bone defect.

Occipital nerve block is usually considered to be a very simple and safe regional anaesthetic technique. We describe a case of sudden unconsciousness during a lesser occipital nerve block in a patient with an occipital bone defect. A 63-year-old man complained of headache, which was localized to the right occipital region. A right lesser occipital nerve block with a local anaesthetic was performed for treatment. During the lesser occipital nerve block, the patient suddenly became disturbed and lost consciousness. Two hours after the incident, the patient was fully awake without neurological sequelae. He had previously undergone a microvascular decompression for right trigeminal neuralgia. The patient had a bone defect following craniotomy. We believed that the loss of consciousness during lesser nerve block may be due to a subarachnoid injection. Occipital nerve block is relatively contraindicated in the presence of a bone defect.

Anesthetics, Local↗
PubMed2002

Unconscious sedation in children: a prospective multi-arm clinical trial.

BACKGROUND: We report the evaluation of six sedative-hypnotic and analgesic combinations administered to children undergoing brief periods of unconscious (or deep) sedation for painful procedures. METHODS: In a prospective, open-label, randomized, controlled study of six groups of 27-30 children each, patients were randomly assigned to receive propofol or methohexital for sedation-hypnosis, and one of three incremental doses of fentanyl or remifentanil, respectively. RESULTS: An infusion of methohexital (10 mg.ml-1) combined with remifentanil (6.67 micro g.ml-1) provided significantly shorter geometric mean times to initial emergence, to eye-opening and to discharge, and required airway interventions that were not significantly more frequent than all groups sedated with propofol and fentanyl. CONCLUSIONS: The combination of methohexital and remifentanil appears to be a satisfactory method for unconcious sedation for short painful procedures in children.

Anesthesia Recovery Period↗
PubMed1995

Parameters affecting conscious versus unconscious visual discrimination with damage to the visual cortex (V1).

When the visual (striate) cortex (V1) is damaged in human subjects, cortical blindness results in the contralateral visual half field. Nevertheless, under some experimental conditions, subjects demonstrate a capacity to make visual discriminations in the blind hemifield (blindsight), even though they have no phenomenal experience of seeing. This capacity must, therefore, be mediated by parallel projections to other brain areas. It is also the case that some subjects have conscious residual vision in response to fast moving stimuli or sudden changes in light flux level presented to the blind hemifield, characterized by a contentless kind of awareness, a feeling of something happening, albeit not normal seeing. The relationship between these two modes of discrimination has never been studied systematically. We examine, in the same experiment, both the unconscious discrimination and the conscious visual awareness of moving stimuli in a subject with unilateral damage to V1. The results demonstrate an excellent capacity to discriminate motion direction and orientation in the absence of acknowledged perceptual awareness. Discrimination of the stimulus parameters for acknowledged awareness apparently follows a different functional relationship with respect to stimulus speed, displacement, and stimulus contrast. As performance in the two modes can be quantitatively matched, the findings suggest that it should be possible to image brain activity and to identify the active areas involved in the same subject performing the same discrimination task, both with and without conscious awareness, and hence to determine whether any structures contribute uniquely to conscious perception.

Adult↗
PubMed2005

Unconscious operant conditioning in the paradigm of brain-computer interface based on color perception.

This study investigate the mutual fine-tuning of ongoing EEG rhythmic features with RGB values controlling color shades of computer screen during neuro-feedback training. Fifteen participants had not been informed about the existence of neurofeedback loop (NF), but were guided only to look at the computer screen. It was found that during such unconscious NF training, a variety of color shades on the screen gradually changed from rather various types to the main one within the framework of color palette specified for each individual. This phenomenon was not observed in control experiments with simulated neuro-feedback. Individual color patterns induced on the screen during NF did not depend on the schema of connection between of EEG rhythms and RGB controller. It is suggested that the basic neurophysiological mechanism of described NF training consists of the directed selection of EEG patterns reinforced by comfortable color shades without conscious control.

Adult↗
PubMed1984

Possible unconscious significance of the positions of the analysand and analyst in psychoanalysis.

When Freud chose to have his patients lie on a couch and seated himself at their head out of sight, none of these procedures were without precedents in the medical culture of his day. The recumbent position was standard for the examination of the abdomen and for many surgical procedures. Sitting at the patient's head was routine for the anesthetist. Being out of the patient's sight was necessary for the examination of the lungs and spine (not to mention the Roman Catholic confession box). Yet, the combination of these three factors was unique and was quickly recognized as a hallmark of psychoanalysis. It is remarkable that relatively little has been written concerning the symbolic meaning of the positions of the analysand and analyst considering that this is a daily feature of every analyst's work and that lying on the couch has become a vernacular equivalent for the psychoanalytic process itself. This paper is an attempt to examine some unconscious symbolic meanings of these positions, which may have been involved even before Freud's choice made them standard.

Fathers↗
PubMed2005

Children and young adults in a prolonged unconscious state due to severe brain injury: outcome after an early intensive neurorehabilitation programme.

