Monitoring what is real: The effects of modality and action on accuracy and type of reality monitoring error

Possible Worlds Theory: How the Imagination Transcends and Recreates Reality

The imagination is central to human social life but undervalued worldwide and underexplored in psychology. Here, we offer Possible Worlds Theory as a synthetic theory of the imagination. We first define the imagination, mapping the mental states it touches, from dreams and hallucinations to satire and fiction. The conditions that prompt people to imagine range from trauma to physical and social deprivation, and they challenge the sense of reality, stirring a need to create possible worlds. We theorize about four cognitive operations underlying the structure of the mental states of the imagination. We then show how people embody the imagination in social behaviors such as pretense and ritual, which give rise to experiences of a special class of feelings defined by their freedom from reality. We extend Possible Worlds Theory to four domains-play, spirituality, morality, and art-and show how in flights of the imagination people create new social realities shared with others.

Delusional Unreality and Predictive Processing

BACKGROUND

Phenomenological psychopathologists have recently highlighted how people with delusions experience multiple realities (delusional and nondelusional) and have suggested that this double bookkeeping cannot be explained via predictive processing. Here, we present data from Kamin blocking and extinction learning that show how predictive processing might, in principle, explain a pervasive sense of dual reality.

METHODS

This cross-sectional study involved 3 participant groups: patients with schizophrenia (SZ) (n = 42), healthy participants with elevated esoteric beliefs (EEBs) (clairaudient psychics) (n = 31), and healthy control participants (HCs) with neither illness nor significant delusional ideation (n = 62). We examined belief formation using a Kamin blocking causal learning task with extinction and delusions with the 40-item Peters Delusion Inventory, specifically the unreality item "Do things around you ever feel unreal, as though it was all part of an experiment?" as a proxy for unreality experiences and beliefs. A clinician also assessed symptoms with a structured clinical interview.

RESULTS

Some people with SZ did not report a sense of unreality, and some people with elevated esoteric beliefs (but no psychotic illness) reported unreality experiences. No HCs reported them (despite reporting other delusion-like beliefs). Unreality experiences in clinical delusions and nonclinical delusion-like beliefs were associated with different types of aberrant prediction error processing.

CONCLUSIONS

These data suggest how predictive processing may explain the sense of unreality. They indicate that different prediction error dysfunctions are associated with delusions with different contents. In this case, we have used predictive processing to address a salient issue raised by our phenomenological colleagues, namely the impact of psychosis on experiences of and beliefs about reality.

A Qualitative Analysis of First-Hand Accounts of Diphenhydramine Misuse Available on YouTube

Deliriants are the least studied class of hallucinogens and display noticeable subjective effects, including dysphoria, hallucinations, and substantial alterations in thought. High doses of diphenhydramine (DPH), an over-the-counter antihistamine medication, can produce deliriant effects due to secondary anticholinergic activity. We sought to characterize the subjective experiences produced by DPH misuse to better understand deliriants more broadly and the context under which DPH misuse occurs. To conduct our analysis, 32 first-hand accounts of DPH misuse publicly available in YouTube videos were analyzed using inductive thematic analysis. Video makers discussed alterations in most sensory modalities, confusion, and a tendency for strongly unpleasant experiences. Occasionally, video makers reported positive effects, although these were rare and often overshadowed by negative aspects of the experience. Video makers frequently warned against misusing DPH, and these individuals occasionally reported adverse post-acute effects. Despite the prevalence of adverse experiences, patterns of repeated misuse were sometimes discussed. Motives for misusing DPH, when mentioned, included accessibility, affordability, and legality. Overall, findings suggest DPH misuse can produce substantial psychoactive effects that are often distressing and share some phenomenological overlap with experiences produced by psychosis.

Reality monitoring and metacognitive judgments in a false-memory paradigm

How well do we distinguish between different memory sources when the information from imagination and perception is similar? And how do metacognitive (confidence) judgments differ across different sources of experiences? To study these questions, we developed a reality monitoring task using semantically related words from the Deese-Roediger-McDermott (DRM) paradigm of false memories. In an orientation phase, participants either perceived word pairs or had to voluntarily imagine the second word of a word pair. In a test phase, participants viewed words and had to judge whether the paired word was previously perceived, imagined, or new. Results revealed an interaction between memory source and judgment type on both response rates and confidence judgments: reality monitoring was better for new and perceived (compared to imagined) sources, and participants often incorrectly reported imagined experiences to be perceived. Individuals exhibited similar confidence between correct imagined source judgments and incorrect imagined sources reported to be perceived. Modeling results indicated that the observed judgments were likely due to an externalizing bias (i.e., a bias to judge the memory source as perceived). Additionally, we found that overall metacognitive ability was best in the perceived source. Together, these results reveal a source-dependent effect on response rates and confidence ratings, and provide evidence that observers are surprisingly prone to externalizing biases when monitoring their own memories.

