Koro: a socially-transmitted delusional belief.

INTRODUCTION: Koro is a delusion whereby a man believes his penis is shrinking into his abdomen and this may result in his death. This socially-transmitted non-neuropsychological delusional belief occurs (in epidemic form) in South-East and South Asia. We investigated whether the two-factor theory of delusion could be applied to epidemic Koro. METHODS: We scrutinised the literature on epidemic Koro to isolate features relevant to the two questions that must be answered to provide a two-factor account: What could initially prompt the Koro delusional hypothesis? Why is this hypothesis adopted as a belief? RESULTS: We concluded that the Koro hypothesis is usually prompted by the surprising observation of actual penis shrinkage-but only if the man has access to background beliefs about Koro. Whether the hypothesis is then adopted as a belief will depend on individual factors such as prior belief in the Koro concept or limited formal education and sociocultural factors such as deference to culture, to media, or to rumours spread by word of mouth. Social transmission can influence how the first factor works and how the second factor works. CONCLUSION: The two-factor theory of delusion can be applied to a socially-transmitted delusion that occurs in epidemic form.

Visual hallucinations of autobiographical memories: a single-case study.

Introduction: We report an epileptic patient who experienced hallucinatory visual experiences of autobiographical memories from her past. These visual experiences were confined to the lower left quadrant of her visual field.Methods: We carried out a single-case study that used brain-imaging, EEG and behavioural methods to study this patient.Results: We found that this patient had an incomplete left inferior homonymous quadrantanopia due to a lesion of right occipital cortex, and also that she showed neurological abnormalities in right temporal cortex, a region that is part of the brain's autobiographical-memory circuit.Conclusion: We attribute the occurrence of this patient's autobiographical-memory hallucinations to the combination of degraded visual input to right temporal cortex plus hyperexcitability of that region.

Cotard delusion, emotional experience and depersonalisation.

INTRODUCTION: Cotard delusion-the delusional belief "I am dead"-is named after the French psychiatrist who first described it: Jules Cotard. Ramachandran and Blakeslee proposed that the idea "I am dead" comes to mind when a neuropathological condition has resulted in complete abolition of emotional responsivity to the world. The idea would arise as a putative explanation: if "I am dead" were true, there would be no emotional responsivity to the world. METHODS: We scrutinised the literature on people who expressed the delusional belief "I am dead", looking for data on whether such patients are reported as entirely lacking in emotional responsivity. RESULTS: In numerous cases, patients with Cotard delusion are described as experiencing emotions including anxiety, fear, guilt, distress, euphoria and worry. CONCLUSIONS: We conclude that complete absence of emotional responsivity cannot be what prompts the delusional idea that one is dead. We propose that, in at least some cases, the idea "I am dead" comes to mind in response to symptoms of depersonalisation or derealisation, often present in cases of Cotard delusion, and give examples of Cotard patients with abnormalities in various neural areas that could be responsible for the presence of such symptoms.

What is Capgras delusion?

INTRODUCTION: Capgras delusion is sometimes defined as believing that close relatives have been replaced by strangers. But such replacement beliefs also occur in response to encountering an acquaintance, or the voice of a familiar person, or a pet, or some personal possession. All five scenarios involve believing something familiar has been replaced by something unfamiliar. METHODS: We evaluate the proposal that these five kinds of delusional belief should count as subtypes of the same delusion. RESULTS: Personally familiar stimuli activate the sympathetic nervous system (SNS) much more strongly than unfamiliar stimuli. In Capgras delusion, this difference is absent, prompting the delusional idea that a familiar person is actually a stranger. We suggest this absence of an effect of familiarity on SNS response will occur in all five scenarios and will prompt the idea that the familiar has been replaced by the unfamiliar. CONCLUSIONS: We propose that: (a) all five scenarios be referred to as subtypes of Capgras delusion; (b) in all five, ideas about replacement are prompted by weakness of SNS responses to familiar stimuli; (c) this is insufficient to generate delusion. For a delusional idea to become a belief, a second factor (impaired hypothesis evaluation) must also be present.