PRIMARY OBJECTIVE: The Rehabilitation Centre Leijpark in The Netherlands provides an Early Intensive Neurorehabilitation Programme (EINP) to children and young adults in a prolonged unconscious state after severe brain injury. In an extensive research project the effects of EINP were studied. This part of the project focused on the outcome in terms of level of consciousness (LOC) in relation to the specific characteristics of a retrospectively studied cohort. RESEARCH DESIGN: This study was executed according to a one-group archived pre-test-post-test design. SUBJECTS: Subjects were all consecutively admitted patients (n=145, 72% male) between December 1987-January 2001. Inclusion criteria were: age 0-25 years, within 6 months after injury, LOC at admission vegetative state (VS) or minimally conscious state (MCS). One hundred and four patients (72%) suffered a traumatic injury and 41 patients (28%) a non-traumatic injury. METHODS AND PROCEDURES: All patients had received EINP until they reached consciousness or until it was concluded that no progress was achieved during 3 months after the start of EINP. Medical files were investigated to collect the patients' characteristics and injury data, to determine the LOC at admission and at discharge and to determine the discharge destination. RESULTS: Almost two-thirds of the patients reached full consciousness. LOC at admission, aetiology and interval since injury were found to be significant prognostic factors. Traumatic patients had a much better outcome than non-traumatic patients. A comparison with earlier outcome studies showed a more favourable outcome than expected. It is argued that a multi-centre study is needed to confirm possible effects of EINP.

Adolescent↗
PubMed2005

When elaboration leads to appropriation: unconscious plagiarism in a creative task.

Brown and Murphy's (1989) three-stage paradigm (generation, recall-own, generate-new) was used to assess the effects of participant elaboration on rates of unconscious plagiarism in two experiments using a creative task. Following the generation phase, participants imagined and rated a quarter of the ideas (imagery elaboration), generated improvements to another quarter (generative elaboration), and listened to a quarter of the ideas again without elaboration, with the remaining ideas acting as control. A week later, participants attempted to recall their own ideas, and generate new solutions to the same cues. In Experiment 1 both forms of elaboration equally increased correct recall, and decreased plagiarism in the generate-new task. However, generative elaboration led to significantly greater plagiarism in the recall-own task, but imagery elaboration did not. Participants in Experiment 2 were encouraged not to plagiarise by means of a financial incentive. However, they showed the same pattern as seen in Experiment 1. Therefore, contrary to a simple strength account, the probability of a person plagiarising another's ideas is linked to the particular nature of the elaboration carried out on that idea, rather than its familiarity.

Awareness↗
PubMed2006

Hemispheric asymmetries for the conscious and unconscious perception of emotional words.

The current research examines the interactions between hemispheric asymmetries for visual perception and emotion. In a series of four experiments, participants completed tasks measuring both conscious and unconscious perception of linguistic stimuli. In these studies, stimulus-presentation parameters (brief exposure duration vs masking) and the emotional valence of the test stimuli (negative vs positive) were manipulated in order to create studies in which the visual and emotional asymmetries were congruent (favoured the same hemispheres) or were incongruent (favoured opposing hemispheres). The results demonstrated that negative emotional stimuli led to a right-hemisphere advantage for conscious perception only when stimuli were shown for brief exposures (17 ms). Positive emotional words did not elicit hemispheric asymmetries. The results are discussed in terms of their relevance for theories of emotional lateralisation.

Affect↗
PubMed1995

Explicit memory and repetition priming in dementia: evidence for a common basic mechanism underlying conscious and unconscious retrieval deficits.

The present study was designed to assess performance of Alzheimer's (AD) and Multi-infarct (MID) demented patients on the explicit and implicit versions of two memory tasks, namely Word-Stem Completion and Word-Pair Learning. Consistently with previous studies, the AD patients were deficient on the explicit and implicit versions of both tasks. In MID patients, a dissociation emerged between normal implicit and deficient explicit Word-Stem Completion. Two multiple regression analyses were performed to evaluate patients' ability on measures of lexical-semantic competence, explicit memory, and global intellective efficiency in predicting level of repetition priming. The results demonstrate a close association between explicit and implicit memory performance in AD patients but no relation between repetition priming level and measures of lexical-semantic competence or general intelligence. Overall, the results of the present study do not support previous conceptualizations suggesting that a breakdown in the structure of semantic memory is at the root of deficient priming in demented patients. Alternative interpretations of the deficient repetition priming effect in dementia, based on a common mechanism underlying conscious and unconscious retrieval deficits, are discussed.

Aged↗
PubMed1994

Hyperventilation-induced unconsciousness during labour.

We report the development of unconsciousness caused by hyperventilation in an otherwise healthy woman in labour. Extradural analgesia resulted in restoration of full consciousness and normal respiratory state. The pathophysiology of hyperventilation and aspects of respiratory physiology in pregnancy are discussed.

Adult↗
PubMed2004

Unconscious auditory priming during surgery with propofol and nitrous oxide anaesthesia: a replication.

