Video Which of the following statements about the effects of subliminal perception is true ?
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Họ và tên học viên đang tìm kiếm từ khóa Which of the following statements about the effects of subliminal perception is true được Update vào lúc : 2022-11-17 19:05:09 . Với phương châm chia sẻ Mẹo Hướng dẫn trong nội dung bài viết một cách Chi Tiết 2022. Nếu sau khi Read tài liệu vẫn ko hiểu thì hoàn toàn có thể lại Comment ở cuối bài để Ad lý giải và hướng dẫn lại nha.Subliminal Perception
Nội dung chính Show- Subliminal PerceptionDownstream Effects of Subliminal Perception: BehaviorDefense MechanismsSocial Cognitive Neuroscience, Cognitive Neuroscience, Clinical Brain MappingUnresponsive Wakefulness Syndrome (Vegetative State) and Related States☆Unresponsive State and Neural Correlates of ConsciousnessNeurobiology of the Placebo Effect Part I3.2 Nonconscious Processes Shape BehaviorNeurobiological Theories of ConsciousnessLooking for Neural Correlates, Not Neural BasesThe Innate
Alarm SystemInnate Defense Responses in HumansAlcohol and Hippocampal Epileptiform ActivityAlcohol Withdrawal SyndromeThe history and definition of fibromyalgiaEarly researchNetworks in Mood and Anxiety DisordersWhich of the following statements most accurately describes the research on subliminal messages?What is subliminal perception in psychology?Which of the following statements is the most accurate about subliminal and regular advertising?Which of the following statements is true of sensation and perception?
P.K. Smith, K.C. McCulloch, in Encyclopedia of Human Behavior (Second Edition), 2012
Downstream Effects of Subliminal Perception: Behavior
Though evidence of subliminal stimuli affecting judgments and attitudes is intriguing, it does not necessarily follow that such stimuli will also affect individuals’ overt behavior. Indeed, a lengthy literature in social psychology has demonstrated far less correspondence between, for example, attitudes and behaviors than might be expected. Effects of subliminal stimuli on behavior are also more controversial, as the issue of subliminal advertising and persuasion fall under this heading.
In the past 20 years, social psychologists have repeatedly demonstrated that the same subliminal stimuli that can affect judgments and attitudes can also affect overt behavior. Bargh proposed that stimuli, including subliminal stimuli, can influence behavior directly, via a perception-behavior link that bypasses conscious thought. In one experiment, Bargh and colleagues asked subjects to complete a long, boring task on a computer. During the task, subjects were subliminally exposed to photographs of either Black or White faces. (Previous research had shown that exposure to Black names or faces activated the concept of hostility, part of the Black stereotype.) Then, after many trials, an error message appeared, and the experimenter informed subjects they would have to start the task again from the beginning. Subjects’ reactions to this news were recorded with a hidden camera. Judges (blind to condition) who viewed these tapes indicated that subjects subliminally exposed to Black faces responded in a more hostile manner than subjects exposed to White faces.
Though plausible alternatives to the direct perception–behavior link have been proposed in the last decade, the more fundamental idea that subliminally presented stimuli can affect behavior has not been questioned. However, it is important to note that this type of research involves behavior that is both natural and appropriate to the particular situation involved. In fact, most models of such subliminal effects emphasize that these effects would not occur if they were inappropriate to the situation hand. In other words, subliminal priming cannot cause people to do what they would not naturally do. These effects are also assumed to be transient, lasting minutes best.
However, not all subliminal priming effects are assumed to be transient. In addition to the direct, perception–behavior route, subliminal perception also affects behavior through an indirect route, via goal activation. The representation of a goal consists of the means by which the goal operates or is carried out. Therefore, activating a goal representation will lead to the activation of its corresponding means, which in turn will result in the greater likelihood of the means being carried out. According to Atkinson and Birch's dynamic theory of action, goal-directed action tendencies increase in strength over time until the goal is acted on. Thus, in contrast to other forms of priming, in which construct activation decreases over time so priming effects are transient, the effects of goal priming actually increase over time.
Goals can be activated by a variety of primes. For example, people that are closely associated with particular goals can serve as primes for these goals. In one experiment, Shah used the names of significant others as primes for an achievement-related goal. Subjects were initially asked to provide the name of a significant other who would most want them to possess an achievement-related goal, and the name of a significant other who would care the least about this. Subjects were subliminally primed with either of the two names or a control prime (i.e., a random letter string). Subjects were then given an anagram task designed to measure goal-striving. Subjects subliminally primed with the name of the significant other who cared the most that they possess the goal persisted longer on the anagram task and found more correct solutions than those in the control group, and those primed with the name of the person that cared the least persisted less and found fewer correct solutions than those in the control condition. In sum, the subliminal activation of a goal can lead to not only better performance, but also persistence, another distinct feature of goal pursuit.
These sorts of behavioral and motivational effects differ from the single most controversial area within the domain of subliminal psychological processes: subliminal persuasion. The line between the previously described effects and the area of subliminal persuasion is fuzzy, but one key difference is that subliminal persuasion generally involves causing people to do things they cannot or would not normally do. Various people, beginning memorably with James Vicary in 1957, have made grandiose yet largely unsubstantiated claims about the effectiveness of subliminal persuasion. For example, in the 1980s, self-help audiotapes were very popular in the United States, despite the lack of rigorous scientific research on their effectiveness. When various researchers decided to test the claims of such tapes, they found that the tapes were ineffective. In one experiment, Greenwald and colleagues tested two tapes, one designed to improve memory and the other designed to improve self-esteem. Subjects were given one of the two types of tapes and were asked to listen to their tape daily. However, the experimenters switched the labels on half of the tapes. In other words, some subjects received a memory tape that had been mislabeled as self-esteem improvement, some subjects received a self-esteem tape that had been mislabeled as memory improvement, and the remaining half of subjects received correctly labeled tapes. After 5 weeks, the subjects completed self-esteem and memory tests and also indicated if they believed the tapes had been effective. The subliminal tapes had no effects on either self-esteem or memory, but there was an effect of subjects’ expectations on whether they thought the tapes were effective. That is, subjects who thought they had listened to a self-esteem tape thought their self-esteem had improved, and subjects who thought they had listened to a memory tape thought their memory had improved, regardless of which tape they had actually received.
