The earliest electrophysiological correlate of visual awareness?

To examine the neural correlates and timing of human visual awareness, we recorded event-related potentials (ERPs) in two experiments while the observers were detecting a grey dot that was presented near subjective threshold. ERPs were averaged for conscious detections of the stimulus (hits) and nondetections (misses) separately. Our results revealed that hits, as compared to misses, showed a negativity around 180-350 ms at occipital and posterior temporal sites. It was followed by a positive wave after 400-500 ms, peaking at parietal sites. These correlates were not affected by a manipulation of attention. The early negativity, called 'visual awareness negativity' (VAN), may be a general, primary electrophysiological correlate of visual awareness. The present data show that it can be observed in response to appearance of a stimulus in visual awareness and that it generalizes across different manipulations of stimulus visibility.     

Intimate distances: William James’ introspection, Buddhist mindfulness, and experiential inquiry

The recent and growing interest in ‘mindfulness’ and ‘mindfulness meditation’ across disciplines in the West presents us with a unique opportunity to reconsider whether Buddhism has anything to offer our contemporary psychological investigations. I argue that the Buddhist-inspired practice of mindfulness has potentially profound implications for the ways in which we conduct our investigations as psychologists, and that, as a style of experiential inquiry, it has at least one Western antecedent in the early introspectionist method of William James. Both are practices of becoming aware of experience; and paradoxically becoming intimately distant with our experience. I present a non-dualistic approach in which introspection and mindfulness are seen not only as psychological but also as social practices, operating simultaneously at the boundary of the individual/inner and social/outer, collapsing such distinctions in practice, and radically undermining the distinction between self and other. While there are similarities between James’ practice of introspection and mindfulness, there are also differences, and I suggest that they should not be easily conflated. Clarifying their relationship should be helpful, not only in distinguishing them from one another, but also in pointing to how mindfulness might allow a broader application than James’ introspection once did.     

The electrophysiological correlates of stimulus visibility and metacontrast masking

There are conflicting views concerning the electrophysiological correlates of visual consciousness. Whereas one view considers a relatively late positive deflection (LP) as a primary correlate of consciousness, another model links consciousness with earlier negativity (VAN). The present experiment utilized metacontrast masking in investigating the electrophysiological correlates of visual consciousness. The participants were presented with target-mask sequences in three stimulus onset asynchronies. The target stimuli were followed by either a metacontrast mask or a similar-looking, but ineffective pseudomask. The results showed that the first deflection that correlated with target visibility was VAN which was followed by LP. We argue that the VAN is the primary correlate target visibility, while the LP reflects later, postperceptual processing stages.     

Tracking the processes behind conscious perception: a review of event-related potential correlates of visual consciousness

Event-related potential (ERP) studies have attempted to discover the processes that underlie conscious visual perception by contrasting ERPs produced by stimuli that are consciously perceived with those that are not. Variability of the proposed ERP correlates of consciousness is considerable: the earliest proposed ERP correlate of consciousness (P1) coincides with sensory processes and the last one (P3) marks postperceptual processes. A negative difference wave called visual awareness negativity (VAN), typically observed around 200 ms after stimulus onset in occipitotemporal sites, gains strong support for reflecting the processes that correlate with, and possibly enable, aware visual perception. Research suggests that the early parts of conscious processing can proceed independently of top-down attention, although top-down attention may modulate visual processing even before consciousness. Evidence implies that the contents of consciousness are provided by interactions in the ventral stream, but indispensable contributions from dorsal regions influence already low-level visual responses.     

