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The technological advances in recent years are influencing and redefining our daily lives, communications, and social relationships. While these advances bring us many benefits, their negative effects may also cause concern. Although often studied, the potential benefits of digital deprivation are still disputed. This laboratory study investigates the impact of short digital deprivation (7 min and 30 s) on the psychophysiological state and time perception of 90 participants. Three experimental conditions were created for the task performed during the waiting period (30 subjects per condition). Participants had to either freely use their smartphone, perform a non-digital task (sudoku), or wait (i.e. passive digital deprivation). Indicators of electrodermal activity and heart rate variability were calculated for the baseline and waiting periods, along with measures of subjective affective state. Four measures of time perception were also collected after the waiting period. Regardless of their experimental condition, the participants underestimated the duration of the waiting period on average (5 min 44 vs. 7 min 30). Passive digitally deprived participants felt that the time passed more slowly and were more bored than participants engaged in a task, regardless of whether the task was digital or not. Sudoku induced more positive affect and was more cognitively engaging than the free use of a smartphone regarding heart rate variability measures. The results suggest that performing a digital task (free smartphone use) is less cognitively demanding than a non-digital task (sudoku) and alters time perception in the same way. The digital nature of a task might also impact one’s affective reaction. A similar study in the field with longer or repetitive digital deprivation periods and a different non-digital task to perform (e.g., reading news) should be conducted to confirm the results obtained in this study.

Meaning in life and nature connectedness are indicators of a healthy life and correlate with health and well-being. We conducted a validation study of German versions of the Meaning in Life Questionnaire (Steger et al. 2006) and Nature Connection Index (Richardson et al. 2019) and assessed mindfulness as a trait and personality (big five personality traits) among participating students (n = 353). Results indicated a significant positive correlation between nature connectedness and presence of meaning in life. Presence of meaning correlated significantly with less neuroticism, more openness to new experiences, greater conscientiousness, and moderately with the two mindfulness subscales, ‘acceptance’ and ‘presence’. Search for meaning was associated with more neuroticism and less acceptance. A higher nature-connectedness score correlated with more presence and acceptance (mindfulness), greater openness, and less neuroticism (personality traits). Furthermore, we introduce a nature-assisted model of meaning fulfilment that can be applied in healthcare practices, counselling, and (psycho-) therapeutic treatment. Our results contribute to growing evidence on the preventive and curative effects of nature connectedness and meaning in life and their role as health-related resources. Nature connectedness and meaning in life are effective resources considering various aspects related to (global) crises such as climate change and the corona pandemic.

The P3b is a prominent event-related potential (ERP) with maximal amplitude between 250 ms and 500 ms after the onset of a rare target stimulus within a sequence of standard non-target stimuli (oddball paradigm). Several studies found reduced P3b amplitudes in patients with schizophrenia compared to neurotypicals. Our work and the literature suggest that temporal imprecision may play a large pathophysiological role in schizophrenia. Here, we investigated whether reduced P3b amplitudes result from reduced neural activity (power) or temporal imprecision (inter-trial phase coherence; ITC) in delta and theta bands, using two EEG datasets from different studies with different oddball paradigms (Study 1: 19 patients with schizophrenia and 17 matched controls, Study 2: 26 patients and 26 controls). Both studies revealed typical P3b ERP components with smaller amplitudes in patients. Reduced ITC in patients was found in the delta band, which correlated with P3b peak amplitudes for all participant groups (ρ = 0.58-0.89). In Study 1, we also found significant differences between patients and controls in ITC in the theta band, which also correlated with P3b peak amplitudes (patients' ρ = 0.64, controls' ρ = 0.54). This was not found in Study 2. The results indicate that P3b amplitude reduction in patients with schizophrenia is linked to a reduction in temporal precision of neural activity. These results expand the notion of imprecision in temporal processing at phenomenological, psychological, and neurological levels that have been related to disturbances of the sense of self. They confirm that temporal imprecision may be more important than the reduction of neural activity itself.

In accordance with Bud (A.D.) Craig's theories, we maintain that ascending physiological signals in their temporal dynamics are a necessary prerequisite for human time judgments. Functional neuroimaging and psychophysiological evidence have increasingly demonstrated that the subjective judgment of time is based on the physical and emotional self. The psychological literature reveals how emotions and related body feelings shape subjective time. Empirical studies of altered states of consciousness, namely meditative states, are also of prime interest as the perception of the physical state is strongly modulated and thereby affects the subjective experience of time. Our conclusion is that the sense of time is strongly embodied.

