Perceptual Deprivation Research Articles

Visual hallucinations induced by Ganzflicker and Ganzfeld differ in frequency, complexity, and content

Visual hallucinations can be phenomenologically divided into those of a simple or complex nature. Both simple and complex hallucinations can occur in pathological and non-pathological states, and can also be induced experimentally by visual stimulation or deprivation—for example using a high-frequency, eyes-open flicker (Ganzflicker) and perceptual deprivation (Ganzfeld). Here we leverage the differences in visual stimulation that these two techniques involve to investigate the role of bottom-up and top-down processes in shifting the complexity of visual hallucinations, and to assess whether these techniques involve a shared underlying hallucinatory mechanism despite their differences. For each technique, we measured the frequency and complexity of the hallucinations produced, utilising button presses, retrospective drawing, interviews, and questionnaires. For both experimental techniques, simple hallucinations were more common than complex hallucinations. Crucially, we found that Ganzflicker was more effective than Ganzfeld at eliciting simple hallucinations, while complex hallucinations remained equivalent across the two conditions. As a result, the likelihood that an experienced hallucination was complex was higher during Ganzfeld. Despite these differences, we found a correlation between the frequency and total time spent hallucinating in Ganzflicker and Ganzfeld conditions, suggesting some shared mechanisms between the two methodologies. We attribute the tendency to experience frequent simple hallucinations in both conditions to a shared low-level core hallucinatory mechanism, such as excitability of visual cortex, potentially amplified in Ganzflicker compared to Ganzfeld due to heightened bottom-up input. The tendency to experience complex hallucinations, in contrast, may be related to top-down processes less affected by visual stimulation.

The cloud of unknowing: Cognitive dedifferentiation in whole-body perceptual deprivation.

An altered sensory environment, especially a homogeneous one like a ganzfeld, can induce a wide range of experiences in people immersed in it. The ganzfeld of our current focus is the OVO Whole-Body Perceptual Deprivation chamber (OVO-WBPD). Previous literature has found this specific immersive environment to be capable of softening and dissolving perception of boundaries across time and sensory modalities, among other domains. Since recent published electrophysiological results demonstrated that immersion in the OVO-WBPD significantly increased delta and beta activity, in the left inferior frontal cortex and in the left insula, we sought to better understand the subjective experiences of participants utilizing this altered sensory environment via semi-qualitative methodology. Consequently, semi-structured interviews of participants were analyzed by three independent evaluators focusing on several domains of experience often reported in perceptual deprivation environments. We found a significantly shared consensus on the presence of experiences belonging to semantic domains of altered experience, demonstrating that the OVO-WBPD chamber consistently elicits positively connotated, bodily-oriented and cognitively dedifferentiated subjective states of consciousness in the majority of 32 examined participants.

Lockdown and visual hallucinations in older people: a community perspective

ObjectiveAfter COVID-19 was declared as a pandemic, different countries have enforced lockdowns, and shielding to mitigate the spread of the virus as preventing loss of lives was the priority.Our aim is to look for possible explanations for increased rates of visual hallucinations presented to Community Mental Health Teams for Older People during the period of lockdown.Case reportA review of clinical cases presenting with new onset visual hallucinations to the Community Mental Health Teams for Older People during the lockdown period in 2020 was summarised in two case scenarios. One scenario represents cases with known background of dementia, while the other scenario represents new referrals during the lockdown period with no known psychiatric background. In those cases, the visual hallucinations started during lockdown with no clear cause, did not respond to psychotropic medications, physical health investigations were all normal and hallucinations improved markedly with the end of the lockdown and social isolation.DiscussionFrom clinical practice point of view, during the period of lockdown in the COVID-19 pandemic, visual hallucinations has been one of the commonest presentations reported to the Community Mental Health Teams for Older People. Families were calling frequently reporting that their loved ones were “seeing things”. Possible underlying causes include: social isolation, sensory and perceptual deprivation, visual impairment and Charles Bonnet syndrome, lack of cognitive stimulation activities with progress of dementia, superimposed delirium, in addition to depression secondary to loneliness, reduction in community support, increased alcohol consumption and negative effects of repeated media consumption.ConclusionThere has been a marked increase in reporting visual hallucinations in the shielding older people population in the community during the period of lockdown in the COVID-19 pandemic. This shielded population was not exposed to COVID-19, so it didn't give an explanation to this new phenomenon. Though there are multiple possible causative factors, the effect of the lockdown itself with its resultant social isolation and sensory deprivation remains to be the most significant. Shielding the older people population throughout the COVID-19 pandemic came as an essential measure as the physical safety and preventing loss of lives was the priority; however the lockdown had significant negative effects on the mental health of the shielding population. It remains unclear if those negative effects are going to be reversible in the future, resulting in poor quality of life.