What separates such tapes from the previously described research on subliminal effects on behavior, so that the tapes were not influential? One obvious difference is that subliminal self-help tapes claim to present long messages, such as phrases or entire sentences. Research by Greenwald and colleagues has demonstrated that individuals cannot process an entire sentence when it is presented subliminally. In one experiment, Greenwald and Liu subliminally presented two-word sentences to subjects. For each sentence, the meaning of the sentence differed from the meaning of the individual words. For example, the sentence ‘enemy loses’ has a positive meaning, but it consists of two words, ‘enemy’ and ‘loses,’ that are negative in meaning. The effects of the subliminally presented sentences were driven by the meaning of the individual words rather than by the meaning of the entire sentence.
Strahan, Spencer, and Zanna proposed that even presenting single words would not be sufficient for subliminal persuasion. They pointed out that a person's goals and motives are critical for subliminal persuasion to occur. Subliminal priming can be used to prime goal-relevant cognitions, but this priming needs to be combined with a motive to pursue the goal, for subliminal persuasion to occur. In one experiment, Strahan and colleagues brought subjects into the lab supposedly for a study on marketing research. All individuals were asked to refrain from eating or drinking for a few hours before the session. Once they arrived, half of subjects were given water to drink, and the other half were not. Thus, the latter group of subjects was thirsty and the former group not. Then all subjects completed a task on computer in which they were subliminally presented with either thirst-related words (i.e., thirst and dry) or neutral words (i.e., pirate and won). Finally, all subjects were asked to taste-test some beverages. Only subjects who were thirsty and had been subliminally presented with thirst-related words showed subliminal persuasion: they drank more of the beverages than the other subjects.
Can such persuasion be carried over to actual consumer choices? Strahan and colleagues found that their subliminal persuasion effects also led subjects to prefer products that were advertised as fulfilling their goal. For example, subjects who were thirsty and had been subliminally primed with thirst-related words preferred a beverage advertised as thirst-quenching over another beverage. Karremans and colleagues took this research a step further, proposing that if individuals already have a particular motive, they will be persuaded by subliminal priming of a brand that can satisfy that motivation. In one experiment, half of the subjects were given a very salty candy to consume to make them thirsty. Then all subjects completed a task on the computer in which they were subliminally presented with either the brand name of a beverage (‘Lipton Ice’) or nonwords made by scrambling the letters of the brand name (‘Npeic Tol’). Finally, subjects were asked to indicate which of two brand name beverages they would choose if they were offered a drink right now. Subjects who were thirsty and had been subliminally primed with Lipton Ice were the only ones to choose Lipton Ice more often than the alternative. Hence, you can subliminally lead a horse to water only if it is thirsty in the first place. It is when people are in a motivated state that specific subliminal primes can affect choice.
One of the last truyền thông outcries regarding subliminal priming was in the political sphere. In 2000, the word RATS was flashed very briefly in tandem with images of Al Gore before the entire word ‘bureaucrats’ was presented onscreen in a television commercial sponsored by the Republican National Committee. Could briefly presenting a negative word in combination with an image of a person indeed color the impression of that person? The scientific community largely dismissed this as unlikely for numerous reasons, the least of which was because a single pairing of a negative word with a well-known person is not likely to produce a change in the preexisting attitude toward that person.
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Defense Mechanisms
Bert Westerlundh, in Advances in Psychology, 2004
Discussion
The use of subliminal stimuli raises a number of questions. The use of verbal subliminal stimuli was discussed by Spence in a path-breaking paper (Spence, Klein, & Fernandez, 1986). His conclusions, while complex, were quite negative for the subliminal psychodynamic activation paradigm. My own studies (Westerlundh, 1986) show that Spence is partly correct. Subliminal sentences are not read syntactically, or are read so only under special circumstances. However, there seems to be a highly emotional unconscious appraisal of the individual words presented, and the outcome of this may result in complex psychodynamic activation effects on the dependent variables. However, the simple messages presented in this study should not be problematical. Each of the two provoking subliminal words, “fd,” individually or in any combination, should result in a steering of the interpretation of the tachistoscopic stimuli in the intended direction.
There seems to be some agreement on an operational definition of strict subliminality: the subject’s inability to discriminate the experimental from a control stimulus the time of the experiment. The usual method of assessing this is a forced-choice guessing task. This is of course the strategy that, following the lead olf Silverman (1966) has been implemented in this experiment. This inability to guess correctly corresponds to the objective recognition threshold of Cheesman and Merikle (1986), in contrast to the subjective threshold of not being able to report a perceptual experience. Methods used in the field of subliminal perception vary, and give different results. Today, main research paradigms include that of Greenwald (Greenwald, Draine, & Abrams, 1996) which produces short lived non-spreading semantic activation, and that of Bargh (Bargh, Chaiken, Go vender & Pratto, 1992), which in contrast is used as a priming procedure to activate social knowledge. The method used in this study is different from these tachistoscopic techniques. It is based on relatively long, quite weak presentations. It always seemed to me that this is a more ecologically valid approach, since the realm in nature where we find subliminal stimuli is the night.
