Belief Formation Program
The Belief Formation Program aims to advance understanding of the normal processing systems for higher-order cognition that are required for healthy belief formation and revision, and the psychiatric symptoms that reflect disorders of these systems. We acknowledge the contribution of our many collaborators and report on a sample of our research below.
- The two-factor theory of delusional belief
- Genetics and structural brain imaging
- Hypnosis Research
- Society and beliefs
- Monitoring our actions and bodies
- Applying vision science to study hallucinations and delusions
- Metacognitive training for delusions
For the past 15 years, researchers of the Belief Formation Program have been developing an influential two-factor theory of delusions. According to this theory, the presence of any delusion can be explained by answering two questions. First: what caused the delusional idea to occur in the first place? Second: why does the patient persist in believing it is true even when family, friends and clinicians offer contradictory evidence? This year we have been considering the ways in which delusions are (as per the traditional definition) resistant to counter-evidence, how delusional individuals treat disconfirmatory evidence, and why these individuals 'jump to conclusions' on data gathering paradigms. In other work we have examined the phenomenological characteristics of auditory verbal hallucinations including hearing voices, to determine which, if any, distinguish between voice-hearers with delusional beliefs and those who believe that their voices are self-generated. We have also been asking whether an analytical thinking style is compromised in delusional people and how inhibitory dysfunction might explain belief revision failures.
Schizophrenia is a severe psychiatric illness characterised by delusions. Some people with schizophrenia also show pervasive cognitive impairments, but others do not. Building upon Green's NHMRC funded research, which established the existence of 'cognitive deficit' and 'cognitively spared' schizophrenia subtypes, we have used support-vector machine learning to distinguish between the patterns of brain volume loss in these subgroups and have investigated genetic associations. We have also studied the structural brain abnormalities associated with delusions in people with schizophrenia. Our findings show reduced surface area of the right dorsolateral prefrontal cortex, reduced hippocampal volume, and reduced thickness of the right anterior cingulate cortex in patients with current persistent delusions as compared to healthy controls and patients with remitted delusions.
Our research has shown that hypnotic suggestions can produce temporary, reversible 'virtual patients' who closely resemble clinical cases. This year we used hypnotic models to study the waxing and waning of delusions and a phenomenon known as 'double bookkeeping'. We have used a classic hypnotic paradigm where we tell subjects that there is a hidden part of themselves - the 'hidden observer' - who knows what is really going on when they are hypnotised. We have also been using transcranial magnetic stimulation (TMS) to study the neural underpinnings of increased hypnotisability and have had two TMS experiments accepted for a Registered Report by the journal Cortex. We have also been working to improve the measurement of hypnotic suggestibility, and we have been studying the distortions of agency that are seen during hypnotic responding in highly suggestible individuals and which resemble the distortions of agency seen in people with schizophrenia.
This broad research stream goes beyond a focus on clinically deluded individuals to study the social, emotional and cultural dimensions of beliefs. We have used the methods of 'cultural evolution' to study the transmission of culture and belief, studied shared beliefs (and delusions), and started to work on the emotional causes and consequences of affectively-laden beliefs. We have also considered the legal and moral issues that arise when delusional people act on their delusions and cause harm. In particular, we have been examining the capacities for moral judgment and moral reasoning in people with schizophrenia.
In this research we seek to understand how we develop a sense of controlling our actions and thoughts, how we recognise the distinction between our bodies and other objects in space, and how our self-representations change in different contexts. We also consider applied implications, such as a user's sense of agency during human-computer interaction, and interventions to remediate agency abnormalities in different disorders. We utilise self-reports about experiences during self-generated actions, behavioural illusion paradigms with ambiguous sensory stimuli, qualitative interviews with people who experience anomalous self-monitoring, including patients with 'passivity' symptoms and expert sportspeople who report states of flow, and experimental manipulations of different agency cues. This year we have also been using consumer grade virtual reality technologies to develop new methods to assess self-representations in the laboratory. In related cross-disciplinary work with our philosopher colleagues we have also been examining the underlying causes of normal and pathological beliefs about one's body, such as delusional denial of one's limb.
This research addresses key knowledge gaps concerning how disruptions of sensory processing contribute to distorted perceptions and beliefs (i.e., delusions) in people with schizophrenia. Our current findings using a well-studied visual illusion, the Tilt Illusion, suggest that people with schizophrenia misuse internally generated proprioceptive information to guide their perception of the visual world. In collaborative work with Professor Gillian Rhodes and her colleagues, we have also found that unconscious processing of gaze information is intact in people with schizophrenia, indicating that any misjudgements of gaze direction that might contribute to socially themed delusions, including paranoia, must manifest at a later stage of conscious processing.
In this treatment-focused research we have been investigating the efficacy of a novel psychotherapy designed specifically for delusional people with schizophrenia - 'metacognitive training' (MCT). The MCT approach targets the cognitive biases that contribute to delusion formation and maintenance in schizophrenia. In turn, the aims of the MCT approach are to alleviate the severity of delusions in people with schizophrenia and to improve their level of insight and satisfaction with life. In related work we have been investigating the efficacy of cognitive remediation treatments to improve general cognitive function in people with schizophrenia.