Can we recreate delusions in the laboratory?

Using Extended Reality to Study the Experience of Presence

Extended reality (XR), encompassing various forms of virtual reality (VR) and augmented reality (AR), has become a powerful experimental tool in consciousness research due to its capability to create holistic and immersive experiences of oneself and surrounding environments through simulation. One hallmark of a successful XR experience is when it elicits a strong sense of presence, which can be thought of as a subjective sense of reality of the self and the world. Although XR research has shed light on many factors that may influence presence (or its absence) in XR environments, there remains much to be discovered about the detailed and diverse phenomenology of presence, and the neurocognitive mechanisms that underlie it. In this chapter, we analyse the concept of presence and relate it to the way in which humans may generate and maintain a stable sense of reality during both natural perception and virtual experiences. We start by reviewing the concept of presence as developed in XR research, covering both factors that may influence presence and potential ways of measuring presence. We then discuss the phenomenological characteristics of presence in human consciousness, drawing on clinical examples where presence is disturbed. Next, we describe two experiments using XR that investigated the effects of sensorimotor contingency and affordances on a specific form of presence related to the sense of objects as really existing in the world, referred to as 'objecthood'. We then go beyond perceptual presence to discuss the concept of 'conviction about reality', which corresponds to people's beliefs about the reality status of their perceptual experiences. We finish by exploring how the novel XR method of 'Substitutional Reality' can allow experimental investigation of these topics, opening new experimental directions for studying presence beyond the 'as-if' experience of fully simulated environments.

The epistemic innocence of clinical memory distortions

In some neuropsychological disorders, distorted reports seem to fill gaps in people's memory of their past, where people's self-image, history, and prospects are often enhanced. False beliefs about the past compromise both people's capacity to construct a reliable autobiography and their trustworthiness as communicators. However, such beliefs contribute to people's sense of competence and self-confidence, increasing psychological well-being. Here, we consider both the psychological benefits and epistemic costs and argue that distorting the past is likely to also have epistemic benefits that cannot be obtained otherwise, such as enabling people to exchange information, receive feedback, and retain key beliefs about themselves.

Using hypnosis to model Fregoli delusion and the impact of challenges on belief revision

Fregoli delusion involves the belief that strangers are known people in disguise. We aimed to model aspects of this delusion for the first time using hypnosis. We informed hypnotised subjects that someone would enter the room (a confederate) and they would believe this person was someone they knew in disguise. After testing their reaction to the confederate, we challenged their delusion by directly contradicting their belief and then asking them to focus on the confederate's voice and gait. Finally, we indexed whether they could identify photographs of the confederate. We found that just over half of our high hypnotisable subjects identified the confederate as someone they knew in disguise. Although many highs abandoned their belief in response to challenges, some maintained strong, unwavering conviction that the confederate was a known person. We discuss these findings in terms of how evidence might be evaluated during both hypnotic and clinical delusions.

Hypnosis and imaging of the living human brain

Over more than two decades, studies using imaging techniques of the living human brain have begun to explore the neural correlates of hypnosis. The collective findings provide a gripping, albeit preliminary, account of the underlying neurobiological mechanisms involved in hypnotic phenomena. While substantial advances lend support to different hypotheses pertaining to hypnotic modulation of attention, control, and monitoring processes, the complex interactions among the many mediating variables largely hinder our ability to isolate robust commonalities across studies. The present account presents a critical integrative synthesis of neuroimaging studies targeting hypnosis as a function of suggestion. Specifically, hypnotic induction without task-specific suggestion is examined, as well as suggestions concerning sensation and perception, memory, and ideomotor response. The importance of carefully designed experiments is highlighted to better tease apart the neural correlates that subserve hypnotic phenomena. Moreover, converging findings intimate that hypnotic suggestions seem to induce specific neural patterns. These observations propose that suggestions may have the ability to target focal brain networks. Drawing on evidence spanning several technological modalities, neuroimaging studies of hypnosis pave the road to a more scientific understanding of a dramatic, yet largely evasive, domain of human behavior.

