I did that. Did I?
BNA 2013: Festival of Neuroscience, which took place at the Barbican last week, brought together scientists from across the field for an exciting meeting of minds that combined a scientific conference with a public programme of events. A group of science writers from the Wellcome Trust attended the scientific conference. Here, Penny Bailey reports on one seminar that she chose to attend…at least, she thinks she did.
Choosing and Doing: the neuroscience of voluntary action, was a symposium convened by Professor Patrick Haggard (UCL) on Tuesday 9th April as part of BNA 2013: Festival of Neuroscience.
A strong theme emerging from the ‘Choosing and Doing’ seminar was that predictability is rarely a good thing. If a species behaves in predictable ways it puts them at a significant disadvantage – they are more likely to be beaten by competitors and eaten by predators.
Whether or not we are ‘predictable’ is also indicative of how much ‘free will’ we have. Modern neuroscience refutes Descarte’s notion of a ‘ghost in the machine’ – that we have a mind that is independent of our body generating intentions within our brain, which in turn prompt our bodies to act. The consensus now is that our mind and body are one – our mental states are purely physical.
That being the case, the debate about how much ‘agency’ we have over our actions centres largely on deterministic versus stochastic models of the brain. In a deterministic model, our future intentions can be predicted from the initial conditions or starting point and the external forces acting on us. In a stochastic model however, we demonstrate ‘spontaneous behavioural variability’ – the ability to spontaneously choose to act in unpredictable ways. The latter has an evolutionary advantage in that it allows us to elude predators, explore new environments and discover hidden resources. It also suggests we have a degree of individual freedom or agency.
The notion of agency is important to us – we have a strong sense of ownership of our actions and feel very in control of ourselves and our world. If we raise our left arm, we think ‘That’s OK, I did that’. Or ‘I pressed the button and the lift came.’ This helps us not to feel constantly surprised (and alarmed) at the things our bodies are doing.
The degree to which we really ‘own’ the action of raising our left arm or pressing the lift button depends on a number of factors: whether we independently formed the intention to execute the action, whether we were aware of that intention, and whether we were aware of the action as we executed it.
A number of experiments in which participants are asked to carry out very simple tasks, such as pressing a button and estimating when they decided to press that button, indicate that we have less awareness of our intentions – and may not always be the ’free’ generator of them – than we like to think. Researchers can predict when our intentions will form -– from our eye signals and patterns of brain activity – seven to eight seconds before we ourselves are aware of the intention.
The effect is more pronounced in individuals with Tourettes syndrome (which produces involuntary ticks). People with the condition are aware of their movements, but significant ‘signalling noise’ reduces their experience/awareness of any intention driving the movement.
The comforting notion that in the absence of disorders like Tourettes, we are the independent generator of that intention has also been undermined. Research has shown that stimulating people’s brain directly with an external electrical current can act as the ‘deus ex machina’, producing an ‘urge’ (intention) to move a particular body part. When the current was increased, people actually ‘involuntarily’ executed that movement.
We go to considerable mental lengths to hold onto our sense of agency – the belief that we form an intention then execute a movement that impacts on the world in that order – in the face of these somewhat unnerving findings. When we press a button and hear a subsequent beep, we link the two causally (‘intentional binding’) by attributing a shorter interval of time between our action and the beep than was actually the case. People with ‘alien hand movement’ – a disorder in which their awareness of their hand movements is disrupted – perceive the interval between action and beep as even shorter (‘action binding’); they compensate for a weak volitional signal by strongly capturing their awareness of the movement.
All in all, we’re starting to look a lot more predictable than we might like to think, although a strong caveat is that this is only in very simple tasks designed to allow researchers to pinpoint precisely what is happening at the neuronal level. We’re complex creatures and neuroscience can’t yet predict who we will marry or where we’ll be in five years time before we have any idea ourselves of who or where that is likely to be.