Tuesday, 19 June 2018

Hierarchical Bayesian Models of Delusion


Today's post is by Dan Williams, a PhD candidate in the Faculty of Philosophy, at the University of Cambridge.



If you had to bet on it, what’s the probability that your loved ones have been replaced by visually indistinguishable imposters? That your body is overrun with tiny parasites? That you’re dead? As strange as these possibilities are, each of them captures the content of well-known delusional beliefs: Capgras delusion, delusional parasitosis, and Cotard delusion respectively.

Delusional beliefs come in a wide variety of forms and arise from a comparably diverse range of underlying causes. One of the deepest challenges in the contemporary mind sciences is to explain them. Why do people form such delusions? And why on earth do they retain them in the face of seemingly overwhelming evidence against them?

My new paper “Hierarchical Bayesian Models of Delusion” presents a review and critique of a fascinating body of research in computational psychiatry that attempts to tackle these questions. To cut a long story short, that research suggests that delusions arise from dysfunctions in a process of hierarchical Bayesian inference.

To understand what this means, you have to grasp three ideas.

The first is the idea that information processing in the brain is hierarchical. It’s not always clear exactly how this claim should be understood (see below). The core idea, however, draws inspiration from the structure of sensory and motor areas of the neocortex, as well as the extraordinary success of deep (i.e. hierarchical) neural networks in machine learning.

For example, the ventral pathway of the visual cortex contains a cascade of functional areas (e.g. LGN-V1-V2-V4-IT) where low levels represent simple stimulus features such as edge-segments and basic colour and contrast information and higher levels process information at increasingly greater levels of spatiotemporal scale and abstraction, eventually reaching representations of things like faces and houses. Many neuroscientists extrapolate from such findings that all information processing in the neocortex is hierarchical, with perceptual experiences existing at lower hierarchical levels and beliefs existing at higher levels.

The second is the idea that information flow in this hierarchy is bi-directional: information flows up the hierarchy to higher levels, but it also flows back down from higher levels to primary sensory areas.

The third idea is that this process of bi-directional information processing implements a form of (approximate) Bayesian inference, combining prior expectations about the state and structure of the world carried via top-down connections with incoming sensory evidence in a statistically optimal way.

When all is going well, this process of hierarchical Bayesian inference is alleged to leverage the noisy and ambiguous sensory signals the brain receives to put us into contact with their worldly causes at multiple spatiotemporal scales. When the process malfunctions, however, the very properties that make this information processing regime effective at creating that contact with reality imbue it with the capacity to remove that contact in especially sinister ways.

That—in an extremely schematic nutshell—is the basic story of the emergence of psychosis in conditions such as schizophrenia advanced by the work in computational psychiatry that I criticise in my recent paper. The details are of course much more complex and nuanced than I can do justice to here. (See my article and the references therein for a review of those details and some compelling evidence in favour of this story).

In any case, the two challenges that I put forward for hierarchical Bayesian models of delusion are relatively straightforward.

First, I am sceptical that beliefs—delusional or otherwise—exist at the higher levels of a unified inferential hierarchy in the neocortex. Specifically, I think that every way of characterising this proposed hierarchy that I have seen in the literature is inadequate. For example, 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 or not. (Delusional parasitosis concerns tiny parasites). As far as I can tell, however, available ways of avoiding this problem are either inadequate or rely on an appeal to an understanding of “the” hierarchy so nebulous that it ceases to be interestingly hierarchical at all.

Second, I am sceptical that belief fixation is Bayesian. Hierarchical Bayesian models of delusion—and indeed similar models of conditions such as autism—model the brain as an approximately optimal statistical inference machine. I think that this story is plausible for our broadly perceptual and sensorimotor capacities, where most of the evidence for such models exists. I think that it is much less plausible for beliefs, however, which—in my reading of the empirical literature, at least—emerge from a complex stew of bias, suboptimality, motivated reasoning, self-deception, and social signalling. If ordinary belief fixation is not Bayesian, however, we shouldn’t try to explain delusions in terms of dysfunctions in a process of Bayesian inference.

