Review: ‘The Mind is Flat’ by Nick Chater

The nature of consciousness is a topic that psychologists and philosphers have spilt much ink and many pixels over. Outside of psychoanalytic circles, what has been less discussed is the nature of the ‘unconscious mind’. Claims made by some psychologists about the power of the unconscious mind to influence behaviour have proven controversial.

Now, in a book that will have psychoanalysts and many others protesting loudly, cognitive scientist Nick Chater has plunged a stake through the very concept of an unconscious mind. In The Mind Is Flat Chater argues that our minds have no depths, let alone hidden ones. His primary claim is that the brain exists to make sense of the world by creating a stable perception of it and ourselves; but the brain does not provide us with an account of its own workings. These perceptions are created from our interpretations of a limited number of sensory inputs, with the assistance of various memory traces (themselves based on our interpretations of past events).

Chater’s opening chapter, The Power of Invention, describes how we can create an apparently rich internal picture of a fictional person or location based on a limited description that may have gaps or inconsistencies (Chater discusses Anna Karenina and Gormenghast). So it is with our perceptions of the actual world and, indeed, ourselves.  Most of our visual receptors are incapable of colour detection, yet we perceive the world in glorious colour. Our eyes are continually darting about all over the place, yet our perception of the world is smooth, not jerky. In short, much or most of what we perceive is an illusion foisted upon us by our brains.

For centuries, philosophers consulted their ‘inner oracle’ in order to determine how the world works. Yet, Chater points out, the inner oracle has consistently misled us about concepts such as heat, weight, force and energy. Early researchers in artificial intelligence (AI) tried to do the same thing. They tried to excavate the mental depths of experts, recover ‘common sense theory’ and then devise methods to reason over this database. However, by the 1980s it had become clear that this program was going nowhere, and so was quietly abandoned.

As Chater puts it:

The mind is flat: our mental ‘surface’, the momentary thoughts, explanations and sensory experiences that make up our stream of consciousness is all there is to mental life. (p.31)

One reason why we are unaware of the fictional nature of our perceptions is precisely because our eyes are constantly moving about and picking up new sensory fragments. I may be unaware of the type of flower on the mantelpiece, but if you mention it my eyes go there automatically. In gaze-contingent eye tracking studies, the text on a screen changes according to where a person is looking. In fact, most of the text on the screen consists of Xs. As a participant’s eyes move across the screen the Xs that would have been in their fixation point change to become real words, and the area where they had been looking reverts to Xs. The participant, however, perceives that the entire page consists of meaningful text.

Likewise, when we construct a mental image it is never truly a ‘picture in the mind’. If we are asked to describe some details from the image, we simply ‘create’ those in our imagination in response to the question. Nothing is being retrieved from a complete image.

We often talk about a battle between ‘the heart and the head’, but Chater argues that we are in fact simply posing one reason against another reason. Citing the Kuleshov Effect, and the work of Schacter & Singer (1962) and Aron & Dutton (1974) on the labeling of emotional states, Chater concludes that “our feelings do not burst unbidden from within – they do not pre-exist at all” (p.98). Indeed:

The meaning of pretty much anything comes from its place in a wider network of relationships, causes and effects – not from within. (p.107)

Despite, or perhaps because of, our lack of inner depth, we are extremely good at dreaming up explanations for all kinds of things, including our inner motives. Perhaps my favourite example is from the work on choice blindness, in which participants were asked to choose the most attractive of two faces, each of which was presented on a card. After a participant made their choice, the researcher supposedly passed them the card they had chosen and asked them to explain why they had preferred that face. In fact, the researcher used sleight-of-hand to pass them the face they hadn’t chosen. Most people didn’t spot the discrepancy and readily provided an explanation as to why they preferred the face that they had not in fact chosen.

This research links to a wider body of work in decision making research, which shows that people’s preferences are constructed during the process of choice, depending on various contextual factors, as opposed to the conventional economic account that assumes people to have stable preferences that are revealed by the choices they make.

Chater also goes on to talk about people’s attentional limitations, arguing that – in almost all circumstances – our brains are only able to work on one problem at a time (where a problem is something which requires an act of interpretation on our part, rather than an habitual action such as putting one foot in front of the other when walking). This also fits with decades of work on human judgment, which has repeatedly found that people are unable to reliably integrate multiple items of information when trying to make a judgment.

Finally, Chater isn’t arguing that there are no unconscious processes. However, these unconscious processes aren’t ‘thoughts’. The mind isn’t like an iceberg, with a few thoughts appearing in consciousness and many others below the level of consciousness. Rather, the real nature of the unconscious is “the vastly complex patterns of nervous activity that create and support our slow, conscious experience” (p.175). Thus:

There is just one type of thought, and each thought has two aspects: a conscious read-out, and unconscious processes operating the read-out. And we can have no more conscious access to these brain processes than we can have conscious awareness of the chemistry of digestion or the biophysics of our muscles.

 The Mind is Flat is a book that I wish I’d written, in that it expresses, with evidence, a viewpoint that I have held for some time. The writing is clear and entertaining, and I devoured the book in just a few days. Recommended.