Psychotic-like experiences may reflect disrupted signal discrimination, whereby individuals overinterpret noisy sensory input as meaningful. Drawing on predictive coding accounts, we investigated whether increased sensory precision and reduced data-gathering relate to psychotic-like experiences in a signal discrimination task. We fitted drift-diffusion models to Random Dot Motion (RDM) task...
Hallucinations are deeply intriguing phenomena but conducting research on them can be challenging. Ineffable experiences can test the limits of traditional research methods and can rely on individu...
Introduction: Hallucinations research is increasingly incorporating philosophy or the work of philosophically trained individuals. We present three different ways in which this is successfully implemented to the enhancement of knowledge and understanding of hallucinations and related phenomena.Method: We review contributions from phenomenology, philosophy of cognitive science, and philosophy of...
BACKGROUND: Unusual experiences in Tulpamancer and Autonomous Sensory Meridian Response (ASMR) communities are generally positive and sought after, unlike hallucinations and delusions in clinical populations. Metacognition, the ability to reflect on self-referential experiences, may aid sense-making around unusual experiences, reducing distress. This study investigated group differences in...
According to the High-order Theory of Emotional Consciousness (HOTEC), every emotional process is a conscious and high-order state of mind carried out by the General Networks of Cognition (GNC), which consists mainly of prefrontal mechanisms. This means that anxiety is also an emotional state of mind carried out by the GNC (positive correlation). However, numerous studies have suggested what is...
Impairment in Theory of mind (TOM) has frequently been associated with schizophrenia and with schizotypy. Studies have found that a tendency to over-attribute intentions and special meaning to events and to people is related to positive psychotic symptoms. Further, it has been suggested that this intentionality bias may be due to a broader deficit in context processing (CP). The aim of the...
INTRODUCTION: Metacognition, or "thinking about thinking", is a higher-order thought process that allows for the evaluation of perceptual processes for accuracy. Metacognitive accuracy is associated with the grey matter volume (GMV) in the prefrontal cortex (PFC), an area also impacted in schizophrenia. The present study set out to investigate whether deficits in metacognitive accuracy are...
Introduction: Hallucinations that involve shifts in the subjectively experienced location of the self, have been termed "out-of-body experiences" (OBEs). Early psychiatric accounts cast OBEs as a specific instance of depersonalisation and derealisation disorder (DPD-DR). However, during feelings of alienation and lack of body realism in DPD-DR the self is experienced within the physical body....
Dreams might represent a window on altered states of consciousness with relevance to psychotic experiences, where reality monitoring is impaired. We examined reality monitoring in healthy, non-psychotic individuals with varying degrees of dream awareness using a task designed to assess confabulatory memory errors - a confusion regarding reality whereby information from the past feels falsely...
Introduction: The current study examined the presence of cortical hyperexcitability, in nonclinical hallucinators, reporting different forms of anomalous bodily experiences (ABEs). Groups reporting visual out-of-body experiences and nonvisual sensed-presence experiences were examined. It was hypothesised that only those hallucinators whose experiences contained visual elements would show...
Out-of-body experiences present a unique paradigm to investigate cognitive and neural mechanisms of bodily-self processes and their disorders. Previous work on out-of-body experiences associated with sleep paralysis supported a model in which illusory movement experiences reflect disrupted bodily-self integration generating anomalous vestibular and motor sensations. Further disintegration and...
INTRODUCTION: Aberrant experience of agency is characteristic of schizophrenia. An understanding of the neurobiological basis of such experience is therefore of considerable importance for developing successful models of the disease. We aimed to characterise the effects of ketamine, a drug model for psychosis, on sense of agency (SoA). SoA is associated with a subjective compression of the...
Delusional beliefs have sometimes been considered as rational inferences from abnormal experiences. We explore this idea in more detail, making the following points. First, the abnormalities of cognition that initially prompt the entertaining of a delusional belief are not always conscious and since we prefer to restrict the term "experience" to consciousness we refer to "abnormal data" rather...
This paper proposes the hypothesis that aesthetics plays an important role in the construction and maintenance of delusional ideas in schizophrenia. A selective review of the literature on the cognitive science of aesthetics, beginning with the work of William James on the stream of thought, was undertaken together with a review of some of the cognitive neuroscience literature on delusion...
Although delusions of reference are one of the most common psychotic symptoms, they have been the focus of little research, possibly because they have been considered to be integral to persecutory delusions. Evidence has now emerged that there are two kinds of delusion of reference. One of these, referential delusions of communication, which involves beliefs that others are communicating in...
Introduction: Spatial properties of hallucinations have received relatively little systematic investigation. We present evidence from a web-based study of the spatial properties of a broad array of hallucinations associated with sleep paralysis. Predictions regarding spatial characteristics of hallucinations were based on proposed neurophysiological mechanisms underlying different types of...
Introduction: Quantitative evidence has begun to emerge where human studies suggest that repeated recreational use of +/- 3,4-methylenedioxy-methamphetamine (MDMA or "Ecstasy") produces lasting impairments in explicit memory. The purpose of this investigation was to further explore the nature and pattern of component memory processes in abstinent MDMA users. Methods: Accordingly, 15 MDMA users...
Many thousands of people around the world firmly believe that they have been abducted by alien beings and taken on board spaceships where they have been subjected to painful medical examination. Given that such accounts are almost certainly untrue, four areas of neuroscience are considered with respect to possible clues that may lead towards a fuller understanding of the alien abduction...
Introduction: ''Autoscopic phenomena refer to different illusory reduplications of one's own body and self. This article proposes a phenomenological differentiation of autoscopic reduplication into three distinct classes, i.e., autoscopic hallucinations, heautoscopy, and out-of-body experiences (OBEs). Method: Published cases are analysed with special emphasis on the subject's point of view...
Autoscopic phenomena involve the illusory reduplication of one's own body. The literature on the topic is widely scattered and suffers from considerable terminological and conceptual inconsistencies. This article proposes a classification scheme based on phenomenological criteria. Along with examples of illustrative cases, we outline the main features of autoscopic hallucinations, heautoscopy...