The multimodal Ganzfeld-induced altered state of consciousness induces decreased thalamo-cortical coupling

Different pharmacologic agents have been used to investigate the neuronal underpinnings of alterations in consciousness states, such as psychedelic substances. Special attention has been drawn to the role of thalamic filtering of cortical input. Here, we investigate the neuronal mechanisms underlying an altered state of consciousness (ASC) induced by a non-pharmacological procedure. During fMRI scanning, N = 19 human participants were exposed to multimodal Ganzfeld stimulation, a technique of perceptual deprivation where participants are exposed to intense, unstructured, homogenous visual and auditory stimulation. Compared to pre- and post-resting-state scans, the Ganzfeld data displayed a progressive decoupling of the thalamus from the cortex. Furthermore, the Ganzfeld-induced ASC was characterized by increased eigenvector centrality in core regions of the default mode network (DMN). Together, these findings can be interpreted as an imbalance of sensory bottom-up signaling and internally-generated top-down signaling. This imbalance is antithetical to psychedelic-induced ASCs, where increased thalamo-cortical coupling and reduced DMN activity were observed.

Immersion, Absorption, and Spiritual Experience: Some Preliminary Findings.

Many traditions have utilized silent environments to induce altered states of consciousness and spiritual experiences. Neurocognitive explorations of spiritual experience can aid in understanding the underlying mechanism, but these are surprisingly rare. We present the verbal report and the electroencephalographic (EEG) alpha profile of a female participant scoring a maximal 34 on the Absorption Scale, recorded before and while she was immersed in a whole-body perceptual deprivation (WBPD) tank. We analyze her trancelike experience in terms of the imagery reported: a spaceship, corridors, doors, a man dressed in white, speaking to God, the sun, supernova, concentric images, and an out-of-body experience. Her report is indicative of a spiritual experience, given that she felt that she was “meeting God” in the laboratory. She exhibited both frontal and parietal left > right alpha power asymmetry at baseline, whereas in the WBPD condition, there was a global increase in alpha power and especially a sharp increase in right-frontal alpha power. Her verbal report and EEG alpha profile were compared to those of another female participant, also scoring high on absorption, whose verbal report was also indicative of a trancelike experience. For further comparison, we present the data for two participants scoring low on absorption. Spiritual experience that can be verbalized might be associated with a marked increase in right-frontal alpha power, as reported here. In contrast, a mystical experience characterized by ineffability would be indicated by a marked increase in left-frontal alpha power.

Electrophysiological and phenomenological effects of short-term immersion in an altered sensory environment.

We examined the spontaneous cerebral electrophysiology and phenomenology during short-term perceptual deprivation consisting of an edgeless visual field combined with monotonous auditory input that eliminated potential grounding cues (multimodal Ganzfeld). Subjects (N = 22) were instructed to self-report perceptual fading using a button press. Relaxed wakefulness with closed eyes and viewing of a time-varying stimulus array served as control conditions. The power of parieto-occipital alpha rhythms during perceptual deprivation was midway between the eyes-closed and eyes-open conditions, with a state-specific frequency acceleration. Oscillatory alpha power remained enhanced in the multimodal Ganzfeld relative to viewing time-varying signals, despite no indication of diminished brain arousal. Subjects experienced a range of perceptual phenomena while in the altered sensory environment and individuals with faster alpha oscillations self-reported a greater number of fading episodes. We suggest that alpha-band electroencephalogram (EEG) dynamics signal internally oriented mentation in response to brief perceptual deprivation.