A novel model of divergent predictive perception

Predictive processing theories state that our subjective experience of reality is shaped by a balance of expectations based on previous knowledge about the world (i.e. priors) and confidence in sensory input from the environment. Divergent experiences (e.g. hallucinations and synaesthesia) are likely to occur when there is an imbalance between one's reliance on priors and sensory input. In a novel theoretical model, inspired by both predictive processing and psychological principles, we propose that predictable divergent experiences are associated with natural or environmentally induced prior/sensory imbalances: inappropriately strong or inflexible (i.e. maladaptive) high-level priors (beliefs) combined with low sensory confidence can result in reality discrimination issues, a characteristic of psychosis; maladaptive low-level priors (sensory expectations) combined with high sensory confidence can result in atypical sensory sensitivities and persistent divergent percepts, a characteristic of synaesthesia. Crucially, we propose that whether different divergent experiences manifest with dominantly sensory (e.g. hallucinations) or nonsensory characteristics (e.g. delusions) depends on mental imagery ability, which is a spectrum from aphantasia (absent or weak imagery) to hyperphantasia (extremely vivid imagery). We theorize that imagery is critically involved in shaping the sensory richness of divergent perceptual experience. In sum, to predict a range of divergent perceptual experiences in both clinical and general populations, three factors must be accounted for: a maladaptive use of priors, individual level of confidence in sensory input, and mental imagery ability. These ideas can be expressed formally using nonparametric regression modeling. We provide evidence for our theory from previous work and deliver predictions for future research.

Explanatory power by vagueness. Challenges to the strong prior hypothesis on hallucinations exemplified by the Charles-Bonnet-Syndrome

Predictive processing models are often ascribed a certain generality in conceptually unifying the relationships between perception, action, and cognition or the potential to posit a 'grand unified theory' of the mind. The limitations of this unification can be seen when these models are applied to specific cognitive phenomena or phenomenal consciousness. Our article discusses these shortcomings for predictive processing models of hallucinations by the example of the Charles-Bonnet-Syndrome. This case study shows that the current predictive processing account omits essential characteristics of stimulus-independent perception in general, which has critical phenomenological implications. We argue that the most popular predictive processing model of hallucinatory conditions - the strong prior hypothesis - fails to fully account for the characteristics of nonveridical perceptual experiences associated with Charles-Bonnet-Syndrome. To fill this explanatory gap, we propose that the strong prior hypothesis needs to include reality monitoring to apply to more than just veridical percepts.

'Sleepy Joe' and 'Donald, King of Whoppers': Reality Monitoring and Verbal Deception in the 2020 U.S. Presidential Election Debates

The 2020 U.S. Presidential election was a campaign that could be characterized as 'one of the nastiest presidential campaigns in recent memory,' partly because the general election debates were highly contentious and featured frequent interruptions and several insults and invectives between candidates. This research compared the language used in the debates to fact-checked truths and lies using a Reality Monitoring (RM) deception detection algorithm in Linguistic Inquiry and Word Count (LIWC) to investigate the veracity of real-life high-stakes verbal messages in the political context. We found that overall RM scores were lower and not significantly different between debate language and fact-checked lies, and RM scores were significantly higher in fact-checked truth statements, indicating that most debate language uttered was deceptive. This result supports the finding that the RM algorithm in LIWC distinguishes truth from lies and debate language in the context of politics. The 60.7% classification rate in this study may reflect a problem with the relatively short word counts of fact-checked lie and truth statements, but most probably reflects individual candidates' deviations in RM features used in their statements. Each individual has a style that they use in communication-'the way people talk and write have been recognized as stamps of individual identity.' Even with a corpus of many statements from the same individual candidates, they probably regularly amplify certain features of RM and diminish other features of RM in their truthful and deceptive messages. This is a fruitful area of research that could be explored in future studies.

