When the heart meets the mind: Exploring the brain-heart interaction during time perception.

Recent studies suggest that time estimation relies on bodily rhythms and interoceptive signals. We provide the first direct electrophysiological evidence suggesting an association between the brain's processing of heartbeat signals and duration judgment. We examined heartbeat-evoked potential (HEP) and contingent negative variation (CNV) during an auditory duration-reproduction task and a control reaction-time task spanning 4, 8, and 12-second intervals, in both male and female participants. Interoceptive awareness was assessed with the Self-Awareness Questionnaire (SAQ) and interoceptive accuracy through the heartbeat-counting task (HCT). Results revealed that SAQ scores, but not the HCT, correlated with mean reproduced durations with higher SAQ scores associating with longer and more accurate duration reproductions. Notably, the HEP amplitude changes during the encoding phase of the timing task, particularly within 130-270 ms (HEP1) and 470-520 ms (HEP2) after the R peak, demonstrated interval-specific modulations that didn't emerge in the control task. A significant ramp-like increase in HEP2 amplitudes occurred during the duration-encoding phase of the timing but not during the control task. This increase within the reproduction phase of the timing task correlated significantly with the reproduced durations for the 8s and the 4s intervals. The larger the increase in HEP2, the greater the under-reproduction of the estimated duration. Additionally, CNV components during the encoding phase of the timing task were more negative than those in the reaction-time task, suggesting greater executive resources orientation towards time. We conclude that interoceptive awareness (SAQ) and cortical responses to heartbeats (HEP) predict duration reproductions, emphasizing the embodied nature of time.Significance statement Recent fMRI meta-analyses have confirmed that the insula, the primary interoceptive cortex, is one of two regions in the brain essential for processing time passage. It has also been shown that the heart rate influences subjective duration. The notion of embodiment in this context suggests that the interoceptive system creates the sense of time. Besides the neuroanatomical and heart-rate correlations with subjective time, not much is known about the heart-brain interactions while individuals judge duration. Here we show how specific components of the heartbeat-evoked potential in the EEG are related to performance in a duration-reproduction task. A ramp-like increase in HEP2 amplitudes across estimated durations predicts duration reproduction, a neural signature not found in a control reaction-time task.

The inner sense of time: how the brain creates a representation of duration.

A large number of competing models exist for how the brain creates a representation of time. However, several human and animal studies point to 'climbing neural activation' as a potential neural mechanism for the representation of duration. Neurophysiological recordings in animals have revealed how climbing neural activation that peaks at the end of a timed interval underlies the processing of duration, and, in humans, climbing neural activity in the insular cortex, which is associated with feeling states of the body and emotions, may be related to the cumulative representation of time.

Time reproduction deficits in essential tremor patients.

BACKGROUND: Although motor symptoms predominate in essential tremor, increasing evidence indicates additional cognitive deficits. According to the pivotal role of cognitive functioning for temporal information processing and acknowledging the relevance of temporal information processing for movement coordination, we investigated whether essential tremor patients exhibit time reproduction deficits. METHODS: A total of 24 essential tremor patients and 24 healthy controls performed sub- and suprasecond visual duration reproduction tasks of 500 to 900 milliseconds and 1.6 to 2.4 seconds, respectively. To differentiate deficient time processing from motor or other cognitive dysfunctions, the average temporal reproduction errors were correlated with tremor severity, immediate and delayed word-list recall performance, and verbal fluency. RESULTS: Essential tremor patients significantly underreproduced sub- and suprasecond time intervals longer than 800 milliseconds. Moreover, time compression correlated significantly with semantic verbal fluency and word-list retrieval performance, but not with tremor severity. CONCLUSION: Data suggest impaired temporal processing in essential tremor, corroborating evidence for specific cognitive deficits. © 2016 International Parkinson and Movement Disorder Society.

Altered states of consciousness are related to higher sexual responsiveness.

Altered states of consciousness lead to profound changes in the sense of self, time and space. We assessed how these changes were related to sexual responsiveness during sex. 116 subjects reported (a) intensity of awareness concerning body, space and time, and (b) satisfaction, desire, arousal, and orgasm occurrence. We differentiated vaginal intercourse orgasm from noncoital orgasm. Female vaginal intercourse orgasm was further differentiated as with or without concurrent clitoral masturbation. Overall, sexual responsiveness was related to greater body awareness and lesser time and space awareness. Satisfaction, desire, and arousal were especially associated with less time awareness in women. Female orgasms during vaginal intercourse were related to greater body awareness and lesser time awareness, but noncoital orgasms were unrelated. Our findings provide empirical support for the hypotheses that altered states of consciousness with attentional absorption are strongly related to sexual responsiveness in women, and to a lesser extent in men.

