Imperfect Cognitions

Today's post is by  Chenwei Nie  on his recent paper, " Revisiting Maher’s one-factor theory of delusion " ( Neuroethics , 2023). Currently, he is a Teaching Fellow in Philosophy at the University of Warwick, UK. Chenwei Nie Suppose your friend, Ava, is suffering from a delusional belief that her partner is replaced by an imposter. Despite overwhelming evidence to the contrary - such as the supposed imposter's identical appearance to her partner and knowledge of intimate details, and reassurances from you and her other friends - Ava steadfastly maintains this belief. In this unfortunate circumstance, it is obvious that something must have gone wrong in the formation and maintenance of Ava’s belief. It is likely that Ava would be diagnosed with the Capgras delusion. Unravelling what exactly has gone wrong, however, has proven challenging. According to a classic one-factor theory of delusion developed by Brendan Arnold Maher (1924-2009), the only factor, i.e. departure ...

This week we feature the AHRC Project Deluded by Experience , led by Ema Sullivan-Bissett , who is a Reader in Philosophy at the University of Birmingham. In today's post she overviews the first of the Project’s outputs, co-authored with Paul Noordhof (Co-I): ‘ The Clinical Significance of Anomalous Experience in the Explanation of Monothematic Delusions ’, recently published in Synthese (open access).  Subjects with monothematic delusions often undergo some highly anomalous experiences. For example, in Capgras delusion, the strange experience has been understood as one of absence of something expected, the subject has reduced affective response to familiar faces traceable to ventromedial prefrontal damage (Tranel, Damasio, and Damasio 1995, Coltheart 2007), or right lateral temporal lesions and dorsolateral prefrontal damage (Wilkinson 2015, Corlett 2019). Empiricists about delusion formation take it that these experiences play an explanatory role in the formation and maintenan...

This week we feature the project  Deluded by Experience , led by  Ema Sullivan-Bissett , who is a Reader in Philosophy at the University of Birmingham. The project will last 30 months (January 2021–June 2023) and is funded by the Arts and Humanities Research Council, with Ema as PI and  Paul Noordhof  as Co-I. You can follow the Project on twitter  @del_by_ex .  In today's blog, I ask Ema about the project. LB: What is  Deluded by Experience  about?  ESB:  Deluded by Experience  is focused on three main areas. The first is monothematic delusion formation. Philosophers, psychologists, and cognitive neuroscientists have argued that subjects with monothematic delusions have anomalous experiences in which delusions are rooted. However, few take anomalous experience to be the only clinically relevant factor. This is the one-factor approach. The current orthodoxy has it that a second clinical factor (cognitive deficit, bias...

Today’s post is by Ema Sullivan-Bissett , who is a Senior Lecturer in Philosophy at the University of Birmingham. Here she overviews her paper ‘ Unimpaired Abduction to Alien Abduction: Lessons on Delusion Formation ’, recently published in Philosophical Psychology. Last year, when millions of people had marked themselves as attending a storming of Area 51, Ema also wrote about her research for the Birmingham Perspective . In the academic year 2013–14, I was a Postdoctoral Research Fellow on Lisa Bortolotti’s AHRC project on the Epistemic Innocence of Imperfect Cognitions . Towards the end of the Project, I was extremely fortunate to have the opportunity to be a Visiting Researcher at Macquarie University’s ARC Centre of Excellence in Cognition and Its Disorders. Professor John Sutton hosted me for that month, but I was also lucky to spend some time with Professor Max Coltheart , and interviewed him for this blog. In the first part of the interview we talked about delusion for...

In this post, Phil Corlett replies to Ryan McKay 's summary of his paper " Measles, Magic and Misidentifications: A Defence of the Two-Factor Theory of Delusions ", itself a response to Phil's earlier post on his paper " Factor one, familiarity and frontal cortex: a challenge to the two-factor theory of delusions ". See also Amanda Barnier 's important commentary on the debate, and Phil's reply . Got all that? Right, on with the post! I am grateful to Ryan for his careful and collegial rebuttal of my critique. I am grateful too for the opportunity to respond. Ryan’s response does mollify some of my points. However, I am sure no one will be surprised that I have not updated my beliefs about 2-factor theory. First, Ryan suggests that 2-factor theorists knew about the breadth of the deficits of vmPFC cases, since they were described in Langdon and Coltheart’s ( 2000 ) paper. They were indeed described. Why then, 19 years (and hundreds...