In attempts to experimentally provoke intrapsychic conflict-such as in the present study-not all predictions have the same theoretical status. A simple diagram of the hypothetical process would involve the following components: experimental provocation- (activated impulse)- threat/danger-anxiety signal-defense-eventual outcome, possibly iterated in a number of loops before a conscious representation is achieved and re-ported in the dependent measure. This is a statement within the directional topographic model of psychoanalysis, a type of model I with Reyher (Moses & Reyher, 1985) hold to be indispensable in the conceptual understanding of the type of process studied here. Its consequences are that while, ceteris paribus, valid experimental and control conditions give rise to different reported spectra of defense, it is probable but not necessary that they will produce differences in reports of danger, fear, and anxiety, and of the “defensive struggle,” what has here been called general indications of psychological conflict. A specific danger may be countered by an efficient defense, inhibiting conscious unpleasure and different in form from defensive reports in the baseline condition, but not in, for example, number or place in the series of reports. A number of content and intensity factors will determine the outcome. This is seen in, for example, a series of studies on experimentally manipulated superego functioning in men and women (Westerlundh & Terjestam, 1987). In these, the general indications sometimes show, sometimes fail to show condition differences.
What then are the results of the present study? The design is not invalidated by sequence effects. The only significant differences of this type are found for incorrect sex attributions, which are reported by fewer subjects in the second series. This type of result has been reported for the DMT (Sjöbäck, 1972; Westerlundh, 1976). In the DMT context, this finding has generally been attributed to stimulus differences. Here, an explanation in terms of set, induced by the perception of the first series, is nearer hand. All three types of general indication show significant results in predicted directions. One-third of the comparisons give such results.
Of the fd/tw predictions, the important one concerning a defense mechanism, reaction formation dominance in Woman fd, is verified. The one concerning fear and anxiety does not receive support. This type of prediction was discussed above. The reports studied as signs of female aggression give interesting results- they seem to be related to girl-woman rather than girl-man interactions, and thus to be topical to the area of interest. On the other hand, they do not differentiate between Woman fd and Woman tw. Possibly, even without subliminal steering the oedipal interpretation of the Girl-Woman stimuli is so close hand that a number of subjects have given the reports in the control condition.
The predictions for the Man/Woman comparisons concerning the use of repression and isolation by and large receive support. The same is true for the other predictions (aggression, introaggression, fear) with regard to these comparisons. For instance, reports of aggression are much more frequent in both Man fd and Man tw as compared to the Woman conditions. Reactions to percept-genetic stimuli with a pp who really is aggressive and threatening (as in the DMT) are of interest in this context. Interindividual differences do not come to an end when the aggressive content is perceived. Male subjects who see boy-aggressive man stimuli often give reports of the type “Man beats boy.” Female subjects who see girl-aggressive woman stimuli hardly ever report “Woman beats girl.” Instead, if physical violence is reported by women in this situation, it is with the pp transformed to a man, even though exposure times are quite long. Direct violence belongs to a sphere of male activity. There is a middle ground where the sexes meet: “Man gives boy a rating” and “Woman gives girl a rating” are rather common reports for respective sex. Finally, there is a typically female form of report to this type of stimulus: “She (pp) is so angry and sorry because the girl will not eat what she has served her,” etc. Male subjects may report pp as angry and completely mad, or as angry and physically hurt, but the angry-and-sad combination is a distinct female mode of aggression.
Some results were not predicted. Denials of aggression show the same pattern as reports of aggression. This is generally found, but so few subjects use denial that predictions for the category as a rule are not given. Faulty sex ascriptions and reports of a young pp are fairly common in the Woman group, and especially in the neutral condition, Woman tw, they tend to be associated. The subjects report neutral but pleasant scenes with a girl and a boy together. To quote Kragh (1985), “this is not a genuine defense mechanism but rather a sign of object relations.
Thus, this study gives experimental support to aspects of the psycho-analytic theory of the female Oedipus complex and its precipitates in later mental functioning. Of especial importance is the verification of predictions concerning differential use of defense mechanisms (repression, isolation, and reactionformation) in contrasting conditions. Of course, what has been studied here relates to the dynamic propositions of psychoanalysis- those concerning unconscious anxieties, wishes, defenses, and fantasies motivating behavior in the “here-and now” (Silverman, 1983). General propositions concerning the nature of mental conflict and specific propositions about types of content frequently involved in such conflict receive support. On the other hand, genetic propositions-those that link present functioning to earlier experiences and events-cannot, in the nature of things, be directly investigated by laboratory techniques. Such propositions serve as connecting frameworks, pointing to probable regularities in the present (in this case with success).
Much can be said about psychoanalytic theory. Its highly colorful and mythographic appearance may make it hard for it to gain adherents among those used to the machine analogies of academic psychology. But-in contrast to the latter-its predictions are not trivial. They concern central aspects of human functioning and development. (For a full and spirited statement of this position, see Kline, 1988.) Many of these predictions are empirically testable if the proper methods- for instance, percept-genetic ones-are used.
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Social Cognitive Neuroscience, Cognitive Neuroscience, Clinical Brain Mapping
R.P. Spunt, in Brain Mapping, 2015
Awareness
Awareness refers to the extent to which the subject is phenomenally aware of the stimulus that initiates a process, the operation of the process itself, and/or the output of the process. What does it mean to say that a person has awareness of a neural process? In the current state of the psychological and brain sciences, this is more of a metaphysical question than a scientific one. However, from a methodological perspective, one can establish operation without awareness by testing if subliminal stimulus variation impacts neural activity. In terms of experimental design, the logic is identical to behavioral studies employing subliminal primes (Bargh & Chartrand, 2000). Yet unlike behavioral studies, the researcher is not dependent on measuring a behavioral outcome (e.g., response latency or recall) to establish that the subliminal stimulus induced a nonconscious process. Instead, measures of brain activity can be used to establish nonconscious processing. For example, numerous fMRI studies have now observed amygdala sensitivity to variation in the emotional expression (Whalen et al., 1998) or value (Morris, Ohman, & Dolan, 1999) of faces presented subliminally. On the basis of such data, one can conclude that some component of face processing in the amygdala can occur in the absence of awareness.