Modulations of the experience of self and time.

Empirical findings in the Cognitive Sciences on the relationship between feeling states and subjective time have led to the assumption that time perception entails emotional and interoceptive states. The perception of time would thereafter be embodied; the bodily self, the continuous input from the body is the functional anchor of phenomenal experience and the mental self. Subjective time emerges through the existence of the self across time as an enduring and embodied entity. This relation is prominently disclosed in studies on altered states of consciousness such as in meditative states, under the influence of hallucinogens as well as in many psychiatric and neurological conditions. An increased awareness of oneself coincides with an increased awareness of time. Conversely, a decreased awareness of the self is associated with diminished awareness of time. The body of empirical work within different conceptual frameworks on the intricate relationship between self and time is presented and discussed.

First-person approaches in neuroscience of consciousness: brain dynamics correlate with the intention to act.

The belief in free will has been frequently challenged since Benjamin Libet published his famous experiment in 1983. Although Libet's experiment is highly dependent upon subjective reports, no study has been conducted that focused on a first-person or introspective perspective of the task. We took a neurophenomenological approach in an N=1 study providing reliable and valid measures of the first-person perspective in conjunction with brain dynamics. We found that a larger readiness potential (RP) is attributable to more frequent occurrences of self-initiated movements during negative deflections of the slow cortical potentials (SCP). These negative deflections occur in parallel with an inner impulse reported by an expert meditator which may in turn lead to a voluntary act. We demonstrate in this proof-of-principle approach that the first-person perspective obtained by an expert meditator in conjunction with neural signal analysis can contribute to our understanding of the neural underpinnings of voluntary acts.

Induction of altered states of consciousness during Floatation-REST is associated with the dissolution of body boundaries and the distortion of subjective time.

Floatation-REST (Reduced Environmental Stimulation Therapy) minimizes stimulation of the nervous system by immersing subjects in an environment without sound or light while they effortlessly float in thermoneutral water supersaturated with Epsom salt. Here we investigated the relationship between altered states of consciousness (ASC) and its association with the affective changes induced by Floatation-REST. Using a within-subject crossover design, 50 healthy subjects were randomized to 60 min of Floatation-REST or 60 min of Bed-REST (an active control condition that entailed lying supine on a warm waterbed in a dark and quiet room). Following Floatation-REST, subjects felt significantly more relaxed, less anxious, and less tired than after Bed-REST. Floatation-REST also induced significantly more pronounced ASC characterized by the dissolution of body boundaries and the distortion of subjective time. The loss of body boundaries mediated the loss of anxiety, revealing a novel mechanism by which Floatation-REST exerts its anxiolytic effect.

Spontaneous EEG fluctuations determine the readiness potential: is preconscious brain activation a preparation process to move?

It has been repeatedly shown that specific brain activity related to planning movement develops before the conscious intention to act. This empirical finding strongly challenges the notion of free will. Here, we demonstrate that in the Libet experiment, spontaneous fluctuations of the slow electro-cortical potentials (SCPs) account for a significant fraction of the readiness potential (RP). The individual potential shifts preceding self-initiated movements were classified as showing a negative or positive shift. The negative and positive potential shifts were analyzed in a self-initiated movement condition and in a no-movement condition. Comparing the potential shifts between both conditions, we observed no differences in the early part of the potential. This reveals that the apparently negative RP emerges through an unequal ratio of negative and positive potential shifts. These results suggest that ongoing negative shifts of the SCPs facilitate self-initiated movement but are not related to processes underlying preparation or decision to act.

Increased relaxation, less boredom, and a faster passage of time during a period of silence in the forest.

INTRODUCTION: There is growing evidence of the beneficial effects of exposure to nature on health and well-being. Time spent in nature can decrease stress, anxiety, depression, and improve mood. In the present study, we compared the experience of a short period of silence in the natural environment of a forest with the same amount of silence in a seminar room. METHODS: We applied an intra-subject design with two 6:30-min sessions of silence in two different environments (forest, seminar room). The participants (n=41) were assigned to four groups. Two groups started with the indoor condition and two groups with the outdoor condition. After 1 week, the two groups were exposed to the other condition. Participants filled out personality-trait scales on meaning in life and belief in oneness with the world, as well as state scales assessing emotional reactions, relaxation, boredom, and the subjective sense of self, time, and space. RESULTS: Participants felt significantly more relaxed and less bored in the forest compared to indoors. They experienced time less intensely, judging it to pass faster and to last shorter in the forest. Regarding trait variables, the higher the search for meaning, the higher oneness beliefs in participants. The higher oneness beliefs, the more positive participants felt during silence in the forest. DISCUSSION: Interest in nature-assisted therapy is increasing in the healthcare sector. Exposure to silence in the natural setting of a forest could prove to be an effective complement to interventions applied in nature-assisted therapy, such as forest therapy.