*Thanks to Marcella Montagnese for helpful comments.

Thursday, 14 June 2018

Shadows of the Soul: Philosophical Perspectives on Negative Emotions

This post is by Fabrice Teroni, Associate Professor in philosophy at the University of Geneva, and Christine Tappolet, Full Professor in philosophy at the University of Montreal.






Try to name as many types of positive emotions as you can. Now do the same for negative emotions. You will probably agree with the often-heard claim that the vocabulary we have at our disposal is especially rich for negative emotions: we distinguish between sadness, fear, disgust, regret, remorse, despair, resentment, indignation, contempt, jealousy, hatred, etc. Many of our everyday discussions turn around these negative emotions, aiming at a better understanding of their causes and moderation of their sometimes devastating effects.

That being said, we harbor ambivalent attitudes towards negative emotions; we do not always undergo them reluctantly, for instance. Not only do we think that some situations or objects merit negative emotions, but we also actively pursue them—the aim of many recreational and artistic activities is to elicit fear, and we sometimes enjoy undergoing emotions such as anger and disgust. So, if we do often try to get rid of negative emotions, we certainly do not aim at a purely positive affective life, a life whose interest and coherence can itself be questioned. Indeed, the interest and depth of episodes of satisfaction and joy often appear to be enhanced by the negative emotions to which we are prone.

Moreover, is it not difficult, perhaps even incoherent, to attribute the sorts of attachments to values (justice, generosity, friendship), persons and institutions that prove so central in our self-conception to an individual deprived of negative affect? What would remain of a sense of justice if we lacked the disposition to be outraged when confronted with a blatant injustice?

Shadows of the Soul is the first volume to consider negative emotions as a topic of philosophical study in its own right. It gathers fourteen original contributions (approx. 5000 words each) written by experts in the field and aimed at a non-specialist audience. These articles allow the reader to explore the diversity and complexity of negative emotions, as well as some of the fascinating philosophical issues they raise. The book opens with the exploration of the most fundamental amongst these issues: what makes an emotion negative, and how does the existence of negative emotions affect philosophical approaches to the emotions?

Next, it explores the role of negative emotions in imaginative resistance – the fact that we have a hard time imagining evaluative contents that contradict our convictions (e.g., that killing girls at birth is a good thing) – and in emotional ambivalence – how should we explain the fact that we often have negative and positive attitudes towards a given event? Is this irrational? Beyond these broad theoretical issues, the study of any negative emotion raises a variety of more specific but no less important questions.

The remainder of the contributions allow the reader to explore a fair share of them: the nature of being moved, negative existential feelings, nausea and its relation to aesthetic properties, the distinctive relation between disgust and stench, the value of anxiety, the rationality of grief, the moral standing of shame and contempt, the role of negative emotions in racism, and the irrationality of jealously.  Our hope is that the volume showcases both the intrinsic interest of exploring negative emotions as well  as its potential impact on theorizing about the emotions, which must give due attention to the richness and complexity of our affective lives.

Tuesday, 12 June 2018

Poetry, Philosophy and Mental Health

Lynn-Marie Harper participated in the Philosophy of Mind workshop series for people with various interests in, and experiences of, mental health that Project PERFECT ran in partnership with Mind in Camden in the autumn of 2017. 

Here, she shares some of her poetry. She has always written but started to share her poetry when taking workshops with the poet, novelist and confidence inspiring tutor Aoife Mannix in 2010. Some of the poems below are a direct response to the philosophy workshops, and some address life-experience more generally.




The two poems I presented at Conway Hall at the conference on our last meeting of the Philosophy of Mind course were both written during the workshop series. The first, ‘Rocking the Foundations” was written initially as a response to an assignment on metaphor set by a poetry class tutor, Poet Philosopher Alan Murray.

It served a purpose beyond the assignment though in that I could express my feelings and reactions to a longstanding and ongoing situation involving the house I live in, in what sounds like an exaggerated form, however there was truth lingering within it and hence I could present it as it uses the language of mental distress to describe feelings elicited by movement and deficiencies in building structure.