Another method for tapping process awareness involves establishing a disconnect between self-reported behavioral intentions and a neural process known to be associated with the intended behavior. To the extent that such a disconnect is observed, one can conclude that the subject is unaware of the neural process. Using this logic, researchers have suggested that the formation of movement intentions operates unconsciously insofar as neural activity associated with the production of movements actually precedes participants' self-reported decision to move (Desmurget & Sirigu, 2009). Using a similar logic, work from our group has shown in several studies that neural processes work during the consumption of persuasive messages do a better job of predicting participants' ensuing behavior than does the participants' own self-reported intentions to engage in those behaviors (Falk, Berkman, Mann, Harrison, & Lieberman, 2010; Falk, Berkman, Whalen, & Lieberman, 2011). On the flip side, claims that a neural process is available to awareness can be supported by observations of tight coupling between self-reported phenomenal states (e.g., frustration) and a neural process (e.g., the neural response to errors; Spunt, Lieberman, Cohen, & Eisenberger, 2012). These studies suggest that, in addition to the use of subliminal stimulus variation, the careful assessment of (self-reported) phenomenal experience can be used to make claims about processing (un)awareness.
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Unresponsive Wakefulness Syndrome (Vegetative State) and Related States☆
O. Gosseries, ... B. Kotchoubey, in Reference Module in Neuroscience and Biobehavioral Psychology, 2022
Unresponsive State and Neural Correlates of Consciousness
After several decades of ignoring, the modern psychology and neuroscience are presently actively interested in the problem of human (and animal) consciousness. From an analytical perspective, conscious phenomena are frequently subdivided into wakefulness versus awareness, level versus content, or nontransitive consciousness (“just consciousness”) versus transitive consciousness (“consciousness of”). The transitive consciousness is further subdivided into simple sentience (pain, pleasure, sensitivity to colors, sounds, etc.) and self-awareness (including self as the agent of actions, thinking, etc.). From this point of view, UWS presents the model of dissociation between the transitive and nontransitive consciousness: By definition, patients are awake but not aware of anything. Investigations of UWS can therefore clarify the issue of neural correlates of consciousness (NCC). Namely, because UWS patients do not possess subjective experience, any brain activity found in these patients can be eliminated from the list of possible NCC, and any brain region remaining intact in UWS is therefore not a seat of subjective awareness. Conversely, those brain processes and brain activations, which are lacking in UWS but present in MCS patients are candidates for the role of NCC.
This unbeatable logic, however, is based on two important assumptions: (1) that the definition of the UWS is consistent, and (2) that the rate of diagnostic errors is low enough to neglect, when comparing UWS and MCS groups, the possibility of some patients being incorrectly assigned. As stated previously, the former assumption is regarded by many authors as problematic and the latter is blatantly wrong. Thus, UWS research cannot directly identify brain mechanisms of awareness, but it can yield useful hints, which should be compared with other indications based on a priori or a posteriori criteria.
A priori criteria are such that if a being fulfills them, everybody will believe that the being is conscious. An example of such a criterion is that the being's responses follow our complex verbal instruction. The problem with these criteria is their high conservatism. Thus, the ability to follow verbal instructions proves not sentience but self-awareness and concentrated attention. A posteriori criteria are those we develop from the results of empirical studies of consciousness beyond the UWS domain (eg, studies of sleep, anesthesia, and brain responses to subliminal stimuli). Several theoretical attempts have been undertaken to integrate UWS findings into the broader context of the present-day a posteriori evidence of NCC. These attempts are summarized in the following hypotheses:
1.Consciousness requires, least, the activity of secondary sensory and associative regions of the cortex. Accordingly, UWS is characterized by the lack of activity in these “higher-level” areas despite the preserved activity in the primary sensory and motor areas.
2.The substrate of consciousness is not particular brain regions but a widely distributed network of synchronized activity across many cortical regions. Accordingly, UWS is primarily a disconnection syndrome in which various cortical areas and local processing modules remain working, but their integration is lacking.
3.Consciousness depends on the functioning network linking the medial parietal structures (posterior cingulum and precuneus) with the thalamus and prefrontal cortex.
These hypotheses come from the findings obtained with the classical neuroimaging techniques reviewed above. These techniques alone are, however, not always sufficient to provide an accurate diagnosis of consciousness. In order to identify a definite NCC, developing a theoretical framework defining the mechanisms linking consciousness and the brain is the next necessary step. The concrete application of such a theoretical framework to the neuroimaging-based diagnosis of consciousness has been undertaken recently, for example with the integrated information theory of consciousness (IITC). This theory predicts that consciousness-supporting networks should present an optimal balance between functional integration and differentiation, which has been tested and confirmed using TMS-EEG (see previous section on EEG).
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Neurobiology of the Placebo Effect Part I
Karin B. Jensen, in International Review of Neurobiology, 2022
3.2 Nonconscious Processes Shape Behavior
There is general evidence suggesting that behavior can be shaped by nonconscious processes (Custers & Aarts, 2010; Dijksterhuis, Aarts, & Smith, 2005). In fact, fundamental aspects of human cognition are thought to operate outside of conscious awareness, for example, in reward processing (Bijleveld, Custers, & Aarts, 2010; Pessiglione et al., 2008), fear learning (Carlsson et al., 2004; Öhman, Carlsson, Lundqvist, & Ingvar, 2007), and social behavior (Doyen, Klein, Pichon, & Cleeremans, 2012; Strahan, Spencer, & Zanna, 2002). One way to study nonconscious influences on behavior is to use subliminal stimuli. Subliminal means that a stimulus is presented below (sub) the threshold (limen) for conscious recognition, yet the stimulus can still affect behavior as it has been registered a basic level of perception (even if there is likely not a fixed threshold; for an overview of methods for subliminal validation, see Sand & Nilsson, 2022). For example, an experimental study that included phobic individuals showed that fearful reactions were triggered in response to subliminal images. Images of phobic stimuli were shown so quickly they could not be consciously perceived, yet they evoked increased arousal and negative valence ratings in phobic participants (Carlsson et al., 2004). In the case of fear reactions, it is thought that rapid responses may give a survival advantage (LeDoux, 1990). Hence, higher-order cognitive processes that include conscious awareness may be attenuated, whereas the performance of automatic responses is facilitated (Ohman, Carlsson, Lundqvist, & Ingvar, 2007). In favor of survival, there is evidence to suggest that predictive cues (signaling threat or reward) may be recognized subliminally and mediate nonconscious effects on human cognition and behavior.