Individual EEG alpha profiles are gender-dependent and indicate subjective experiences in Whole-Body Perceptual Deprivation

We use a unique environment of Whole Body Perceptual Deprivation (WBPD) to induce an altered state of consciousness (ASC) in our participants, and employ online EEG recording. We present individual EEG alpha profiles, and show how these data can be analyzed at the individual level. Our goal is to investigate to what degree subjective experience matches EEG alpha profile, and in particular, the various alpha hemispheric asymmetries observed in the frontal, parietal, and occipital lobes. Specifically, we consider positive (frontal L < R) or negative (frontal L > R) affect; a more verbal (L > R) or a more imagistic (R > L) mode of thinking; and a more trancelike (frontal > parietal) or more reflective (frontal < parietal) state of consciousness. Our results indicate that the individual alpha profiles are reflected in individual differences in subjective experience. However, the alpha profiles are confounded with the gender of the participant. Specifically, there is a predominant R > L asymmetry found for male participants, and a predominant L > R asymmetry found for female participants.

Fully immersed: State absorption and electrophysiological effects of the OVO Whole-Body Perceptual Deprivation chamber.

Absorption, the ability to highly focus attention, as well as openness to self-altering experiences, is an important psychological construct, closely related to deep-meditation states and other altered states of consciousness. Yet, little is known about the electrophysiological profile of states of absorption, possibly due to the difficulty to induce this state in the lab. While most studies have used a visual Ganzfeld (homogeneous perceptual field), here we use a novel technique of full immersion-the OVO Whole-Body Perceptual Deprivation (OVO-WBPD) chamber, which is an altered sensory environment in the form of a human-sized egg. Consequently, the aims of the current study were to investigate whether the OVO-WBPD chamber induces state absorption, using first-person reports, as well as to examine electrophysiological change following immersion in this altered sensory environment. Fourteen participants volunteered to participate in the study. Trait absorption was measured using the Tellegen Absorption Scale (TAS). State absorption was assessed by analyzing the content of the subjective reports, using sub-categories of the absorption construct (e.g., synesthesia). EEG was measured before and during a 20-min OVO-WBPD experience. Using exact low-resolution brain electromagnetic tomography (eLORETA), we analyzed change in oscillatory EEG activity and localized the generators of the scalp EEG power spectra following the OVO-WBPD. Our results show that OVO-WBPD immersion leads to a state of absorption in all participants. We also report significant increased oscillatory activity in the delta and beta bands, in the left inferior frontal cortex, with a peak in the sub-lobar of the left insula. In addition, a positive correlation was found between change in delta activity and trait absorption. The results are discussed in light of other meditative practices and altered states of consciousness.

Monocular Perceptual Deprivation from Interocular Suppression Temporarily Imbalances Ocular Dominance

Early visual experience sculpts neural mechanisms that regulate the balance of influence exerted by the two eyes on cortical mechanisms underlying binocular vision [1, 2], and experience's impact onthis neural balancing act continues into adulthood [3-5]. One recently described, compelling example of adult neural plasticity is the effect of patching one eye for a relatively short period of time: contrary to intuition, monocular visual deprivation actually improves the deprived eye's competitive advantage during a subsequent period of binocular rivalry [6-8], the robust form of visual competition prompted by dissimilar stimulation of the two eyes [9, 10]. Neural concomitants of this improvement in monocular dominance are reflected in measurements ofbrainresponsiveness following eye patching [11,12]. Here we report that patching an eye is unnecessary for producing this paradoxical deprivation effect: interocular suppression of an ordinarily visible stimulus being viewed by one eye is sufficient to produce shifts in subsequent predominance of that eye to an extent comparable to that produced by patching the eye. Moreover, this imbalance in eye dominance can also be induced by prior, extended viewing of two monocular images differing only in contrast. Regardless of how shifts in eye dominance are induced, the effect decays once the two eyes view stimuli equal in strength. These novel findings implicate the operation of interocular neural gain control that dynamically adjusts the relative balance of activity between the two eyes [13, 14].

