1 Book review Glimcher, P.W. (2003). Decisions Uncertainty and the ...

Book review
Glimcher, P.W. (2003). Decisions Uncertainty and the Brain: The Science of
Neuroeconomics. Cambridge, MA: MIT Press.
By Wändi Bruine de Bruin, Carnegie Mellon University, Department of Social and
Decision Sciences
Glimcher’s book describes the emerging field of neuroeconomics, which combines
expertise from economics and neuroscience. Neuroscience provides physiological tools
to search for neural events that might underlie the choice behaviors studied in economics.
Using brain imaging techniques, neuroeconomics holds the promise of opening the ‘black
box,’ and providing a better scientific understanding of brain-behavior relationships.
The first section describes historical approaches to studying the brain, starting with a
chapter on Descartes. According to Descartes, behavior could be categorized into simple
behaviors that show a predictable deterministic response to outside stimuli, and complex
behaviors that are unpredictable and a result of free will. Over the past few decades,
Glimcher and other neuroscientists have moved away from this dualist approach, treating
behavior as goal-oriented, expressed in terms of mathematical computations borrowed
from economics.
The second section of the book describes neuroeconomic approaches to studying the
brain. Glimcher explains how brain imaging techniques allow neuroscience researchers
to determine which parts of the brain are active, while research participants being
scanned engage in choice tasks. Glimcher argues that, if the firing rates of neurons in one
area are correlated with changes in behavior, that area is likely relevant to the choice
under consideration. Such findings would help researchers to better understand the brain
and, ultimately, choice behavior.
The book appears to provide a limited view of neuroeconomics. Most examples use
Glimcher’s own work, which is described in great detail. One topic missing from the
book is the growing body of neuroeconomic research on the effect of emotions on
decision making (e.g., Loewenstein, Weber, Hsee, & Welch, 2001; Slovic, Finucane,
Peters & MacGregor, 2004). For example, intertemporal choice has been associated with
activity in the limbic area, thought to reflect emotion, and the posterior parietal cortex,
which is traditionally associated with cognition, in intertemporal choice. Specifically,
greater activity in affective systems has been associated with choosing earlier rewards
more often (McClure, Laibson, Loewenstein, & Cohen, 2004).
Limitations of neuroscience also receive relatively little attention in Glimcher’s book.
Drawing conclusions about the meaning of brain images relies on how well
neuroscientists understand the specific functions of different brain areas. Currently,
much of that knowledge is still being developed. For example, in Chapter 10, Glimcher
describes the debate about the precise role of the parietal cortex in movements guided by
sensory events. Under the traditional reflex-oriented approach, the topic of the debate
has been whether this area is the last step in sensory processing or the first step for
movement production. Much of the research involves tracking neural activity in thirsty
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monkeys, who are rewarded with fruit juice for shifting their eyes in a specific direction.
Recent work by Platt and Glimcher (1999) suggests that the firing rate of neurons in
monkeys’ lateral intraparietal cortex (LIP) is correlated with the anticipated juice reward
for making a particular eye movement. Thus, the area may engage in sensorimotor
processing relevant to choice behavior.
Another limitation is the correlational nature of neuroeconomic analyses. Additional
evidence is needed to establish that an activated brain structure is essential for performing
the task under study. Lesion studies help to determine whether areas are, in fact,
necessary for carrying out specific functions. There have been cases in which structures
activated in brain imaging studies failed to reveal impairments when lesioned (Adolphs,
2003).
Finally, an inherent limitation of brain imaging is that activity in itself does not show
what is being processed. Several other approaches have been used to study decision
processes, and are much less costly than brain imaging. They include think-aloud
protocols (Ericsson & Simon, 1980), tracking eye movements (Russo & Rosen, 1974),
computer tools tracing the information acquisition process (Payne, Bettman, & Johnson,
1993), as well as the experimental methods used in behavioral economics (see Kahneman
& Tversky, 2003; Camerer, Loewenstein, & Rabin, 2003). Although each method has its
strengths and weaknesses, in combination with brain imaging, they may provide broader
insight into the function of different brain areas, and, eventually, how people are making
decisions.
As brain imaging techniques improve, and scientific understanding of the brain evolves,
neuroeconomics will continue to inform our understanding of the link between the brain
and behavior. Such insights may increase our understanding of how people make
choices, and influence theories of decision making. Ultimately, they may improve
economic models, and our ability to make economic predictions. As Glimcher explains,
some exciting progress has already been made.
References
Adolphs, R. (2003). Investigating the cognitive neuroscience of social behavior.
Neuropsychologia, 41, 119-126.
Camerer, C.F., Loewenstein, G.F., & Rabin, M. (2003). Advances in Behavioral
Economics. Princeton: Princeton University Press.
Ericsson, K.A. & Simon, H.A. (1980). Verbal reports as data. Psychological Review, 87,
215-251.
Kahneman, D., & Tversky, A. (2003). Choices, values, and frames. New York:
Cambridge University Press.
Loewenstein, G.F., Weber, E.U., Hsee, C.K., & Welch, N. (2001). Risk as feelings.
Psychological Bulletin, 127, 267-286.
McClure, S.M., Laibson, D.I., Loewenstein, G.F., & Cohen, J.D. (2004). Separate neural
systems value immediate and delayed monetary rewards. Science, 306, 503-507.
Payne, J.W., Bettman, J.R., & Johnson, E.J. (1993). The adaptive decision maker. New
York, NY: Cambridge University Press.
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Platt, M. L. & Glimcher, P.W. (1999). Neural correlates of decision variables in parietal
cortex. Nature, 400, 233-238.
Russo, J.E., & Rosen, L.D. (1974). An eye fixation analysis of multialternative choice.
Memory and Cognition, 3, 267-276.
Slovic, P., Finucane, M., Peters, E., & MacGregor, D. (2004). Risk as analysis and risk
as feelings: Some thoughts about affect, reason, risk and rationality. Risk Analysis,
24, 311-322.
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