Decisions, Decisions, Decisions Choosing a Biological Science of Choice

AbstractBehavioral ecologists argue that evolution drives animal behavior to efficiently solve the problems animals face in their environmental niches. The ultimate evolutionary causes of decision making, they contend, can be found in economic analyses of organisms and their environments. Neurobiologists interested in how animals make decisons have, in contrast, focused their efforts on understanding the neurobiological hardware that serves as a more proximal cause of that same behavior. Describing the flow of information within the nervous system without regard to these larger goals has been their focus. Recent work in a number of laboratories has begun to suggest that these two approaches are beginning to fuse. It may soon be possible to view the nervous system as a representational process that solves the mathematically defined economic problems animals face by making efficient decisions. These developments in the neurobiological theory of choice, and the new schema they imply, form the subject of this article

An expected utility maximizer walks into a bar

We conducted field experiments at a bar to test whether blood alcohol concentration (BAC) correlates with violations of the generalized axiom of revealed preference (GARP) and the independence axiom. We found that individuals with BACs well above the legal limit for driving adhere to GARP and independence at rates similar to those who are sober. This finding led to the fielding of a third experiment to explore how risk preferences might vary as a function of BAC. We found gender-specific effects: Men did not exhibit variations in risk preferences across BACs. In contrast, women were more risk averse than men at low BACs but exhibited increasing tolerance towards risks as BAC increased. Based on our estimates, men and women's risk preferences are predicted to be identical at BACs nearly twice the legal limit for driving. We discuss the implications for policy-maker

Flexible valuations for consumer goods as measured by the Becker-DeGroot-Marschak mechanism

Economists have long been interested in mechanisms that lead to truthful revelation of the relative values individuals place on diff erent goods. In this paper we take one of the most popular of such mechanisms, and show that valuations obtained using the Becker-DeGroot-Marschak (BDM) procedure depend on the distribution of prices presented to subjects when the mechanism is implemented. We show that this eff ect of price distribution occurs quite frequently, significantly impacts reported valuations, and that it is unlikely to be caused by misconceptions about BDM. This eff ect is the largest when pricing distributions show a large peak just above or just below an individual's average valuation of the good being considered. We also show that a simple non-incentive compatible subject rating of the desirability of goods can be used to predict the likelihood that pricing distributions will influence BDM valuations. Valuations for goods subjects report that they most want to purchase are most likely to be influenced by distributional structure. Our results challenge some of the dominant theoretical models of how BDM-like valuation procedures relate to standard notions of utility

The Neural Correlated of Subjective Value During Intertemporal Choice

Neuroimaging studies of decision-making have generally related neural activity to objective measures (such as reward magnitude, probability or delay), despite choice preferences being subjective. However, economic theories posit that decision-makers behave as though different options have different subjective values. Here we use functional magnetic resonance imaging to show that neural activity in several brain regions—particularly the ventral striatum, medial prefrontal cortex and posterior cingulate cortex—tracks the revealed subjective value of delayed monetary rewards. This similarity provides unambiguous evidence that the subjective value of potential rewards is explicitly represented in the human brain

The Neurobiology of Decision: Consensus and Controversy

We review and synthesize recent neurophysiological studies of decision making in humans and nonhuman primates. From these studies, the basic outline of the neurobiological mechanism for primate choice is beginning to emerge. The identified mechanism is now known to include a multicomponent valuation stage, implemented in ventromedial prefrontal cortex and associated parts of striatum, and a choice stage, implemented in lateral prefrontal and parietal areas. Neurobiological studies of decision making are beginning to enhance our understanding of economic and social behavior as well as our understanding of significant health disorders where people\u27s behavior plays a key role

Neuroeconomic Studies of Impulsivity: Now or Just as Soon as Possible?

Existing behavioral studies of intertemporal choice suggest that both human and animal choosers are impulsive. One possible explanation for this is that they discount future gains in a hyperbolic or quasi-hyperbolic fashion (David I. Laibson 1997; Shane Frederick, George Loewenstein, and Ted O’Donoghue 2002). This observation stands in contrast to standard normative theory, which predicts exponential discounting for any single maximizing agent (Robert H. Strotz 1956). This disparity between empirical and normative approaches is typically explained by proposing that human choosers suffer from inner conflict, balancing an impulse for an immediate gratification against other forces calling for delayed gratification (Richard H. Thaler and H. M. Shefrin 1981; Laibson 1997; Drew Fudenberg and David K. Levine 2006; Jess Benhabib and Alberto Bisin 2005; B. Douglas Bernheim and Antonio Rangel 2004; Faruk Gul and Wolfgang Pesendorfer 2001). We hoped to better understand both the behavioral and algorithmic roots of this phenomenon by conducting a series of behavioral and neurobiological experiments on intertemporal choice. The results of our behavioral experiments deviate significantly from the predictions of both normative and inner conflict models. The results of our neurobiological experiments provide new algorithmic insights into the mechanisms of intertemporal choice

Free choice shapes normalized value signals in medial orbitofrontal cortex

Normalization is a common cortical computation widely observed in sensory perception, but its importance in perception of reward value and decision making remains largely unknown. We examined (1) whether normalized value signals occur in the orbitofrontal cortex (OFC) and (2) whether changes in behavioral task context influence the normalized representation of value. We record medial OFC (mOFC) single neuron activity in awake-behaving monkeys during a reward-guided lottery task. mOFC neurons signal the relative values of options via a divisive normalization function when animals freely choose between alternatives. The normalization model, however, performed poorly in a variant of the task where only one of the two possible choice options yields a reward and the other was certain not to yield a reward (so called: “forced choice”). The existence of such context-specific value normalization may suggest that the mOFC contributes valuation signals critical for economic decision making when meaningful alternative options are available

An Experimental Comparison of Risky and Riskless Choice—Limitations of Prospect Theory and Expected Utility Theory

Prospect theory, used descriptively for decisions under both risk and certainty, presumes concave utility over gains and convex utility over losses; a pattern widely seen in lottery tasks. Although such discontinuous gain-loss reference-dependence is also used to model riskless choices, only limited empirical evidence supports this use. In incentive-compatible experiments, we find that gain-loss reflection effects are not observed under riskless choice as predicted by prospect theory, even while in the same subjects gain-loss reflection effects are observed under risk. Our empirical results challenge the application of choice models across both risky and riskless domains

Neuroanatomy Predicts Individual Risk Attitudes

Over the course of the last decade a multitude of studies have investigated the relationship between neural activations and individual human decision-making. Here we asked whether the anatomical features of individual human brains could be used to predict the fundamental preferences of human choosers. To that end, we quantified the risk attitudes of human decision-makers using standard economic tools and quantified the gray matter cortical volume in all brain areas using standard neurobiological tools. Our whole-brain analysis revealed that the gray matter volume of a region in the right posterior parietal cortex was significantly predictive of individual risk attitudes. Participants with higher gray matter volume in this region exhibited less risk aversion. To test the robustness of this finding we examined a second group of participants and used econometric tools to test the ex ante hypothesis that gray matter volume in this area predicts individual risk attitudes. Our finding was confirmed in this second group. Our results, while being silent about causal relationships, identify what might be considered the first stable biomarker for financial risk-attitude. If these results, gathered in a population of midlife northeast American adults, hold in the general population, they will provide constraints on the possible neural mechanisms underlying risk attitudes. The results will also provide a simple measurement of risk attitudes that could be easily extracted from abundance of existing medical brain scans, and could potentially provide a characteristic distribution of these attitudes for policy makers