Consciousness and Cognition
April 1, 2020
Jona Förster, Mika Koivisto, Antti Revonsuo
176 citations
The earliest and most reliable brain signal linked to visual phenomenal consciousness is the visual awareness negativity (VAN), a negative voltage deflection occurring around 200-300 milliseconds after a stimulus appears over posterior scalp regions. A later positive component, the late positivity (LP), which appears over frontal areas around 300-500 milliseconds, likely reflects later cognitive processes such as reflective or access consciousness rather than phenomenal awareness itself. This conclusion is supported by a review of event-related potential and magnetoencephalography studies published since 2010 that directly compared brain responses to consciously perceived versus unseen stimuli. The evidence strengthens VAN's role as the primary neural correlate of phenomenal consciousness and further undermines LP as a marker of phenomenal awareness.
Contemporary Hypnosis
September 1, 2003
Sakari Kallio, Antti Revonsuo
133 citations
There is broad agreement that hypnotic suggestions alter subjective experience, not just observable behavior, but no consensus exists on the theoretical explanation for these experiential changes. The debate between 'state' and 'nonstate' views centers on whether a special internal state is necessary to explain hypnosis. Placing this disagreement within a multilevel explanatory framework reveals that the conflict is about the appropriate level of description for the phenomenon. A novel multilevel approach is proposed to generate empirically testable hypotheses about hypnosis, aiming to integrate hypnosis research with multidisciplinary consciousness studies.
The American Journal of Psychology
April 1, 2009
Katja Valli, Antti Revonsuo
132 citations
The threat simulation theory (TST) proposes that dreaming about threatening events serves a biological function. This review examines studies that tested TST using the Dream Threat Scale (DTS), a system for identifying and classifying threats in dreams. The reviewed research includes dreams from Finnish and Swedish university students, traumatized and nontraumatized Kurdish, Palestinian, and Finnish children, and recurrent dreams and nightmares from Canadian participants. The authors conclude that new evidence and direct tests yield strong support for TST, and its strengths outweigh its weaknesses.
Neuropsychologia
November 1, 2009
Mika Koivisto, Pasi Kainulainen, Antti Revonsuo
107 citations
Visual attention and awareness are intricately linked, but different types of attention play distinct roles. Experiments tracking brain responses show that spatial attention is necessary for the earliest brain correlate of phenomenal consciousness—the raw experience of seeing. This early marker emerged regardless of whether objects were selected by nonspatial attention, though later parts of it were modified by such selection. In contrast, the brain correlate of reflective consciousness, which allows the contents of phenomenal experience to be used for thought and memory, depended on both spatial attention and nonspatial selection. These findings indicate that the relationship between attention and awareness requires distinguishing between different forms of attention and different levels of consciousness.
The Journal of neuroscience : the official journal of the Society for Neuroscience
February 24, 2021
Annalotta Scheinin, Oskari Kantonen, Michael Alkire et al.
92 citations
Consciousness often persists even when unresponsiveness occurs. In two experiments involving 76 healthy males, brain activity was measured during varying states of consciousness induced by propofol and dexmedetomidine (n = 39) and during sleep-deprived wakefulness and non-REM sleep (n = 37). Most participants reported internally generated experiences while unresponsive. Key brain regions, including the thalamus and cingulate cortices, were found critical for consciousness, showing consistent activity patterns regardless of anesthetic type or sleep state, highlighting a core network essential for conscious awareness.
The American Journal of Psychology
August 21, 2017
Pilleriin Sikka, Diana Feilhauer, Katja Valli et al.
63 citations
How emotions in dreams are measured can lead to opposite conclusions about whether dreams are mostly positive or negative. Over three weeks, 44 participants reported their dreams each morning and rated their own emotional experiences using a standard emotion scale. Two external judges rated the same 552 dream reports using the same scale. Self-ratings showed dreams as more emotional and more positive, with most dreams rated positively. External ratings showed most dreams as negatively valenced. The two methods partially agreed on negative emotions but diverged sharply on positive emotions. This suggests negative emotional experiences may be measured more reliably than positive ones, and the two methods may capture different phenomena and should be used together.
