Tuesday, 30 June 2015

Sense of Agency and Delusions of Alien Control

Glenn Carruthers
This is the fifth and final post in a series of posts on the papers published in an issue of Avant on Delusions. Here Glenn Carruthers summarises his paper 'Difficulties for Extending Wegner and Colleagues' Model of the Sense of Agency to Deficits in Delusions of Alien Control'.

One of Christopher Frith's (e.g. 1992) ideas that has really taken hold is that part of the problem in delusions of alien control is a deficit in the sense of agency. Given that the sense of agency is the feeling that one controls one's actions we can see how a deficit in this feeling could lead to people saying things like:

When I reach my hand for the comb it is my hand and arm which move, and my fingers pick up the pen, but I don’t control them… I sit there watching them move, and they are quite independent, what they do is nothing to do with me… I am just a puppet who is manipulated by cosmic strings. When the strings are pulled my body moves and I cannot prevent it. (Mellor 1970: 18)

Perhaps part of the reason such patients think someone is controlling them is that they do not have this normal sense of agency. To investigate this further we would like to know how the sense of agency is elicited and why it is deficient in these cases. There have been a bunch of hypotheses developed to explain this. Here I will focus on one which was developed by Daniel Wegner and his collaborators (Wegner et al 2004; Wegner and Wheatley 1999).

Wegner and colleagues' hypothesised that the sense of agency is elicited when a subject (unconsciously) infers that one or other of their mental states (e.g. an intention) caused their action. This is called the inference to apparent mental state causation and it occurs automatically when three principles are met:

Priority: The mental state occurs at an appropriate time prior to the action.

Consistency: The mental state is consistent with the action (e.g. the intention specifies the action that actually occurred).

Exclusivity: The mental state is the only plausible cause of the action.

Do we have any reason to suppose that any or all of these principles are systematically violated in cases of delusions of alien control? We can think of many ways in which such principles may be violated. The one I want to squeeze in here is the idea that patients suffering from this delusion represent their actions as occurring later than they should, thus violating the principle of priority. For the patient there is too long a gap between their mental states which might cause their actions and the action itself for the mental state to be a plausible cause.

Suggestive evidence for this comes from ‘intentional binding’ studies. This effect is the apparent binding together in time of actions and their effects. After learning that pushing a button produces a tone subjects are asked to estimate when they pushed the button or when the sound occurred. For those actions which are felt to be voluntary subjects estimate that the button press and tone occur closer together in time than when the button press is involuntary (Haggard et al 2002). In healthy subjects this binding is the result of both the action seeming to occur later and the tone seeming to occur earlier in the voluntary button push condition. Importantly for the above hypothesis the lateness of the button push is exaggerated in patients diagnosed with paranoid schizophrenia (Voss et al., 2010). These patients experience their actions as occurring later healthy controls.

Is violation of the principle of priority likely to explain sense of agency deficits associated with delusions of control? It is difficult to see how this deficit would explain action monitoring problems associated with delusions of control. Frith and Done (1989) had patients play a video game in which they fired a gun at a target which appeared on the left or right of a screen by moving a joystick left or right. Errors were induced by altering the relationship between joystick movements and the direction the gun fired. On some trails a rightward movement fired the gun right, on others a rightward movement fired the gun left (and vice versa). Although no worse than healthy controls or those diagnosed with schizophrenia but not suffering from delusions of control at keeping track of this relationship (Frith and Done 1989: 362), those suffering delusions of control failed to correct errors when they couldn’t see the direction the bullet moved after being fired.

The apparent delay in action which violates the principle of priority seems unlikely to be helpful here. Whilst intuitively we may expect a delay in error correction in those suffering delusions of control we would expect this to be of a similar size to the delay suggested by Martin Voss and colleagues study. In this study those suffering from schizophrenia experienced their actions as occurring in the order of 10s of milliseconds later than controls (Voss et al 2010: 3107). In contrast in Frith and Done’s (1989) study the time subjects had to correct their actions before the bullet became visible was two orders of magnitude greater at 2s. Intuitively, it seems those suffering delusions of control would be able to correct within this time if their only problem were the misrepresentation of the time of their action.

It seems that Wegner and colleagues' hypothesis regarding how the sense of agency is elicited could be used to develop an explanation as to how the sense of agency fails to be elicited in delusions of alien control. Yet when it comes to extending this to account for other problems related to this symptom it falls short. That's a shame, but there are options out there which do not face this problem.

Monday, 29 June 2015

All that glitters...

Emily T. Troscianko
This week Emily T. Troscianko, Knowledge Exchange Fellow at the Oxford Research Centre in the Humanities, and member of the Medieval and Modern Languages Faculty at the University of Oxford, writes about anorexia for our series of accounts by experts-by-experience. Emily also contributes to Psychology Today with a blog called A Hunger Artist.

If there’s any mental illness that offers the sufferer an illusion of having it all, it’s anorexia. The twin towers of that disingenuous promise are thinness and control, bedfellows familiar from pop psychology and the diet industry. No other mental illness gets under observers’ skins (incomprehension, fear, anger, envy) quite like anorexia, and that’s because none other is quite so physical. And it’s in the interplay between the mental and the physical that the hollowness of anorexia’s illusions gets exposed.

In the early days, the heady ‘hunger high’ gets you hooked, the admiring comments about your weight loss keep you hooked, and very soon starvation has kicked in, and then all its profound psychological effects, and all the tenacious feedback loops between the physical and the psychological, make it extremely hard to get unhooked. Take hunger, for example – a powerful nexus of some of the central paradoxes of anorexia. It’s extremely rare for anorexia to involve a consistent absence of hunger. In the vast majority of cases, hunger is an achingly constant companion, and the moments of endorphin-fuelled exhilaration grow rapidly rarer.

