Philosophy of Mind and Psychology Reading Group -- Predictive Mind chapter 10

Welcome to the Philosophy of Mind and Psychology Reading Group hosted by the Philosophy@Birmingham blog. This month, I am introducing chapter 10 of Jakob Hohwy's The Predictive Mind (OUP, 2013).


Chapter 10 - Perceptual Unity in Action
Presented by Lisa Bortolotti

In this chapter, Hohwy attempts to provide answers to two key questions about perceptual unity by relying on the prediction error minimisation (PEM) model. This is part of the project of showing that the model can account for all the core characteristics of conscious experience, such as having a first-person perspective, being cognitively penetrable, being subject to illusions, etc.

(1) Why do the elements of conscious unity hang together?
(2) Why is there one perceptual state subsuming all other ones?

Tim Bayne (2010, page 75) endorses the "unity thesis", i.e. the idea that conscious states of any subject of experience at any one point in time will occur as the components of a single total phenomenal state, a unitary phenomenal field. Hohwy agrees with Bayne that the unity thesis is true and claims that it is an important (but contingent) feature of consciousness. His task is to explain the unity thesis (as it applies to conscious perception) via the PEM mechanism.

In PEM we switch from seeing a coffee shop and feeling thirsty to making a decision about whether to buy a coffee in the shop or go home and have a glass of water (this is Hohwy's example of a switch from perceptual to active inference as described in previous chapters of the book). The switch involves making many predictions on the basis of different hypotheses and evaluating them in the light of contextually relevant considerations (e.g., money, daily intake of caffeine, time) in order to make a decision and act. What we do as agents who are limited to do one thing at a time is to select one hypothesis as "the best prediction error minimizer". This delivers one perceptual field, and no more.

To answer questions (1) and (2), in Hohwy's words, "perception is unified because it is based on hypotheses in a causally structured hierarchical model". Creatures like us can use only one hypothesis at the time to "sample the world" and make decisions about what to do. Building bridges with the work of Susan Hurley (1998, page 3) on the link between consciousness and action, Hohwy claims that "there would be no need for unity if there were no agency". That said, he rejects Hurley's externalism about perception. Causes of sensory input need to be inferred as they are to some extent hidden.

I found the picture sketched by Hohwy in this chapter both clear and attractive. I would be interested in examples where problems of agency (such as disruptions in the capacity to choose one option over another or in the capacity to act consistently) could be explained as problems of "perceptual disunity". If the transition from perceptual to active inference were somehow compromised and, say, two hypotheses were seen as prediction error minimisers, maybe not simultaneously but in very close temporal succession, then would paralysis of action or inconsistent action patterns result? Could this maybe explain phenomena such as "double-bookkeeping" in delusions?

The Probability of Time Travel

Dr Nikk Effingham discusses some of the philosophical issues relating to his new project, 'The Probability of Time Travel'.

Time travel isn’t merely of interest to Dr. Who fans; philosophers and physicists alike worry about whether or not it’s possible. You probably know the sort of story that causes concern: if time travel were possible you could kill your maternal grandmother long before your mother’s conception, but if you did then how would you be born in order to go back in time and commit the dreadful act of murder in the first place? This ‘Grandfather Paradox’ seems to tell against time travel’s possibility.

Within philosophy the most famous contribution to this debate is David Lewis’s ‘The Paradoxes of Time Travel’. We could travel in time, says Lewis, but don’t think you can thereby do the impossible – that (unsurprisingly!) is something you will definitely fail to do. If you go back in time and try and bring about a paradox, then something will get in your way. Perhaps you slip on a banana peel and miss, perhaps the gun jams, perhaps you bump into the man/woman of your dreams and decide an evening of romance is better than an evening of blood-soaked ancestor murder, perhaps… well, lots of things might stop you. Lewis nonetheless assures us that one of those possibilities will definitely come about if you go back in time and try.

