Interior Traces - Devon

I'll be at Dartington Hall in the depths of Devon this Thursday evening (after first adding my democratic weight to the swing seat of Hampstead & Kilburn), taking part in a panel discussion on Interior Traces, a play written by my friend and collaborator Louise Whiteley and James Wilkes. It takes a look at how knowing about the brain shapes our views of responsibility, the self, volition and personality, and how this knowledge is shaping the relationship between society and the individual.

If you happen to be in Devon and would like to come along (or indeed to any of the other tour locations), tickets are available here.

I'll be putting a post up shortly on interesting points from the debate.

Introspection

Just read a very thought-provoking working paper on introspection posted by Eric Schwitzgebel:

http://schwitzsplinters.blogspot.com/2010/03/introspection-what.html

It proposes that what we might call introspection arises from a family of both introspective and non-introspective judgments that probably interact in a myriad of complicated ways. So, if we can pick apart the (neural) processes underlying this family of computations, can we deconstruct introspection?

Paper out on the status quo bias

Our paper looking at mechanisms for overcoming a simple bias towards the default in difficult perceptual decisions is out in the Early Edition of PNAS (open access link can be found here).

And for a nice bite-size summary of the findings (better than I could muster here!) check out Deborah Franklin's article in NPR's health blog Shots:
http://www.npr.org/blogs/health/2010/03/the_biology_of_dithering.html

Opticon1826 Issue 7 published

The finishing touches have now been made to Opticon's 7th Issue, which is now out now online. This is my last issue as Life Sciences Editor, and it has been a very enjoyable and rewarding couple of years. Issue 7 is as strong and diverse as ever, with science pieces ranging from Prof. Roger Wotton's on the biology behind mythical flying beasts, to Irma Kurniawan's commentary on the neuroscience of sport.

Enjoy!

Lessons from physics - the independence of vision?

Recently I have been delving into the strange and wonderful world of theoretical physics, by reading Brian Greene's mind-widening book The Fabric of the Cosmos. Some of the ideas (special relativity; time's arrow; quantum uncertainty) were familiar to me from physics classes at secondary school, but back then, through seen-it-all-before teenage eyes, I had never really grasped that what we were learning about was real!

And apart from instilling wonderment, this book has opened my eyes to the parallel perplexities faced by both theoretical physicists and us cognitive scientists. Both fields are trying to know a system (reality; the mind) which refuses to give up its secrets without a little probing and experimentation. And the common thread is that the very act of probing destroys what one is trying to measure. In physics this is known as Heisenberg's uncertainty principle, which states that you can never know certain pairs of physical properties, such as the position and velocity of a particle, at the same time: measuring one peturbs the system and prevents you measuring the other. This is similar to the problem faced when  measuring conscious states and their associated neural correlates. To know whether someone is conscious of, for example, a dim light, we need to elicit a report, which itself fundamentally changes the consciousness (and attendant brain states) of the observer.

This tension I think underpins the ongoing debate over whether phenomenal visual consciousness can be separated from our "access" to that consciousness, as proposed by Ned Block. This is a fundamental and fascinating question, and one that cuts to the heart of the mind-brain relationship. Block (1995; 2007) states that phenomenal (P) consciousness is indeed independent of cognitive access to it, in the sense that we can have private visual experiences without necessarily being able to report these facts to others. He argues that a “mesh” between psychology and neuroscience – an inference to the best explanation – allows us to establish beyond reasonable doubt whether phenomenal consciousness (at “the back of the head”) requires access to be conscious. He focuses on the Landman et al. (2003) study, which found that in response to a secondary cue, subjects could only report part of an 8 object visual array, despite claiming phenomenal consciousness of the whole scene. Importantly, different cues gave access to different parts of the array, thus at some level the information is indeed “there”, ready to be accessed. Block claims that this shows that the information is phenomenally conscious at this early stage. However, epistemic correlationism would say that every piece of data requires a “correlating” report – how else are we to really know what the subject is doing, seeing, or thinking? If this is the case, then we cannot claim for sure that there is phenomenology without access, as it is not scientifically tractable. Again, back to physics: it is rather like Schrodinger’s cat – the cat theoretically might be dead, or it theoretically might be alive, but to know you have to open the box. As for the cat, as for epistemic correlationism in the neurosciences – the only way to know is to open the box and ask the subject.

Block goes on to argue that there is a candidate mechanism for phenomenology in the brain – weak “coalitions” of neural activity in the back of the head (early visual cortex – see e.g. studies by Dehaene on graded conscious processing) that do not get broadcast to frontal areas, and are therefore unreportable. But this logic assumes a priori that phenomenology without some sort of access can exist – if we assume for a moment that it cannot, then the fact that these coalitions are not broadcast (cognitively accessed) would preclude them from being phenomenally conscious. Without these strong assumptions, we cannot know the subjective correlates of these patterns of neural activity. To return to Schrodinger’s cat: imagine that we could perform a scan on the box which would give us some image or pattern to look at. If we assume the cat is alive, we then might be able to say, yes, this assumption would correspond nicely with the fact that the image has such-and-such properties. If the cat is dead when we subsequently open the box, do we have enough evidence to say that the cat was alive at the time we took the image? Of course not. The inference that the cat was alive rests exclusively on the a priori assumption that the cat is assumed to be alive. In the same way, the inference that losing coalitions of visual cortical activity are phenomenally conscious rests on the a priori assumption that the subject is having a phenomenally conscious experience at the time they are recorded.

