In defence of cognitive neuroscience

“If the imperialist ambitions of Neuromania and Darwinitis were fully realized, they would swallow the image of humanity in the science of biology”. So begins the penultimate chapter of Raymond Tallis’ opus on the sinister forces of the mind-sciences, Aping Mankind. In a thoroughly enjoyable book, he identifies two: Neuromania, the addition of a neuro- prefix to just about every humanities discipline you can think of (art, literature, law), and Darwinitis, the reduction of human flourishing to evolutionary primitives that seethe under the surface of the psyche.

For a neuroscientist, reading Tallis is humbling. He emphasises just how far we still have to go in order to understand even the most mundane aspects of the human mind. Consider his account of taking a catch in a cricket match, an action you might think of as “automatic”:

So surely you did not catch the ball; your body did, and you were just a fortunate bystander who took the credit.

No one really thinks this, and for good reasons. First, in order to catch the ball, you had to participate in a game of cricket. This requires that you should have (voluntarily) turned up to a particular place on a particular day, that you understood and assented to the rules of cricket and that you understood the role of the fielder, in particular that of the slip fielder. More importantly, in order to make the catch, you would have had to practise. This means hours spent in the nets, preparing yourself for this moment, which would bring such glory upon you. You would have to order your affairs so that you would be able to go to the nets at the booked time: negotiating the traffic; making sure your day was clear so you could take up your booked slot; and so on.

In the same vein, Tallis grumpily dismisses hype-grabbing studies claiming to explain the enjoyment of art or Shakespeare simply by looking at a brain scan. In doing so, he reaffirms the mystery of the human condition. He has no time for sloppy thinking, complaining when “things which belong to common-sense are presented as truths uncovered by the biological sciences”.  His writing is laced with the rare authority of a scholar steeped in both the sciences and the humanities.

Which makes it all the more surprising when, in dismantling a neuroscience of the humanities, the book slips into attacking a neuroscience of, well, neuroscience. The culmination of this attack is a section entitled “Why there can never be a brain science of consciousness: the disappearance of appearance”. Unfortunately, this conclusion is based on false premises. Let us see if we can set a few things straight.

First, there is the claim that psychological functions are equivalent to locations, or patterns, of brain activity. Locations and patterns are aspects of brain activity that might be picked up by scans or neural recordings, but they do not constitute an account of function. Instead, we need to understand what a brain region is doing, how its function affects a broader network of activity, and how, ultimately, this network affects the organism’s behaviour. A brain scan might provide a glimpse onto these functional dynamics, but it is not the final story.

Instead, it is a model of the underlying brain-behaviour link that matters, rather than any particular location or pattern of activity. Models are more than ideas: as Lewandowsky & Farrell write, “Even intuitively attractive notions may fail to provide the desired explanation for behavior once subjected to the rigorous analysis required by a computational model”. For example, one can build a toy network of two populations of neurons “deciding” between two options in response to different inputs, and ask whether there are correlates of this process in the living brain. The location of such activity does not explain the ability to decide; instead, it is the dynamics (and, ultimately, the link between these dynamics and other brain circuits involved in perception and action) that can give us greater insight into what it means to make a decision. A good model accommodates the bumps and curves of individual datasets, both behavioural and neural, and provides a set of hypotheses that can be refined through further study. Discussion of models is sparse in Aping Mankind, perhaps because they are less easy to lambast than neuromanic studies of love and wisdom.

But these oversights pale in comparison to the ultimate straw-man complaint that: “neuroscience does not address, even less answer, the fundamental question of the relation(s) between matter and mind, body and mind, or brain and mind”. This is the famous “hard problem” of consciousness: how does subjectivity arise out of a lump of biological material? As Tallis writes, “Consciousness is, at the basic level, appearances or appearings-to, but neither nerve impulses nor the material world have appearances.” Quite so, and nor should we expect them to. And if they did, this would only beg the question: appearances to whom? As a squarely metaphysical, rather than empirical, discussion, it is no surprise that it is not addressed by neuroscience.

After making this confusion, Tallis is often caught in the headlights of the hard problem. He references the richness of subjective experience to parody the “laughable crudity” of cognitive neuroscience. In fact, most of the ongoing and vibrant science of consciousness adopts “bridging principles”, experimental paradigms that mediate between behaviour and subjective experience. In recent years there have been ingenious bridging principles developed to investigate neural systems underpinning perceptual awareness, the sense of agency, and the shifting nature of one’s body image. First-person satisfaction is not the primary criterion of this research program.

Of course, Tallis is right to point out that these are baby steps. His example of catching a ball highlights aspects of the mind that neuroscience has only just begun to explore; a wilderness of the prefrontal cortex that is yet to be staked out. In doing so, we would do well to keep in mind Tallis’ deconstruction of the complexity of action. But initial dissatisfaction is no reason to down tools.