Strange-face-in-the-mirror illusion and schizotypy during adolescence

Strange-face-in-the-mirror illusions: specific effects on derealization, depersonalization, and dissociative identity

Anomalous strange-face illusions (SFIs) are produced when mirror gazing under a low level of face illumination. In contrast to past studies in which an observer's task was to pay attention to the reflected face and to perceive potential facial changes, the present research used a mirror gazing task (MGT) that instructed participants to fixate their gaze on a 4-mm hole in a glass mirror. The participants' eye-blink rates were thus measured without priming any facial changes. Twenty-one healthy young individuals participated in the MGT and a control panel-fixation task (staring at a hole in a gray non-reflective panel). The Revised Strange-Face Questionnaire (SFQ-R) indexed derealization (deformations of facial features; FD), depersonalization (bodily face detachment; BD), and dissociative identity (new or unknown identities; DI) scales. Mirror-fixation increased FD, BD, and DI scores compared to panel-fixation. In mirror-fixation, FD scores revealed fading specific to facial features, distinct from "classical" Troxler- and Brewster-fading. In mirror-fixation, eye-blink rates correlated negatively with FD scores. Panel-fixation produced low BD scores, and, in a few participants, face pareidolias as detected on FD scores. Females were more prone to early derealization and males to compartmentalization of a dissociative identity. SFQ-R may be a valuable instrument for measuring face-specific dissociation (FD, BD, DI) produced by MGT. Use of MGT and panel-fixation task for differential diagnoses between schizophrenia and dissociative identity disorder is discussed.

Strange face illusions: A systematic review and quality analysis

BACKGROUND

Strange face illusions describe a range of visual apparitions that occur when an observer gazes at their image reflected in a mirror or at another person's face in a dimly lit room. The illusory effects range from mild alterations in colour, or contrast, to the perception of distorted facial features, or new strange faces.The current review critically evaluates studies investigating strange face illusions, their methodological quality, and existing interpretations.

METHOD

Searches conducted using Scopus, PubMed, ScienceDirect and the grey literature until June 2022 identified 21 studies (N = 1,132; healthy participants n = 1,042; clinical participants n = 90) meeting the inclusion criteria (i.e., providing new empirical evidence relating to strange face illusions). The total sample had a mean age of 28.3 years (SD = 10.31) and two thirds (67 %) of participants tested to date are female. Results are reported using the Preferred Reporting Items for Systematic Reviews and meta-Analyses (PRISMA) guidelines. The review was preregistered at the Open Science Framework (OSF: https://osf.io/ek48d).

RESULTS

Pooling data across studies, illusory new strange faces are experienced by 58% (95%CI 48 to 68) of nonclinical participants. Study quality as assessed by the Appraisal Tool for Cross-Sectional Studies (AXIS) revealed that 3/21 (14.28%) studies were rated as high, 9/21 (42.86%) as moderate and 9/21 (42.86%) as low quality. Whilst the items relating specifically to reporting quality scored quite highly, those relating to study design and possible biases were lower and more variable. Overall, study quality accounted for 87% of the variance in reporting rates for strange faces, with higher quality being associated with lower illusion rates. The prevalence of illusions was also significantly greater in samples that were older, had higher proportions of female participants and for the interpersonal dyad (IGDT) compared to the mirror gaze paradigm (MGT). The moderating impact of study quality persisted in a multiple meta-regression involving participant age, paradigm type (IGDT vs MGT) and level of feature distortion. Our review point to the importance of reduced light levels, face stimuli and prolonged eye fixation for strange face illusions to emerge.

CONCLUSION

Strange face illusions reliably occur in both mirror-gazing and interpersonal gazing dyad paradigms. Further research of higher quality is required to establish the prevalence and particularly, the mechanisms underpinning strange face illusions.