Flashing forward

It's not often I become excited about a TV show. 24 did it, and so did The West Wing. And House occasionally panders to my occasional yearnings to become, well, House. But recently Flashforward (Mondays, 9pm, Channel 5) has given Mondays a new edge. And in no small part because it meshes the supernatural with run-of-the-mill events to raise lots of "what if" questions about the human mind.

The premise is simple. One day, everyone (on the whole planet) blacks out for 2 minutes and 17 seconds exactly. Workers fall down at their desks, in the gym; surgeons stop operating, planes crash. Worldwide carnage ensues. But then as the cleanup begins, people start to realise that everyone had some kind of "flashforward" during the blackout, to a precise time 6 months from now. And this is where it starts to get interesting. Everyone is fairly sure that these blackouts provide them with a veridical window on the future. They have seen what is going to occur, but the intrigue in the show is how this knowledge affects the characters' behaviour.

The sociologist Robert Merton first coined the term "self-fulfilling prophecy" to define a set of circumstances where simply believing that something will occur leads it to become so. The characters in Flashforward are in the ultimate self-fulfilling prophecy - they have seen what they think is the future, and their actions then become concordant with it. We saw echoes of this type of positive feedback loop in the recent banking collapses: if traders believe a bank is weak, then they tend to act in accordance with this belief, eventually selling the bank so short that it ends up collapsing anyway.

So, if you were offered a glimpse of your future in 6 months, would you take it?

Losing half a brain, and other stories

Last week I had the pleasure of attending the meeting of the British Association for Cognitive Neuroscience. As well as the impressive selection of cake during teabreaks, the conference featured a steady trickle of tidbits and tasters of cutting edge research, in London and beyond. Two of the most striking talks were on the subject of plasticity, both neural and mental.

First up, Dr. Frederique Liegois gave us a stunning reminder of the gross scale plasticity in early childhood. She reported on the mental and linguistic faculties of children who have undergone drastic but necessary removal of a whole cerebral hemisphere to prevent recurrent epileptic seizures. These children literally have lost half their brain. The talk emphasised what we can learn from such neuropsychological cases, in terms of adverse effects on linguistic and cognitive development. While differences exist, Liegois' data suggest the benefits of the operation outweigh its drawbacks. And this is truly staggering. Because on several measures, intellectual development proceeds close to normal, and in some cases the right hemisphere picks up the linguistic slack from the dominant left hemisphere. Speech is often close-to-normal, with only slightly altered lilt and pronunciation. All with only half a brain. It makes you wonder about the benefits of having two, symmetrical hemispheres. Like having two eyes, it offers redundancy in the case of injury. But surely the energy needed to run both sides of the brain is too much of an evolutionary cost to make this the only reason?

Second, Dr. Katerina Fotopoulou reminded us that just like the brain, the mind is plastic. In a recent issue of Neuropsychologia, Fotopoulou and colleagues report a fascinating case of recovery from anosognosia. Anosognosia (Greek - without knowledge) is the term given to a lack of awareness or insight into a particular neurological condition. In extreme forms, anosognosia can result in very bizarre symptoms, such as in Anton's syndrome where cortically blind patients claim vigorously that they are able to see. Dr. Fotopoulou's patient was a 67 year old lady who had hemiplegia - paralysis of half of the body following a right-hemisphere stroke. However, she claimed to be able to move her arm, and breezily asserted that she could clap her hands. This was until Dr. Fotopoulou showed her a video of herself being examined:

"As soon as the video stopped, LM immediately and spontaneously commented: “I have not been very realistic”. Examiner (AF): “What do you mean?” LM: “I have not been realistic about my left-side not being able to move at all”. AF: What do you think now?” “I cannot move at all”. AF:“What made you change your mind?” LM: “The video. I did not realize I looked like this”."

This sudden onset of self-awareness was still present 6 months later. It appeared that allowing the patient a third-person perspective on herself had "cured" her anosognosia, and induced changes in the representation of her own body. While this is a single case report, and may not be representative, the data are tantalising. In particular, they suggest that onset of self-awareness can be sudden and transformative. This makes sense - we all have experienced the sudden "aha" moment accompanying retrieval of the name of that actor that you couldn't drum up during dinner the previous evening. Changes in awareness of the self may share similarities with other change in other aspects of consciousness, such as semantic knowledge, appearing from a first-person perspective as being all-or-nothing. Whether this mental plasticity is accompanied by some rapid form of neural reorganisation, or only a "change in the software", remains an open question.

Fotopoulou et al. (2009), “Self-observation reinstates motor awareness in anosognosia for hemiplegia, Neuropsychologia 47, 5: 1256-1260.