Language facilitates introspection: Verbal mind-wandering has privileged access to consciousness

Introspection and language are the cognitive prides of humankind, but their interactions in healthy cognition remain unclear. Episodes of mind-wandering, where personal thoughts often go unnoticed for some time before being introspected, offer a unique opportunity to study the role of language in introspection. In this paper, we show that inner speech facilitates awareness of mind-wandering. In two experiments, we either interfered with verbal working memory, via articulatory suppression (Exp. 1), or entrained it, via presentation of verbal material (Exp. 2), and measured the resulting awareness of mind-wandering. Articulatory suppression decreased the likelihood to spontaneously notice mind-wandering, whereas verbal material increased retrospective awareness of mind-wandering. In addition, an ecological study using smartphones confirmed that inner speech vividness positively predicted mind-wandering awareness (Exp. 3). Together, these findings support the view that inner speech facilitates introspection of one’s thoughts, and therefore provides empirical evidence for a positive relation between language and consciousness.     

Meditative introspection promotes the First-person's science of consciousness via intuitive pathways: A hypothesis based on traditional Buddhist and contemporary Monist frameworks

What forms the basis for validating any knowledge? Should it be always verified based on the objective and analytical methods that we adapt according to our progressive advancements in science or is there any other way of conceiving knowledge? This is the context where modern sophistication should embrace an ancient perspective. Recently, there have been great advancements in the science of consciousness and meditation. Meditation received much attention as a practice for wellbeing and as a tool for cognitive enhancement. Even though, hundreds of objective studies have been conducted on different practices of meditation across different traditions, there is one essential element missing in almost all of these studies: the discussion of the subjective experience of meditation. Embracing the traditional insights on meditation, we study this element by defining meditation based on the concept of introspection. In addition, we hypothesize that introspective meta-awareness associated with the non-conceptual experience of meditation may result in the conceptual understanding of natural phenomena via pathways of intuition. The proposed advancement bears implications for the ontological and epistemological basis of experiential knowledge, as well as, for developing introspection and meditation-based interventions for self and consciousness disorders.     

The neural basis of event-time introspection

We explored the neural mechanisms allowing humans to report the subjective onset times of conscious events. Magnetoencephalographic recordings of neural oscillations were obtained while human subjects introspected the timing of sensory, intentional, and motor events during a forced choice task. Brain activity was reconstructed with high spatio-temporal resolution. Event-time introspection was associated with specific neural activity at the time of subjective event onset which was spatially distinct from activity induced by the event itself. Different brain regions were selectively recruited for introspection of different event types, e.g., the bilateral angular gyrus for introspection of intention. Our results suggest that event-time introspection engages specific neural networks to assess the contents of consciousness. Subjective event times should therefore be interpreted as the result of complex interactions between introspection and experience networks, rather than as direct reproduction of the individual’s conscious state or as a mere post hoc interpretation.     

Consciousness and emotion: ERP modulation and attentive vs. pre-attentive elaboration of emotional facial expressions by backward masking

Facial stimulus processing is an important topic to explain how people comprehend affective disposition in others. The effect of attentive and pre-attentive elaboration of emotional facial expression was explored in the present research by using backward masking procedure. Specifically, unconscious mental process of emotion comprehension was analyzed: pictures presenting a happy, sad, angry, fearful, disgusted, surprised expressions were submitted to 21 subjects in both attentive and pre-attentive conditions and event-related potentials (ERPs) were registered in the two conditions. The two processes, attentive and pre-attentive, seem to be similar in their nature, since they are marked by analogous ERP deflections. In fact, two ERP effects were found, a positive (P300) deflection, maximally distributed on the parietal regions, and a negative (N200) deflection, more localized on the frontal sites. Nevertheless, some differences between the two conditions were found in terms of quantitative modulations of the two peaks. The N200 effect, ampler in attentive condition, may be considered such as an index of conscious processing of emotional faces, whereas the P3 (P3a) effect, higher in pre-attentive condition, was considered a specific marker of the automatic, unconscious process during the emotional face comprehension.     

