Dreaming during a pandemic: Low incorporation of COVID-19-specific themes and lucidity in dreams of psychiatric patients and healthy controls

The present study examined the impact of the COVID-19 pandemic on the emotional quality of dreams, the incorporation of pandemic-related themes, and the occurrence of lucid dreaming. Dream reports and lucidity ratings of psychiatric outpatients (n = 30) and healthy controls (n = 81) during two lockdowns in Germany were compared to those of healthy controls (n = 33) before the pandemic. Results confirmed previous reports that pandemic-specific themes were incorporated into dreams. Overall, however, incorporation into dreams was rare. Contrary to expectations, psychiatric outpatients did not differ from controls in the frequency of dream incorporation of pandemic-related content. Moreover, incorporation was independent of psychiatric symptoms and loneliness. Loneliness was, however, associated with threat-related content, suggesting that it represents a risk for bad dreams but not for crisis-specific dream incorporation. Regarding lucid dreaming, both groups had similar scores for its underlying core dimensions, i.e., insight, control, and dissociation, during the two lockdowns. Scores for control and dissociation but not insight were lower compared to the pre-pandemic sample. Our working hypothesis is that REM sleep during lockdowns intensified as a means of increased emotional consolidation, rendering the associated mental state less hybrid and thereby less lucid. (AU)

Dreaming during a pandemic: Low incorporation of COVID-19-specific themes and lucidity in dreams of psychiatric patients and healthy controls.

The present study examined the impact of the COVID-19 pandemic on the emotional quality of dreams, the incorporation of pandemic-related themes, and the occurrence of lucid dreaming. Dream reports and lucidity ratings of psychiatric outpatients (n = 30) and healthy controls (n = 81) during two lockdowns in Germany were compared to those of healthy controls (n = 33) before the pandemic. Results confirmed previous reports that pandemic-specific themes were incorporated into dreams. Overall, however, incorporation into dreams was rare. Contrary to expectations, psychiatric outpatients did not differ from controls in the frequency of dream incorporation of pandemic-related content. Moreover, incorporation was independent of psychiatric symptoms and loneliness. Loneliness was, however, associated with threat-related content, suggesting that it represents a risk for bad dreams but not for crisis-specific dream incorporation. Regarding lucid dreaming, both groups had similar scores for its underlying core dimensions, i.e., insight, control, and dissociation, during the two lockdowns. Scores for control and dissociation but not insight were lower compared to the pre-pandemic sample. Our working hypothesis is that REM sleep during lockdowns intensified as a means of increased emotional consolidation, rendering the associated mental state less hybrid and thereby less lucid.

Adapting to a major crisis: Sleep and mental health during two lockdowns.

The present study aimed at investigating the impact of the pandemic on sleep and mental health in healthy individuals (n = 78) as well as in psychiatric outpatients (n = 30) during the first and the second lockdown in Germany, in March and November 2020, respectively. Sleep quality and anxiety were worse in patients compared with controls during both lockdowns. Further, patients but not controls exhibited higher levels of depression and overall psychiatric symptomatology during the second lockdown. No differences were found in the perceived threat evoked by the pandemic. The data suggest that healthy individuals adapt flexibly to the difficult situation over the time course of the pandemic, whereas psychiatric patients seem to get worse, indicating difficulties in adapting to stressful circumstances.

Investigating Nuisance Effects Induced in EEG During tACS Application.

Transcranial alternating-current stimulation (tACS) in the frequency range of 1-100 Hz has come to be used routinely in electroencephalogram (EEG) studies of brain function through entrainment of neuronal oscillations. It turned out, however, to be highly non-trivial to remove the strong stimulation signal, including its harmonic and non-harmonic distortions, as well as various induced higher-order artifacts from the EEG data recorded during the stimulation. In this paper, we discuss some of the problems encountered and present methodological approaches aimed at overcoming them. To illustrate the mechanisms of artifact induction and the proposed removal strategies, we use data obtained with the help of a schematic demonstrator setup as well as human-subject data.

Food has the right of way: Evidence for prioritised processing of visual food stimuli irrespective of eating style.