The moderating role of early traumatic experiences on the association of schizotypal traits with visual perception

The findings on the association of schizotypal traits with the perception of visual illusions are scarce and inconsistent and have not taken into consideration potential effects of childhood traumatic experiences, a risk factor for schizophrenia-spectrum conditions. Thus, the present study addressed the question of potential moderating effects of early traumatic experiences on the association between different aspects of schizotypal traits with the perception of the Müller-Lyer and Navon's Hierarchical Letters (NHL) illusions. The study revealed that (a) increased suspiciousness was associated with increased liability to the Müller-Lyer illusion, when the exposure to traumatic events was high, whereas the opposite pattern was true when the exposure to traumatic events was low; (b) negative schizotypy was associated with more accurate global perception, and high disorganized schizotypy was associated with superior accuracy when target letters were present during the NHL illusion, when early traumatic experiences were at lower levels; and (c) high negative, disorganized, and total schizotypy were associated with lower accuracy when target letters were present in the NHL paradigm, when early traumatic experiences were at higher levels. The findings of the study suggest that early traumatic events differentially moderate the relationship between various aspects of schizotypal traits and visual perceptual processing.

A Developmental Study of Mirror-Gazing-Induced Anomalous Self-Experiences and Self-Reported Schizotypy from 7 to 28 Years of Age

INTRODUCTION

The mirror-gazing task (MGT) is an experimental paradigm inducing anomalous perceptions and anomalous experiences of self-face (ASEs) in the general population, ranging from changes in light and color, to face deformation, to experiencing one's specular image as another identity. Subclinical ASEs have been related to the emergence of the risk for developing psychotic disorders, and inducing such states in the general population could shed light on the factors underlying interindividual differences in proneness to these phenomena. We aimed to examine the influence of schizotypal personality traits on proneness to experiencing induced ASEs from a developmental perspective, from childhood to adulthood.

METHODS

Two hundred and sixteen children, adolescents, and young adults participated in the MGT, and their schizotypal personality traits were assessed with the Schizotypal Personality Questionnaire. Statistical analyses assessed the relationship between schizotypy dimensions and induced ASEs, and we further tested their dynamic relationship as function of age (from childhood to adulthood).

RESULTS

Results confirmed the developmental trajectory of the different schizotypy dimensions, with scores peaking during adolescence, and proneness to induced ASEs seemed to follow a similar developmental trajectory. Moreover, positive (p = 0.001) and disorganized (p = 0.004) dimensions were found to contribute to the proneness to experiencing induced ASEs. Finally, the developmental model showed that positive schizotypy (p = 0.035) uniquely distinguished between experiencing other-identity phenomena between childhood and adulthood.

CONCLUSION

This study has the potential to inform research on early detection of psychosis through a developmental approach and links the concept of schizotypy with processes of perceptual self-distortions.

Split-mirror gazing increases dissociative states and illusions of self-identity

Previous studies found that mirror-gazing at the subject's reflected own face, under a low illumination level, produces acute dissociation. In the present study, a split-mirror was used, which divides the subject's reflected face vertically into two half-faces, and dissociative states were compared to single-mirror gazing. Twelve healthy naïve individuals, who were sampled from students of an Art Academy, volunteered in a within-subject experiment. Dissociative states were measured through a 9-item self-report questionnaire on three scales: illusions of face deformation (derealization); illusions of body detachment (depersonalization); illusions of different self-identity (dissociated identity). Results showed that split-mirror gazing increased dissociation with respect to single-mirror gazing. Illusions of different self-identity, such as double-identity (i.e., left-identity versus right-identity) or double-personality, increased during split-mirror gazing with respect to single-mirror gazing, whereas illusions of face deformation and body detachment were unchanged. Findings support the distinction between detachment and compartmentalization, and may provide a tool for experimental investigation of dissociative identity disorder (DID). Finally, the students' portraits illustrated illusions of self-identity in split-mirror gazing: left-identity (portrayed in the right side of drawings) displayed illusions of more negative personalities and/or emotions, while right-identity (portrayed in the left side) showed more positive features.