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Neurobiological Theories of Consciousness
S. Kouider, in Encyclopedia of Consciousness, 2009
Looking for Neural Correlates, Not Neural Bases
Should neurobiologists then give up on addressing this issue? Most neurobiologists acknowledge the existence of a hard problem. However, they also endorse the principle that further scientific investigations will ultimately allow us to resolve it. Others explicitly deny the existence of a hard problem in the Chalmerian sense. For some, assigning too much importance to the explanatory gap might actually turn out to be counterproductive and impedes rather than facilitates scientific progress. Accordingly, neurobiologists have mostly focused on the easy problem, considering that this strategy will progressively get us closer to understanding the full issue. They extended the ‘contrastive analysis,’ originally put forward by Bernard Baars, from the cognitive to the neurobiological domain. While this method initially consisted in contrasting conscious and unconscious processes in order to characterize their cognitive features, the neurobiological approach aims characterizing the neural features. A typical example consists in comparing the cerebral activity when subjects are presented with subliminal stimuli they cannot report (unconscious processing) with that of visible stimuli they can report (conscious processing).
In other terms, the current first step in trying to understand the link between consciousness and the brain consists in finding out which neural components are specifically involved during conscious processing, but importantly not during unconscious processing. Francis Crick and Christoph Koch have coined the term ‘neural correlates of consciousness’ (NCC; see Glossary) in order to describe this epistemological approach. According to them, the best strategy for a neurobiological science of consciousness is to search for the NCC. Underneath this approach is the crucial principle that ‘correlates’ do not imply any relation of causality between the occurrence of conscious mental events and their associated physiological structure. Consequently, this strategy has the advantage of leaving aside, least for the moment, the hard problem of finding the neural ‘bases’ of consciousness.
In the following sections, I will provide an overview of the current most influential neurobiological theories of consciousness. These theories will be largely described in an independent manner, such that each of them can be understood individually, that is, without having to frame it in the context of alternative accounts. Only later, in the section labeled ‘Neurobiological standpoints on the hard problem’ will I evaluate their explanatory power by confronting them in relation to some important conceptual issues (e.g., dissociating access vs. phenomenal consciousness, dissociating attention vs. consciousness, panpsychism). I will conclude by emphasizing how promising these theories are in getting us closer to resolve the issue of the hard problem.
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The Innate Alarm System
Daniela Rabellino, ... Ruth A. Lanius, in Stress: Physiology, Biochemistry, and Pathology, 2022
Innate Defense Responses in Humans
Innate defense responses are vital for survival, as they allow rapid and automatic responding to potential danger without the engagement of higher-order cognitive functions.35,41 Such strategies rely on phylogenetically ancient innate mechanisms that have been shown to be adaptive from an evolutionary perspective.41 To investigate innate defense responses in humans, researchers have focused on subconscious processing of threat, utilizing masked subliminal stimuli that are perceived under the threshold of conscious awareness (e.g., due to rapid display time).5
A subcortical pathway, also known as a “low-road” model (as opposed to a “high-road” model employing processing via cortical structures),42 appears the most efficient route for rapid reactions to imminent danger.6,7,9,43 Here, fundamental work by Liddell and colleagues6 using masked fearful stimuli with healthy participants identifies a brainstem-amygdala-cortical alarm system. This alarm system represents the designated route for processing subconsciously perceived threat cues. Brainstem regions closely associated with this system include the SC and locus coeruleus (LC), critical for integrating salient cues and orienting the response, respectively. In addition, the amygdala provides alerting signals to threat, and the pulvinar and prefrontal regions are, in turn, activated by subcortical structures (LC and SC) to process incoming threat. In line with Liddell and colleagues' findings, increased functional connectivity was reported between the right amygdala, pulvinar, and SC among healthy volunteers in response to processing of masked fearful faces (i.e., subconscious processing) as opposed to processing of consciously processed (unmasked) fearful faces.44 Similar findings emerged in a more recent study on functional connectivity during subconscious perception of fearful faces, where the authors reported positive connectivity between the right amygdala, pulvinar, and SC.8 Of note, despite the visual nature of the stimuli being processed, the visual cortex is not involved in this rapid threat-detection route. In keeping with this conclusion, a study using intracranial electrophysiological methods identified early activity in the amygdala preceding activation of the visual cortex in epileptic patients during processing of low spatial frequency components of fearful faces,45 suggesting that processing via the visual cortex is not necessary in order to detect threat. Likewise, a magnetoencephalographic approach identified an amygdala–pulvinar route specific to early visual processing of fearful (but also happy and neutral) faces in healthy participants,46 supporting the notion of a subcortical amygdala–pulvinar pathway for early threat detection (though bearing in mind that no differences in responding were found for different emotional valences).
Taken together, these findings point toward a neural circuit, including the SC, LC, amygdala, and pulvinar that together serve as a preferential subcortical route for fast defensive response to threat in humans.