Introspective reports of reaction times in dual-tasks reflect experienced difficulty rather than timing of cognitive processes

Reports of introspective reaction times (iRTs) have been used to investigate conscious awareness during dual-task situations. Previous studies showed that dual-task costs in RTs (the psychological refractory period, PRP, effect) are not reflected in participants’ introspective reports. This finding has been attributed to conscious awareness of Task 2 being delayed while Task 1 is centrally processed. Here, we test this Temporal model and compare it to an alternative that assumes participants base their iRTs on experienced difficulty. We collected iRTs and difficulty estimates after each trial of a PRP paradigm in which the perceptual difficulty of either Task 2 (Experiment 1) or Task 1 (Experiment 2) was manipulated. Our results largely support the difficulty-based account, suggesting that in a dual-task situation, iRTs do not reflect timing of cognitive processes but are strongly influenced by the experience of difficulty.     

Elimination of bias in introspection: Methodological advances,refinements, and recommendations

Building on past constructive criticism, the present study provides further methodological development focused on the elimination of bias that may occur during first-person observation. First, various sources of errors that may accompany introspection are distinguished based on previous critical literature. Four main errors are classified, namely attentional, attributional, conceptual, and expressional error. Furthermore, methodological recommendations for the possible elimination of these errors have been determined based on the analysis and focused excerpting of introspective scientific literature. The following groups of methodological recommendations were determined: 1) a better focusing of the subject's attention to their mental processes, 2) providing suitable stimuli, and 3) the sharing of introspective experience between subjects. Furthermore, the potential of adjustments in introspective research designs for eliminating attentional, attributional, conceptual, and expressional error is discussed.     

Interactively guided introspection is getting science closer to an effective consciousness meter

The ever-increasing precision of brain measurement brings with it a demand for more reliable and fine-grained measures of conscious experience. However, introspection has long been assumed to be too limited and fallible. This skepticism is primarily based on a series of classic psychological experiments, which suggested that more is seen than can be retrospectively reported (Sperling, 1960), and that we can be easily fooled into retrospectively describing intentional choices that we have never made (Johansson et al., 2005, Nisbett and Wilson, 1977). However, the work by Petitmengin, Remillieux, Cahour, and Carter-Thomas (2013) could resolve this dilemma. They showed that subjects can be interactively guided to become better aware of their past experience, thereby overturning the “choice blindness” results of Johansson et al. (2005). Although some more fine-tuning of the experimental protocol is needed, interactively guided introspection may well become the most reliable and exhaustive measure of consciousness.     

Valuing thoughts, ignoring behavior: The introspection illusion as a source of the bias blind spot

People see themselves as less susceptible to bias than others. We show that a source of this bias blind spot involves the value that people place, and believe they should place, on introspective information (relative to behavioral information) when assessing bias in themselves versus others. Participants considered introspective information more than behavioral information for assessing bias in themselves, but not others. This divergence did not arise simply from differences in introspective access. The blind spot persisted when observers had access to the introspections of the actor whose bias they judged. And, participants claimed that they, but not their peers, should rely on introspections when making self-assessments of bias. Only after being educated about the importance of nonconscious processes in guiding judgment and action—and thereby about the fallibility of introspection—did participants cease denying their relative susceptibility to bias.     

个体智力差异的脑电生理学基础 ——来自EEG和ERP的证据

智力的脑电生理学研究近年来蓬勃发展。文章分析了EEG、ERP这两种主要的电生理学技术在智力差异探究中的应用,在智力水平与大脑激活程度的负相关受到任务难度、内容以及被试性别的影响等方面的研究所取得的进展;指出了以往个体智力差异脑电生理学研究中存在的ERP智力差异研究采用的任务略显简单、难以体现智力活动的本质等问题;认为今后利用多种脑电技术结合研究个体智力差异的趋势日趋明显。     

The effect of introspection on judgment and decision making is dependent on the quality of conscious thinking

That introspection may impair certain judgments and result in fabrication has been attributed to a distracting shift from more adaptive intuitive processing to more analytic and conscious processing. This phenomenon was studied in an experiment where participants made multidimensional visual choices. It was found that the effect of this shift on decision-making performance was dependent on the quality of the explanations during introspection, while the performance in silent conditions was not. Therefore, it appears that the effect of introspection on judgments is not only influenced by the thinking mode per se, but also by the individual’s ability to approach the decision problem analytically.     