The neural signature of reality-monitoring: A meta-analysis of functional neuroimaging studies

Distinguishing imagination and thoughts from information we perceived from the environment, a process called reality-monitoring, is important in everyday situations. Although reality monitoring seems to overlap with the concept of self-monitoring, which allows one to distinguish self-generated actions or thoughts from those generated by others, the two concepts remain largely separate cognitive domains and their common brain substrates have received little attention. We investigated the brain regions involved in these two cognitive processes and explored the common brain regions they share. To do this, we conducted two separate coordinate-based meta-analyses of functional magnetic resonance imaging studies assessing the brain regions involved in reality- and self-monitoring. Few brain regions survived threshold-free cluster enhancement family-wise multiple comparison correction (p < .05), likely owing to the small number of studies identified. Using uncorrected statistical thresholds recommended by Signed Differential Mapping with Permutation of Subject Images, the meta-analysis of reality-monitoring studies (k = 9 studies including 172 healthy subjects) revealed clusters in the lobule VI of the cerebellum, the right anterior medial prefrontal cortex and anterior thalamic projections. The meta-analysis of self-monitoring studies (k = 12 studies including 192 healthy subjects) highlighted the involvement of a set of brain regions including the lobule VI of the left cerebellum and fronto-temporo-parietal regions. We showed with a conjunction analysis that the lobule VI of the cerebellum was consistently engaged in both reality- and self-monitoring. The current findings offer new insights into the common brain regions underlying reality-monitoring and self-monitoring, and suggest that the neural signature of the self that may occur during self-production should persist in memories.

How Processing Fluency Contributes to the Old/New Effects of Familiarity and Recollection: Evidence From the Remember/Know Paradigm

Previous investigations have demonstrated FN400 and LPC, 2 event-related potential old/new effects that respectively reflect familiarity- and recollection-based processes in memory. However, it is unclear whether these effects are susceptible to processing fluency, particularly different types of processing fluency. To address this issue, applying a masked priming paradigm, we conducted an event-related potential experiment by manipulating semantic relations between the prime and the target as identical (reflecting perceptual fluency), thematically and taxonomically related (referring to conceptual fluency), and unrelated. A remember/know (R/K) judgment task in the test phase was used to distinguish familiarity- and recollection-based processes. Behaviorally, both task performance and response speed were modulated by the variables of priming condition, item type, and response type. All 4 priming conditions elicited significant FN400 and LPC. Compared with the K response, the R response was more relevant to the recollection-based processes reflected by LPC. Both FN400 and LPC were modulated by whether there was a response of R, K, or new. The former was susceptible only to conceptual fluency, and the latter was sensitive to both perceptual fluency and conceptual fluency, which offered telling evidence for the dual process model. Considerations for future investigations are proposed. See supplemental materials here: https://www.press.uillinois.edu/journals/ajp/media/evidence_in_remember_know_paradigm/

Evidence for a visual bias when recalling complex narratives

Although it is understood that episodic memories of everyday events involve encoding a wide array of perceptual and non-perceptual information, it is unclear how these distinct types of information are recalled. To address this knowledge gap, we examine how perceptual (visual versus auditory) and non-perceptual details described within a narrative, a proxy for everyday event memories, were retrieved. Based on previous work indicating a bias for visual content, we hypothesized that participants would be most accurate at recalling visually described details and would tend to falsely recall non-visual details with visual descriptors. In Study 1, participants watched videos of a protagonist telling narratives of everyday events under three conditions: with visual, auditory, or audiovisual details. All narratives contained the same non-perceptual content. Participants' free recall of these narratives under each condition were scored for the type of details recalled (perceptual, non-perceptual) and whether the detail was recalled with gist or verbatim memory. We found that participants were more accurate at gist and verbatim recall for visual perceptual details. This visual bias was also evident when we examined the errors made during recall such that participants tended to incorrectly recall details with visual information, but not with auditory information. Study 2 tested for this pattern of results when the narratives were presented in auditory only format. Results conceptually replicated Study 1 in that there was still a persistent visual bias in what was recollected from the complex narratives. Together, these findings indicate a bias for recruiting visualizable content to construct complex multi-detail memories.