Visual attention for food is likely to play an important role for overeating. The attentional bias for visual food stimuli was investigated with respect to self-reported restrained, external and emotional eating style. Using a Rapid Serial Visual Presentation task (N = 103), the effects of visual food stimuli in the context of the attentional blink were examined. Food targets enhanced the attentional blink when presented as first targets in a rapid stream of pictures and impaired the identification of preceding non-food targets in terms of a backward interference when presented as second targets. Task irrelevant food distractors interfered with the identification of subsequent non-food targets. The effects provide evidence for a prioritisation of food stimuli in the allocation of attentional resources. The attentional bias for food emerged as a universal phenomenon irrespective of personal eating style. Therefore, enhanced attention for visual food stimuli seems to play no direct causal role in eating styles associated with overeating.

On ignoring words-exploring the neural signature of inhibition of affective words using ERPs.

In the present study event-related potentials were used to shed further light on the neural signatures of active inhibition of the (affective) content of written words. Intentional inhibition was implemented by simply asking participants (N = 32) to ignore single words that served as primes in an affective priming (AP) task. In AP, evaluations about a priori neutral targets typically tend to shift towards the valence of preceding primes, denoting an AP effect (APE). To create a plausible cover-context emphasizing the usefulness of word inhibition, participants were asked to avoid this shift, that is, to make unbiased target evaluations. Ignoring the prime words was suggested as the most efficient strategy to achieve this aim. Effective inhibition of the words' (affective) content, as suggested by a significant APE present for words processed without any further instruction, but not for ignored ones, affected multiple stages of processing. On the neuronal level, word inhibition was characterized by reduced early perceptual (left-lateralized word-specific N170), later attentional (parietal P300), and affective-semantic processing (reduced posterior semantic asymmetry). Furthermore, an additional recruitment of top-down inhibitory control processes, which was mirrored in increased amplitudes of medial-frontal negativity, showed to be critically involved in intentional word inhibition.

Effects of distinctiveness and memory on lateralized and unlateralized brain-electrical activity during visual word encoding.

The present study investigated a recently introduced left-lateralized component in the event-related potential (ERP), the posterior semantic asymmetry (PSA), in the context of an isolation paradigm. The PSA is a relative negativity that is most pronounced at temporoparietal electrodes, peaks around 300 ms, and is assumed to reflect early semantic processing of visual words. A free-recall, word-list-learning paradigm was conducted. The learning list comprised two stimuli which were physically isolated from the other stimuli (by different font size or different typeface). The typical behavioral isolation effect with higher recall for isolated stimuli was observed. Furthermore, ERP effects of stimulus type and subsequent memory were analyzed. A left-lateralized negativity that matched the topography of the PSA but occurred somewhat later showed an effect of stimulus distinctiveness, with increased amplitudes for isolates, thus suggesting their deeper semantic processing. However, PSA amplitude did not predict subsequent recall. Unlateralized ERPs replicated previous findings of a greater late frontal positivity during elaborated encoding of both isolated stimuli and subsequently recalled stimuli. This recall effect was greater for isolated than standard stimuli. We argue that physical distinctiveness during encoding facilitates recall to the extent that it promotes the frontally-mediated processes that predict better recall in general.

The posterior semantic asymmetry (PSA): specific to written not auditory semantic word processing.

The present study replicates the finding of a posterior semantic asymmetry (PSA; Koppehele-Gossel et al., Brain Lang 157-158:35-43, 2016), a lateralized event-related potential (ERP) suggested to reflect semantic activation from visually presented single words. This ERP negativity, derived from the subtraction of right-side from left-side scalp activity, again peaked around 300 ms at temporoparietal electrodes and was more pronounced in a semantic task, compared to both a silent naming task and a passive viewing task. With analogous tasks, no comparable negativity was found for auditorily presented words. This suggests that the PSA specifically reflects visual-verbal semantic activation. For auditory words, a later variation with the demands on semantic processing was observed for a left-lateralized late positive potential (500-800 ms), which, however, showed a remarkably similar topography as the PSA. Thus, while semantic processing of visual and auditory words converges on left temporoparietal brain areas, the exact patterns of brain electrical activation in terms of time course and polarity are different.

The posterior semantic asymmetry (PSA): An early brain electrical signature of semantic activation from written words.

