Anomalous Perception Research Articles

From sexual abuse to psychosis: A pilot study exploring the social deafferentation hypothesis and the mediating role of avoidance

The social deafferentation hypothesis posits that social withdrawal in vulnerable individuals may result in anomalous perceptual and cognitive experiences that are consistent with psychotic hallucinations and delusions. Both psychosis vulnerability and social withdrawal are characteristic of many individuals who have experienced sexual abuse and a growing literature continues to document associations between experiences of sexual abuse and psychosis. The current study investigated if avoidant personality traits (characterised by social withdrawal) mediated the relationship between sexual abuse and psychosis symptom experience. Using data from the British Psychiatric Morbidity Survey (N = 8580), a mediation model was specified and estimated. The estimates showed that the regression coefficients of avoidant personality traits on sexual abuse (B =.70), psychosis scores on avoidant personality traits (B = .09), and psychosis scores on sexual abuse (B =.45) were statistically significant. The mediated effect of sexual abuse on psychosis scores via avoidant personality traits was also significant (B = .06). The parameters of this mediated model were statistically significant after controlling for a range of demographic variables and potential risk factors for psychosis. Avoidance and social deafferentation may constitute a plausible hypothesis for exploring experiences of psychosis among victims of sexual abuse in some cases.

Visual context processing in bipolar disorder: a comparison with schizophrenia

Anomalous perception has been investigated extensively in schizophrenia, but it is unclear whether these impairments are specific to schizophrenia or extend to other psychotic disorders. Recent studies of visual context processing in schizophrenia (Tibber et al., 2013; Yang et al., 2013) point to circumscribed, task-specific abnormalities. Here we examined visual contextual processing across a comprehensive set of visual tasks in individuals with bipolar disorder and compared their performance with that of our previously published results from schizophrenia and healthy participants tested on those same tasks. We quantified the degree to which the surrounding visual context alters a center stimulus' appearance for brightness, size, contrast, orientation and motion. Across these tasks, healthy participants showed robust contextual effects, as indicated by pronounced misperceptions of the center stimuli. Participants with bipolar disorder showed contextual effects similar in magnitude to those found in healthy participants on all tasks. This result differs from what we found in schizophrenia participants (Yang et al., 2013) who showed weakened contextual modulations of contrast but intact contextual modulations of perceived luminance and size. Yet in schizophrenia participants, the magnitude of the contrast illusion did not correlate with symptom measures. Performance on the contrast task by the bipolar disorder group also could not be distinguished from that of the schizophrenia group, and this may be attributed to the result that bipolar patients who presented with greater manic symptoms showed weaker contrast modulation. Thus, contrast gain control may be modulated by clinical state in bipolar disorder. Stronger motion and orientation context effects correlated with worse clinical symptoms across both patient groups and especially in schizophrenia participants. These results highlight the complexity of visual context processing in schizophrenia and bipolar disorder.

1847 – Cognitive and emotional anomalies implicated in pathogenesis of delusional idea in delusional disorder

Introduction Four theoretical models have been postulated in formation and maintenance of delusional idea in schizophrenia: 1. Cognitive biases (attentional bias, jumping-to-conclusion, need-for-clousure, attributional bias), 2. Social cognition alterations (theory-of-mind, emotion facial recognition), 3. Perceptive alterations of anomalous experiences and 4. Emotional anomalies (anxiety, depression, self-esteem, “self” discrepancies). However, there is poor evidence about the implication of these anomalies in pathogenesis of delusional idea in delusional disorder (DD). Objectives To exam the joint influence of these anomalies in delusional activity in DD. Methods We studied the delusional activity measured by the “Maudsley Assessment of Delusion Schedule” in 68 patients with DD (n=68) diagnosed by SCID-I (DSM-IV-TR). Cognitive biases were evaluated by “Emotional Stroop”, “Experimental Beads Task”, “Need-for-Closure Scale”, “Internal, Personal and Situational Attributions Questionnaire”. Social cognition alterations were measured by Faux-pas Task and Eyes-Test; perceptive alterations by “Cardiff Anomalous Perceptions Scale”; and emotional anomalies by “Hamilton Anxiety Rating Scale”, “Beck Depression Inventory”, “Rosenberg Self-esteem Scale” and “Personal Qualities Questionnaire”. The relationship between delusional activity and these cognitive anomalies were examined using lineal regression models controlled by socio-demographic characteristics, premorbid IQ (“NART”), negative symptomatology (“PANSS”) and neuropsychological function (attention, verbal learning, working memory and executive function). Results High scores in delusion activity were significantly associated with high scores in jumping-to-conclusion and depression and low scores in faux-pas and self-esteem, after being adjusted by number of studied years and negative symptomatology. Conclusions Cognitive biases (jumping-to-conclusions), social cognition deficit (faux-pas) and emotional alterations are the most implicated anomalies in formation and maintenance of delusional idea in DD.