Brain and Cognition
December 1, 2011
Valdas Noreika, Leila Jylhänkangas, Levente Móró et al.
62 citations
Subjective experiences can occur even when a person appears unresponsive under sedation. In a nonsurgical setting, participants given dexmedetomidine, propofol, sevoflurane, or xenon recalled having subjective experiences in almost 60% of sessions after regaining responsiveness. During dexmedetomidine sessions, such experiences were linked to shallower sedation depth as measured by an EEG-based monitor. The findings indicate that unresponsiveness does not guarantee absence of consciousness, and studies on phenomenal consciousness under anesthetics should assess subjective states through post-recovery interviews.
Neuroscience of Consciousness
January 1, 2020
William Wong, Valdas Noreika, Levente Móró et al.
35 citations
In a test of whether brain activity alone can reveal when someone is dreaming, researchers used an unsupervised machine learning classifier to distinguish dreamful from dreamless sleep based on EEG spectral power and electrode location. Nine participants contributed 54 one-minute polysomnograms from non-rapid eye movement sleep—27 with dreams and 27 without. A blinded Analysis Team attempted to classify each recording over five iterations with gradually reduced blindness. At no stage did the classifier perform significantly better than chance, indicating that EEG spectral power features could not reliably detect signatures of phenomenal consciousness in this dataset.
May 16, 2023
William Wong, Kátia C. Andrade, Thomas Andrillon et al.
21 citations
preprint
A new open-access database, DREAM, combines sleep magneto/electroencephalography (M/EEG) recordings with standardized dream reports to enable large-scale neurocognitive research on dreaming. The initial release includes 20 datasets from 561 participants and 2649 awakenings, each with at least 20 seconds of high-frequency M/EEG data and a classification of the subject's experience. Analyses demonstrate that features extracted from EEG can predict whether a person reports having had a conscious experience during both REM and NREM sleep. The database aims to overcome the limitations of small sample sizes and methodological variability in dream research, allowing new questions to be addressed at a scale unattainable by individual labs.
Epilepsy & behavior : E&B
August 1, 2008
Mirja Johanson, Katja Valli, Antti Revonsuo et al.
19 citations
People with partial epilepsy experience widespread distortions in their subjective experience during seizures, yet the pattern of those distortions remains consistent from one seizure to the next. A standardized questionnaire called the Phenomenology of Consciousness Inventory (PCI) proved suitable for capturing these changes in consciousness. The findings suggest that the PCI could help researchers and clinicians better understand the nature of phenomenal consciousness in epilepsy.
Nature Communications
August 13, 2025
William Wong, Rubén Herzog, Kátia Cristine Andrade et al.
10 citations
A new open database, the DREAM database, combines standardized sleep magneto/electroencephalography (M/EEG) recordings with dream reports from 505 participants across 20 datasets, totaling 2,643 awakenings. Each awakening includes at least 20 seconds of high-resolution sleep EEG (≥100 Hz, ≥2 electrodes) and a classification of the sleeper's reported experience. Analyses showed that reports of conscious experiences during sleep can be predicted from objective EEG features in both REM and NREM sleep. The database aims to overcome limitations of small sample sizes and methodological variability in dream research, enabling larger-scale investigations of the neurocognitive basis of dreaming.
Neuroimage
April 15, 2025
Dmitri Filimonov, Saana Lenkkeri, Mika Koivisto et al.
6 citations
The neural correlates of consciousness (NCC) for auditory awareness include auditory awareness negativity (AAN) and late positivity (LP), but it is unclear which is the true NCC. By inducing simple auditory hallucinations through a Pavlovian conditioning paradigm, where participants rated near-threshold tones and stimulus-absent trials, AAN appeared as an early event-related potential difference between aware and unaware stimuli, suggesting it is a genuine NCC for auditory consciousness. Late positivity was absent in these hallucinations, indicating it may not be essential for auditory awareness.
Consciousness and Cognition
February 8, 2024
Ville Loukola, Jarno Tuominen, Santeri Kirsilä et al.