Hunger is the thing to be denied – to yourself and to other people (no thanks, I’ve already eaten). Hunger is why you starve yourself – what higher proof of control than shutting your ears to that screaming bodily need, day after day? But hunger always risks stopping you starving yourself – the closer you get to total control, the closer you get to its opposite, in this case bingeing. Hunger is why eating is the most important thing in your day, to be controlled to perfection and indulged in with ecstasy. Hunger distracts you from other pain, and is the ultimate distraction from anything more meaningful. And because so often denied and debarred, and because of the stomach shrinkage and digestive lethargy that come from denying it often enough, hunger deserts you and nausea attacks at the critical moments when you really want to try, and try to want, to eat: on your brother’s birthday, in exam season, when you embark on recovery.

Thursday, 25 June 2015

Valuing Health Conference

University College London
On 4th June I attended some talks at the Valuing Health Conference at University College London, where the themes of Dan Hausman’s book, Valuing Health (Oxford University Press, 2015) were discussed. The event was organised by Jo Wolff and James Wilson. The intended audience was philosophers, economists, and also healthcare policy makers.

The conference started with a brief overview of the arguments in the book, presented by Dan Hausman (University of Wisconsin). There are two basic problems the book was meant to address: (1) we need to be able to compare health improvements brought by different policies; (2) we need to know what to do with the information (e.g., maximise health). Thus, the book provides answers to the following questions: How do we assign values to health states? How do we assess policies on the basis of those values? What role should people play in assigning values to policies? The discussion raises further questions about the relationship between health and wellbeing (the notion of wellbeing is clarified in chapter 6 of the book, and the distinction between wellbeing and the value of health is examined in chapter 10).

Valuing Health
by Daniel Hausman

Tuesday, 23 June 2015

Amending the Revisionist Model of the Capgras Delusion

This is the fourth in a series of posts on the papers published in an issue of Avant on Delusions. Here Garry Young summarises his paper 'Amending the Revisionist Model of the Capgras Delusion: A Further Argument for the Role of Patient Experience in Delusional Belief Formation'.

I currently work as a senior lecturer in psychology at Nottingham Trent University, although my postgraduate studies were in philosophy. My research interests cover three distinct areas. First, I am interested in embodied cognition, particularly the relationship between consciousness and procedural knowledge (knowing how to do something, rather than knowledge of facts). I have argued, using cases of visual pathology (e.g. blindsight and visual agnosia), that a form of knowledge-how (knowing how to do something) can occur in the absence of conscious accompaniment. I am also interested in the ethics underlying the virtual enactment of real-world taboos, such as murder or physical/sexual assault, particularly in the context of video games. Finally, and more pertinent to what we are discussing here, I am interested in the experiences of patient suffering from specific types of delusion, such as the Cotard and Capgras delusions.

In 'Amending the Revisionist Model of the Capgras Delusion: A Further Argument for the Role of Patient Experience in Delusional Belief Formation', I challenge recent attempts to account for the Capgras delusion (the belief that a wife or husband, some family member or significant other, is an impostor) in the absence of an explanatory role for patient experience. In particular, I argue that a recent revisionist model proposed by Max Coltheart and colleagues is partly incorrect and therefore in need revision. I challenge two important (revisionist) claims made by Coltheart and colleagues (2010): (1) that a fully-formed belief enters consciousness (such as 'This person is not my wife, she is an imposter'), and (2) that this is the first conscious delusion-related event.

Thursday, 18 June 2015

Conference on Psychiatry and Society (2)

On 12th May 2015 in London I attended the "Psychiatry and Society" conference organised by the Psychiatry Section of the Royal Society of Medicine. Here I will summarise the talks I heard in sessions 2 and 3, emphasising those themes that have already been discussed in the blog. (If interested in session 1 of the conference, I reported on it last week).

Session 2: Genetics, Neuroscience and Mental Disorder

Pamela Sklar
Neuroscientist Pamela Sklar asked "How may genetics change our understanding of mental illness?" and she focused on schizophrenia as a "mystery", that is a disorder that is both inherited and very common. Thousands of DNA alleles are involved in the risk of developing schizophrenia and bipolar disorder. The difficulty in identifying the genetic bases of such disorders made some people think that research in this area was doomed to failure. But both for bipolar disorder and for schizophrenia some regions that increase risk have been discovered so there is reason for optimism. One very controversial issue is whether genetic risk factors are shared or split among diseases. There is significant more overlap than one would think by following the DSM or the ICD (examples: bipolar and schizophrenia, schizophrenia and autism). Progress in this area will help distinguish between successful and unsuccessful pharmacological treatment, and implies a rejection of current diagnostic categories.

Robin Murray
Psychiatrist and psychiatry researcher Robin Murray discussed Pamela's paper and commented on the large study showing which regions are involved in the genetic risks for schizophrenia, welcoming the day we will stop talking about schizophrenia and start using terms that better reflect the advances in genetics and neuroscience. Latest results in neuroscience suggests that there is no one gene responsible for schizophrenia and that schizophrenia is not a categorical concept. Rather, we need to adopt a dimensional view of schizophrenia because this is supported by current research (in other words, we all have some risk of developing schizophrenia).

Risk of psychosis seems to be increased by: (1) childhood adversities; (2) adverse life events; (3) abuse of cannabis and drug abuse; (4) migration and ethnicity.