Childhood trauma and cognitive biases associated with psychosis: A systematic review and meta-analysis

Childhood trauma is associated with an increased risk of psychosis, but the mechanisms that mediate this relationship are unknown. Exposure to trauma has been hypothesised to lead to cognitive biases that might have causal effects on psychotic symptoms. The literature on whether childhood trauma is associated with psychosis-related cognitive biases has not been comprehensively reviewed. A systematic review and meta-analysis or narrative synthesis of studies examining the association between childhood trauma and the following biases: external locus of control (LOC), external attribution, probabilistic reasoning, source monitoring, top-down processing, and bias against disconfirmatory evidence. Studies were assessed for quality, and sources of heterogeneity were explored. We included 25 studies from 3,465 studies identified. Individuals exposed to childhood trauma reported a more external LOC (14 studies: SMD Median = 0.40, Interquartile range 0.07 to 0.52), consistent with a narrative synthesis of 11 other studies of LOC. There was substantial heterogeneity in the meta-analysis (I2 = 93%) not explained by study characteristics examined. Narrative syntheses for other biases showed weaker, or no evidence of association with trauma. The quality of included studies was generally low. Our review provides some evidence of an association between childhood trauma and a more external LOC, but not with the other biases examined. The low quality and paucity of studies for most of the cognitive biases examined highlights the need for more rigorous studies to determine which biases occur after trauma, and whether they mediate an effect of childhood trauma on psychosis.

Hallucinations as intensified forms of mind-wandering

This paper argues for a novel way of thinking about hallucinations as intensified forms of mind-wandering. Starting from the observation that hallucinations are associated with hyperactive sensory areas underlying the content of hallucinatory experiences and a confusion with regard to the reality of the source of these experiences, the paper first reviews the different factors that might contribute to the impairment of reality monitoring. The paper then focuses on the sensory characteristics determining the vividness of an experience, reviews their relationship to the sensory hyperactivity observed in hallucinations, and investigates under what circumstances they can drive reality judgements. Finally, based on these considerations, the paper presents its main proposal according to which hallucinations are intensified forms of mind-wandering that are amplified along their sensory characteristics, and sketches a possible model of what factors might determine if an internally and involuntarily generated perceptual representation is experienced as a hallucination or as an instance of mind-wandering. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

UnReal? Investigating the Sense of Reality and Psychotic Symptoms with Virtual Reality

Distortions of reality, such as hallucinations, are common symptoms of many psychiatric conditions. Accordingly, sense of reality (SoR), the ability to discriminate between true and false perceptions, is a central criterion in the assessment of neurological and psychiatric health. Despite the critical role of the SoR in daily life, little is known about how this is formed in the mind. Here, we propose a novel theoretical and methodological framework to study the SoR and its relation to psychotic symptoms. In two experiments, we employed a specialized immersive virtual reality (VR) environment allowing for well-controlled manipulations of visual reality. We first tested the impact of manipulating visual reality on objective perceptual thresholds (just noticeable differences). In a second experiment, we tested how these manipulations affected subjective judgments of reality. The results revealed that the objective perceptual thresholds were robust and replicable, demonstrating that SoR is a stable psychometric property that can be measured experimentally. Furthermore, reality alterations reduced subjective reality judgments across all manipulated visual aspects. Finally, reduced sensitivity to changes in visual reality was related to self-reported prodromal psychotic symptoms. These results provide evidence for the relevance of SoR in the assessment of psychosis and other mental disorders in which reality is distorted.

Mnemonic monitoring in anosognosia for memory loss

OBJECTIVE

Anosognosia, or unawareness, for memory loss has been proposed to underlie cognitive functions such as memory and executive function. However, there is an inconsistent association between these constructs. Recent studies have shown that compromise ongoing self-monitoring of one's memory associates with anosognosia for memory loss. Yet to date it is unclear which memory monitoring mechanisms are impaired in these patients. In this study, we examined the extent to which temporal monitoring or orbitofrontal reality filtering (e.g., ability to monitor the temporal relevance of a memory) and source monitoring (e.g., the ability to distinguish which memories stem from internal as opposed to external sources) are associated with awareness of memory deficits.

METHOD

A total of 35 patients (M = 69 years; M = 14 years of education) with memory difficulties following a stroke were recruited from outpatient clinics. Patients were assessed with measures of self-awareness of memory difficulties, cognitive abilities and 2 experimental paradigms assessing source and temporal monitoring.