Assessing Anomalous Perceptual Experiences in Nonpsychiatric Individuals and Outpatients with Psychosis in Taiwan: An Investigation Using the Cardiff Anomalous Perceptions Scale (CAPS)

The Cardiff anomalous perceptions scale (CAPS) has been recently designed for the assessment of anomalous perceptual experiences in the general population, and includes dimensions that measure distress, intrusiveness, and frequency. The purpose of this study was to assess the psychometric properties of a Taiwanese version of the CAPS. The English version of the CAPS was translated into Taiwanese (CAPS-T) and the latter was applied to this study. We administered the questionnaire to a consecutive sample of 192 participants with (n=106; clinical group including schizophrenia and affective psychosis) or without psychotic disorders (n=86; non-clinical group). In addition to the CAPS-T, the Taiwanese version of the brief psychiatric symptom rating scale (BSRS) measured the severity of the psychopathology. We also tested the psychometric properties of the CAPS-T including construct validity, internal consistency, test-retest reliability, and convergent and discriminative validity. Overall, the CAPS-T showed good construct validity, internal consistency, and stability over time and correlated significantly with the psychoticism subscale of the BSRS. As predicted, the mean differences in CAPS-T scores between participants with or without a psychotic disorder were significant. Convergent and discriminative validity were satisfactory. A score of 5 was found to the best threshold in discriminating between clinical and non-clinical samples. Our findings indicate that the Taiwanese version of the CAPS is a reliable and valid instrument to measure the multidimensionality of perceptual anomalies in general and appears to complement the clinical measures of psychosis proneness in Taiwan.

Visual perception during mirror gazing at one's own face in schizophrenia

BackgroundIn normal observers gazing at one's own face in the mirror for some minutes, at a low illumination level, triggers the perception of strange faces, a new perceptual illusion that has been named ‘strange-face in the mirror’. Subjects see distortions of their own faces, but often they see monsters, archetypical faces, faces of dead relatives, and of animals. MethodsWe designed this study to primarily compare strange-face apparitions in response to mirror gazing in patients with schizophrenia and healthy controls. The study included 16 patients with schizophrenia and 21 healthy controls. In this paper we administered a 7 minute mirror gazing test (MGT). Before the mirror gazing session, all subjects underwent assessment with the Cardiff Anomalous Perception Scale (CAPS). When the 7minute MGT ended, the experimenter assessed patients and controls with a specifically designed questionnaire and interviewed them, asking them to describe strange-face perceptions. ResultsApparitions of strange-faces in the mirror were significantly more intense in schizophrenic patients than in controls. All the following variables were higher in patients than in healthy controls: frequency (p<.005) and cumulative duration of apparitions (p<.009), number and types of strange-faces (p<.002), self-evaluation scores on Likert-type scales of apparition strength (p<.03) and of reality of apparitions (p<.001). In schizophrenic patients, these Likert-type scales showed correlations (p<.05) with CAPS total scores. ConclusionsThese results suggest that the increase of strange-face apparitions in schizophrenia can be produced by ego dysfunction, by body dysmorphic disorder and by misattribution of self-agency. MGT may help in completing the standard assessment of patients with schizophrenia, independently of hallucinatory psychopathology.