Integrated assessment of visual perception abnormalities in psychotic disorders and relationship with clinical characteristics

BACKGROUND

The visual system is recognized as an important site of pathology and dysfunction in schizophrenia. In this study, we evaluated different visual perceptual functions in patients with psychotic disorders using a potentially clinically applicable task battery and assessed their relationship with symptom severity in patients, and with schizotypal features in healthy participants.

METHODS

Five different areas of visual functioning were evaluated in patients with schizophrenia and schizoaffective disorder (n = 28) and healthy control subjects (n = 31) using a battery that included visuospatial working memory (VSWM), velocity discrimination (VD), contour integration, visual context processing, and backward masking tasks.

RESULTS

The patient group demonstrated significantly lower performance in VD, contour integration, and VSWM tasks. Performance did not differ between the two groups on the visual context processing task and did not differ across levels of interstimulus intervals in the backward masking task. Performances on VSWM, VD, and contour integration tasks were correlated with negative symptom severity but not with other symptom dimensions in the patient group. VSWM and VD performances were also correlated with negative sychizotypal features in healthy controls.

CONCLUSION

Taken together, these results demonstrate significant abnormalities in multiple visual processing tasks in patients with psychotic disorders, adding to the literature implicating visual abnormalities in these conditions. Furthermore, our results show that visual processing impairments are associated with the negative symptom dimension in patients as well as healthy individuals.

Seeing myself through my heart: Cortical processing of a single heartbeat speeds up self-face recognition

Recent research has highlighted the contribution of interoceptive signals to different aspects of bodily self-consciousness (BSC) by means of the cardio-visual stimulation - i.e. perceiving a pulsing stimulus in synchrony with one's own heart. Here, for the first time, we investigate the effects of individual heartbeats on a critical feature of BSC, namely the recognition of one's own face. Across two studies, we explored the cardiac-timing effects on a classic self-face recognition task. In Study 1, participants saw morphed faces that contained different percentages of the self-face and that of another unfamiliar individual. Study 2 used a similar design, albeit participants saw morphed faces of the self-face and that of a familiar other to provide a better control of self-familiarity. Results from both studies consistently revealed that the cortical processing of cardiac afferent signals conveyed by the firing of arterial baroreceptors affects the speed, but not the accuracy, of self-face recognition, when a single picture is presented during cardiac systole, as compared to diastole. This effect is stronger and more stable for stimuli with more self-cues than other-cues and for 'ambiguous' stimuli - i.e. at the individual point of subjective equality. Results from Study 2 also revealed that cardiac effects on the speed of self-face recognition cannot be explained simply on the basis of the imbalanced familiarity between the self's and other's faces used. The present findings highlight the interoceptive contributions to self-recognition and may be expand our understanding of pathological disturbances of self-experience.

Uncanny Mirroring: A Developmental Perspective on the Neurocognitive Origins of Self-Disorders in Schizophrenia

Varieties of anomalous subjective experiences, i.e. "basic self-disorders" (SDs), have been empirically demonstrated as core clinical features of schizophrenia spectrum disorders, predating full-blown psychotic symptoms. However, the clinical stage in which SDs emerge and their putative neurocognitive origins remain unsolved issues. Focusing on a prototypical anomalous mirror experience (i.e., a stable, trait-like subjective feeling of nonexisting while looking at oneself in the mirror) reported by an 11-year-old boy at familial high risk for schizophrenia and diagnosed as attenuated psychosis syndrome, we outline some possible developmental pathways leading to SDs. Such pathways are hypothesized in accordance with the documented early impairments in perceptual integration across distinct modalities in children at risk for schizophrenia spectrum disorders and to the specific features of mirror experience as provided by phenomenological and developmental psychology perspectives. We conclude that SDs could presumably have an early developmental origin, although children become progressively more aware of them. Although further hypothesis testing in clinical samples and longitudinal empirical investigation of at-risk children is badly needed, we propose that age-appropriate, phenomenologically oriented assessment of SDs could be useful for the early identification of psychotic risk.