RESULTS AND CONCLUSION

Results showed that patients unaware of their memory difficulties were more likely to externalize the source of their memories. Specifically, those unaware of their deficits were more likely to assign an external source to memories that were internally produced (e.g., imagined). No differences were observed in relation to temporal monitoring between patients aware and unaware of their deficits. This study informs current theoretical models of self-awareness of memory loss. Future studies should attempt to replicate these findings and explore different memory monitoring mechanisms in relation to anosognosia for memory loss. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Parietal memory network and default mode network in first-episode drug-naïve schizophrenia: Associations with auditory hallucination

Atypical spontaneous activities in resting‐state networks may play a role in auditory hallucinations (AHs), but networks relevant to AHs are not apparent. Given the debating role of the default mode network (DMN) in AHs, a parietal memory network (PMN) may better echo cognitive theories of AHs in schizophrenia, because PMN is spatially adjacent to the DMN and more relevant to memory processing or information integration. To examine whether PMN is more relevant to AHs than DMN, we characterized these intrinsic networks in AHs with 59 first‐episode, drug‐naïve schizophrenics (26 AH+ and 33 AH−) and 60 healthy participants in resting‐state fMRI. We separated the PMN, DMN, and auditory network (AN) using independent component analysis, and compared their functional connectivity across the three groups. We found that only AH+ patients displayed dysconnectivity in PMN, both AH+ and AH− patients exhibited dysfunctions of AN, but neither patient group showed abnormal connectivity within DMN. The connectivity of PMN significantly correlated with memory performance of the patients. Further region‐of‐interest analyses confirmed that the connectivity between the core regions of PMN, the left posterior cingulate gyrus and the left precuneus, was significantly lower only in the AH+ group. In exploratory correlation analysis, this functional connectivity metric significantly correlated with the severity of AH symptoms. The results implicate that compared to the DMN, the PMN is more relevant to the AH symptoms in schizophrenia, and further provides a more precise potential brain modulation target for the intervention of AH symptoms.

Reality-monitoring deficits and visual hallucinations in schizophrenia

The presence of visual hallucinations in addition to auditory hallucinations (V + AH) is associated with poor prognosis in patients with schizophrenia. However, little consideration has been given to these symptoms and their underlying cognitive bases remain unclear. Based on cognitive models of hallucinations, we hypothesized that V + AH are underpinned by an impairment in reality-monitoring processes. The objective of the present study was to test whether reality-monitoring deficits were associated with V + AH in schizophrenia. This study examined reality-monitoring abilities in two groups of patients with schizophrenia: a group of patients with V + AH (n = 24) and a group of patients with AH only (n = 22). Patients with V + AH were significantly more likely to misremember imagined words as being perceived from an external source, compared to patients with AH only (p = 0.008, d = -0.82). In other words, V + AH patients display a larger externalization bias than patients with AH only. One explanation for these results could be that experiencing hallucinations in two sensory modalities may contribute to increased vividness of mental imagery and, in turn, lead to disruption in reality-monitoring processes. This study helps to refine our understanding of the cognitive processes underlying the presence of both auditory and visual hallucinations in patients with schizophrenia.

Sensitivity of Reality Monitoring to Fluency: Evidence from Behavioral Performance and Event-Related Potential (ERP) Old/New Effects

Background

Item memory and source memory are differently processed with both behavioral and event-related potential (ERP) evidence. Reality monitoring, a specific type of source memory, which refers to the ability to differentiate external sources from internal sources, has been drawing much attention. Among factors that have an impact on reality monitoring, fluency has not been well-studied. Therefore, the current study aimed to investigate whether fluency could affect reality monitoring, through observations on both behavioral performance and electrophysiological patterns.

Material/Methods

Adopting ERP techniques, participants were required either to watch the presentation of a name/picture pair, or to imagine a picture for each displayed name, once (low fluency) or twice (high fluency). Later they completed a reality monitoring task of identifying names as perceived, imagined, or novel items. Behavioral performance was measured, and ERP waveforms were recorded.

Results

Behaviorally, high fluency items were faster and more accurately attributed to the sources than low fluency items. ERP waveforms revealed that late positive component (LPC) occurred for all 4 types of items, while imagined items of low fluency did not record a robust FN400 or late frontal old/new effect.

Conclusions

As results revealed, the factor of fluency does influence reality monitoring in terms of accuracy and responding speed. Meanwhile, for imagined items of low fluency, the absence of FN400 and frontal old/new effect also suggests the sensitivity of reality monitoring to fluency, because these representatives of familiarity-based processing and post-retrieval monitoring are inevitably involved in the process of differentiating internal source from external source.