How unexpected observations lead to new beliefs: A Peircean pathway.

People acquire new beliefs in various ways. One of the most important of these is that new beliefs are acquired as a response to experiencing events that one did not expect. This involves a form of inference distinct from both deductive and inductive inference: abductive inference. The concept of abduction is due to the American pragmatist philosopher C. S. Peirce. Davies and Coltheart (in press) elucidated what Peirce meant by abduction, and identified two problems in his otherwise promising account requiring solution if that account were to become fully workable. Here we propose solutions to these problems and offer an explicit cognitive model of how people derive new beliefs from observations of unexpected events, based on Peirce's work and Sokolov's ideas about prediction error triggering new beliefs. We consider that this model casts light not only upon normal processes of belief formation but also upon the formation of delusional beliefs.

Characterizing spoken responses in masked-onset priming of reading aloud using articulography.

A key method for studying articulatory planning at different levels of phonological organization is masked-onset priming. In previous work using that paradigm the dependent variable has been acoustic response time (RT). We used electromagnetic articulography to measure articulatory RTs and the articulatory properties of speech gestures in non-word production in a masked-onset priming experiment. Initiation of articulation preceded acoustic response onset by 199 ms, but the acoustic lag varied by up to 63 ms, depending on the phonological structure of the target. Onset priming affected articulatory response latency, but had no effect on gestural duration, inter-gestural coordination, or articulatory velocity. This is consistent with an account of the masked-onset priming effect in which the computation from orthography of an abstract phonological representation of the target is initiated earlier in the primed than in the unprimed condition. We discuss the implications of these findings for models of speech production and the scope of articulatory planning and execution.

Failure of hypothesis evaluation as a factor in delusional belief.

INTRODUCTION: In accounts of the two-factor theory of delusional belief, the second factor in this theory has been referred to only in the most general terms, as a failure in the processes of hypothesis evaluation, with no attempt to characterise those processes in any detail. Coltheart and Davies ([2021]. How unexpected observations lead to new beliefs: A Peircean pathway. Consciousness and Cognition, 87, 103037. https://doi.org/10.1016/j.concog.2020.103037) attempted such a characterisation, proposing a detailed eight-step model of how unexpected observations lead to new beliefs based on the concept of abductive inference as introduced by Charles Sanders Peirce. METHODS: In this paper, we apply that model to the explanation of various forms of delusional belief. RESULTS: We provide evidence that in cases of delusion there is a specific failure of the seventh step in our model: the step at which predictions from (delusional) hypotheses are considered in the light of relevant evidence. CONCLUSIONS: In the two-factor theory of delusional belief, the second factor consists of a failure to reject hypotheses in the face of disconfirmatory evidence.

The assumptions of cognitive neuropsychology: Reflections on Caramazza (1984, 1986).

Approximately 30 years ago, Caramazza (1984. The logic of neuropsychological research and the problem of patient classification in aphasia. Brain and Language, 21, 9-20; 1986. On drawing inferences about the structure of normal cognitive systems from the analysis of patterns of impaired performance. Brain and Language, 5, 41-66) proposed that cognitive neuropsychology needs to make four assumptions in order for its inferences from pathological performance to the structure of intact cognitive systems to be justifiable. These assumptions were: fractionation, modularity, transparency and universality. Analysis of the current status of these assumptions leads me to conclude that all four remain defensible today.

Beliefs about hearing voices.

People who experience auditory verbal hallucinations (AVHs) vary in whether they believe their AVHs are self-generated or caused by external agents. It remains unclear whether these differences are influenced by the "intensity" of the voices, such as their frequency or volume, or other aspects of their phenomenology. We examined 35 patients with schizophrenia or schizoaffective disorder who experienced AVHs. Patients completed a detailed structured interview about their AVHs, including beliefs about their cause. In response, 20 (57.1%) reported that their AVHs were self-generated, 9 (25.7%) were uncertain, and 6 (17.1%) reported that their AVHs were caused by external agents. Several analytical approaches revealed little or no evidence for associations between either AVH intensity or phenomenology and beliefs about the AVH's cause; the evidence instead favoured the absence of these associations. Beliefs about the cause of AVHs are thus unlikely to be explained solely by the phenomenological qualities of the AVHs.