4 citations
During the COVID-19 pandemic, dreams did not become more threatening or nightmarish overall compared to before the pandemic. Analysis of 1,132 pandemic-era dreams and 166 pre-pandemic dreams found no differences in the number of threatening events, disease-related threats, or severity of threats between the two periods. However, the minority of dreams that directly referenced the pandemic did contain more threats, disease-related threats, and severe threats. The findings suggest the pandemic's impact on dream content was limited to a subset of dreams rather than causing a general increase in threatening dream content.
Cognitive Neuroscience
September 1, 2010
Antti Revonsuo, Mika Koivisto
3 citations
Event-related brain potential (ERP) evidence supports two key ideas in Lamme's theory of consciousness. The earliest brain signal linked to visual consciousness appears over the back of the head about 100-200 milliseconds after a stimulus is presented, consistent with recurrent processing in visual cortex. This early signal is largely separate from later brain responses that reflect selective attention and working memory. The findings suggest that phenomenal consciousness of a visual stimulus arises before access consciousness, and that attention and awareness rely on different neural processes.
April 9, 2021
Pilleriin Sikka, Katja Valli, Antti Revonsuo et al.
2 citations
preprint
Across the wake-sleep cycle, the positivity bias typical of waking experiences diminishes. Mind-wandering episodes are more positively valenced than dreams, and both are more negatively valenced than active wakefulness. When participants rated their own affect, all episodes were predominantly positive. However, analysis of verbal reports describing the same experiences showed a shift from positively valenced waking reports to affectively balanced mind-wandering reports to negatively valenced dream reports. These findings indicate that the nature of affective experiences depends on the measurement method and the state of consciousness, calling for integration across emotion, mind-wandering, and dream research.
Journal of Sleep Research
April 2, 2026
Ville Loukola, J T Tuominen, Eveliina Malinen et al.
Individual factors, such as low life satisfaction and fewer positive emotions, are better predictors of threatening dream content during the COVID-19 pandemic than daily situational factors like worry or media consumption. In a large Finnish sample of prospective dream diaries, lower life satisfaction was the only statistically significant predictor of threatening events in dreams, while experiencing fewer positive emotions in the past two weeks was the only significant predictor of pandemic-related threatening events. The findings suggest that the tendency to have threatening dreams is more a stable trait than a daily fluctuating feature, supporting the threat simulation theory's idea that individual differences in simulating threats interact with daily experiences.
Neuroimage
January 29, 2026
Dmitri Filimonov, Mika Koivisto, Antti Revonsuo
The most reliable brain-activity markers of visual consciousness, measured with EEG, are an early component called visual awareness negativity (VAN) and a later component called late positivity (LP). Three prior reviews concluded that VAN is specifically tied to awareness, while LP also reflects other mental processes. This review of 53 new studies published since 2020 confirms that VAN remains the most robust neural correlate of visual consciousness, whereas LP is not uniquely linked to consciousness. However, questions remain about how VAN relates to attention and other physiological factors.
September 11, 2025
Ville Loukola, Jarno Tuominen, Eveliina Malinen et al.
preprint
During the COVID-19 pandemic, individual factors such as life satisfaction and positive emotions were better predictors of threatening dream content than daily situational factors like worry about the virus or media consumption. In a large Finnish sample using prospective dream diaries, lower life satisfaction was the only statistically significant predictor for threatening events in dreams, and fewer positive emotions in the past two weeks was the only significant predictor for pandemic-related threatening events. These findings suggest that the tendency to experience threatening dreams is more of a stable trait than a daily fluctuating feature, consistent with the threat simulation theory of dreaming.
Consciousness and Cognition
June 19, 2024
Dmitri Filimonov, Sampo Tanskanen, Antti Revonsuo et al.
The level-of-processing (LoP) hypothesis, which describes how awareness of visual stimuli can be either gradual or all-or-none depending on feature depth, was tested in hearing for the first time. Participants heard words from different categories spoken in different pitches near the perceptual threshold. Results indicate that LoP also applies to the auditory modality. The auditory awareness negativity (AAN) was an early correlate of awareness independent of LoP, while late positivity (LP) was modulated by awareness, performance accuracy, and level of processing.