Introspection during visual search

Recent advances in the field of metacognition have shown that human participants are introspectively aware of many different cognitive states, such as confidence in a decision. Here we set out to expand the range of experimental introspection by asking whether participants could access, through pure mental monitoring, the nature of the cognitive processes that underlie two visual search tasks: an effortless “pop-out” search, and a difficult, effortful, conjunction search. To this aim, in addition to traditional first order performance measures, we instructed participants to give, on a trial-by-trial basis, an estimate of the number of items scanned before a decision was reached. By controlling response times and eye movements, we assessed the contribution of self-observation of behavior in these subjective estimates. Results showed that introspection is a flexible mechanism and that pure mental monitoring of cognitive processes is possible in elementary tasks.     

The level of frontal-temporal beta-2 band EEG synchronization distinguishes anterior cingulate cortex from other frontal regions

Recent findings indicate that complex cognitive functions are organized at a global level in the brain and rely on large-scale information processing requiring functional integration of multiple disparate neural assemblies. The critical question of the integration of distributed brain activities is whether the essential integrative role can be attributed to a specific structure in the brain or whether this ability is inherent to the cognitive network as a whole. The results of the present study show that mean values of the running correlation function in frontal-temporal EEG pairs with one electrode in the anterior cingulate cortex (ACC) are significantly higher than the same values in other frontal-temporal pairs. These findings indicate a particular role of the ACC in large-scale communication, which could reflect its unique integrative functions in cognitive processing.     

The relation between electroencephalogram asymmetry and attention biases to threat at baseline and under stress

Electroencephalogram (EEG) asymmetry in the alpha frequency band has been implicated in emotion processing and broad approach-withdrawal motivation systems. Questions remain regarding the cognitive mechanisms that may help elucidate the observed links between EEG asymmetry and patterns of socioemotional functioning. The current study observed frontal EEG asymmetry patterns at rest and under social threat among young adults (N = 45, M = 21.1 years). Asymmetries were, in turn, associated with performance on an emotion-face dot-probe attention bias task. Attention biases to threat have been implicated as potential causal mechanisms in anxiety and social withdrawal. Frontal EEG asymmetry at baseline did not predict attention bias patterns to angry or happy faces. However, increases in right frontal alpha asymmetry from baseline to the stressful speech condition were associated with vigilance to angry faces and avoidance of happy faces. The findings may reflect individual differences in the pattern of response (approach or withdrawal) with the introduction of a mild stressor. Comparison analyses with frontal beta asymmetry and parietal alpha asymmetry did not find similar patterns. Thus, the data may reflect the unique role of frontal regions, particularly the dorsolateral prefrontal cortex, in cognitive control and threat detection, coupled with ruminative processes associated with alpha activity.     

Exogenous attention to unseen objects?

Attention and awareness are closely related phenomena, but recent evidence has shown that not all attended stimuli give rise to awareness. Controversy still remains over whether, and the extent to which, a dissociation between attention and awareness encompasses all forms of attention. For example, it has been suggested that attention without awareness is more readily demonstrated for voluntary, endogenous attention than its reflexive, exogenous counterpart. Here we examine whether exogenous attentional cueing can have selective behavioural effects on stimuli that nevertheless remain unseen. Using a task in which object-based attention has been shown in the absence of awareness, we remove all possible contingencies between cues and target stimuli to ensure that any cueing effects must be under purely exogenous control, and find evidence of exogenous object-based attention without awareness. In a second experiment we address whether this dissociation crucially depends on the method used to establish that the objects indeed remain unseen. Specifically, to confirm that objects are unseen we adopt appropriate signal detection task procedures, including those that retain parity with the primary attentional task (by requiring participants to discriminate the two types of trial that are used to measure an effect of attention). We show a significant object-based attention effect is apparent under conditions where the selected object indeed remains undetectable.