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Alcohol and Hippocampal Epileptiform Activity
Victor Diego Cupertino Costa, ... Antônio-Carlos Guimarães de Almeida, in Neuroscience of Alcohol, 2022
Alcohol Withdrawal Syndrome
AWS is a state of tissue hyperexcitability that is characterized by a variety of neuropsychiatric disorders such as anxiety, fear, muscular rigidity, delirium tremens, and generalized clonic–tonic seizures with epileptiform characteristics (N’Gouemo & Rogawski, 2006; Victor & Brausch, 1967). It may be associated with reduced hippocampal volume, especially during chronic exposure to alcohol. In addition to neurodegenerative and cell death processes, other functional modifications caused by processes that are compensatory to chronic alcohol use can be exacerbated during AWS. Again, the imbalance established by increased glutamatergic excitation along with decreased GABAergic inhibition caused by chronic alcohol use sets the stage for seizures, but seizures usually do not occur as long as ethanol intake continues. In the interval of 12–48 hours after abrupt withdrawal of alcohol, there is a rebound activation of NMDA and GABA receptors. At this time, brain circuits, especially in limbic and cortical areas, are prone to a state of hyperexcitability. Subliminal stimuli may trigger epileptiform seizures that are refractory to benzodiazepine anticonvulsants that are commonly used in these cases (Lovinger et al., 1989). Stepanyan et al. (2008) suggest that this refractory activity is due to the complexity of the affected neurotransmitter systems, since benzodiazepines only modulate the GABAergic functions. These effects increase the hyperexcitability of tissues that are more sensitive to ethanol, especially the HF, resulting in seizure generation as an adaptive response of the CNS. Exposure to several continual episodes of AW (whether through sleep or any other reason) induces the overgrowth of limbic structures, as proposed by Ballenger and Post (1978). In the hippocampus of rats, the number of spikes and epileptiform events increase with repeated episodes of AW, causing spontaneous activity. These results are correlated with the duration and number of withdrawal episodes, with the onset of memory disorders, and with the prolonged reduction in the convulsive threshold (Bartolomei, 2006). Neuronal hyperexcitability caused by abstinence from chronic alcohol use seems to be related to the mechanisms of kindling. This has been demonstrated by the increase in responses evoked during abstinence (Victor & Brausch, 1967) and by the reduction in the spontaneous seizure threshold. Researchers have measured electrical activity in subcortical structures and the limbic system of animals during abstinence and have demonstrated abnormalities. Similar patterns of disturbances in EEG recordings were demonstrated in rats by. An initial delay is followed by isolated epileptiform spikes that increase in frequency and amplitude until they are organized in paroxysmal bursts and finally support epileptic discharges in the hippocampus, amygdala, thalamus, and frontal cortex regions. These abnormalities in EEG recordings occur before or concurrently with the appearance of the behavioral signs of termination and are similar in type, anatomical location, and propagation of those characterized by the EEG recordings of animals in the process of kindling (Fig. 14.2C). In addition, in experimental animal models, these electroencephalographic abnormalities are cumulative, becoming progressively more severe with each repeated episode of abstinence (N’Gouemo & Rogawski, 2006).
Figure 14.2. Normal, binge drinking and AWS hippocampal formations.
(A) Normal HF; (B) HF submitted to the binge drinking exposure; and (C) HF after AWS.
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The history and definition of fibromyalgia
Leon Chaitow ND DO, ... Joanna Cameron, in Fibromyalgia Syndrome, 2010
Early research
A great giảm giá of research into FMS (under different names – see Box 1.1), and of the physiological mechanisms that increase our understanding of the FMS phenomenon, has been conducted over the past century (and earlier) and is worthy of review. Additional research in parallel with that focused on chronic muscular pain may clarify processes work in this complex condition.
Korr's work on facilitationAmong the most important researchers in the area of musculoskeletal dysfunction and pain over the past half century has been Professor Irwin Korr, whose work in explaining the facilitation phenomenon offers important insights into some of the events occurring in FMS and, more specifically, in myofascial pain settings. Needless to say, these often overlap. As suggested above, in a clinical context it is vital to know what degree of the pain being experienced in FMS is the result of myofascial pain, since this part of the pain package can relatively easily be modified or eliminated (see Chs 8 and 9).
Neural structures can become hyper-reactive in either spinal and paraspinal tissues or almost any other soft tissue. When they are found close to the spine the phenomenon is known as segmental facilitation. When such changes occur in ligaments, tendons or periosteal tissues, they are called trigger points; if situated in muscles or in fascia they are termed ‘myofascial’ trigger points. In early studies by the most important researcher into facilitation, Irwin Korr (1970, 1976), he demonstrated that a feature of unilateral segmental facilitation was that one side would test as having normal skin resistance to electricity compared with the contralateral side, the facilitated area, where a marked reduction in resistance was present. When ‘stress’ – in the form of needling or heat – was applied elsewhere in the body toàn thân, and the two areas of the spine were monitored, the area of facilitation showed a dramatic rise in electrical (i.e. neurological) activity. In one experiment volunteers had pins inserted into a calf muscle in order to gauge the effect on the paraspinal muscles, which were monitored for electrical activity. While almost no increase occurred in the normal region, the facilitated area showed greatly increased neurological activity after 60 seconds (Korr 1977) (Fig. 1.5). This and numerous similar studies have confirmed that any form of stress impacting the individual – be it climatic, toxic, emotional, physical or anything else – will produce an increase in neurological output from facilitated areas.
In Chapter 9, Carolyn McMakin describes how some forms of trauma, particularly those affecting cervical structures, can lead to chronic local facilitation, resulting in FMS-like pain. She reports that treatment utilizing microcurrent, manual modalities and nutritional support can frequently ease, or even remove, such symptoms.
Professor Michael Patterson (1976) explains the concept of segmental (spinal) facilitation as follows:
The concept of the facilitated segment states that because of abnormal afferent or sensory inputs to a particular area of the spinal cord, that area is kept in a state of constant increased excitation. This facilitation allows normally ineffectual or subliminal stimuli to become effective in producing efferent output from the facilitated segment, causing both skeletal and visceral organs innervated by the affected segment to be maintained in a state of overactivity. It is probable that the somatic dysfunction with which a facilitated segment is associated, is the direct result of the abnormal segmental activity as well as being partially responsible for the facilitation.
Wind-up and facilitationThe process known as wind-up (Fig. 1.6) supports the concepts of facilitation, in different terms. Staud (2006) has described the relationship between peripheral pain impulses that lead to central sensitization as follows:
Increasing evidence points towards peripheral tissues as relevant contributors of painful impulse input that might either initiate or maintain central sensitization, or both. It is well known that persistent or intense nociception can lead to neuroplastic changes in the spinal cord and brain, resulting in central sensitization and pain. This mechanism represents a hallmark of FM and many other chronic pain syndromes, including irritable bowel syndrome, temporomandibular disorder, migraine, and low back pain. Importantly, after central sensitization has been established only minimal nociceptive input is required for the maintenance of the chronic pain state. Additional factors, including pain related negative affect and poor sleep have been shown to significantly contribute to clinical FM pain.