Why overlearned sequences are special: distinct neural networks for ordinal sequences

Several observations suggest that overlearned ordinal categories (e.g., letters, numbers, weekdays, months) are processed differently than non-ordinal categories in the brain. In synesthesia, for example, anomalous perceptual experiences are most often triggered by members of ordinal categories (Rich et al., 2005; Eagleman, 2009). In semantic dementia (SD), the processing of ordinal stimuli appears to be preserved relative to non-ordinal ones (Cappelletti et al., 2001). Moreover, ordinal stimuli often map onto unconscious spatial representations, as observed in the SNARC effect (Dehaene et al., 1993; Fias, 1996). At present, little is known about the neural representation of ordinal categories. Using functional neuroimaging, we show that words in ordinal categories are processed in a fronto-temporo-parietal network biased toward the right hemisphere. This differs from words in non-ordinal categories (such as names of furniture, animals, cars, and fruit), which show an expected bias toward the left hemisphere. Further, we find that increased predictability of stimulus order correlates with smaller regions of BOLD activation, a phenomenon we term prediction suppression. Our results provide new insights into the processing of ordinal stimuli, and suggest a new anatomical framework for understanding the patterns seen in synesthesia, unconscious spatial representation, and SD.

P-804 - Neurofunctional basis of social cognition in subclinical paranoid ideation and social anxiety

Impaired social functioning is a hallmark characteristic of several mental disorders including those characterized by paranoid ideation (P) and social anxiety (SA). Social deficits have been related to impaired social cognition. To investigate the neurofunctional basis of social cognition in people with subclinical P and SA. 13 healthy participants with high paranoid ideation; 12 healthy participants with high social anxiety. Procedures and Instruments: Paranoid Thoughts Scale, Liebowitz Social Anxiety Scale, Cardiff Anomalous Perceptions Scale. Brain response to social stimuli was investigated with two event-related fMRI experiments with implicit processing of facial. expressions of happiness and anger in two different intensities, and with faces expressing no emotion. People with P recruit differentially and positively the Left Lingual (p < 0,05 FWEcorr), and close to significant (p < 0,06 FWEcorr) the Right Caudate when processing neutral faces. People with SA only showed significant positive differences (p < 0,05 FWEcorr) in the Right Inferior frontal gyrus when processing anger stimuli at 100%. When comparing both groups, we did not find significant differences. The preliminary results indicate a stronger recruitment of emotional and visual areas in P subjects when processing neutral faces and a stronger recruitment of cognitive processing areas in SA subjects when processing angry faces.

Evidence for elevated cortical hyperexcitability and its association with out-of-body experiences in the non-clinical population: New findings from a pattern-glare task

Individuals with no history of neurological or psychiatric illness can report hallucinatory Out-of-Body Experiences (OBEs) and display elevated scores on measures of temporal-lobe dysfunction (Braithwaite et al., 2011). However, all previous investigations of such biases in non-clinical populations are based on indirect questionnaire measures. Here we present the first empirical investigation that a non-clinical OBE group is subject to pattern-glare, possibly as a result of cortical hyperexcitability (Wilkins et al., 1984). Fifty-nine students at the University of Birmingham viewed a series of square-wave gratings with spatial frequencies of approximately .7, 3 and 11 cycles-per-degree, both black/white and of contrasting colours. The illusions and discomfort reported when viewing gratings with mid-range spatial frequency have been hypothesized to reflect cortical hyperexcitability (Wilkins, 1995; Huang et al., 2003). Participants also completed the Cardiff Anomalous Perception Scale (CAPS: Bell et al., 2006) which included experiential measures of disruptions in ‘Temporal-lobe Experience’. Participants who reported OBEs also reported significantly more visual illusions/distortions and significantly greater discomfort as a result of viewing the mid-frequency gratings. There were no such differences with respect to gratings with relatively lower or higher spatial frequency. The OBE group also produced significantly elevated scores on the CAPS measures of Temporal-lobe Experience, relative to controls. Collectively, the results are consistent with there being a neural ‘vulnerability’ in the cortices of individuals pre-disposed to some hallucinations, even in the non-clinical population.