A qualitative analysis of sensory phenomena induced by perceptual deprivation

Previous studies have shown that misperceptions and illusory experiences can occur if sensory stimulation is withdrawn or becomes invariant even for short periods of time. Using a perceptual deprivation paradigm, we created a monotonous audiovisual environment and asked participants to verbally report any auditory, visual or body-related phenomena they experienced. The data (analysed using a variant of interpretative phenomenological analysis) revealed two main themes: (1) reported sensory phenomena have different spatial characteristics ranging from simple percepts to the feeling of immersion in a complex multisensory environment and (2) the active contribution of the perceiver where participants report engaging in exploratory processes even when there is nothing to find. Detailed analysis of the qualitative data further showed that participants who reported more perceptual phenomena were more likely to report internal bodily sensations, move more during the experiment and score higher on the Revised Hallucination Scale than those reporting fewer percepts explicitly linking perceptual deprivation to somatic phenomena. The results demonstrate how the variety of sensory experiences induced by perceptual deprivation can give further insight into the factors mediating conscious awareness and may suggest ways in which the brain imposes meaning on the environment under invariant sensory conditions.

ENTERING TRAIT AND CONTEXT INTO A COGNITIVE-TIMER MODEL FOR TIME ESTIMATION

Subjects were exposed to conditions of perceptual deprivation and perceptual overload, and were then asked to produce short intervals of time. It was hypothesized that the greater the variation in the sensory environment (i.e. perceptual overload vs perceptual deprivation), the shorter would be the time estimation obtained by this method of production. It was further assumed that the personality trait of Experience Seeking could moderate this influence of the altered sensory environments on the functioning of the cognitive timer. A trait–context interaction was uncovered, indicating this moderating effect. Furthermore, both trait and context effects were specific to the measure constant of the psychophysical function relating produced time to required time. These results are presented within a contextualistic approach to the study of subjective time.

Subjective Time Estimation in Altered Sensory Environments

The influence of prior exposure to an altered sensory environment on subsequent subjective time estimation was the focus of the present study. It was hypothesized that the more varied the sensory environment (i.e., perceptual overload versus perceptual deprivation), the longer the time that is verbally estimated, and the shorter the time estimation obtained by the method of production. This hypothesis was supported for the data gathered by the latter method, but not by the former one, in a 3 x 4 factorial design employing 96 subjects, who were exposed to various combinations of auditory and visual stimulation. The conclusion drawn is that visual and auditory stimulation interact in their production of an altered sensory environment, and that the rate of functioning of the cognitive timer is environment dependent.

Perceptual deprivation in the acute phase of spinal injury rehabilitation.

Patients in intensive care units are often reported to experience psychological disturbances which may be attributable to a number of well-researched causes. However, it is suggested that the total lack of proprioceptive and motor feedback after spinal trauma may be a significant factor in the genesis of these disturbances which are unique to this group of patients. All cases admitted to the Regional Spinal Injuries Centre in Southport from January 1987 through December 1990 were assessed (n = 187) and the conditions surrounding the occurrence of behavioural disturbances (n = 23, 12.3%) established. The level of interaction with relatives and significant others was established for all acute admissions, and low frequency was found to correlate significantly with the development of perceptual deprivation experiences. The effects of inadequate somatosensory input, lesion level, increasing age, and visitor variability for spinal patients is discussed and an algorithm presented to highlight the potential factors associated with aetiology and treatment of the problem. The implications of these findings for the future management of acute spinal trauma are discussed.

The induction of an altered state of consciousness as a function of sensory environment and experience seeking

This paper reports on the results of two experiments concerned with the induction of an altered state of consciousness (ASC) in the laboratory. In these experiments different conditions of sensory stimulation were operationally defined (altered sensory environments), and employed in an attempt to change the psychophysiological state of the subject, and thus induce an ASC. Visual and auditory sources of stimulation were used, and conditions of overload and deprivation were defined. The goal of the first study was to investigate how trait (experience seeking) and environment interact to codetermine subjective experience. In the second study, optimal conditions were employed for the induction of an ASC. Two groups of subjects, divided into ‘high’ and ‘low’ experience seekers by median split, were randomly allocated to these conditions and completed the experiment. It was found that more than 85% of high experience seekers, exposed to a condition of perceptual deprivation, experienced an ASC.

Perceptual deprivation, extraversion—introversion and the autokinetic phenomenon

Abstract The present study examines the relationships between perceptual-deprivation tolerance and three variables: extraversion, the autokinetic (AK) phenomenon and field-dependence. In addition, the relationship between extraversion and autokinesis (AK) was investigated. Thirty-three male subjects were subjected to 3 hr of perceptual deprivation and, in addition, their scores on each of the three independent variables were obtained. It was found, as hypothesized, that perceptual-deprivation tolerance was negatively related to extraversion and positively related to the intensity of the AK effect. Field-dependence was not related to perceptual-deprivation tolerance. The correlation between extraversion and the autokinetic effect was significant but moderate. The nature of the relationship between these two variables is discussed.