During visual imagination, a perceptual representation is activated in the absence of sensory input. This is sometimes described as seeing with the mind's eye. A number of physiological studies indicate that the brain uses more or less the same neural resources for visual perception of sensory information and visual imagination. The intensity of visual imagination is typically assessed with questionnaires, while more objective measures are missing. Aim of the present study was, to test a new experimental paradigm that may allow to objectively quantify imagination. For this, we used priming and adaptation effects during observation of ambiguous figures. Our perception of an ambiguous stimulus is unstable and alternates spontaneously between two possible interpretations. If we first observe an unambiguous stimulus variant (the conditioning stimulus), the subsequently presented ambiguous stimulus can either be perceived in the same way as the test stimulus (priming effect) or in the opposite way (adaptation effect) as a function of the conditioning time. We tested for these conditioning effects (priming and adaptation) using an ambiguous Necker Cube and an ambiguous Letter /Number stimulus as test stimuli and unambiguous variants thereof as conditioning stimuli. In a second experimental condition, we tested whether the previous imagination of an unambiguous conditioning stimulus variant - instead of its observation - can have similar conditioning effects on the subsequent test stimulus. We found no systematic conditioning effect on the group level, neither for the two stimulus types (Necker Cube stimuli and Letter /Number stimuli) nor for the two conditions (Real and Imaginary). However, significant correlations between effects of Real and Imaginary Condition were observed for both stimulus types. The absence of conditioning effects at the group level may be explained by using only one conditioning time, which may fit with individual priming and adaptation constants of some of our participants but not of others. Our strong correlation results indicate that observers with clear conditioning effects have about the same type (priming or adaptation) and intensity of imaginary conditioning effects. As a consequence, not only past perceptual experiences but also past imaginations can influence our current percepts. This is further confirmation that the mechanisms underlying perception and imagination are similar. Our post-hoc qualitative observations from three self-defined aphantasic observers indicate that our paradigm may be a promising objective measure to identify aphantasia.

In recent years, there has been a renewed interest in the conceptual and empirical study of altered states of consciousness (ASCs) induced pharmacologically or otherwise, driven by their potential clinical applications. To draw attention to the rich history of research in this domain, we review prominent classification schemes that have been proposed to introduce systematicity in the scientific study of ASCs. The reviewed ASC classification schemes fall into three groups according to the criteria they use for categorization: (1) based on the nature, variety, and intensity of subjective experiences (state-based), including conceptual descriptions and psychometric assessments, (2) based on the technique of induction (method-based), and (3) descriptions of neurophysiological mechanisms of ASCs (neuro/physio-based). By comparing and extending existing classification schemes, we can enhance efforts to identify neural correlates of consciousness, particularly when examining mechanisms of ASC induction and the resulting subjective experience. Furthermore, an overview of what defining ASC characteristics different authors have proposed can inform future research in the conceptualization and quantification of ASC subjective effects, including the identification of those that might be relevant in clinical research. This review concludes by clustering the concepts from the state-based schemes, which are suggested for classifying ASC experiences. The resulting clusters can inspire future approaches to formulate and quantify the core phenomenology of ASC experiences to assist in basic and clinical research.

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 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 s 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 did not 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 8 s and the 4 s intervals. The larger the increase in HEP2, the greater the under-reproduction of the estimated duration. 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 toward time. We conclude that interoceptive awareness (SAQ) and cortical responses to heartbeats (HEP) predict duration reproductions, emphasizing the embodied nature of time.