These questions about the possibility of time travel are still live questions, and are still discussed in the philosophical literature. What have received less attention are issues concerning the probability of time travel. The ‘Probability and Time Travel’ project headed by myself and Alastair Wilson investigates just these questions. For instance, if it’s definitely the case that something will stop you when you go back in time to kill your grandmother, and one of those things is having a stroke, does that mean that the chance of having a stroke when travelling in time is higher than it would be if you stayed at home? Is time travel hazardous to your health? If so, how hazardous is it?

Nor are these the only questions. Time travel gives rise to all sorts of strange situations called bootstrapping paradoxes. The famous example is Robert Heinlein’s story ‘–All You Zombies–’ wherein the protagonist, who undergoes a sex change and travels through time, is both their own mother and father (the just-released Australian film Predestination is directly based on it). The person ‘comes from nowhere’; they ‘bootstrap’ themselves into existence. Or perhaps (spoiler alert!) you’ve seen the recent blockbuster Interstellar: there mankind is set on a course for extinction but humans from the future interact with the past to save mankind – they ‘bootstrap’ the survival of the entire human race. Similarly there are ‘information paradoxes’ where information appears only through the use of time travel e.g. a time traveler coming back from the future and telling themselves how to build a time machine.

These situations are all very interesting, and the philosophical consensus is that they are, in fact, logically possible (at least, they are if you buy into the possibility of time travel in the first place!). But how likely are they? If time machines were commonplace, should we expect lots of people to be bootstrapped people, or virtually no-one to be bootstrapped? And why focus on humans? Couldn’t a Tyrannosaur Rex bootstrap itself into existence? And why stop with actually existing things? If time travel were possible you could meet a Wookie that only exists because he’s his own mother and father. Is a Wookie as likely to bootstrap itself into existence as a human? Similarly, if mankind is about to die (and we’re certain time travel is possible) should we expect our time travelling future selves to save us? With the information paradoxes we have the same questions. Is Stephen Hawking as likely as Joey Essex to find his future self telling him how to build a time machine? Am I as likely to meet myself coming from the future telling myself how to build a time machine as I am to meet myself coming from the future telling me how to answer a tricky crossword puzzle?

Answers to these questions are difficult to figure out. They also appear to be relevant. For instance, these issues feature in various attempts to reconcile quantum physics with relativity. Such theories talk about ‘closed timelike curves’ – effectively tunnels through space and time that go back to the past – and so what one says about probability and time travel will have bearing on these difficult questions in physics. So musing about Wookies appearing from nowhere and the likelihood of slipping on banana peels is more than mere navel gazing.

The Probability and Time Travel Project is headed by Nikk Effingham and Al Wilson. It is funded by the ‘New Agendas for the Study of Time: Connecting the Disciplines’ project based at the University of Sydney. As part of the project a two day workshop took place in Sydney on the 19^th and 20^th of November 2014.  A second workshop is scheduled to take place in Birmingham, UK, during 2015.

Doctoral Researcher Lauren Traczykowski Speaks at Themes in Emergency Services 2014

One of the appealing aspects of working in the field of Global Ethics is that it provides an opportunity for cross-discipline research. Last week, Lauren Traczykowski, a Global Ethics PhD student, applied ethics to natural disaster intervention at a Nottingham Trent University conference. Her presentation focused on issues of leadership in the wake of the 2005 Pakistan earthquake and the 2010 Haitian earthquake. In it she questioned ethical assumptions underpinning natural disaster response. In particular, she argued that the possibility of military intervention for natural disasters is ethically permissible and ethically required if we are to adequately support those affected by a natural disaster and, at the same time, make headway into actually addressing operational lessons learned.

The conference was titled Themes in Emergency Services 2014 and is hosted biannually by the Emergency Services Research Unit (ESRU) within NTU. This kind of academic-practitioner forum is beneficial because it means that there can be a cross-pollination of ideas. Ultimately, this means that the way we act will be influenced by both experience and research. For natural disasters, better action means better response – and that means more lives saved.