The similarities between modern neurological observations and Korr's original work are clear.
Arousal and facilitationEmotional arousal is also able to affect the susceptibility of neural pathways to sensitization. The increase in descending influences from the emotionally aroused subject would result in an increase in toxic excitement in the pathways and allow additional inputs to produce sensitization lower intensities. This implies that highly emotional people, or those in a highly emotional situation, would be expected to show a higher incidence of facilitation of spinal pathways or local areas of myofascial distress (Baldry 1993).
This has a particular relevance to fibromyalgia, where heightened arousal (for a variety of possible reasons, as will become clear), in addition to possible limbic system dysfunction, leads to major influences from the higher centres (Goldstein 1996). Since the higher brain centres do influence the tonic levels of the spinal paths, it might be expected that physical training and mental attitudes would also tend to alter the tonic excitability, reducing the person's susceptibility to sensitization from everyday stress. Thus the athlete would be expected to withstand a comparatively high level of afferent input prior to experiencing the self-perpetuating results of sensitization. This, too, has a relevance to fibromyalgia, where there exists ample evidence of beneficial influences of aerobic training programmes (McCain 1986, Richards & Scott 2002).
Selective motor unit recruitmentResearchers have shown that a small number of motor units, located in particular muscles, may display almost constant or repeated activity when influenced psychogenically. Low amplitude activity (using surface EMG) was evident even when the muscle was not being employed, if there was any degree of emotional arousal. ‘A small pool of low-threshold motor units may be under considerable load for prolonged periods of time … motor units with Type 1 [postural] fibers are predominant among these. If the subject repeatedly recruits the same motor units, the overload may result in a metabolic crisis.’ (Waersted et al 1993). The implications of this research are profound for they link even low grade degrees of emotional distress with almost constant sensitization of specific myofascial structures, with the implications associated with facilitation and pain generation. This aetiology parallels the proposed evolution of myofascial trigger points, as suggested by Simons et al (1999).
Not only myelinated fibresResearch by Ronald Kramis has shown that, in chronic pain settings, non-nociceptive neurons can become sensitized to carry pain impulses (Kramis 1996).
Hypersensitization of spinal neurons may actually involve non-nociceptive neurons altering their phenotype so that they commence releasing substance P. This, it is thought, may play a significant part in FMS pain perception, as increased levels of substance P in the cerebrospinal fluid maintain heightened amplification of what would normally be registered as benign impulses. The research suggests that impulses from associated conditions such as ongoing viral activity, ‘muscular distress’ or irritable bowel may be adequate to maintain the central pain perception.
Local facilitationApart from paraspinal tissues, where segmental facilitation, as described above, manifests, localized areas of neural facilitation can occur in almost all soft tissues: these are called myofascial trigger points.
Much of the basic research and clinical work into this aspect of facilitation has been undertaken by doctors Janet Travell and David Simons (Simons et al 1999; Travell 1957; Travell & Simons 1986, 1992; see also Chs 6 and 8). Travell and Simons are on record as stating that if a pain is severe enough to cause a patient to seek professional advice (in the absence of organic disease), it usually involves referred pain, and therefore a trigger area is probably a factor. They remind us that patterns of referred pain are constant in distribution in all people, and that only the intensity of referred symptoms/pain will vary.
The implication for the fibromyalgia patient is the possibility (according to Travell and Simons this is a veritable certainty) that their pain has as part of its make-up the involvement of myofascial trigger points, which are themselves areas of facilitation (see Ch. 8 by Dommerholt & Issa). This suggests that trigger points, and the pain (and tingling, numbness, etc.) which they produce, will be exaggerated by all forms of stress influencing that individual patient. Travell has confirmed that her research indicates that the following factors can all help to maintain and enhance myofascial trigger point activity:
•nutritional deficiencies (especially vitamins C and B complex, and iron)
•hormonal imbalances (low thyroid hormone production, menopausal or premenstrual dysfunction)
•infections (bacteria, viruses or yeasts)
•allergies (wheat and dairy in particular)
•low oxygenation of tissues (aggravated by tension, stress, inactivity, poor respiration) (Simons et al 1999, Travell & Simons 1986, 1992).
This list corresponds closely with factors that are key aggravating agents for many (most) people with fibromyalgia, suggesting that the connection between facilitation (trigger point activity) and FMS is close (Starlanyl & Copeland 1996). Myofascial trigger points are, however, not the cause of fibromyalgia, and myofascial pain syndrome is not FMS, although they may coexist in the same person the same time. Myofascial trigger points do undoubtedly frequently contribute to the painful aspect of FMS, and as such are deserving of special attention.
As will be explained in later chapters, there are a number of ways in which deactivation or modulation of myofascial trigger points can be achieved. Some practitioners opt for approaches that giảm giá with them manually, while others prefer microcurrents or electro-acupuncture methods or variations on these themes, with yet others suggesting that reduction in the number and intensity of stress factors – of whatever type – offers a safer approach to reducing the influence of facilitation on pain.
Following this introduction to the concept of hyper-reactive, sensitized (facilitated) neural structures, it would be justifiable to enquire as to whether or not what is happening in the brain and in the neural network, as described by Goldstein, is not simply facilitation on a grand scale. The outline of some of the leading current hypotheses as to the aetiology of FMA in Chapter 4 may shed light on this possibility.
