Books and Arts

Nature 452, 938-939 (24 April 2008) | doi:10.1038/452938a; Published online 23 April 2008

Biased brains, messy memories

Sandra Aamodt1

BOOK REVIEWEDKluge: The Haphazard Construction of the Human Mind

by Gary Marcus

Houghton Mifflin: 2008. 224 pp. $24

BOOK REVIEWEDA Portrait of the Brain

by Adam Zeman

Yale University Press: 2008. 256 pp. $27.50

Public interest in the brain seems to be insatiable, judging from the many popular books about the topic that have been published in the past few years. Highlighting the diversity of this expanding genre, two books aimed at general readers provide views of brain science in very different styles.

In Kluge, psychologist Gary Marcus presents a lively tour of the shortcomings of human minds and concludes that evolution has left us with something of a mess. In an argument reminiscent of David Linden's The Accidental Mind, Marcus makes his case by describing cognitive difficulties, including false beliefs, linguistic ambiguity, impulsiveness and mental illness.

The blame, he asserts, rests with our imperfect memory, "arguably the mind's original sin". Perhaps we would reason more effectively if the brain could store and retrieve data as accurately and as simply as a computer. Instead we must contend with a limited system. Brains locate memories by matching them to the current context rather than having unbiased access to all of our experiences. This contextual dependence makes it hard during an argument, for example, to recall how often our spouse does the housework, because thinking of one failure inclines our brains to remember similar situations rather than contrary examples.

Many of these problems result from conflicts between the brain's two basic styles of thinking. The reflexive system, having evolved earlier, controls most behaviour. It is fast and can accurately assess statistics — such as the likelihood of finding food in certain locations — but is prone to overgeneralization and snap judgements. The deliberative system, by contrast, is slow, effortful and logical, at least intermittently. The reflexive system readily overrides the deliberative system, especially when we are tired or rushed. Marcus believes our lives would be improved if we engaged the deliberative system more often, although he acknowledges that "it often settles for reasoning that is less than ideal".

Biased brains, messy memories


Powers of persuasion: human brain images have piqued public interest in neuroscience and psychology.

Evolutionary psychology has tempted many scientists to indulge in just-so stories, as Marcus notes; asserting that our brains are poorly engineered is an equally risky business. Computer memories are more factual than those of humans, but computers lag far behind the reflexive system on other problems, such as distinguishing cats from dogs. Whether any biological system (or a computer) could combine both sets of virtues remains an open question.

Marcus closes with experimentally verified ways for people to deliberate more effectively, a welcome change from the usual self-help prescriptions. For example, he suggests imagining that your decisions might be checked by someone else. Although few biologists will need to be convinced of the evolutionary arguments in this book, it remains intriguing to contemplate which aspects of our minds could be improved and how we might compensate for those weaknesses.

A Portrait of the Brain is constructed with equal care, but in a very different style. Neurologist Adam Zeman takes on an ambitious project: explaining brain function from atoms to neural networks to, unexpectedly, the soul. Clearly an Oliver Sacks fan, Zeman weaves case studies of patients together with basic science, history, etymology, classical literature and art to produce an erudite discourse on brain components.

Describing the many aspects of neurons, the fifth chapter explains, for instance, how early neuroanatomists determined that brains are composed of cells, tells the story of a bus driver with religious feelings caused by epileptic seizures who ultimately became a priest, and is laced with asides about scientific rivalry, brain development, the hobbies of neuroscientist Santiago Ramón y Cajal and how action potentials are generated. The science is clear, and the stories of patients are suspenseful and gripping. Yet in some places, the relationship between topics feels a bit forced.

In the final chapter, Zeman grapples with consciousness. He outlines how brains that are predisposed to tell stories and that attribute actions to agents rather than chance might lead us to believe in an immortal soul. His own view is that this is "no more than a wonderful fiction". (Marcus makes the same point less gently.) Zeman struggles with science's failure to find an emotionally satisfying replacement story, conceding that such questions may be more in the realm of art than science.

What is the impetus for this deluge of brain books? Applications outside of science may explain the popularity of some topics, such as the potential for behavioural economics to illuminate the decisions of investors. Brain-scan images themselves may also have amplified interest in neuroscience. Both the public and the media are drawn to the powerful and persuasive visual message of such images. Fundamentally, however, people remain interested in neuroscience and psychology because understanding our brains helps us to understand ourselves.

  1. Sandra Aamodt is former editor of Nature Neuroscience and author of Welcome to Your Brain: Why You Lose Your Car Keys But Never Forget How to Drive and Other Puzzles of Everyday Life.