There are two winds blowing through neuroscience and psychology right now. The first is carrying loads of research funding that aims to "unlock the mysteries of the human mind" through more expansive neuroscience research programs. Of particular focus with this funding is using neuroimaging to localize behaviours and mental illnesses in the brain. The second wind carries whispers that the aforementioned enterprise is an overfunded and misguided field that has failed to do much if anything, for our knowledge if cognition and consciousness.

Although this backlash against neuroscience has become an exponentially more popular viewpoint in the mainstream just recently, the role of neuroscience and, in particular, neuroimagery has long been debated. The conclusions of these debates are always variations on a theme: Neuroimaging has a role to play alongside the "classical" behavioural research methods (eye tracking, response times, looking times, sorting tasks, etc.) in answering questions about cognition.

But, most psychologists add, it is not the last word in cognitive science, and its discoveries often confirm things we already knew from other measures. For example, psychologists have long believed that there are two underlying cognitive systems that support humans' unique counting abilities one that counts small sets and another that estimates large sets. By placing people in an fMRI, we can see brain activity that corresponds to this view: brain activity varies by whether the task requires counting small or large set sizes.

These converging findings are reassuring for the field and the hallmark of good, replicable science. But for many people, brain evidence like this qualitatively changes the way they see the phenomenon: Seeing the neural basis of some behaviour somehow makes the behaviour itself "just an effect" of some deeper cause, and a cause beyond the person's control. This is hugely important: Neurological explanations have the tendency to "explain away" peoples' actions, even when they are clearly punishable by law.

It is as if seeing where something happens in the brain changes people from believers in free will to believers in absolute (and, I daresay, oversimplified) determinism. I agree that behaviour is, broadly speaking, the causal product of genetics and experience, with a little bit of random noise. But why does it take neuroimaging to convince people of this?

One could say that these images provide some sort of "missing link" between human experience and future behaviour - a link that completes the causal system. But the brain is not a clear, independent cause of future behaviour - it is also the product of past behaviour, experience, and random noise in the system. For example, consider how the brain adapts to the speech sounds of one's native language. Babies are initially born with the ability to tell apart the sounds from (almost) all of the world's languages, even sounds they have never and will never hear. But by the end of their first year, this ability has diminished: They now best discriminate the sounds in the language(s) that they are acquiring. This of course rewires the brain, and so we have a unique biological brain state that will causally influence how this infant hears speech sounds, and even how - when she grows up - she can learn a second language. But this brain state is a product of experience that was beyond the infant's control (i.e., where her family lived). The brain is embedded in a complex, dynamic causal system, and to simplify it as the one missing causal link is incorrect.

Moreover, one would be stretched to explain how the this causal link was ever "missing" in the first place. Modern Western psychology is founded on a principle of brain-mind monism and to describe activity in the brain is to re-describe activity in the mind at another level. Thus the things we notice at one level (i.e., the behavioural, or social level) must have some corresponding phenomena to be described at the biological level (i.e., the brain).

These multiple levels of explanation of the same phenomena are not unique to psychology. In explaining what happened in a soccer game, I can explain the outcome of each half, the outcome of each shot, the outcome of each player's every move on the field, etc. There is no clear "best" explanation overall - this depends on the goal of the description. The same is true in psychology. Explaining a behaviour in terms of its underlying brain state is just another level of description. And even if we don't know exactly what the brain state is, we have to assume that it exists and is distinct from other brain states. Thus the causal link elucidated by brain images was never missing, it was just a bit blurry.

I can't explain, then, why brain imagery and neuroscience have the power they do in shifting people to a deterministic perspective. Scholars have long questioned whether someone can be criminally responsible for their behaviour if we believe that all behaviour is determined and not governed by free will. These questions will and should live on. However, the idea that neuroscience makes them any more pressing appears to come from a basic misunderstanding of human cognition.

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