This study replicates and extends the findings of Koppehele-Gossel, Schnuerch, and Gibbons (2016) of a posterior semantic asymmetry (PSA) in event-related brain potentials (ERPs), which closely tracks the time course and degree of semantic activation from single visual words. This negativity peaked 300 ms after word onset, was derived by subtracting right- from left-side activity, and was larger in a semantic task compared to two non-semantic control tasks. The validity of the PSA in reflecting the effort to activate word meaning was again attested by a negative correlation between the meaning-specific PSA increase and verbal intelligence, even after controlling for nonverbal intelligence. Extending prior work, current source density (CSD) transformation was used. CSD results were consistent with a left temporo-parietal cortical origin of the PSA. Moreover, no PSA was found for pictorial material, suggesting that the component reflects early semantic processing specific to verbal stimuli.

Affective priming and cognitive load: Event-related potentials suggest an interplay of implicit affect misattribution and strategic inhibition.

Prior research suggests that the affective priming effect denoting prime-congruent evaluative judgments about neutral targets preceded by affective primes increases when the primes are processed less deeply. This has been taken as evidence for greater affect misattribution. However, no study so far has combined an experimental manipulation of the depth of prime processing with the benefits of ERPs. Forty-seven participants made like/dislike responses about Korean ideographs following 800-ms affective prime words while 64-channel EEG was recorded. In a randomized within-subject design, three levels of working-memory load were applied specifically during prime processing. Affective priming was significant for all loads and even tended to decrease over loads, although efficiency of the load manipulation was confirmed by reduced amplitudes of posterior attention-sensitive prime ERPs. Moreover, ERPs revealed greater explicit affective discrimination of the prime words as load increased, with strongest valence effects on central/centroparietal N400 and on the parietal/parietooccipital late positive complex under high load. This suggests that (a) participants by default tried to inhibit the processing of the prime's affect, and (b) inhibition more often failed under cognitive load, thus causing emotional breakthrough that resulted in a binding of affect to the prime and, hence, reduced affect misattribution to the target. As a correlate of affective priming in the target ERP, medial-frontal negativity, a well-established marker of (low) stimulus value, increased with increasing negative affect of the prime. Findings support implicit prime-target affect transfer as a major source of affective priming, but also point to the role of strategic top-down processes.

A template model of embodiment while dreaming: Proposal of a mini-me.

Dreams are usually centered around a dream self capable of tasks generally impossible in waking, e.g. flying or walking through walls. Moreover, the bodily dream self appears relatively stable and insensitive to changes of the embodied wake self, raising the question of whether and to what extent the dream self is embodied. To further explore its determinants, we tested whether the dream self would be affected by either pre-sleep focused attention to a body part or by its experimental alteration during the day. Choosing a repeated-measures design, we analyzed how often key words reflecting the experimental manipulations appeared in the dream reports. Results suggest that the dream self is not affected by these manipulations, strengthening the hypothesis that, in the majority of dreams, the dream self is only weakly embodied, utilizing a standard template of embodiment akin to a prototype of self operating independently from the physical waking self.

A brain electrical signature of left-lateralized semantic activation from single words.

Lesion and imaging studies consistently indicate a left-lateralization of semantic language processing in human temporo-parietal cortex. Surprisingly, electrocortical measures, which allow a direct assessment of brain activity and the tracking of cognitive functions with millisecond precision, have not yet been used to capture this hemispheric lateralization, at least with respect to posterior portions of this effect. Using event-related potentials, we employed a simple single-word reading paradigm to compare neural activity during three tasks requiring different degrees of semantic processing. As expected, we were able to derive a simple temporo-parietal left-right asymmetry index peaking around 300ms into word processing that neatly tracks the degree of semantic activation. The validity of this measure in specifically capturing verbal semantic activation was further supported by a significant relation to verbal intelligence. We thus posit that it represents a promising tool to monitor verbal semantic processing in the brain with little technological effort and in a minimal experimental setup.

Validity of content-based techniques to distinguish true and fabricated statements: A meta-analysis.

