Decisions, Uncertainty, and the Brain: the Science of Neuroeconomics

Uncertainty. The mere sound of the word elicits a shaky feeling, and in Voltaire’s case, an unpleasant one. Uncertainty makes investments risky and decisions difficult, and, for better or worse, it spices most experiences. Engineers try to control it, financiers try to reduce it, and it haunts most of our everyday decisions. According to Paul Glimcher, we should embrace uncertainty, model it and use it to connect our growing knowledge of brain function to cognition. And from where will the new neural models of uncertainty arise? Economics. This premise is enticing, but the scientific issues in this book require a lot of unpacking. Who is Paul Glimcher and what is he saying? A talented neuroscientist at New York University, Glimcher has produced the first full-length book in the fledgling field of neuroeconomics. This nascent area, which has already attracted several economists and neuroscientists, assumes that the brain generates economic behaviour;consequently, economics can benefit from neuroscience. The benefits can also flow in the reverse direction: economic theory can be used to frame, model and understand neuroscience experiments. Glimcher is not just enthusiastic about this latter direction, he’s downright evangelistic. To fully understand the nature of his fervour, one has to tackle the entire book. Glimcher’s enthusiasm derives from a conceptual problem that he thinks has plagued most neuroscience research since the time of René Descartes. Glimcher argues (across four chapters) that Descartes’ legacy is an implicit model, shared by most neuroscientists, in which the reflex is the underlying mechanism from which more complicated functions such as decisionmaking are constructed. We all know about reflexes. If you knock the knee with a rubber mallet, signals return to the spinal cord, relay to output neurons there, and cause an extension of the lower limb. Hold a candle to an outstretched hand and the hand withdraws, again a simple reflex. Glimcher’s claim is that this idea of the reflex ossified into a neural prescription for the way in which all complex behaviours are constructed. According to Glimcher, the idea of the reflex provides “a simple set of basic operations that could be combined in different ways to yield a working model for any determinate behavior”. He calls this idea ‘reflexology’. Most readers will probably assume that Descartes and maybe some of the more strident behaviourists are the only reflexologists. Wrong, says Glimcher — the vast majority of neuroscientists are basically reflexologists in this sense. And so too are all the neural-network people. Yikes! And what’s worse, we really aren’t aware of our problem. The case that Glimcher builds has many parallel streams and can be difficult to follow.Let’s continue to unpack his ideas. Glimcher thinks that neuroscience is in this state because we wrongly view ‘reflex thinking’ merely as a way of collecting data about simple nervous systems or small isolated parts of complex nervous systems. Instead, says Glimcher, reflexology is really a theory, or a philosophical stance on how to break neural function into its component pieces, and it is woefully inadequate. But there is a solution: computational goals and economic analysis. According to Glimcher, the computer scientist and neural theorist David Marr was the first to propose a way out of the murky waters of reflexology. Glimcher praises books and arts