Resting-State Networks of Adolescents Experiencing Depersonalization-Like Illusions: Cross-sectional and Longitudinal Findings

The mirror-gazing task (MGT) experimentally induces illusions, ranging from simple color changes in the specular image of oneself, to depersonalization-like anomalous self-experiences (ASE) as in experiencing one's specular image as someone else. The objective was to characterize how connectivity in resting-state networks (RSNs) differed in adolescents reporting such depersonalization-like ASEs during the MGT, in a cross-sectional (Y1) and in a longitudinal manner (a year after). 75 adolescents were recruited; for the cross-sectional analysis, participants were split into 2 groups: those who reported depersonalization-like ASEs on the MGT (ASE), and those who did not (NoASE). For the longitudinal analysis, participants were split into 3 groups whether they experienced MGT depersonalization-like ASEs: only at Y1 (Remitters), both times (Persisters), or never (Controls). Participants also filled out self-reports assessing schizotypal personality (Schizotypal Personality Questionnaire [SPQ]), and underwent resting-state functional MRI procedure (rs-fMRI). A group level Independent Component Analysis (ICA) was conducted and voxel-wise inter-group differences within RSNs were examined. The rs-fMRI analysis revealed lower connectivity of specific visual areas within the primary visual network (PVN), and higher connectivity of regions within the Default Mode Network (DMN) when contrasting the ASE and NoASE groups. The areas that were atypically connected within the PVN further presented differential pattern of connectivity in the longitudinal analysis. Atypical connectivity of visual area within the DMN at Y1 was associated with higher scores on the disorganized dimension of schizotypy at the second evaluation. The present study uncovers a subtle signature in the RSNs of non-clinical adolescents who experienced task-induced ASEs.

Inducing dissociation and schizotypal experiences through "vision-deforming" glasses

Derealization, depersonalization and schizotypal experiences are described as separate concepts but they can be hard to distinguish. One way to show the uniqueness of these concepts is by showing a dissociation between these experiences. The aim of this study was to experimentally induce derealization without inducing depersonalization or schizotypal experiences. Healthy participants watched a neutral video in one of four conditions: (1) with stroboscopic light, (2) while wearing deforming glasses, (3) with stroboscopic light and while wearing "vision deforming glasses" or (4) without any manipulation. The results show that the "vision deforming" glasses induced derealization without inducing depersonalization but not without inducing schizotypal experiences. The stroboscopic light showed no significant effect, nor was there a significant interaction between the stroboscopic light and the deforming glasses. The results indicate that using "vision deforming" glasses as a manipulation method can show a single dissociation between derealization and depersonalization but cannot dissociate derealization from state schizotypy. This association between derealization and schizotypal experiences might be helpful in understanding the high comorbidity rate between dissociative disorders and schizophrenia spectrum disorders.

A Perceptual Inference Mechanism for Hallucinations Linked to Striatal Dopamine

Hallucinations, a cardinal feature of psychotic disorders such as schizophrenia, are known to depend on excessive striatal dopamine. However, an underlying cognitive mechanism linking dopamine dysregulation and the experience of hallucinatory percepts remains elusive. Bayesian models explain perception as an optimal combination of prior expectations and new sensory evidence, where perceptual distortions such as illusions and hallucinations may occur if prior expectations are afforded excessive weight. Such excessive weight of prior expectations, in turn, could stem from a gain-control process controlled by neuromodulators such as dopamine. To test for such a dopamine-dependent gain-control mechanism of hallucinations, we studied unmedicated patients with schizophrenia with varying degrees of hallucination severity and healthy individuals using molecular imaging with a pharmacological manipulation of dopamine, structural imaging, and a novel task designed to measure illusory changes in the perceived duration of auditory stimuli under different levels of uncertainty. Hallucinations correlated with a perceptual bias, reflecting disproportional gain on expectations under uncertainty. This bias could be pharmacologically induced by amphetamine, strongly correlated with striatal dopamine release, and related to cortical volume of the dorsal anterior cingulate, a brain region involved in tracking environmental uncertainty. These findings outline a novel dopamine-dependent mechanism for perceptual modulation in physiological conditions and further suggest that this mechanism may confer vulnerability to hallucinations in hyper-dopaminergic states underlying psychosis.