Within the scope of judicial decisions, approaches to distinguish between true and fabricated statements have been of particular importance since ancient times. Although methods focusing on "prototypical" deceptive behavior (e.g., psychophysiological phenomena, nonverbal cues) have largely been rejected with regard to validity, content-based techniques constitute a promising approach and are well established within the applied forensic context. The basic idea of this approach is that experience-based and nonexperience-based statements differ in their content-related quality. In order to test the validity of the most prominent content-based techniques, criteria-based content analysis (CBCA) and reality monitoring (RM), we conducted a comprehensive meta-analysis on English- and German-language studies. Based on a variety of decision criteria, 56 studies were included revealing an overall effect size of g = 1.03 (95% confidence interval [0.78, 1.27], Q = 420.06, p < .001, I2 = 92.48%, N = 3,429). There was no significant difference in the effectiveness of CBCA and RM. Additionally, we investigated a number of moderator variables, such as characteristics of participants, statements, and judgment procedures, as well as general study characteristics. Results showed that the application of all CBCA criteria outperformed any incomplete CBCA criteria set. Furthermore, statement classification based on discriminant functions revealed higher discrimination rates than decisions based on sum scores. Finally, unpublished studies showed higher effect sizes than studies published in peer-reviewed journals. All results are discussed in terms of their significance for future research (e.g., developing standardized decision rules) and practical application (e.g., user training, applying complete criteria set). (PsycINFO Database Record

Multiple neural signatures of social proof and deviance during the observation of other people's preferences.

Detecting one's agreement with or deviation from other people, a key principle of social cognition, relies on neurocognitive mechanisms involved in reward processing, mismatch detection, and attentional orienting. Previous studies have focused on explicit depictions of the (in)congruency of individual and group judgments. Here, we report data from a novel experimental paradigm in which participants first rated a set of images and were later simply confronted with other individuals' ostensible preferences. Participants strongly aligned their judgments in the direction of other people's deviation from their own initial rating, which was neither an effect of regression toward the mean nor of evaluative conditioning (Experiment 1). Most importantly, we provide neurophysiological evidence of the involvement of fundamental cognitive functions related to social comparison (Experiment 2), even though our paradigm did not overly boost this process. Mismatches, as compared to matches, of preferences were associated with an amplitude increase of a broadly distributed N400-like deflection, suggesting that social deviance is represented in the human brain in a similar way as conflicts or breaches of expectation. Also, both early (P2) and late (LPC) signatures of attentional selection were significantly modulated by the social (mis)match of preferences. Our data thus strengthen and valuably extend previous findings on the neurocognitive principles of social proof.

Weak encoding of faces predicts socially influenced judgments of facial attractiveness.

Conforming to the majority can be seen as a heuristic type of judgment, as it allows the individual to easily choose the most accurate or most socially acceptable type of behavior. People who process the currently to-be-judged items in a superficial, heuristic way should tend to conform to group judgment more than people processing these items in a systematic and elaborate way. We investigated this hypothesis using electroencephalography (EEG), analyzing whether the strength of neural encoding of faces was related to the tendency to adopt a group's evaluative judgments regarding these faces. As expected, we found that the amplitude of the N170, a specific neural correlate of face encoding, was inversely related to conformity across participants: The weaker the faces were encoded, the more the majority response regarding the faces' attractiveness was adopted instead of relying on the actual qualities of the faces. Applying neurophysiological methodology, we thus provide support for previous claims, based on behavioral data and theorizing, that social conformity is a heuristic type of judgment. We propose that weak encoding of judgment-relevant information is a typical, possibly even necessary, precursor of socially adjusted judgments, irrespective of one's current motivational goal (i.e., to be accurate or accepted).

Induction of self awareness in dreams through frontal low current stimulation of gamma activity.

Recent findings link fronto-temporal gamma electroencephalographic (EEG) activity to conscious awareness in dreams, but a causal relationship has not yet been established. We found that current stimulation in the lower gamma band during REM sleep influences ongoing brain activity and induces self-reflective awareness in dreams. Other stimulation frequencies were not effective, suggesting that higher order consciousness is indeed related to synchronous oscillations around 25 and 40 Hz.

Lucid dreaming: an age-dependent brain dissociation.

The current study focused on the distribution of lucid dreams in school children and young adults. The survey was conducted on a large sample of students aged 6-19 years. Questions distinguished between past and current experience with lucid dreams. Results suggest that lucid dreaming is quite pronounced in young children, its incidence rate drops at about age 16 years. Increased lucidity was found in those attending higher level compared with lower level schools. Taking methodological issues into account, we feel confident to propose a link between the natural occurrence of lucid dreaming and brain maturation.