Neuroscience of Consciousness
January 1, 2024
Dmitri Filimonov, Andreas Krabbe, Antti Revonsuo et al.
Aware auditory experiences are linked to a specific brain signal, the auditory awareness negativity (AAN), which remains unchanged whether listeners pay attention to sounds or must respond to them. In contrast, a later brain signal, the late positivity (LP), is influenced by both attention and the requirement to respond. These findings suggest that AAN is a genuine neural correlate of auditory consciousness, while LP reflects higher-level processing that may depend on a global workspace.
British Journal of Anaesthesia
August 1, 2023
Katja Valli, Linda Radek, Roosa E Kallionpää et al.
Anaesthetic-induced unresponsiveness and non-rapid eye movement (NREM) sleep share similar conscious experiences. In a within-subject study, 39 healthy males received either dexmedetomidine or propofol to induce unresponsiveness, and 37 were later awakened from NREM sleep. Most participants were rousable, with no difference between the two drugs. Lower drug concentrations were linked to being rousable but not to recall of experiences. Of interviews after anaesthesia and sleep, 69.7% and 64.4% included experiences, respectively, with no significant difference in recall. Disconnected dream-like experiences and memory incorporation of the research setting occurred equally often in both states, while awareness was rare. The findings suggest that both states involve disconnected conscious experiences with similar recall frequencies and content.
The Journal of neuroscience : the official journal of the Society for Neuroscience
June 28, 2023
Oskari Kantonen, Lauri Laaksonen, Michael Alkire et al.
Anesthesia-induced disconnectedness—unresponsiveness and unawareness of external events—is linked to reduced activity in the thalamus, but not to widespread cortical suppression, which instead reflects drug exposure itself. In a study of 160 healthy men, four anesthetics (propofol, dexmedetomidine, sevoflurane, S-ketamine) or saline placebo were administered at doses designed to make half of subjects unresponsive. Positron emission tomography showed that, for all anesthetics except S-ketamine, lower thalamic metabolic activity distinguished disconnected from connected states. Widespread cortical metabolic suppression occurred in both connected and disconnected subjects compared with placebo, indicating it is necessary but insufficient for loss of consciousness.
Consciousness and Cognition
November 1, 2021
Linda Radek, Lauri Koskinen, Nils Sandman et al.
Subjective experiences, most often dreaming or incorporating elements of the setting, are common during sedation with anesthetics that act through different molecular mechanisms. In healthy male participants given equisedative doses of dexmedetomidine, propofol, sevoflurane, or S-ketamine for one hour, 46.9% of those who were arousable reported experiences. Dexmedetomidine was associated with the most frequent reports, while S-ketamine produced the most multimodal experiences. Whether participants were responsive at the end of administration did not affect the prevalence or content of the experiences. The differences between drugs were small in this sample.
The Journal of neuroscience : the official journal of the Society for Neuroscience
June 12, 2019
Pilleriin Sikka, Antti Revonsuo, Valdas Noreika et al.
Frontal alpha asymmetry (FAA) during REM sleep and evening wakefulness predicts ratings of anger in dreams. Individuals with greater alpha power in the right frontal hemisphere may be less able to regulate strong affective states, such as anger, in dreams. FAA was positively correlated across wakefulness and REM sleep. These findings imply that FAA may serve as a neural correlate of affect regulation in both waking and dreaming states.
bioRxiv Preprint Server
May 27, 2019
William Wong, Valdas Noreika, Levente Móró et al.
preprint
A test called the Dream Catcher test was conducted for the first time in a simplified form to see if brain activity alone can reveal whether someone is dreaming. Data Team collected brain measurements (polysomnograms) during NREM sleep from 9 participants, producing 54 one-minute recordings—27 from dreamful sleep and 27 from dreamless sleep. A blinded Analysis Team tried to classify each recording as dreamful or dreamless using an unsupervised machine learning classifier based on EEG spectral power and electrode location. Over five iterations with gradually reduced blindness, the team never performed significantly better than chance. The results suggest that EEG spectral power does not carry signatures of phenomenal consciousness, and the study also failed to replicate key findings from earlier reports on dreaming consciousness.