Strange-face Illusions During Interpersonal-Gazing and Personality Differences of Spirituality

Strange-face illusions are produced when two individuals gaze at each other in the eyes in low illumination for more than a few minutes. Usually, the members of the dyad perceive numinous apparitions, like the other's face deformations and perception of a stranger or a monster in place of the other, and feel a short lasting dissociation. In the present experiment, the influence of the spirituality personality trait on strength and number of strange-face illusions was investigated. Thirty participants were preliminarily tested for superstition (Paranormal Belief Scale, PBS) and spirituality (Spiritual Transcendence Scale, STS); then, they were randomly assigned to 15 dyads. Dyads performed the intersubjective gazing task for 10 minutes and, finally, strange-face illusions (measured through the Strange-Face Questionnaire, SFQ) were evaluated. The first finding was that SFQ was independent of PBS; hence, strange-face illusions during intersubjective gazing are authentically perceptual, hallucination-like phenomena, and not due to superstition. The second finding was that SFQ depended on the spiritual-universality scale of STS (a belief in the unitive nature of life; e.g., "there is a higher plane of consciousness or spirituality that binds all people") and the two variables were negatively correlated. Thus, strange-face illusions, in particular monstrous apparitions, could potentially disrupt binding among human beings. Strange-face illusions can be considered as 'projections' of the subject's unconscious into the other's face. In conclusion, intersubjective gazing at low illumination can be a tool for conscious integration of unconscious 'shadows of the Self' in order to reach completeness of the Self.

Mirror self-face perception in individuals with schizophrenia: Feelings of strangeness associated with one's own image

Self-face recognition is crucial for sense of identity and for maintaining a coherent sense of self. Most of our daily life experiences with the image of our own face happen when we look at ourselves in the mirror. However, to date, mirror self-perception in schizophrenia has received little attention despite evidence that face recognition deficits and self abnormalities have been described in schizophrenia. Thus, this study aims to investigate mirror self-face perception in schizophrenia patients and its correlation with clinical symptoms. Twenty-four schizophrenia patients and twenty-five healthy controls were explicitly requested to describe their image in detail during 2min whilst looking at themselves in a mirror. Then, they were asked to report whether they experienced any self-face recognition difficulties. Results showed that schizophrenia patients reported more feelings of strangeness towards their face compared to healthy controls (U=209.5, p=0.048, r=0.28), but no statistically significant differences were found regarding misidentification (p=0.111) and failures in recognition (p=0.081). Symptoms such as hallucinations, somatic concerns and depression were also associated with self-face perception abnormalities (all p-values>0.05). Feelings of strangeness toward one's own face in schizophrenia might be part of a familiar face perception deficit or a more global self-disturbance, which is characterized by a loss of self-other boundaries and has been associated with abnormal body experiences and first rank symptoms. Regarding this last hypothesis, multisensorial integration might have an impact on the way patients perceive themselves since it has an important role in mirror self-perception.

Integration and development in schizotypy research: an introduction to the special supplement

In its fifth decade of existence, the construct of schizotypy is recapturing the early scientific interest it attracted when Paul E. Meehl (1920-2003), who coined the term, pioneered the field of schizotypy research. The International Lemanic Workshop on Schizotypy, hosted at the University of Geneva in December 2013, recently offered an opportunity to address some of the fundamental questions in contemporary schizotypy research and situate the construct in the greater scheme of future scientific projects on schizophrenia and psychological health research. What kind of knowledge has schizotypy research provided in furthering our understanding of schizophrenia? What types of questions can schizotypy research tackle, and which are the conceptual and methodological frameworks to address them? How will schizotypy research contribute to future scientific endeavors? The International Lemanic Workshop brought together leading experts in the field around the tasks of articulating the essential findings in schizotypy research, as well as providing some key insights and guidance to face scientific challenges of the future. The current supplement contains 8 position articles, 4 research articles, and 1 invited commentary that outline the state of the art in schizotypy research today.