The psychometric properties of the Taiwanese version of the Cardiff Anomalous Perceptions Scale

Background The Cardiff Anomalous Perceptions Scale (CAPS) has been recently designed for the assessment of anomalous perceptual experiences in the general population and includes dimensions that measure distress, intrusiveness, and frequency. The purpose of this study was to assess the psychometric properties of a Taiwanese version of the CAPS. Methods The English version of the CAPS was translated into Taiwanese (CAPS-T), and the latter was applied to this study. We administered the questionnaire to a consecutive sample of 192 participants with (n = 106; clinical group including schizophrenia and affective psychosis) or without (n = 86; nonclinical group) psychotic disorders. In addition to the CAPS-T, the Taiwanese version of the Brief Psychiatric Symptom Rating Scale measured the severity of the psychopathology. We also tested the psychometric properties of the CAPS-T including construct validity, internal consistency, test-retest reliability, and convergent and discriminative validity. Results Overall, the CAPS-T showed good construct validity, internal consistency, and stability over time and correlated significantly with the psychoticism subscale of the Brief Psychiatric Symptom Rating Scale. As predicted, the mean differences in CAPS-T scores between participants with or without a psychotic disorder were significant. Convergent and discriminative validity were satisfactory. A score of 5 was found to be the best threshold in discriminating between clinical and nonclinical samples. Conclusions Our findings indicate that the Taiwanese version of the CAPS is a reliable and valid instrument to measure the multidimensionality of perceptual anomalies in general and appears to complement the clinical measures of psychosis proneness in Taiwan.

Correlates of perceptual distortions in clinical and non-clinical populations using the Cardiff Anomalous Perceptions Scale (CAPS): Associations with anxiety and depression and a re-validation using a representative population sample

Although the literature on hallucinations in psychiatric patients shows clear links with anxiety and depression, associations of affect with a wider array of anomalous perceptual experiences have been much less studied. This study investigated patients with psychosis ( N = 29) and a non-clinical population ( N = 193) using the Cardiff Anomalous Perceptions Scale (CAPS), a measure of perceptual distortion and associated distress, intrusiveness and frequency; along with measures of depression, anxiety and worry. The study also allowed a re-validation of the CAPS in a more representative sample of the UK population. Moderate, reliable correlations with depression, anxiety and worry were found in the non-clinical population with the association being stronger in psychotic patients. The study re-confirmed that anomalous perceptual experiences are common in the general population and that a significant minority (11.9%) have higher levels than the mean of psychotic patients. Scale reliability and validity were also re-confirmed, and the CAPS score was found to be unrelated to age or gender in either sample. As in the original study, factor analysis produced a three-factor solution, although factor theme was not fully replicated: as before, a cluster of first-rank symptoms emerged, but with equivocal evidence for a temporal lobe factor and no replication of a ‘chemosensation’ component.

When doors of perception open: Visual contrast sensitivity in never-medicated, first-episode schizophrenia.

Schizophrenia is characterized by impaired visual contrast sensitivity and anomalous perceptual experiences. The aim of this study was to investigate these phenomena in unmedicated patients with first-episode schizophrenia. Visual contrast sensitivity was measured with pulsed-pedestal and steady-pedestal tests, which bias information processing toward the parvocellular and magnocellular pathways, respectively. Anomalous perceptual experiences were investigated with the Structured Interview for Assessing Perceptual Anomalies (SIAPA). Results revealed that patients with schizophrenia (n = 20) exhibited increased contrast sensitivity values on the magnocellular test relative to the control participants (n = 20). In the parvocellular condition, there was no significant difference between the two groups. The higher magnocellular contrast sensitivity values were associated with increased visual SIAPA scores, especially at the two lowest spatial frequencies (0.25 and 0.5 cycles/degree). These results indicate the heightened sensitivity of magnocellular pathways in unmedicated first-episode schizophrenia, which may contribute to anomalous perceptual experiences and sensory overloading.