USING "ANGELS AND DEVILS"

The incidence of perceptual deprivation and social isolation effects, possible correlates of such effects, and the potential for remediation of effects was studied for 32 nursing home residents through playing a discussion-stimulating board game called "Angels and Devils." Results indicate a high incidence of sensory deprivation and social isolation effects in the population, as meausred by resident response to questionnaire items. These do not correlate with length of institutionalization, amount of social contact, or degree of medical restriction and may be reduced by stimulating resident-staff discussion. Findings are interpreted as indicating the need for more research in application of board games to ameliorate negative effects emerging in institutional environments.

Using Angels and Devils: a board game developed for play in nursing homes.

The incidence of perceptual deprivation and social isolation effects, possible correlates of such effects, and the potential for remediation of effects was studied for thirty-two nursing home residents through playing a discussion-stimulating board game called Angels and Devils. Results indicate a high incidence of sensory deprivation and social isolation effects in the population, as measured by resident response to questionnaire items. These do not correlate with length of institutionalization, amount of social contact, or degree of medical restriction, and may be reduced by stimulating resident-staff discussion. Findings are interpreted as indicating the need for more research in application of board games to ameliorate negative effects emerging in institutional environments.

Effects of hypnosis and perceptual deprivation on vigilance in a simulated radar target-detection task.

Detection efficiency of humans deteriorates rapidly in a variety of monotonous monitoring tasks. The experiment was performed to determine whether or not superior vigilance performance could be obtained through hypnosis in the context of perceptual deprivation. Subjects, forty U.S. Navy personnel, were divided into four groups. Subjects worked on a simulated radar target-detection task before and after one of four treatments. Those given post-hypnotic suggestions for increased alertness made significantly fewer errors in target detection while those exposed to suggestions for decreased performance or perceptual deprivation only showed significant increases in errors. Controls showed no significant changes in errors. Change scores were significantly related to Stanford Hypnotic Clinical Scale hypnotizability scores for subjects in the hypnosis-augment performance group but not for other groups.

Sensory Deprivation and Homeostasis

Most afferent inputs are sensory stimulants, and physical activity is probably one of the most significant of all sensory stimulations. Gravity is a constant stimulus. These demands are also known as stress, and the stressor effect as the general adaptation syndrome (Selye). In this study, these demands are called sensory afferent stimuli, which are necessary triggers to start the hypothalamus-pituitary-adrenal mechanism and thus maintain the general mechanical, autonomic and metabolic functions of the body in the state of homeostasis. If the sensory stimulus is removed, there is no stressor effect and the cycle of response is eliminated. This results in a decreased hypothalamus-pituitary response and a decreased production of ACTH and corticoids. A decrease in the sensory input creates changes in the central nervous system and in the musculoskeletal system which are compatible with lack of the hypothalamus-pituitary responses. When a person becomes ill, physical inactivity as well as sensory and perceptual deprivation are at a maximum, and the absence of these stimuli interrupts the cycle of homeostasis. Physical activity is one of the most important stressors (sensory input) or triggering mechanisms for the cycle of homeostasis (hypothalamus-pituitary-adrenal cycle). Therefore, it is imperative to provide the patient with physical activities which ensure motion and take into account the effect of gravity. This is best accomplished by a program of physical, occupational and recreational therapy.

Free-looking time for randomly generated polygons with experimenter present: effects of content and duration of foreperiod.

Free-looking time for randomly generated 18-sided polygons was measured with E present after Ss had been exposed to 2-, 20-, or 45-sec. foreperiods containing either darkness, homogeneous white light, or similar polygons. Free-looking time increased monotonically as a function of foreperiod duration for all three kinds of foreperiod stimuli. Free-looking time following darkness significantly exceeded that following homogeneous light or polygons. Content and duration of foreperiod did not interact. The results are consistent with a tendency by Ss to imitate foreperiod durations during the free-looking period coupled with a constant increment in free-looking time whenever there is a transition from a dark foreperiod to a lighted free-looking period. The results are not consistent with an effect of perceptual deprivation under the conditions tested.