I'm Ryan McKay , Professor of Psychology at Royal Holloway, University of London , and head of the Royal Holloway Morality and Beliefs Lab (MaB-Lab) . I'm interested in how we form and revise beliefs, including delusional beliefs. This post is a summary of my article “Measles, Magic and Misidentifications: A Defence of the Two-Factor Theory of Delusions” in reply to Phil Cortlett's recent paper discussed on the blog last week . The Two-Factor Theory of Delusions One may (a) interpret data falsely, but also (b) receive false data for interpretation. ~ Southard, 1912 , p. 328. The idea that delusions arise when individuals attempt to interpret “false data” has been incorporated in several theories of delusions. Two-factor theorists, however (e.g., Coltheart et al., 2011; Davies & Coltheart, 2000 ; Langdon & Coltheart, 2000 ), view deluded individuals both as “receiving false data for interpretation” (factor one, which furnishes the content of the del...

In this post,  Phil Corlett , Associate Professor of Psychiatry at Yale School of Medicine, discusses some of the ideas in his  paper  ‘Factor one, familiarity and frontal cortex: a challenge to the two-factor theory of delusions’ recently published in the Journal of Cognitive Neuropsychiatry. Over recent years, Imperfect Cognitions has become the premier hub and outlet for work on the neurobiology and cognitive psychology of delusions. It has featured my work on aberrant prediction error and delusions in schizophrenia (Corlett et al., 2007 ), and work that conceptually replicates it (Kaplan et al., 2016 ). There has been work, also highlighted on the blog, from neurological patients that suggest instead that a 2-factor explanation of delusions may be more appropriate (Darby et al., 2017 ), although that work was not conclusive (McKay and Furl, 2017 ). It has all garnered much interest. Partly because delusions inherently fascinating, I think, and partly becaus...

In September 2018, a team of Birmingham philosophers, comprising Kathy Puddifoot , Valeria Motta , Matilde Aliffi , EmaSullivan-Bissett and myself , were in sunny Rijeka, Croatia, to talk a whole lot of Epistemic Innocence at the European Society for Philosophy and Psychology . Epistemic innocence is the idea at the heart of our research at Project PERFECT . A cognition is epistemically innocent if it is irrational or inaccurate and operates in ways that could increase the chance of acquiring knowledge or understanding, where alternative, less costly cognitions that bring the same benefits are unavailable. Over the last few years, researchers on the project and beyond have investigated the implications of epistemic innocence in a range of domains (see a list of relevant work here ). Our epistemic innocence symposium at ESPP2018 was a mark of the relative maturity of the concept, and the opportunity for us to start expanding its applications. I went first, exploring the ...

Today’s post is written by Ema Sullivan-Bissett , who is a Lecturer in Philosophy at the University of Birmingham . Here she overviews her paper ‘ Monothematic Delusion: A case of innocence from experience '. Before taking up my current post as Lecturer in Philosophy, I was a Postdoc on Lisa Bortolotti’s AHRC project on the Epistemic Innocence of Imperfect Cognitions (2013-14). In that year we worked together in developing the notion of epistemic innocence, which we thought could be of use in thinking about the epistemic status of faulty cognitions. We understood a cognition as epistemically innocent when it (1) endows some significant epistemic benefit onto the subject (Epistemic Benefit Condition), which could not otherwise be had, because (2) alternative, less epistemically faulty cognitions are in some sense unavailable to her at that time (No Alternatives Condition). As part of that project, we wrote two papers in which we put that notion to use in discussion of exp...

This post is a reply by Phil Corlett (Yale)  (pictured below) to Dan Williams's recent post on Hierarchical Bayesian Models of Delusions . Dan Williams has put forward a lucid and compelling critique of hierarchical Bayesian models of cognition and perception and, in particular, their application to delusions. I want to take the opportunity to respond to Dan’s two criticisms outlined so concisely on the blog (and in his excellent paper) and then comment on the paper more broadly. Dan is “ sceptical that beliefs—delusional or otherwise—exist at the higher levels of a unified inferential hierarchy in the neocortex . ” He says, “ every way of characterising this proposed hierarchy... is inadequate .” Stating that “ it can’t be true both that beliefs exist at the higher levels of the inferential hierarchy and that higher levels of the hierarchy represent phenomena at large spatiotemporal scales . There are no such content restrictions on beliefs, whether delusional ...