Rocking the Foundations

The overwhelm elicited by cracking walls
coving covering not only fissures but fear

Doorjambs jamming against doors
hearing voices telling truths and lies in split partitions

Mania in moments of discovery
of uneven floors, ill fitting windows

Party walls suffering from personality disorders
reflecting back onto the experiencing entity’s sanity

In anxious episodes, ceilings and skirtings
intact, subsidence heaving with panic

Gaping crevasses only imagined in manic hysteria
paranoia of costs and sectioning, in both senses

Looking to each in despair, depression
creeping along fault lines, foundations undermined

November 2017


The second poem, Or Should I say……… was written immediately I returned home from the last session of the course in response to the question Sophie asked about what impact the course had and I answered in an image ridden poem, which is that it became increasingly evident that we are all on a continuum between mental illness and wellness, both individually and as a greater society of seeming parts, the communal I, we, in fact, all of us, together. It’s a very relieving recognition…

Or should I say……………

Across a broad continuum I float on the sea of dreams
Or should I say I paddle in a round boat of my own seeming making
which I realise is not my own at all but part of that big picture of oneness
or should I say we float, we paddle, we live, we are,
and that we ness, we we weness is all we are waiting for
for the ship to re arrest us as we glide motionless on the sea of expectation

dreams have turned, become some other some else, something nightmarish,
coated in overwhelm sweetened with saccharinous jargon and vicious labelling
overladen with yellow light and electrical voltage, imaged accordingly

Its so simple really. We are all on this continuum, we and all, on and are
arranged in an order that tells of despair and easy reckoning
we look at each other and say we, we talk of how it has been, what we’ve done

thought, felt and name it I. It is the one I, we, and we move along the conveyor belt
at different speeds and in varied configurations but none is left out of this vast continuum
we are all more or less ill, more or less well and at last it is recognised for what it is.

December 14th 2017


Thursday, 7 June 2018

Political Emotions. The Role of Affect in Social Movements

This post is by Katja May, PhD candidate at the University of Kent.




Emotional Politics – The Role of Affect in Social Movements and Organizing took place on 31 May 2018 at the University of Kent in Canterbury. The conference aimed to bring together academics, activists, policy-makers and practitioners to share current concerns and developments in the research and practice surrounding emotion, organizing and social movements. It was co-hosted by the Gender, Sexuality and Culture Research Cluster in the School of Social Policy, Sociology and Social Research at Kent and kindly sponsored by the Centre for Colonial and Postcolonial Studies, the School of English and the Centre for Gender, Sexuality and Writing. The organizers Katja May and Angela Matthews, are both PhD students at Kent, and their joint interest in affect, emotion and social transformation was the driving force behind this conference.

Veteran activist and scholar Angela Y. Davis (2016) claims that in order for a movement to be effective it needs to mobilize the masses. As such, this conference asked:  How does one reach the masses? What motivates people to join a movement, especially if they are not directly affected by the campaign’s agenda and the successful implementation of its goals? How can organizers and campaigners make use of emotion, feeling and affect as these circulate between subjects and objects? What problems may arise in the concrete experience of organizing? Speakers approached these questions from a variety of ways and their various disciplinary backgrounds ranging from sociology, geography and politics to literature, arts and journalism provided an interesting mix of different methodologies and critical arguments.


The morning panels engaged with the topic of collective and distributed emotion as well as with affective media representations of social movements and protests. Afterwards, Carolyn Pedwell, Reader in Cultural Studies at the University of Kent, delivered her brilliant keynote “Digital Tendencies: Intuition, Algorithmic Thought and New Social Movements”. Pedwell drew on a number of different recent examples such as Occupy and Black Lives Matter to flesh out the role of the digital in contemporary organizing.