Wrinkles in subsecond time perception are synchronized to the heart.

The role of the heart in the experience of time has been long theorized but empirical evidence is scarce. Here, we examined the interaction between fine-grained cardiac dynamics and the momentary experience of subsecond intervals. Participants performed a temporal bisection task for brief tones (80-188 ms) synchronized with the heart. We developed a cardiac Drift-Diffusion Model (cDDM) that embedded contemporaneous heart rate dynamics into the temporal decision model. Results revealed the existence of temporal wrinkles-dilation or contraction of short intervals-in synchrony with cardiac dynamics. A lower prestimulus heart rate was associated with an initial bias in encoding the millisecond-level stimulus duration as longer, consistent with facilitation of sensory intake. Concurrently, a higher prestimulus heart rate aided more consistent and faster temporal judgments through more efficient evidence accumulation. Additionally, a higher speed of poststimulus cardiac deceleration, a bodily marker of attention, was associated with a greater accumulation of sensory temporal evidence in the cDDM. These findings suggest a unique role of cardiac dynamics in the momentary experience of time. Our cDDM framework opens a new methodological avenue for investigating the role of the heart in time perception and perceptual judgment.

Dynamics of retrospective timing: A big data approach.

Most interval timing research has focused on prospective timing tasks, in which participants are explicitly asked to pay attention to time as they are tested over multiple trials. Our current understanding of interval timing primarily relies on prospective timing. However, most real-life temporal judgments are made without knowing beforehand that the durations of events will need to be estimated (i.e., retrospective timing). The current study investigated the retrospective timing performance of ~24,500 participants with a wide range of intervals (5-90 min). Participants were asked to judge how long it took them to complete a set of questionnaires that were filled out at the participants' own pace. Participants overestimated and underestimated durations shorter and longer than 15 min, respectively. They were most accurate at estimating 15-min long events. The between-subject variability in duration estimates decreased exponentially as a function of time, reaching the lower asymptote after 30 min. Finally, a considerable proportion of participants exhibited whole number bias by rounding their duration estimates to the multiples of 5 min. Our results provide evidence for systematic biases in retrospective temporal judgments, and show that variability in retrospective timing is relatively higher for shorter durations (e.g., < 30 min). The primary findings gathered from our dataset were replicated based on the secondary analyses of another dataset (Blursday). The current study constitutes the most comprehensive study of retrospective timing regarding the range of durations and sample size tested.

Placebo effects on nausea and motion sickness are resistant to experimentally-induced stress.

Nausea often occurs in stressful situations, such as chemotherapy or surgery. Clinically relevant placebo effects in nausea have been demonstrated, but it remains unclear whether stress has an impact on these effects. The aim of this experimental study was to investigate the interplay between acute stress and placebo effects in nausea. 80 healthy female volunteers susceptible to motion sickness were randomly assigned to either the Maastricht Acute Stress Test or a non-stress control condition, and to either placebo treatment or no treatment. Nausea was induced by a virtual vection drum and behavioral, psychophysiological as well as humoral parameters were repeatedly assessed. Manipulation checks confirmed increased cortisol levels and negative emotions in the stressed groups. In the non-stressed groups, the placebo intervention improved nausea, symptoms of motion sickness, and gastric myoelectrical activity (normo-to-tachy (NTT) ratio). In the stressed groups, the beneficial effects of the placebo intervention on nausea and motion sickness remained unchanged, whereas no improvement of the gastric NTT ratio was observed. Results suggest that placebo effects on symptoms of nausea and motion sickness are resistant to experimentally-induced stress. Stress most likely interfered with the validity of the gastric NTT ratio to measure nausea and thus the gastric placebo effect.

Duration reproduction: lossy integration and effects of sensory modalities, cognitive functioning, age, and sex.

The "dual klepsydra model" (DKM) of internal time representation successfully models duration reproduction data, but relations between the DKM-based parameter kappa ("loss rate") and procedural variables (presentation modality) or individual characteristics (cognitive indices, age, sex) remained as yet unexplored. For that purpose, were-analyzed data from an earlier time reproduction study (N = 100), using visually or acoustically presented intervals of 1-5 sec. duration. Typical values of parameter kappa were approximately 0.03-0.04 sec.(-1), corresponding to relaxation times of internal "lossy integrators" of approximately 30 sec. Significant effects of presentation modality (smaller kappa values for the visual reproduction task) and of age (greater kappa in acoustic reproduction with increasing age) were observed. Cognitive variables (working memory, general fluid reasoning, attention) and sex of participants were not associated with kappa. Cognitive functions seem to play only a minor, if any, role at the level of time representation addressed by the DKM.

