Monitoring frequency of occurrence without awareness: evidence from patients with Alzheimer''s disease

Mouse mammary tumor virus (MMTV) is a type B retrovirus that is transmitted as an infectious milk-borne particle and that causes mammary carcinomas by insertional activation of cellular protooncogenes. Germ line infections result in endogenous Mtv proviruses integrated in the genome of most mouse strains. These endogenous proviruses have been integrated into the genomes of mice for only the past 3-5 million years. The open reading frame present in the 3' long terminal repeat (LTR) of the provirus encodes a superantigen (SAg) which is able to stimulate a large proportion of T cells sharing a common T-cell receptor beta chain variable domain (v beta). Expression of this SAg is critical to the MMTV life cycle. After expression of the SAg in B cells a significant number of T cells are recruited to respond to these MMTV infected cells. As a consequence both the T cells expressing the relevant TCR V beta domain and the infected B cells become activated and start dividing. This would facilitate integration of MMTV and amplify the number of virus infected lymphocytes. Most likely during lactation the mammary glands become receptive to viral infection. The presence of endogenous Mtvs induces an early clonal deletion of reactive T cells. For this reason it has been argued that the presence of these proviruses confers a selective advantage to the mouse population by protecting the host from infection with an exogenous MMTV coding for a cross-reactive SAg. However, recent results discussed herein suggest that Mtv proviruses may also be detrimental to the mouse population by participating in recombinations with exogenous MMTVs, giving rise to highly tumorigenic recombinant particles. These results are discussed in the light of recent reports suggesting the involvement of viral sequences with a high homology to MMTV in human mammary tumorigenesis.     

Memory without awareness: Pigeons do not show metamemory in delayed matching to sample.

Metamemory, the ability to report on memory strength, is clearly established in rhesus macaques (Macaca mulatta) by converging evidence from several paradigms. In contrast, A. Inman and S. J. Shettleworth (1999) found no conclusive evidence of metamemory in pigeons. The authors studied pigeons further in 3 paradigms, with multiple tests of metamemory in each. Pigeons encountered a safe alternative to a matching-to-sample test either before (Experiment 2) or concurrently with (Experiment 3) the matching test. Choices of the safe option did not vary consistently with matching accuracy or change in trials with omitted samples in the way predicted for an animal with metamemory. In Experiment 4, confidence ratings following completion of the matching test also did not vary consistently as predicted by metamemory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Remembering without awareness.

Amnesics reveal savings in their objective performance of a task even though they are not aware of remembering. The authors review experiments that reveal a dissociation of memory and awareness for normals as well as amnesics. The episodic–semantic memory distinction has been employed by others as an account of the dissociation of memory and awareness. An account of this sort leads one to expect that remembering without awareness would be relatively context-free. In contrast, several experiments show that remembering without awareness can be specific to memory for a particular episode. (French abstract) (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception without awareness: Critical issues.

Discusses the conceptual distinction between conscious and unconscious processes and considers problems with measuring conscious perceptual experience. Because of interpretive problems with subjective reports, some investigators prefer to use objective measures to distinguish between aware and nonaware states. However, studies using objective measures have not provided evidence either for or against perception without awareness. Studies are reviewed in which 3 qualitative differences between conscious and unconscious perceptual processes were established. These differences involve predominate code, prediction, and selection. Such demonstrations of qualitative differences in performance across aware and nonaware conditions can both validate measures of awareness and show how conscious and unconscious processes differ. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simon effect with and without awareness of the accessory stimulus.

The authors investigated whether a Simon effect could be observed in an accessory-stimulus Simon task when participants were unaware of the task-irrelevant accessory cue. In Experiment 1A a central visual target was accompanied by a suprathreshold visual lateral cue. A regular Simon effect (i.e., faster cue-response corresponding reaction times [RTs]) was found. Experiment 1B demonstrated that this effect cannot be attributed to perceptual grouping of the target and cue. Experiments 2A, 2B, and 2C showed a reverse Simon effect (i.e., faster noncorresponding RTs) when participants were not aware of the cue. In this condition, the Simon effect would occur relative to the reorientation of attention from the cue, which would initially capture attention, toward the target. This conclusion is supported by the results of Experiments 3A and 3B, in which the reorientation of attention was induced by having the target flash after its onset. With suprathreshold cues either a reverse or regular Simon effect was observed by using a 100-ms or ≥200-ms onset flashing interval, respectively, whereas with subthreshold cues a reverse Simon effect was found irrespective of the interval length. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task-set reconfiguration and perceptual processing: Behavioral and electrophysiological evidence.

