Imperfect Cognitions

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...

This post is by Philip Corlett who is currently engaging in a debate with Ryan McKay on this blog about the two-factor theory of delusions (see Phil's and Ryan's previous posts). Here Phil replies to Amanda Barnier's comment . I am grateful to Amanda for her contributions, to the blog exchange and to the literature on delusions. I am of course aware of her hypnosis work – having spent time at Macquarie and even been hypnotized (I am highly hypnotizable, which is perhaps too much to share here). My article and post were provocative and perhaps too confrontational. Having spent time at the Belief Formation Program Table, I understand how exciting and generative it can be. My word choice was perhaps a little too strong. 'Adherents' may have been better. I see that 'acolytes' may be particularly insulting to practicing scientists. My article was about the basic foundational data and arguments of two-factor theory. Whilst Amanda is right to criti...

This post is by Amanda Barnier , Professor of Cognitive Science and Associate Dean Research in the Faculty of Human Sciences at Macquarie University . She was Deputy Leader of the Belief Formation Program and Chief Investigator of the Australian Research Council (ARC) Centre of Excellence in Cognition and its Disorders from 2011-2018. In her work she has attempted to use hypnotic methods to recreate clinical delusions in the laboratory. Here she contributes to the exchange between Phil Corlett and Ryan McKay on the two-factor theory of delusions. I read Phil Corlett ’s and Ryan McKay ’s blog posts with great interest as well as their original article and commentary . As someone who has worked in the field of delusions (albeit on a bit of a hypnotic tangent) for about 15 years (including for 12 years since I arrived at Macquarie University in 2007 to work with Max Coltheart), I wanted to share some insights. In his original published article in Cognitive Neuropsychiatry, Phi...

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...