For more information on Lauren’s research, check her website http://www.birmingham.ac.uk/schools/ptr/departments/philosophy/research/postgraduateresearch/profiles/traczykowski-lauren.aspxor follow her on twitter @ltraczy. For more information on ESRU follow @ESRU_NTU

Professor Heather Widdows to Speak at Two Events - 21st and 22nd November 2014

One of our own professors, Professor Heather Widdows, will be speaking at two events this weekend. The first on global health and the second on her new project 'Perfect Me!' which considers the dominant beauty ideal, its demands and implications.



Her first talk is on Friday as part of a conference organised in Birmingham's Law School by the Centre for Health Law, Science and Policy, in response to a presentation entitled Global Health Law, by Larry Gostin. Heather's talk is titled, ‘Global health justice and the right to health’. And in it she reflects on whether Larry’s broadly communal vision of global health justice is well served by making the right to health central to his project. She considers some of the reasons why rights-talk might be problematic in the context of health justice; namely, structurally, rights are individual and state-centric and politically they are oppositional and better suited to single-issue campaigns. She will suggest that stripping rights of their individualist assumptions is difficult, and perhaps impossible, and hence alternative approaches, such as those Larry endorses, based on public goods and/or security might deliver much, perhaps most, global health goods, while avoiding the problems of rights-talk.

Details of the conference can be found here:

http://www.birmingham.ac.uk/schools/law/events/2014/conference-global-health-law.aspx


You might also be interested in hearing Larry speak on ‘Ebloa: Towards an International Health Systems Fund’. This is a public lecture on Friday 21st November (5.30-7.30) – all are very welcome.

To register visit:

http://www.birmingham.ac.uk/schools/law/events/2014/ebola-gostin.aspx

 
Heather's second talk is on Saturday in London at Conway Hall in London. Her talk about beauty and happiness, is entitled, ‘More Perfect, More Happy?’. Here she will  consider whether and in what ways appearance and body image – being perfect – is connected to happiness. A current prevalent assumption is that those who are more perfect will be happier. Many women (and men) judge themselves and others on how much they ‘fit’ the dominant ideal, on how perfect they are, and their sense of self often follows from this. That being perfect connects to being happy is often assumed: ‘if I’m thinner, prettier, sexier s/he’ll love me more’ or ‘if I was ten pounds lighter, I’d be happier with myself and my life would go better’. This talk is part of her wider project on beauty and research for the book she is currently writing called ‘Perfect Me!’ (for Princeton University Press). The other two speakers are very impressive: Professor Lord Layard, (co-editor of co-edited the 2012 World Happiness Report), and Professor Elaine Fox (author of Rainy Brain, Sunny Brain).

For more information on this event go to:

https://humanism.org.uk/civi/?page=CiviCRM&q=civicrm/event/info&page=CiviCRM&id=62&snippet=2

Philosophy of Mind and Psychology Reading Group -- The Predictive Mind chapter 9

Chloë FitzGerald

Welcome to the Philosophy of Mind and Psychology Reading Group hosted by the Philosophy@Birmingham blog.

This month, Chloë FitzGerald introduces chapter 9 of Jakob Hohwy's The Predictive Mind (OUP, 2013). Chloë is postdoctoral Fellow on the project Understanding Implicit Bias in Clinical Care at iEH2 (institut Ethique Histoire Humanités), Centre Médical Universitaire, Université de Genève.


Chapter 9 - Precision, Attention and Consciousness
Presented by Chloë FitzGerald

In Chapter 9, Hohwy describes how the PEM framework can be used to explain the functional role of attention and to illuminate the relation of attention to conscious perception. He claims that the PEM theory of attention is the best explanation we currently have of attention.

Hohwy’s account follows Karl Friston and colleagues’ proposal that ‘attention is just optimization of precisions in hierarchical prediction error minimization’ (p. 194). The sensory signals received by the brain vary in how reliable they are and this variability needs to be gauged to enable perceptual inferences to work well. This is why expected precisions are important for PEM. Howry explains that the brain needs to select where to put in most effort in prediction error minimization and that this effort should be spent where the prediction error signals are expected to be most precise. Attention thus ‘requires learning state-dependent patterns of noise and precision and then using such prior beliefs to set the gain on prediction error’ (p. 195).