BACKGROUND: Priming during anaesthesia has been hard to replicate and the conditions under which it occurs remain poorly understood. We replicated and extended a recent study to determine whether intraoperative priming during propofol and nitrous oxide anaesthesia is a reliable phenomenon, whether it occurs due to awareness during word presentation and whether it is suppressed by a dose of fentanyl at induction. METHODS: Words were played through headphones during surgery to 62 patients receiving propofol and nitrous oxide anaesthesia. Thirty-two patients received fentanyl 1.5 microg kg(-1) at induction and 30 received no fentanyl. Neuromuscular blocking drugs were not used. Depth of anaesthesia was measured using the bispectral index (BIS). Anaesthetic variables were recorded at 1 min intervals during word presentation. On recovery, implicit and explicit memory were assessed using an auditory word-stem completion test and a yes-no word-recognition test, respectively. RESULTS: BIS, blood pressure, end-tidal carbon dioxide and heart rate during word presentation did not differ between the study groups. The infusion rate of propofol and the patients' ventilatory frequency were significantly higher in the group not receiving fentanyl. No patient had unprompted explicit recall of surgery, although there was above-zero performance in six patients on the yes-no recognition task (P<0.05). There was no physiological evidence of awareness during anaesthesia (median mean-BIS=38 in the no-fentanyl group and 42 in the fentanyl group). There was evidence for priming (mean priming score=0.09, P<0.05 in the no-fentanyl study group; mean priming score=0.07, P<0.05 in the fentanyl group) even when patients with momentary light anaesthesia (maximum recorded BIS> or =60) and/or positive recognition scores were excluded from the analysis. CONCLUSIONS: Existing knowledge can be primed by information presented during propofol and nitrous oxide anaesthesia. This priming is evidence of unconscious information processing and not the result of moments of awareness.

Acoustic Stimulation↗
PubMed1983

Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act.

The recordable cerebral activity (readiness-potential, RP) that precedes a freely voluntary, fully endogenous motor act was directly compared with the reportable time (W) for appearance of the subjective experience of 'wanting' or intending to act. The onset of cerebral activity clearly preceded by at least several hundred milliseconds the reported time of conscious intention to act. This relationship held even for those series (with 'type II' RPs) in which subjects reported that all of the 40 self-initiated movements in the series appeared 'spontaneously' and capriciously. Data were obtained in at least 6 different experimental sessions with each of 5 subjects. In series with type II RPs, onset of the main negative shift in each RP preceded the corresponding mean W value by an average of about 350 ms, and by a minimum of about 150 ms. In series with type I RPs, in which an experience of preplanning occurred in some of the 40 self-initiated acts, onset of RP preceded W by an average of about 800 ms (or by 500 ms, taking onset of RP at 90 per cent of its area). Reports of W time depended upon the subject's recall of the spatial 'clock-position' of a revolving spot at the time of his initial awareness of wanting or intending to move. Two different modes of recall produced similar values. Subjects distinguished awareness of wanting to move (W) from awareness of actually moving (M). W times were consistently and substantially negative to, in advance of, mean times reported for M and also those for S, the sensation elicited by a task-related skin stimulus delivered at irregular times that were unknown to the subject. It is concluded that cerebral initiation of a spontaneous, freely voluntary act can begin unconsciously, that is, before there is any (at least recallable) subjective awareness that a 'decision' to act has already been initiated cerebrally. This introduces certain constraints on the potentiality for conscious initiation and control of voluntary acts.

Adult↗
PubMed2001

The priming method: imaging unconscious repetition priming reveals an abstract representation of number in the parietal lobes.

Most of the current brain imaging methods are limited by the low spatial resolution of neuroimaging techniques and remain unable to measure activity at the scale of single neurons or small columns of neurons, which are the coding elements of the nervous system. In this work we have adapted the priming method, an emerging research strategy that can overcome some of these spatial limitations, to investigate the coding of numerical quantities in the human brain. This approach combines the logic of psychological priming experiments with the recently discovered neurophysiological phenomenon called repetition suppression (RS). In each trial, while subjects perform a constant task, a subliminal prime is presented prior to each target. By varying the relationship between prime and target, one can detect which brain areas present RS specifically for any given level of prime-target repetition. We first expose the general logic, potential and limitations of the priming method and then illustrate it by demonstrating that a region of parietal cortex is coding for numbers at the quantity level, independently of other stimulus attributes, and that this region processes both consciously and unconsciously perceived stimuli.

Adult↗
PubMed1982

Effects of stimulating psychodynamically relevant unconscious fantasies on schizophrenic psychopathology.

This article reviews a series of studies investigating the relationship between various unconscious fantasies and manifest pathology in adult schizophrenics. The results support the view that the activation of specific fantasies can lead to both the exacerbation and amelioration of symptoms in schizophrenia. The theoretical and clinical implications of the experimental findings are discussed, and suggestions for further research are offered.

Aggression↗