The electroretinogram (ERG), a non-invasive electrophysiological tool used in ophthalmology, is increasingly applied to investigate neural correlates of depression. The present study aimed to reconsider previous findings in major depressive disorder (MDD) reporting (1) a diminished contrast sensitivity and (2) a reduced patten ERG (PERG) amplitude ratio, and additionally, to assess (3) the photopic negative response (PhNR) from the flash ERG (fERG), with the RETeval® device, a more practical option for clinical routine use. We examined 30 patients with a MDD and 42 healthy controls (HC), assessing individual contrast sensitivity thresholds with an optotype-based contrast test. Moreover, we compared the PERG ratio, an established method for early glaucoma detection, between both groups. The handheld ERG device was used to measure amplitudes and peak times of the fERG components including a-wave, b-wave and PhNR in both MDD patients and HCs. MDD patients exhibited diminished contrast sensitivity together with a reduced PERG ratio, compared to HC. With the handheld ERG device, we found reduced a-wave amplitudes in MDD, whereas no significant differences were observed in the fERG b-wave or PhNR between patients and controls. The reduced contrast sensitivity and PERG ratio in MDD patients supports the hypothesis that depression is associated with altered visual processing. The findings underscore the PERG's potential as a possible objective marker for depression. The reduced a-wave amplitude recorded with the RETeval® system in MDD patients might open new avenues for using handheld ERG devices as simplified approaches for advancing depression research compared to the PERG.

With neutron diffraction, the local stress and texture of metallic components can be analyzed non-destructively. For both, highly accurate positioning of the sample is essential, requiring the measurement at the same sample location from different directions. Current sample-positioning systems in neutron diffraction instruments combine XYZ tables and Eulerian cradles to enable the accurate six-degree-of-freedom (6DoF) handling of samples. However, these systems are not flexible enough. The choice of the rotation center and their range of motion are limited. Industrial six-axis robots have the necessary flexibility, but they lack the required absolute accuracy. This paper proposes a visual servoing system consisting of an industrial six-axis robot enhanced with a high-precision multi-camera tracking system. Its goal is to achieve an absolute positioning accuracy of better than 50μm. A digital twin integrates various data sources from the instrument and the sample in order to enable a fully automatic measurement procedure. This system is also highly relevant for other kinds of processes that require the accurate and flexible handling of objects and tools, e.g., robotic surgery or industrial printing on 3D surfaces.

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.

Since the retina shares its embryological origin with the central nervous system, optical coherence tomography (OCT), an imaging technique frequently employed in ophthalmology to analyze the macula and intraretinal layer thicknesses and volumes, has recently become increasingly important in psychiatric research. We examined 34 autistic and 31 neurotypical adults (NT) using OCT. Autistic adults had reduced overall macular and outer nuclear layer (ONL) thickness and volume compared to NT. Both macular and ONL thickness showed significant inverse associations with the severity of autistic symptoms measured with the Social Responsiveness Scale 2 (SRS-2). Longitudinal studies across different age groups are required to clarify whether retinal changes may represent a possible trait marker.

The range of phenomena that can be induced by psychedelic substances is broad and variable, including effects on perception, cognition, and emotion. The umbrella term “psychedelic phenomenology” is used to refer to a combination of altered experiential features, such as hallucinations or ego dissolution, which together constitute a psychedelic experience. However, there is no consensus on the set of alterations of consciousness that qualifies an altered state to be a “psychedelic state.” In this chapter we summarize the most commonly discussed changes in subjective experiences which could be seen as “core features” of psychedelic experiences. While acknowledging the rich history of pioneering phenomenological work of the last century, this chapter focuses on more recent developments in the quantitative work on the assessment of these phenomena. We also address the under-researched phenomenology of distressing effects, often referred to as “challenging experiences” or “bad trips,” and point to their importance in understanding the therapeutic potential and risks associated with psychedelic phenomenology. Historically, one can find many links between psychedelic phenomenology and the phenomenology of psychopathology. We stress the importance to refine the assessment and description also of distressing effects, to identify factors that promote acute experiences which are beneficial and limit those which can have potentially harmful long-term effects.

INTRODUCTION: We tested and validated the German version of a new instrument for measuring "wakefulness," defined as "an expansive, higher-functioning, and stable state of being in which a person's vision of and relationship to the world are transformed, along with their subjective experience, their sense of identity and their conceptual outlook" (Taylor, 2017, p. 22). METHODS: In order to test the construct validity of the new instrument (Inventory of Secular/Spiritual Wakefulness; WAKE-16), we performed a parametric comparison between a group of expert meditators (n=36) with a history of predominantly meditating in silence and demographically matched non-meditators (n=36) for the WAKE-16 and two conceptually related questionnaires of mindfulness and emotion regulation. RESULTS: Significantly higher scores for the meditators on the WAKE-16 indicate construct validity of the new instrument. Meditators scored higher on the two mindfulness subscales "presence" and "acceptance," as well as on the SEE subscales of emotion regulation and body-related symbolization of emotions. Within the group of meditators, there were significant correlations between wakefulness and mindfulness, accepting one's own emotions, and experiencing overwhelming emotions. The only significant correlation in non-meditators was found between wakefulness and accepting one's own emotions. DISCUSSION: The new instrument shows construct validity by discriminating between the two groups. Correlations between wakefulness and related psychological constructs indicate convergent validity. Future studies could attempt to increase discriminatory accuracy of the definition of wakefulness, as well as finding objective methods of measuring.