Paracingulate Sulcus Morphology and Hallucinations in Clinical and Nonclinical Groups

Hallucinations are a characteristic symptom of psychotic mental health conditions that are also experienced by many individuals without a clinical diagnosis. Hallucinations in schizophrenia have been linked to differences in the length of the paracingulate sulcus (PCS), a structure in the medial prefrontal cortex which has previously been associated with the ability to differentiate perceived and imagined information. We investigated whether this putative morphological basis for hallucinations extends to individuals without a clinical diagnosis, by examining whether nonclinical individuals with hallucinations have shorter PCS than nonclinical individuals without hallucinations. Structural MRI scans were examined from 3 demographically matched groups of individuals: 50 patients with psychotic diagnoses who experienced auditory verbal hallucinations (AVHs), 50 nonclinical individuals with AVHs, and 50 healthy control subjects with no life-time history of hallucinations. Results were verified using automated data-driven gyrification analyses. Patients with hallucinations had shorter PCS than both healthy controls and nonclinical individuals with hallucinations, with no difference between nonclinical individuals with hallucinations and healthy controls. These findings suggest that the association of shorter PCS length with hallucinations is specific to patients with a psychotic disorder. This presents challenges for full-continuum models of psychosis and suggests possible differences in the mechanisms underlying hallucinations in clinical and nonclinical groups.

Urban Legends and Paranormal Beliefs: The Role of Reality Testing and Schizotypy

Recent research suggests that unconventional beliefs are locatable within a generic anomalous belief category. This notion derives from the observation that apparently dissimilar beliefs share fundamental, core characteristics (i.e., contradiction of orthodox scientific understanding of the universe and defiance of conventional understanding of reality). The present paper assessed the supposition that anomalous beliefs were conceptually similar and explicable via common psychological processes by comparing relationships between discrete beliefs [endorsement of urban legends (ULs) and belief in the paranormal] and cognitive-perceptual personality measures [proneness to reality testing (RT) and schizotypy]. A sample of 222 volunteers, recruited via convenience sampling, took part in the study. Participants completed a series of self-report measures (Urban Legends Questionnaire, Reality Testing subscale of the Inventory of Personality Organization, Revised Paranormal Belief Scale and the Schizotypal Personality Questionnaire Brief). Preliminary analysis revealed positive correlations between measures. Within schizotypy, the cognitive-perceptual factor was most strongly associated with anomalistic beliefs; disorganized and interpersonal produced only weak and negligible correlations respectively. Further investigation indicated complex relationships between RT, the cognitive-perceptual factor of schizotypy and anomalistic beliefs. Specifically, proneness to RT deficits explained a greater amount of variance in ULs, whilst schizotypy accounted for more variance in belief in the paranormal. Consideration of partial correlations supported these conclusions. The relationship between RT and ULs remained significant after controlling for the cognitive-perceptual factor. Contrastingly, the association between the cognitive-perceptual factor and ULs controlling for RT was non-significant. In the case of belief in the paranormal, controlling for proneness to RT reduced correlation size, but relationships remained significant. This study demonstrated that anomalistic beliefs vary in nature and composition. Findings indicated that generalized views of anomalistic beliefs provide only limited insight into the complex nature of belief.

Brain Mechanisms of Reality Monitoring

Reality monitoring processes are necessary for discriminating between internally generated information and information that originated in the outside world. They help us to identify our thoughts, feelings, and imaginations, and to distinguish them from events we may have experienced or have been told about by someone else. Reality monitoring errors range from confusions between real and imagined experiences, that are byproducts of normal cognition, to symptoms of mental illness such as hallucinations. Recent advances support an emerging neurocognitive characterization of reality monitoring that provides insights into its underlying operating principles and neural mechanisms, the differing ways in which impairment may occur in health and disease, and the potential for rehabilitation strategies to be devised that might help those who experience clinically significant reality monitoring disruption.

Testing continuum models of psychosis: No reduction in source monitoring ability in healthy individuals prone to auditory hallucinations

People with schizophrenia who hallucinate show impairments in reality monitoring (the ability to distinguish internally generated information from information obtained from external sources) compared to non-hallucinating patients and healthy individuals. While this may be explained at least in part by an increased externalizing bias, it remains unclear whether this impairment is specific to reality monitoring, or whether it also reflects a general deficit in the monitoring of self-generated information (internal source monitoring). Much interest has focused recently on continuum models of psychosis which argue that hallucination-proneness is distributed in clinical and non-clinical groups, but few studies have directly investigated reality monitoring and internal source monitoring abilities in healthy individuals with a proneness to hallucinations. Two experiments are presented here: the first (N = 47, with participants selected for hallucination-proneness from a larger sample of 677 adults) found no evidence of an impairment or externalizing bias on a reality monitoring task in hallucination-prone individuals; the second (N = 124) found no evidence of atypical performance on an internal source monitoring task in hallucination-prone individuals. The significance of these findings is reviewed in light of the clinical evidence and the implications for models of hallucination generation discussed.