A quasi-randomized feasibility pilot study of specific treatments to improve emotion recognition and mental-state reasoning impairments in schizophrenia.

BACKGROUND: Impaired ability to make inferences about what another person might think or feel (i.e., social cognition impairment) is recognised as a core feature of schizophrenia and a key determinant of the poor social functioning that characterizes this illness. The development of treatments to target social cognitive impairments as a causal factor of impaired functioning in schizophrenia is of high priority. In this study, we investigated the acceptability, feasibility, and limited efficacy of 2 programs targeted at specific domains of social cognition in schizophrenia: "SoCog" Mental-State Reasoning Training (SoCog-MSRT) and "SoCog" Emotion Recognition Training (SoCog-ERT). METHOD: Thirty-one participants with schizophrenia or schizoaffective disorder were allocated to either SoCog-MSRT (n = 19) or SoCog-ERT (n = 12). Treatment comprised 12 twice-weekly sessions for 6 weeks. Participants underwent assessments of social cognition, neurocognition and symptoms at baseline, post-training and 3-months after completing training. RESULTS: Attendance at training sessions was high with an average of 89.29 % attendance in the SoCog-MSRT groups and 85.42 % in the SoCog-ERT groups. Participants also reported the 2 programs as enjoyable and beneficial. Both SoCog-MSRT and SoCog-ERT groups showed increased scores on a false belief reasoning task and the Reading the Mind in the Eyes test. The SoCog-MSRT group also showed reduced personalising attributional biases in a small number of participants, while the SoCog-ERT group showed improved emotion recognition. CONCLUSIONS: The results are promising and support the feasibility and acceptability of the 2 SoCog programs as well as limited efficacy to improve social cognitive abilities in schizophrenia. There is also some evidence that skills for the recognition of basic facial expressions need specific training. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12613000978763 . Retrospectively registered 3/09/2013.

Analytic cognitive style, not delusional ideation, predicts data gathering in a large beads task study.

INTRODUCTION: It has been proposed that deluded and delusion-prone individuals gather less evidence before forming beliefs than those who are not deluded or delusion-prone. The primary source of evidence for this "jumping to conclusions" (JTC) bias is provided by research that utilises the "beads task" data-gathering paradigm. However, the cognitive mechanisms subserving data gathering in this task are poorly understood. METHODS: In the largest published beads task study to date (n = 558), we examined data gathering in the context of influential dual-process theories of reasoning. RESULTS: Analytic cognitive style (the willingness or disposition to critically evaluate outputs from intuitive processing and engage in effortful analytic processing) predicted data gathering in a non-clinical sample, but delusional ideation did not. CONCLUSION: The relationship between data gathering and analytic cognitive style suggests that dual-process theories of reasoning can contribute to our understanding of the beads task. It is not clear why delusional ideation was not found to be associated with data gathering or analytic cognitive style.

Perception, cognition, and delusion.

Firestone & Scholl's (F&S) critique of putative empirical evidence for the cognitive penetrability of perception focuses on studies of neurologically normal populations. We suggest that a comprehensive exploration of the cognition-perception relationship also incorporate work on abnormal perception and cognition. We highlight the prominence of these issues in contemporary debates about the formation and maintenance of delusions.

The relative importance of heads, bodies, and movement to person recognition across development.