Cognitive correlates of the spontaneous out-of-body experience (OBE) in the psychologically normal population: Evidence for an increased role of temporal-lobe instability, body-distortion processing, and impairments in own-body transformations

Recent findings from studies of epileptic patients and schizotypes have suggested that disruptions in multi-sensory integration processes may underlie a predisposition to report out-of-body experiences (OBEs: Blanke et al., 2004; Mohr et al., 2006). It has been argued that these disruptions lead to a breakdown in own-body processing and embodiment. Here we present two studies which provide the first investigation of predisposition to OBEs in the normal population as measured primarily by the recently devised Cardiff anomalous perception scale (CAPS; Bell et al., 2006). The Launay–Slade Hallucination scale (LSHS) was also employed to provide a measure of general hallucination proneness. In Study 1, 63 University students participated in the study, 17 of whom (26%) claimed to have experienced at least one OBE in their lifetime. OBEers reported significantly more perceptually anomalies (elevated CAPS scores) but these were primarily associated with specific measures of temporal-lobe instability and body-distortion processing. Study 2 demonstrated that OBEers and those scoring high on measures of temporal-lobe instability/body-distortion processing were significantly impaired, relative to controls, at a task requiring mental own-body transformations (OBTs) ( Blanke et al., 2005). These results extend the findings from epileptic patient studies to the psychologically normal population and are consistent with there being a disruption in temporal-lobe and body-based processing underlying OBE-type experiences.

Out-of-Body Experiences and Hallucinatory Experiences: A Psychological Approach

In an out-of-body experience (OBE), the “self,” or center of awareness, seems to temporarily occupy a position spatially remote from one's body. In support of previous studies, undergraduate students reporting OBEs ( N = 132) showed a higher level of cognitive-perceptual schizotypy, absorption, dissociation, fantasy, and hallucination proneness, and visual imagery than did non-OBErs ( N = 516). Absorption and cognitive-perceptual schizotypy were the best discriminators for visual and tactile hallucinations ( p &lt; .001). The results support a dissociation model of OBEs. Some persons reported beneficial adaptive effects from their OBEs. Despite the widespread occurrence of anomalous perceptual experiences, including OBEs, in the general population, the term hallucination still has pejorative overtones. The present results are in agreement with other studies in which measures of fantasy proneness seemed to be successful predictors of psychic phenomena (Myers, Austrin, Grisso, &amp; Nickeson, 1983; Wilson &amp; Barber, 1982). Such findings suggest that OBEs may be related to fantasy proneness and cognitive-perceptual schizotypy, which are correlated with each other. Future research should focus on the role of different types of OBEs in personality and cognitive processing.

Testing the continuum of delusional beliefs: An experimental study using virtual reality.

A key problem in studying a hypothesized spectrum of severity of delusional ideation is determining that ideas are unfounded. The first objective was to use virtual reality to validate groups of individuals with low, moderate, and high levels of unfounded persecutory ideation. The second objective was to investigate, drawing upon a cognitive model of persecutory delusions, whether clinical and nonclinical paranoia are associated with similar causal factors. Three groups (low paranoia, high nonclinical paranoia, persecutory delusions) of 30 participants were recruited. Levels of paranoia were tested using virtual reality. The groups were compared on assessments of anxiety, worry, interpersonal sensitivity, depression, anomalous perceptual experiences, reasoning, and history of traumatic events. Virtual reality was found to cause no side effects. Persecutory ideation in virtual reality significantly differed across the groups. For the clear majority of the theoretical factors there were dose–response relationships with levels of paranoia. This is consistent with the idea of a spectrum of paranoia in the general population. Persecutory ideation is clearly present outside of clinical groups and there is consistency across the paranoia spectrum in associations with important theoretical variables.

