The Biologist, June 2013 //
Professor Bruce Hood tells Tom Ireland how the kilogramme of neurons in our head creates an illusion of identity and consciousness.
Bruce Hood is an experimental psychologist specialising in developmental cognitive neuroscience. Best known for his work on infant development, superstition and identity, he delivered the 2011 Royal Institution Christmas Lectures. In his latest book, The Self Illusion, he suggests the ‘you’ inside your head is not really in charge of your actions at all.
Is there a schism between psychology and neuroscience or do they work well together?
It really depends on who you ask. There are some psychologists who think that brain imaging can’t tell you anything you don’t already know. Then there are also some neuroscientists who think that psychology is just common sense. In general most recognise that complex biological systems, such as humans, have different levels of explanation, from the molecular level to social groups. Bridging the gaps between these levels is the tricky part.
As a psychologist whose work comes from a ‘neuroscience perspective’, is it fair to assume you felt that neuroscience offered more interesting insights than ‘classic’ psychology?
Yes, I think that’s true. Looking at the biology helps to constrain the sorts of explanations you can generate. My early work on infant perception was initially influenced by models with little or no reference to how they may be implemented in the brain. When cognitive neuroscience took off in the late 1980s, it seemed that we might be understanding how the brain actually performs the operations that make perception possible. My thesis on infant visual attention benefited greatly from understanding the neuroscience of eye movements. The trouble is that the more complex the function, the harder it is to disentangle the various mechanisms.
In The Self Illusion you describe holding a human brain. It was clearly a profound experience. What was so special about it?
Psychologists like to build hypothetical models to understand processes. These are usually box diagrams with lots of arrows and feedback loops joining up all the separate modules that must exist and coordinate to produce complex thoughts and behaviours. When you hold or dissect a brain, there are no arrows or wiring diagrams. So you are immediately impressed by the magnitude of the difference between understanding how the mind works and the physical system that generates the mind. Then there is the shocking realisation that the 1.5kg of tissue you are holding in your hands once dreamed, fell in love, told jokes and all the other personal experiences that make up the individual. That’s a profound moment.
How much can neuroscience really tell us about how a lump of neurons creates self-awareness and consciousness?
I do not have an answer, neither does anyone, though there are a number of ideas flying about. The main problem is substance dualism. The brain is material and the mind is immaterial. They are of different substance so how could one arise from the other? This is usually the standard objection to my materialist stance. I don’t have an answer but I know that if I alter your material brain through drugs, disease or damage, then your mind will be altered as well. I think that consciousness is not a state but a continuous process of interpretation. When we are unconscious, we are simply not registering the world at the same level of inspection. When we dream, we are conscious – just not conscious of the external world but rather of our internal memories. When we are unconscious and not dreaming, we have no self-awareness but we know the brain is registering information. So for me, consciousness is a continuum of experience, which I think is the output of neural processes that work on both internal and external information. Not exactly falsifiable so not really testable – but an intriguing idea.
Having read and discussed your book with colleagues and friends, their reaction to its central idea seems to be either a terrified denial that this could be the case, or “well, that’s obvious”. What has been the reaction in the scientific community and among the general public?
Yes, indeed it has divided opinion in both communities. Many colleagues are quite comfortable with the idea that the mind is generated by the brain and, as such, it is the output of separable mechanisms. There is no point where it all comes together as a unified self. After all, that is the framework of cognitive neuroscience. And yet some colleagues disagree that it is an illusion because we function as individual selves. That’s where I think that they are wrong. Vision appears to function like a video camera but this is completely wrong – which is one of the reasons that early attempts to build artificial vision failed miserably. The experience of self is very real and, yes, it functions like an independent, integrated individual, but that is not how it could possibly operate.
As far as the general public is concerned, I think they have found this perspective the most shocking because the experience of a unified self is so compelling and inescapable. That’s the thing about illusions – even when you know that they are not what they seem, you cannot change the experience.
Your book contains some clever experiments to support your theory that we very often don’t behave as we’d expect our ‘self’ to. Do you have a favourite?
It has to be Dan Ariely’s experiment, which I cannot believe he got through an ethics committee. He had males rate their attitudes to dubious sexual practices including unprotected sex, group sex, kinky sex, sex with elderly partners and even if they would drug someone for sex. Not surprisingly, they generally thought these acts immoral.
They were then given pornography to view and asked to pleasure themselves while they again gave their attitudes to these various acts. When they were in this state of arousal, they found the sex acts much more acceptable. Which just goes to show that our emotions can sometimes override our moral reasoning. I think we all could have guessed that, but still, it has to be one of the more bizarre studies in the book.
If a society fully understands why it behaves the way it does and, potentially, that the self and free will are illusions, could it lead to people ‘giving up’ attempting to make rational decisions or taking responsibility, and are there implications for the concept of legal responsibility?
This is a really interesting question as neuroscience is increasingly entering the courtroom as an extenuating circumstance in criminal proceedings. Most of us can readily accept that an individual who suddenly develops a brain tumour which makes them dangerous is not responsible for their actions. The problem is, what is an acceptable brain disorder?
If someone has been traumatised as a child so that they lack empathy, something that shows up as abnormal brain responses, does that make them less culpable?
The more we discover about the brain, the more we will be able to identify biological abnormalities between those who commit crime and those who don’t.
If you believe that punishment is a deterrent, and I am not convinced it is at the moment, then arguably it is a factor that plays into the mix of factors that are responsible for whether or not someone commits a crime. I guess that it is for society to decide whether they believe punishment works. It also depends on whether they believe in free will – something that I personally don’t.
Daniel Bor’s book on consciousness, The Ravenous Brain, notes a fascinating case of Siamese twins joined at the head who were able to delve into each other’s memories and experiences. Do you think technology could ever tap into other people’s experience in this way to see life through another person’s perspective?
No, and not just from a technological limitation. As I noted in the book, it is impossible to know what it would be like to think like a bat – a famous philosophical thought experiment. You cannot think like a bat with a human mind because you cannot be both a human and a bat at the same time. Likewise, you cannot have someone else’s mental experiences and maintain your own at the same time. You would become them.