Children have been shown to be worse at face recognition than adults even into their early teens. However, there is debate about whether this is due to face-specific mechanisms or general perceptual and memory development. Here, we considered a slightly different option--that children use different cues to recognition. To test this, we showed 8-year-olds, 10-year-olds, and adults whole body, head only, and body only stimuli that were either moving or static. These were shown in two tasks, a match-to-sample task with unfamiliar people and a learning task, to test recognition of experimentally familiar people. On the match-to-sample task, children were worse overall, but the pattern of results was the same for each age group. Matching was best with all cues or head available, and there was no effect of movement. However, matching was generally slower with moving stimuli, and 8-year-olds, but not 10-year-olds, were slower than adults. In general, more cues were faster than heads or bodies alone, but 8-year-olds were surprisingly slow when still bodies were shown alone. On the learning task, again all age groups showed similar patterns, with better performance for all cues. Both 8- and 10-year-olds were more likely to say that they knew someone unfamiliar. Again, movement did not provide a clear advantage. Overall, this study suggests that any differences in face recognition between adults and children are not due to differences in cue use and that instead these results are consistent with general improvements in memory.

What can we learn about visual attention to multiple words from the word-word interference task?

In this work, we develop an empirically driven model of visual attention to multiple words using the word-word interference (WWI) task. In this task, two words are simultaneously presented visually: a to-be-ignored distractor word at fixation, and a to-be-read-aloud target word above or below the distractor word. Experiment 1 showed that low-frequency distractor words interfere more than high-frequency distractor words. Experiment 2 showed that distractor frequency (high vs. low) and target frequency (high vs. low) exert additive effects. Experiment 3 showed that the effect of the case status of the target (same vs. AlTeRnAtEd) interacts with the type of distractor (word vs. string of # marks). Experiment 4 showed that targets are responded to faster in the presence of semantically related distractors than in presence of unrelated distractors. Our model of visual attention to multiple words borrows two principles governing processing dynamics from the dual-route cascaded model of reading: cascaded interactive activation and lateral inhibition. At the core of the model are three mechanisms aimed at dealing with the distinctive feature of the WWI task, which is that two words are presented simultaneously. These mechanisms are identification, tokenization, and deactivation.

Delusions and prediction error: re-examining the behavioural evidence for disrupted error signalling in delusion formation.

INTRODUCTION: There is now significant evidence that prediction error signalling is mediated by dopamine in the midbrain, and that dopamine dysfunction is implicated in people experiencing psychotic symptoms, including delusions. There has also been significant theorizing and experimentation concerning the remaining link in this triad, namely that deviant prediction error signalling produces or maintains psychotic symptoms. METHODS: The research supporting the link between prediction error signalling and delusional symptoms was reviewed. Numerous studies indirectly support this link, but only one set of studies claim to directly test this hypothesis by combining three crucial elements: a patient sample, a manipulation of prediction error and neuroimaging. This particular set of studies were examined in detail. RESULTS: Important methodological limitations in these studies were observed, and a reinterpretation of their data was offered. CONCLUSIONS: Methodological inconsistencies significantly weaken the claims made by these studies, but their data are consistent with current theorizing and they are instructive for future lines of inquiry in this field.

Dismissing subliminal perception because of its famous problems is classic "baby with the bathwater".

Newell & Shanks (N&S) appeal to well-known problems in establishing subliminality to argue that there is little convincing evidence that subliminally presented stimuli can affect decision making. We discuss how recent studies have successfully addressed these well-known problems and, in turn, have revealed clear evidence that subliminally presented stimuli can affect decision making.

A laboratory analogue of mirrored-self misidentification delusion: the role of hypnosis, suggestion, and demand characteristics.

Mirrored-self misidentification is the delusional belief that one's own reflection in the mirror is a stranger. In two experiments, we tested the ability of hypnotic suggestion to model this condition. In Experiment 1, we compared two suggestions based on either the delusion's surface features (seeing a stranger in the mirror) or underlying processes (impaired face processing). Fifty-two high hypnotisable participants received one of these suggestions either with hypnosis or without in a wake control. In Experiment 2, we examined the extent to which social cues and role-playing could account for participants' behaviour by comparing the responses of 14 hypnotised participants to the suggestion for impaired face processing (reals) with those of 14 nonhypnotised participants instructed to fake their responses (simulators). Overall, results from both experiments confirm that we can use hypnotic suggestion to produce a compelling analogue of mirrored-self misidentification that cannot simply be attributed to social cues or role-playing.