Brain-Heart Interaction and the Experience of Flow While Playing a Video Game.

The flow state - an experience of complete absorption in an activity - is linked with less self-referential processing and increased arousal. We used the heart-evoked potential (HEP), an index representing brain-heart interaction, as well as indices of peripheral physiology to assess the state of flow in individuals playing a video game. 22 gamers and 21 non-gamers played the video game Thumper for 25 min while their brain and cardiorespiratory signals were simultaneously recorded. The more participants were absorbed in the game, the less they thought about time and the faster time passed subjectively. On the cortical level, the fronto-central HEP amplitude was significantly lower while playing the game compared to resting states before and after the game, reflecting less self-referential processing while playing. This HEP effect corresponded with lower activity during gameplay in brain regions contributing to interoceptive processing. The HEP amplitude predicted the level of absorption in the game. While the HEP amplitude was overall lower during the gaming session than during the resting states, within the gaming session the amplitude of HEP was positively associated with absorption. Since higher absorption was related to higher performance in the game, the higher HEP in more absorbed individuals reflects more efficient brain-heart interaction, which is necessary for efficient game play. On the physiological level, a higher level of flow was associated with increased overall sympathetic activity and less inhibited parasympathetic activity toward the end of the game. These results are building blocks for future neurophysiological assessments of flow.

The subjective experience of time during the pandemic in Germany: The big slowdown.

Several COVID-19 studies on the felt passage of time have been conducted due to the strong feeling of time distortion many people have experienced during the pandemic. Overall, a relative decelaration of time passage was generally associated with negative affect and social isolation; a relative acceleration was associated with an increase in routine in daily life. There is some variability in results depending on the country of study and COVID-19 restrictions introduced, participants' demographics, and questionnaire items applied. Here we present a study conducted in May 2021 in Germany including n = 500 participants to assess time perception, emotional reactions, and attitudes towards the countermeasures. The passage of time judgments (POTJ) for the preceding 12 months during the pandemic were compared to data addressing the same question posed in previous studies conducted before the outbreak of COVID-19. The previous year was rated as having passed relatively slower during the pandemic compared to the ratings from before the pandemic. The duration judgments (DJ) of the 14 months since the start of the pandemic showed a bimodal distribution with both relatively shorter and relatively longer DJs. Higher levels of several negative emotions, as well as less social satisfaction, were associated with prolonged DJs and partially slower POTJs. Fear for health was not linked with the subjective experience of time, but exploratory analyses suggested that higher levels of fear were linked to more positive evaluations and approval of the governmental countermeasures. Those who reported higher levels of negative, agitated-aggressive emotions showed lower levels of consent with these measures.

Disrupting times in the wake of the pandemic: Dispositional time attitudes, time perception and temporal focus.

Introduction: The COVID-19 pandemic has majorly disrupted many aspects of people's lives, provoking psychosocial distress among students. People's positive and negative attitudes towards the past, present and future were a dispositional pre-COVID-19 reality. Faced with a pandemic, people have reported disruptions in the speed of passing time. People can shift their attention more towards the past, present or future when major changes in society occur. These aspects of psychological time would be key to understanding the quality of psychosocial adjustment to the pandemic. We hypothesized that dispositional time attitudes impact psychosocial distress because they would trigger situational changes in our time perception and temporal focus. Methods: One hundred and forty-four university students in Uruguay responded to self-report questionnaires online while in-person classes were cancelled. Students reported on shifts in temporal focus, changes in time awareness and dispositional time attitudes. Reactive psychological, social and learning environment distress were reported. Results: Students reported substantial changes in time perception and temporal focus. A correlation matrix showed significant relationships between time attitudes, focus and awareness. For example, psychological distress was correlated with negative time attitudes, slower passage of time, boredom, blurred sense of time and shifting focus to the past. Mediation models were derived. The indirect effect of time attitudes on psychological distress was significant through past focus. Discussion: Dispositional time attitudes would impact students' capacity to cope with the pandemic. Situational shifts in temporal focus and perception were prevalent and can be viewed as temporal coping mechanisms in the wake of powerful societal change. Our mediation models showed that those with negative time attitudes experienced more psychological distress because they shifted their attention to the past. Future directions for research and practical implications are discussed.

Changes in Subjective Time and Self during Meditation.