A hypnotic analogue of clinical confabulation

Confabulation-fabricated or distorted memories about oneself-occurs in many disorders, but there is no reliable technique for investigating it in the laboratory. The authors used hypnosis to model clinical confabulation by giving subjects a suggestion for either (a) amnesia for everything that had happened since they started university, (b) amnesia for university plus an instruction to fill in memory gaps, or (c) confusion about the temporal order of university events. They then indexed different types of memory on a confabulation battery. The amnesia suggestion produced the most confabulation, especially for personal semantic information. Notably, subjects confabulated by making temporal confusions. The authors discuss the theoretical implications of this first attempt to model clinical confabulation and the potential utility of such analogues.

Elucidating unconscious processing with instrumental hypnosis

Most researchers leverage bottom-up suppression to unlock the underlying mechanisms of unconscious processing. However, a top-down approach - for example via hypnotic suggestion - paves the road to experimental innovation and complementary data that afford new scientific insights concerning attention and the unconscious. Drawing from a reliable taxonomy that differentiates subliminal and preconscious processing, we outline how an experimental trajectory that champions top-down suppression techniques, such as those practiced in hypnosis, is uniquely poised to further contextualize and refine our scientific understanding of unconscious processing. Examining subliminal and preconscious methods, we demonstrate how instrumental hypnosis provides a reliable adjunct that supplements contemporary approaches. Specifically, we provide an integrative synthesis of the advantages and shortcomings that accompany a top-down approach to probe the unconscious mind. Our account provides a larger framework for complementing the results from core studies involving prevailing subliminal and preconscious techniques.

Shifting self, shifting memory: testing the self-memory system model with hypnotic identity delusions

According to Conway's self-memory system (SMS) model, autobiographical memories may be facilitated, inhibited, or misremembered to be consistent with current self. In 3 experiments, the authors tested this by hypnotically suggesting an identity delusion and indexing whether this shift in self produced a corresponding shift in autobiographical memory. High hypnotizable participants displayed a compelling identity delusion and elicited specific autobiographical events that they could justify when challenged. These memories were reinterpretations of previous experiences that supported the suggested identity. Importantly, autobiographical memories that were no longer consistent with the hypnotically deluded self were less accessible than other memories. The authors discuss these findings in the context of Conway's SMS model and propose 2 accounts of autobiographical remembering during hypnotic and clinical delusions.

Mirrored-self misidentification in the hypnosis laboratory: recreating the delusion from its component factors

INTRODUCTION

Mirrored-self misidentification is the delusional belief that one's reflection in the mirror is a stranger. According to Langdon and Coltheart's (2000) "two-factor" theory of monothematic delusions, the delusion can arise from deficits in face processing (Factor 1) and belief evaluation (Factor 2). This study gave participants separate hypnotic suggestions for these two factors to create a hypnotic analogue of the delusion.

METHOD

Forty-six high hypnotisable participants received a hypnotic suggestion for either Factor 1 alone or for Factors 1 and 2, either with hypnosis (hypnosis condition) or without (wake condition). Participants were asked to look into a mirror and to describe what they saw. Participants who reported seeing a stranger in the mirror also received a series of challenges.

RESULTS

Overall, 70% of participants in the hypnosis condition passed the delusion; only 22% of participants in the wake condition passed. Importantly, in hypnosis, the Factor 1 alone suggestion was just as effective in creating the delusion as the combined Factor 1 and Factor 2 suggestion.

CONCLUSION

These results suggest that hypnotic suggestion can recreate the mirrored-self misidentification delusion from its component factors. Notably, the hypnotic context, itself known to disrupt belief evaluation, can act as Factor 2.

In Defence of Modest Doxasticism About Delusions

Here I reply to the main points raised by the commentators on the arguments put forward in my Delusions and Other Irrational Beliefs (OUP, 2009). My response is aimed at defending a modest doxastic account of clinical delusions, and is articulated in three sections. First, I consider the view that delusions are in-between perceptual and doxastic states, defended by Jacob Hohwy and Vivek Rajan, and the view that delusions are failed attempts at believing or not-quite-beliefs, proposed by Eric Schwitzgebel and Maura Tumulty. Then, I address the relationship between the doxastic account of delusions and the role, nature, and prospects of folk psychology, which is discussed by Dominic Murphy, Keith Frankish, and Maura Tumulty in their contributions. In the final remarks, I turn to the continuity thesis and suggest that, although there are important differences between clinical delusions and non-pathological beliefs, these differences cannot be characterised satisfactorily in epistemic terms.