In an earlier study, Rupert Sheldrake, Pam Smart, and Michael Nahm reviewed accounts of end-of-life experiences (ELEs) involving non-human animals. They showed animal ELEs to be similar to human ELEs, suggesting common underlying processes. Here, we consider apparent after-death communications (ADCs) from non-human animals and compare them to accounts of ADCs from humans. We collected 442 accounts of animal ADCs from our own appeals and from reports in the literature. We found a close resemblance between ADCs from animals and from humans in the types of experience—dream visitations, a sense of presence, visual, auditory, tactile, and olfactory apparitions, and psychokinetic effects. As with human ADCs, the great majority of animal ADCs were reported to have occurred in the first hours or days after death, with a dramatic falling off over time. Moreover, our data show that people grieve their pets in much the same fashion as they grieve their human loved ones, suggesting that human bereavement studies would do well to take into account the animal data to which we draw attention. Doing so may help clarify issues regarding the fundamental nature of the experiences—determining whether they are best regarded as internal hallucinations, as living-agent-psi-mediated subjective or objective phenomena, or as actual contacts with the deceased—which in turn carries implications not only for academic studies of bereavement but for clinical practice with the bereaved.

The sporadic occurrence of unusually enhanced mental clarity before death has been documented over time and cultures, and reported in patients with and without neurodegenerative diseases, psychiatric disorders, and other neurocognitive deficits, as well as those with nonterminal and terminal conditions. Using a purposive sampling method via existing professional networks, clinical presentations of terminal lucidity in pediatric populations, as witnessed by pediatric oncologists and medical personnel, were solicited. We document clinical presentations suggestive of terminal lucidity in children, which were compiled by their attending physician at two large tertiary pediatric hospitals. Unanticipated and unexplained changes in mental clarity, verbal communication, and/or physical capability in the days and hours before the death of the pediatric patients were observed. Each patient's medical condition should not have allowed for such changes. The phenomenon known as terminal lucidity provides a conceptual framework for these deviations, although more systematic documentation and clinical research is required before definitive conclusions can be drawn.

PURPOSE: Perception of the motion quartet (MQ) alternates between horizontal and vertical motion, with a bias toward vertical motion. This vertical bias has been explained by the dominance of intrahemispheric processing. In albinism, each hemisphere receives input from both visual hemifields owing to enhanced crossing of the optic nerves at the optic chiasm. This might affect the perception of the ambiguous MQ and particularly the vertical bias. METHODS: The effect of optic nerve misrouting in persons with albinism and nystagmus (PWA, n = 14) on motion perception for MQ was compared with healthy controls (HC; n = 11) and with persons with nystagmus in the absence of optic nerve misrouting (PWN; n = 12). We varied the ratio of horizontal and vertical distances of MQ dots (aspect ratio [AR]) between 0.75 and 1.25 and compared the percentages of horizontal and vertical motion percepts as a function of AR between groups. RESULTS: For HC, the probability of vertical motion perception increased as a sigmoid function with increasing AR exhibiting the expected vertical percept bias (mean, 58%; median, 54%; vertical motion percepts). PWA showed a surprisingly strong horizontal bias independent of the AR with a mean of 11% (median, 10%) vertical motion percepts. The PWN was in between PWA and HC, with a mean of 34% (median, 47%) vertical perception. Nystagmus alone is unlikely to explain this pattern of results because PWA and PWN had comparable fixation stabilities. CONCLUSIONS: The strong horizontal bias observed in PWA and PWN might partly result from the horizontal nystagmus. The even stronger horizontal bias in PWA indicates that the intrahemispherical corepresentation of both visual hemifields may play an additional role. The altered perception of the MQ in PWA opens opportunities to (i) understand the interplay of stability and plasticity in altered visual pathway conditions and (ii) identify visual pathway abnormalities with a perception-based test using the MQ.

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.