PW01-169 - Affective attunement. Towards an alternative explanation of delusion

In the course of this paper it will be argued that the Cotard's and Capgras' delusions results from an anomalous perceptual experience, caused by the lack of affective responsiveness. The central difference seems to lie in the attributional manner: Capgras patients interpret the resultant experiences in a paranoid, projective attributional manner, while Cotard patients interpret them in a depressive, introjective attributional manner.The main idea of this paper is that a philosophical analyse of anomalous experience in these delusions can help us to modify the traditional assumptions about the primacy of cognitive or theoretical attitudes to the world. I will argue that primacy is to be granted to an affective attunement to the world, which functions as a subpersonal mechanism of qualitative bodily responses. What these delusions show us is that the disruption of this affective attunement leads to a cognitive deficit, in which the patient accepts a belief that is incoherent with the rest of her believes.

Why overlearned sequences are special: distinct neural networks in the right hemisphere for ordinal sequences

AbstractWritten and spoken words activate left hemisphere areas involved in language processing. However, we here show that overlearned sequences (e.g. letters, numbers, weekdays, months) involve an unexpected right hemispheric activation in both the middle temporal gyrus and temporoparietal junction. Our findings offer a framework for understanding neuropsychological patterns seen in conditions such as synesthesia, in which anomalous perceptual experiences are triggered by overlearned sequences, and also in semantic dementia, in which left hemisphere damage disrupts word knowledge even while sequences can be spared.

Normalizing Endophenotypes of Schizophrenia: The Dip and Draw Hypothesis

Schizophrenia is a multifactorial complex genetic disorder generally characterized by a copious and polarized array of features that cause an anomalous perception of reality and social dysfunction. Timely and accurate diagnosis of schizophrenia can be obscured due to comorbidity and treatment is often unsatisfactory. Two models, the dopamine and glutamate hypothesis, attempt to explain the underlying mechanisms of the disease. Importantly, the hypotheses are not mutually exclusive and may work together in the manifestation of schizophrenia, each playing an independent role for a subset of symptoms. Finding causes of the disease has been extremely difficult, largely due to its phenomic complexity. As a consequence, psychiatrists have begun to document endophenotypes, quantifiable symptoms with a molecular basis, for the disease in attempts to deconstruct, simplify and focus schizophrenia research. Endophenotypes can be present in model organisms, allowing for elegant and controlled experimentation. A recently generated reversible animal model of aberrant dopaminergic activity provides support for a novel understanding of how the brain may respond to antipsychotics. A prediction herein named the dip and draw hypothesis is presented to explain discrepancies between the early and delayed-onset hypotheses of antipsychotic action. Although progress in schizophrenia research has been modest over the last century, the recent union of theory and technology may provide the potential for better treatment.

ALTEA: The instrument calibration

The ALTEA program is an international and multi-disciplinary project aimed at studying particle radiation in space environment and its effects on astronauts’ brain functions, as the anomalous perception of light flashes first reported during Apollo missions.The ALTEA space facility includes a 6-silicon telescopes particle detector, and is onboard the International Space Station (ISS) since July 2006.In this paper, the detector calibration at the heavy-ion synchrotron SIS18 at GSI Darmstadt will be presented and compared to the Geant 3 Monte Carlo simulation. Finally, the results of a neural network analysis that was used for ion discrimination on fragmentation data will also be presented.

Are Anomalous Perceptual Experiences Necessary For Delusions?

Several theories of delusions suggest that anomalous perceptual experience is necessary for delusion formation. This study evaluated levels of anomalous perceptual experience in a large group of nonclinical participants from the general population (N = 337), a group of psychotic inpatients (N = 20), and 2 groups of hallucinating (N = 24) and nonhallucinating (N = 24) deluded patients. The aims of the study were to evaluate the hypothesis that pathological levels of anomalous perceptual experience were necessarily associated with delusions. Using the Cardiff Anomalous Perceptions Scale, the main finding was that as a group, nonhallucinating deluded patients were not significantly different from nonclinical participants on any of the anomalous perceptual experience indices. We conclude that anomalous perceptual experience, as measured by the Cardiff Anomalous Perceptions Scale, is not necessary for the presence of delusions.

Patients' First Encounter Can Color Schizophrenia's Course

Patients' First Encounter Can Color Schizophrenia's Course