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Networks in Mood and Anxiety Disorders
Hamada Hamid, in Neuronal Networks in Brain Function, CNS Disorders, and Therapeutics, 2014
Amygdala
The amygdala establishes the emotional tone of the neuronal network. Amygdalar function and circuits have been extensively reviewed1,9,10 and may be summarized as playing a central role in fear conditioning and extinction, emotional regulation, consolidation of emotional memories, and interpretation of emotional cues. The amygdala may be divided into 12 different nuclei; however, the primary nuclei involved in emotional processing are the lateral (LA), basal (B), accessory basal (AB), and central (CE) nuclei. Structural networks, based on rodent and primate models, show that afferent projections to the amygdala arrive from the orbital and mesial prefrontal cortex and appear to modulate fear learning (Figure 24.1). Afferent pathways from the primary auditory cortex, auditory association cortex, and medial geniculate body toàn thân process aversive auditory and sensory stimuli and terminate in the LA.11 When the LA is lesioned, fear learning in response to auditory stimuli is prevented. The amygdala, particularly the CE, projects to neurons in the hypothalamus that mediate autonomic responses, such as increased heart rate and blood pressure, sweating, and piloerection. Efferent projections to the basal ganglia mediate behavioral responses such as avoidance and freezing when faced with threat.
FIGURE 24.1. This model demonstrates the central role of the amygdala in the emotional memory network. Condition stimulus (CS) when paired with unconditioned stimulus (US) induces synaptic plasticity within the lateral nucleus of the amygdala (LA). With emotional stimulation the central nucleus (CE) activates neural modulators such as norepinephrine (NE), dopamine (DA), acetylcholine (Ach), and serotonin (5HT). Neural modulators stimulate the paraventricular nucleus of the hypothalamus (PVN) releasing hormones; central grey of the periaqueductal grey (CG) mediates freezing behavior during fear; the lateral hypothalamus (LH) mediates the autonomic nervous system's (ANS) response to fear.
(Source: LeDoux J. Evolution of Human Brain Emotion in “Evolution of the Primate Brain, Volume 195: From Neuron to Behavior (Progress in Brain Research)” Eds Hofman MA & Falk D. page 437 with permission from Elsevier.)The central role of amygdalar circuits in fear learning has been delineated using Pavlov's classical conditioning model in rodent and primate models. The model pairs innately fearful exposures as unconditioned stimuli (US) with emotionally neutral conditioned stimuli (CS), resulting in development of a fearful reaction to the CS (see Chapter 13). Since classical conditioning is modulated by the amygdala and is independent of the hippocampi and frontal regions, fear may develop unconsciously or through subliminal stimuli. In contrast, explicit fear memories are processed through pathways linking the ventral hippocampus to B and AB.12,13 Rodents may be conditioned in an environmental context with lights, sounds, and smells when these are paired with electric shocks in a chamber. Rodents with intact amygdala and hippocampal connections will freeze when returned to the chamber that they were previously conditioned to fear. However, when hippocampal connections to the amygdala are lesioned, freezing behavior no longer occurs. Even with hippocampal lesions, rodents continue to freeze when exposed to the US (whether it is light, sound, or smell). This suggests that the amygdala is the central component to fear learning; however, the hippocampus plays a primary role in contextualizing fear memories.
The role of the amygdala in anxiety disorders, such as generalized anxiety disorders and panic attacks, is clear when considering fear learning and the classical conditioning model. Social phobias and generalized anxiety disorders are likely a consequence of fear conditioning through amygdalar pathways. Functional imaging studies of people with anxiety disorders demonstrate heightened amygdalar activity,14–16 whereas structural imaging has in large part failed to show significant volumetric changes in the amygdala, with a few exceptions in the case of people with posttraumatic stress disorder (PTSD).14,17 Functional imaging studies have consistently shown overactivity of the amygdala in a variety of tasks. Increased amygdalar responsiveness has been demonstrated in a variety of paradigms in subjects with PTSD, including traumatic narratives,18–20 combat sounds,21,22 combat pictures,23 and words.24 Amygdalar hyperactivity has also been shown in people with PTSD during resting state25 and with neutral tasks.26,27 Two treatment studies have demonstrated suppression of amygdalar hyperactivity with successful cognitive-behavioral therapy.28,29
The amygdala's role in mood disorders has been demonstrated through emotional-processing paradigms.30 People with major depressive disorder attend to negative faces more than neutral or happy faces.30,31 People with depression tend to assign negative interpretations to neutral words and recall sad words more than neutral or happy ones.32,33 Multiple resting-state functional imaging studies have shown increased left amygdala activity in depressed subjects compared to healthy controls. Functional neuroimaging studies demonstrate increased amygdalar activity in people with depression compared to healthy controls when they are presented with sad faces or fearful faces. Furthermore, increased amygdalar activity is suppressed with successful antidepressant therapy34,35 and cognitive-behavioral therapy.36,37
F-fluoro-2-deoxy-d-glucose (F-FDG) positron emission tomography (PET) imaging has shown amygdala overactivity in subjects with bipolar depression; however, the role of laterality is inconsistent.38,39 Drevets et al.40 also showed that amygdalar activity remained elevated in spite of depression remission and that activity was suppressed in patients in remission who were taking mood stabilizers.40 Several functional magnetic resonance imaging (fMRI) studies demonstrated increased amygdalar activity with emotional facial tasks in bipolar depression. One study demonstrated that increased activity amygdala was suppressed with mood-stabilizing agents in bipolar depression.40,41
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Which of the following statements most accurately describes the research on subliminal messages?
Which of the following statements most accurately describes the research on subliminal messages? Subliminal messages can have a small impact on influencing brief changes in behavior that have little consequence.What is subliminal perception in psychology?
Subliminal perception can be defined as the influence of a series of external stimulus on emotions or actions involuntarily, or in other words, subconsciously.Which of the following statements is the most accurate about subliminal and regular advertising?
Which of the following is the most accurate statement regarding the use of subliminal perception in advertising? Researchers have gathered scientific evidence that subliminal perception does not work in advertising.Which of the following statements is true of sensation and perception?
Regarding sensation and perception, which of the following statements is true? Sensation involves the activation of sense receptors; perception involves interpretation. Tải thêm tài liệu liên quan đến nội dung bài viết Which of the following statements about the effects of subliminal perception is true