Oriet and Jolic?ur (2003) proposed that an endogenous task-set reconfiguration process acts as a hard bottleneck during which even early perceptual processing is impossible. We examined this assumption using a psychophysiological approach. Participants were required to switch between magnitude and parity judgment tasks within a predictable task sequence while event-related potentials (ERPs) were recorded. Stimulus contrast and response stimulus interval (RSI) were manipulated. Behavioral data demonstrated typical task switch costs that decreased as RSI increased. However, whereas ERP analysis of visual ERP component latencies sensitively revealed the contrast effect, a switch-specific postponement of perceptual processing during task-set reconfiguration at short RSIs was not observed. The present findings indicate that the process of task-set reconfiguration does not constitute a hard bottleneck that delays perceptual processing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Memory performance awareness in younger and older adults.

Reports on the course of memory-monitoring skills across adulthood are discrepant in conclusions and limited in scope. The purpose of this study was to build a large data base (3 samples and 7 different tasks) to assess performance awareness. Younger (19–41 years) and older (59–93 years) Ss estimated performance either before (i.e., predictions) or after (i.e., postdictions) completing each task. Predictions were less accurate than postdictions at both age levels, suggesting Ss monitored performance during the study–test cycle. Overall, the data suggested no consistent age effects in performance awareness: Age differences in monitoring occurred only in predictions and only for some tasks. Between-tasks differences in age effects could not be attributed to a single mediating mechanism like those suggested in previous reports. Why previous research has produced conflicting conclusions about metacognitive development in adulthood is discussed in light of these data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Laboratory studies of behavior without awareness.

Behavior without awareness has been extensively studied in the laboratory. On the basis of a review of these studies, it is concluded that "the only type of behavior without awareness which can be easily reproduced on the basis of published reports is the classical type, in which S knows what he is supposed to be discriminating, but does not know that he is discriminating, because of the absence of the usual sensory experiences to which he is accustomed under the given type of stimulation." There is a need to establish experimental procedures under which the other types of conditions can be unequivocally demonstrated. 76-item bibliography. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Metacognitive awareness and prevention of relapse in depression: Empirical evidence.

Metacognitive awareness is a cognitive set in which negative thoughts/feelings are experienced as mental events, rather than as the self. The authors hypothesized that (1) reduced metacognitive awareness would be associated with vulnerability to depression and (2) cognitive therapy (CT) and mindfulness-based CT (MBCT) would reduce depressive relapse by increasing metacognitive awareness. They found (1) accessibility of metacognitive sets to depressive cues was less in a vulnerable group (residually depressed patients) than in nondepressed controls; (2) accessibility of metacognitive sets predicted relapse in residually depressed patients; (3) where CT reduced relapse in residually depressed patients, it increased accessibility of metacognitive sets; and (4) where MBCT reduced relapse in recovered depressed patients, it increased accessibility of metacognitive sets. CT and MBCT may reduce relapse by changing relationships to negative thoughts rather than by changing belief in thought content. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognition without awareness: Subliminal influences upon conscious thought.

A method was developed to record the impact of a subliminal registration upon the nature, extent, and quality of a S's conscious impressions of a perceived stimulus. The main questions raised were: (a) will impressions of a pictured person of ambiguous sex be affected by subliminal sexual drawings, and (b) will impressions of pictured person be differently affected by realistic and by symbolic subliminal sexual pictures? A balanced design was employed with 24 male medical students as Ss. It was found that Ss tended either to incorporate or exclude attributes of the subliminal sexual picture in their impressions of the perceived figure. Additional findings are discussed. 25 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of masked stimuli on motor activation: Behavioral and electrophysiological evidence.

Three experiments investigated the influence of unperceived events on response activation. Masked primes were presented before a target. On compatible trials, primes and targets were identical; on incompatible trials, opposite responses were assigned to them. Forced-choice performance indicated that prime identification was prevented by the masking procedure, but overt performance and motor activation as mirrored by the lateralized readiness potential (LRP) were systematically influenced by the prime. The direction of these effects was unexpected: Performance costs for compatible and performance benefits for incompatible trials were obtained relative to a neutral trial condition. The LRP revealed a sequential pattern of motor activation. A partial activation of the response corresponding to the prime was followed by a reverse activation pattern. It is argued that these effects primarily reflect an inhibition of the response initially triggered by the prime. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Remembering with and without awareness in a depressed mood: Evidence of deficits in initiative.