While conscious of the, at times, certainly problematic connection between social media, affect and neoliberalism, she tried to move away from a narrow analysis of the digital as either negative or positive. Instead, Pedwell argued that the digital can be useful in the development of social movements and ultimately in the adoption of social change. As a medium for communication and continuous engagement it can be used by people to react to that which is in process and may enable movements to “combine a tendency to oppose oppression with a capacity to sense change as it is happening”.



The afternoon included panels on organizing and the ethics of care, the scholar-activist, affective sites of communication and the affective struggles of those who sometimes find themselves on the far side of social change and activism. Jennifer Chisholm from the University of Cambridge, presented findings from her PhD research on women leaders in the Favela Housing Rights Movement in Rio de Janeiro. She argued that the women employ what she terms “vulnerability talk” as a form of “patriarchal bargaining” to justify their position of leadership among male community members. Only by presenting themselves as “leaders-cum-caregivers” appear these women to be able to secure their active position within the movement. A different perspective was offered by Audrey Reeves, from Cardiff University who examined “the importance of affective connections to material objects” in a series of American war heritage sites.

Marked by a dynamic atmosphere and lots of engaging discussion, the day then concluded with inspiring poetry performances by Kat Peddie and Betsy Porritt (both Kent) whose creative work addressed the conference theme in different but equally insightful ways. To find out more about what happened during the conference in this Twitter story.

Tuesday, 5 June 2018

Do Folk Actually Hold "Folk Economic Beliefs"?


Today's post is by Ben Tappin, graduate student in psychology at Royal Holloway at the University of London. In the post he introduces the paper "Do the folk actually hold folk-economic beliefs?" that he has co-authored with Robert Ross and Ryan McKay.

  Ben Tappin (above)

Robert Ross (above)

 Ryan McKay (above)

How do individuals arrive at their beliefs about the economic impact of immigration? More specifically, what are the psychological processes that underpin seemingly widespread beliefs like “immigrants steal jobs” or “immigrants abuse the welfare system?” Just how typical are these (and related) beliefs, and does their prevalence have implications for theorizing about the psychological processes that give rise to them? In the current political climate of Western Europe and the US, these questions seem as relevant now as any time before.

Recently, psychologists Pascal Boyer and Michael Bang Petersen suggested that negative beliefs about the economic impact of immigration – such as those cited above – are widespread; and they theorized that this prevalence is due to the operation of certain evolved cognitive systems. In a commentary on their theory, forthcoming in Behavioral and Brain Sciences, my co-authors and I question whether negative beliefs about the economic impact of immigration are as typical and as widespread as they perhaps appear. To that end, we discuss evidence of substantial variation in individuals’ beliefs about the economic impact of immigration, and, moreover, that positive beliefs about the economic impact of immigration are often as prevalent, if not more so, than their negative counterparts.

Data from the 2015 British Social Attitudes survey, for example, indicate that a large minority of Britons believe immigration is “good” or “very good” for the British economy (roughly 42%). In that survey, a similar proportion reported that it is “bad” or “very bad” (37%). These figures parallel responses to the 2014 European Social Survey, where approximately 40% of Britons said they believed immigration to be good for the economy, while 36% believed it to be bad. Across the Atlantic, more recent evidence paints a similar picture.

A Pew survey conducted in 2017 suggests that a majority (65%) of US adults believe immigrants “strengthen the US with their hard work and talents,” whereas only a minority (26%) consider immigrants a “burden.” These data undermine the notion that beliefs about the economic impact of immigration are typically negative in content; on the contrary, positive beliefs may be as prevalent—if not more so. At the same time, however, this evidence does reveal substantial variation in beliefs about the economic impact of immigration. What might explain such variation?

Perhaps unsurprisingly, partisan identity is a strong predictor of beliefs in the US. A large majority (84%) of individuals who identify with the Democratic party report positive beliefs about the economic impact of immigration, compared to a minority of those who identify with the Republican party (42%) (these figures are also from Pew). In addition to political affiliation, educational attainment appears to be a reliable predictor of belief content; more educated individuals consistently report more positive beliefs about the economic impact of immigration.