This study examined the effects of meditative states in experienced meditators on present-moment awareness, subjective time, and self-awareness while assessing meditation-induced changes in heart-rate variability and breathing rate. A sample of 22 experienced meditators who practiced meditation techniques stressing awareness of the present moment (average 20 years of practice) filled out subjective scales pertaining to sense of time and the bodily self and accomplished a metronome task as an operationalization of present-moment awareness before and after a 20 min meditation session (experimental condition) and a 20 min reading session (control condition) according to a within-subject design. A mixed pattern of increased sympathetic and parasympathetic activity was found during meditation regarding heart-rate measures. Breathing intervals were prolonged during meditation. Participants perceived their body boundaries as less salient during meditation than while reading the story; they also felt time passed more quickly and they paid less attention to time during meditation. No significant differences between conditions became apparent for the metronome task. This is probably the first quantitative study to show how the experience of time during a meditation session is altered together with the sense of the bodily self.

Differences in Time Perspectives Measured under the Dramatically Changing Socioeconomic Conditions during the Ukrainian Political Crises in 2014/2015.

The characteristics of the individual's time perspective in relation to changes in social, economic, and political conditions are of major conceptual interest. We assessed the time orientations of 1588 Ukrainian students living in two different regions (western and south-eastern Ukraine) with the Zimbardo Time Perspective Inventory (ZTPI) before (2010-2013) and during (2014-2016) the socioeconomic, political, and military crises which started in 2014, eight years before the war in 2022. We applied ANOVAs with the ZTPI dimensions as dependent variables and the period of testing (precrisis, postcrisis) as an independent variable for the two Ukrainian regions separately. The time perspectives of residents in the region most distant from the war zone (western), who positively assessed the change in the political situation around 2014, increased in the future time orientation and decreased in the present-fatalistic, past-positive, and 333 present-hedonistic time orientations. The time perspectives of residents in the regions closest to the war zone (southeastern) decreased in the future and increased in the past-negative and present-fatalistic time orientations, reflecting their negative judgments of the events. It is not the crisis itself, but the specific social, economic, and political factors and evaluations which define the time perspectives, which are flexible and adjust to changes during extreme life circumstances.

Prevalence of visual snow and relation to attentional absorption.

Visual snow is a condition of unclear prevalence characterized by tiny flickering dots throughout the entire visual field. It appears to result from visual cortex hyperactivity and possibly correlates with propensity to be engrossed in sensory and imaginary experiences (absorption). The prevalence and correlates of visual snow, and emotional reactions to it, were explored in the general Portuguese population with three studies with online surveys. In Study 1, 564 participants were shown an animated graphic simulation of visual snow and asked to rate how frequently they have similar percepts on a scale anchored by 0% and 100% of their waking time. They also reported their degree of distress and fascination resulting from visual snow. Absorption was measured with the Modified Tellegen Absorption Scale. 44% of respondents reported they see visual snow at least 10% of the time, and 20% reported seeing it between 80% and 100% of the time. Similar to findings in clinical samples, the frequency of visual snow correlated with tinnitus frequency and entoptic phenomena, but not with ophthalmologic problems. It was confirmed that visual snow is related to absorption. Although distress caused by visual snow was generally absent or minimal in our samples, a substantial minority (28%) reported moderate to high levels of distress. High fascination with visual snow was reported by 9%. In Studies 2 and 3, visual snow was measured by means of verbal descriptions without graphic simulation ("visual field full of tiny dots of light" and "world seen with many dots of light", respectively). The results were similar to those in Study 1, but seeing visual snow 80%-100% of the time was less frequent (6.5% in Study 2 and 3.6% in Study 3). Visual snow has been insufficiently investigated. More research is needed to uncover underlying neurophysiological mechanisms and psychological and behavioral correlates.

The Blursday database as a resource to study subjective temporalities during COVID-19.

The COVID-19 pandemic and associated lockdowns triggered worldwide changes in the daily routines of human experience. The Blursday database provides repeated measures of subjective time and related processes from participants in nine countries tested on 14 questionnaires and 15 behavioural tasks during the COVID-19 pandemic. A total of 2,840 participants completed at least one task, and 439 participants completed all tasks in the first session. The database and all data collection tools are accessible to researchers for studying the effects of social isolation on temporal information processing, time perspective, decision-making, sleep, metacognition, attention, memory, self-perception and mindfulness. Blursday includes quantitative statistics such as sleep patterns, personality traits, psychological well-being and lockdown indices. The database provides quantitative insights on the effects of lockdown (stringency and mobility) and subjective confinement on time perception (duration, passage of time and temporal distances). Perceived isolation affects time perception, and we report an inter-individual central tendency effect in retrospective duration estimation.