We propose that depressive deficits in remembering are revealed in tasks that allow the spontaneous use of strategies; tasks that bypass or direct the use of strategies should not produce depressive deficits. College students received depressive- or neutral-mood inductions after answering questions worded to reflect homophones' less common meaning. After the inductions, subjects spelled old and new homophones and showed no effect of the depressive inductions on unaware memory for the old homophones. Subsequent tests of recognition did, however, reveal differences according to the induced mood or the presence of naturally occurring depression (in Experiment 3). The differences, evidence of nondepressed subjects' use of strategies, tended to disappear when all subjects were provided with strategies for spelling or recognition. The results indicate that depressives experience deficits in cognitive initiative. We review the literature on depressive memory from this perspective. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of awareness in Pavlovian conditioning: Empirical evidence and theoretical implications.

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Avoidance conditioning of verbal behavior without awareness: A paradigm of repression.

31 male college students responded to a 15-item word association list receiving an electric shock immediately after 5 arbitrarily selected response words. A number of additional trials were given with shock administered every time as S responded with one of the 5 first-trial punished responses. They were then asked to chain-associate to each of the stimulus words with no shock administered. At the conclusion of the experiment Ss could be classified into insight and non-insight groups on the basis of their levels of verbal awareness as to the reasons for the shocks and what they had done to avoid them. Both groups showed a rapid and marked learning of avoidance behavior and a significant decrement in the number of punished responses occurring during chained associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory, awareness and learning in general anesthesia

Enough information concerning memory and other cognitive functions in total anesthesia is available in the literature. Some basic theories about neuronal mechanisms of memory and consciousness are known. An attempt trying to bridge the gap between psychological and biologic levels is the usage of anesthetics in pharmacologic tests enabling the study of their influence on awareness and memory in humans. With the help of this approach it is possible to inquire into the psychological mechanisms and to demonstrate the influence of anesthetics on them. 44 patients were included in the study, operated on in inhalation anesthesia. The effects of anesthesia on awareness, consciousness, learning and memory in our study sample were following: 1. No episode of awareness was observed during the study; 2. There was an improvement of the memory quotient (MQ) following total inhalation anesthesia (p < 0.05); 3. The pain threshold significantly decreased after anesthesia (p < 0.001); 4. There exists a learning mechanism in total anesthesia more efficient in the group of patients auditively learning pain related words (p < 0.05) comparing to the control group of patients auditively learning pain nonrelated words; 5. Statistical analysis of the number of remembered pain related words and pain nonrelated words revealed significantly higher number of words in the first group of pain related words (p < 0.001). (Tab. 3, fig. 6, Ref. 22.)     

Discrimination of threat cues without awareness in anxiety states.

Investigated whether differences in the way that information related to danger is processed depend on voluntary attention to threat cues or on involuntary processes that may occur in the absence of awareness. 16 Ss (mean age 30.9 yrs) complaining of generalized anxiety states and 16 nonanxious matched controls (mean age 32.6 yrs) completed the State-Trait Anxiety Inventory, the Beck Depression Inventory, and the synonyms section of the Mill Hill Vocabulary Scale. Ss then shadowed neutral passages in a dichotic listening task while simultaneously being exposed to threat- or non-threat-related words in the unattended channel. Anxious Ss were slower in performing a simultaneous reaction time (RT) task when the unattended words were threatening in content, although neither group could report on or recognize the words to which they had been exposed. This finding suggests that threat cues are processed differently by anxious and nonanxious individuals and that this effect depends on a preattentive bias operating prior to awareness. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control over location-based response activation in the Simon task: Behavioral and electrophysiological evidence.

In 4 Simon experiments the authors examined control over 2 routes of sensorimotor processing: response priming in the unconditional route and response selection via the conditional route. The Simon effect diminished as the frequency of noncorresponding trials increased. Location-based response priming was observed only when the stimulus followed a corresponding event but not after a noncorresponding trial. Therefore, the unconditional route appears to be suppressed whenever the task context indicates priming as potentially disadvantageous. Moreover, the task-irrelevant stimulus location was used for response selection as a function of correspondence probability. Although exact repetitions of stimulus-response sequences caused a marked speed-up of responses, this 3rd mechanism is independent of unconditional route suppression and frequency-based adjustments in the conditional route. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of spatial cuing on luminance detectability: Psychophysical and electrophysiological evidence for early selection.

Three experiments were conducted to determine whether attention-related changes in luminance detectability reflect a modulation of early sensory processing. Exps 1 and 2 used peripheral cues to direct attention and found substantial effects of cue validity on target detectability; these effects were consistent with a sensory-level locus of selection but not with certain memory- or decision-level mechanisms. In Exp 3, event-related brain potentials were recorded in a similar paradigm using central cues, and attention was found to produce changes in sensory-evoked brain activity beginning within the 1st 1 msec of stimulus processing. These changes included both an enhancement of sensory responses to attended stimuli and a suppression of sensory responses to unattended stimuli; the enhancement and suppression effects were isolated to different neural responses, indicating that they may arise from independent attentional mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)