Neuroeconomics and irrationality--论文代写范文精选

这个问题不是神经经济学的方面。区分外部和内部评估的合理性。外部合理性的评价规则是有效的。它评估实现特定目标的最优规则。理性的内部评估是评估的一致性,行为和计划。下面的paper代写范文进行论述。

Studies in neuroeconomics are apt to provide meaningful explanations for choice behavior. Loss-aversion and cooperation, oddities from the rational-choice theorist point of view, now make sense as patterns of inference and behavior that follow naturally from the affective dynamics of decision-makers. If rationality is a normative, evaluative concept, one might argue that a theory of decision-making mechanisms can hardly draw a distinction between rational and irrational decisions. Or can it? Classical models of rationality in fact suffer from the exact same problem. As Sen observed, every choice is said to reveal preferences: The reduction of man to a self-seeking animal depends in this approach on careful definition. If you are observed to choose x rejecting y, you are declared to have “revealed” a preference for x over y. Your personal utility is then defined as simply a numerical representation of this “preference,” assigning a higher utility to a “preferred” alternative. With this set of definitions you can hardly escape maximizing your own utility (…). (Sen 322)

  Philosophical theories of rationality that consider rational all those actions explained by beliefs and desires also face this problem. Whatever theory one might choose, a decision can always be described as the product of practical reasoning, whereby the agent infers a 15 choice from her beliefs and her desires. This problem is not particular to neuroeconomics. In order to escape a tautological account of rationality, it is important to distinguish external and internal assessment of rationality. An external assessment of rationality is an evaluation of the effectiveness of a rule or procedure. It assesses the optimality of rules in achieving certain goals. An internal assessment of rationality is an evaluation of the coherence of intentions, actions and plans. An action can hence be rational from the first perspective but not from the second one, and vice versa. Gambling, for instance, can make sense only from the gambler’s point of view: despite knowing that the odds are against her (thus externally irrational, if the goal is money maximization), she trades losses (decision utility) against the pleasurable feeling of gambling (experienced utility).

  The same reasoning can also apply to neural mechanisms discovered by neuroeconomics. Once precise mechanisms are spelled out, their optimality can be evaluated (external perspective) and their coherence made explicit (internal perspective). From an external perspective, TD algorithms plausibly represent decisionmaking processes (Montague), both from a descriptive and a normative point of view. Descriptively, TD models closely mimic human, monkey and bee choices (Montague et al.; Glimcher, Dorris and Bayer; Egelman, Person and Montague). 

  Normatively, these models achieve good performance in tasks that require information-processing under uncertainty, such as Backgammon, spatial delayed response tasks and autonomous robot navigation (Suri and Schultz; Perez-Uribe). In the same vein, making a fair offer in the ultimatum game is also a good strategy: offering a $5/$5 split entails a sure gain of $5, while offering a $1/$9 entails a sure loss. Therefore, from the external perspective, the optimality of neural mechanisms can be assessed, and careful studies can draw a distinction whether, in a particular environment, such-and-such mechanism is effective. TD-learning, for instance, is effective under radical uncertainty, but is beaten by classical rationality under risk.

  From an internal perspective, neuroeconomics studies show how externally irrational choices can be internally rational. Loss-aversion and ambiguity-aversion are not optimal under decision theory, but neuroeconomics shows that loss- and ambiguityaverse subjects are rational in the internal sense, because they try to minimize negative feeling (elicited by amygdala activation). In this sense, it can be rational to maximize experienced utility, based on predicted utility. Loss-aversion can also be internally rational because preferring a sure decision is a way to minimize the painful feeling of loss and the post-decision feeling of regret. Various studies indicate that a loss of money can elicit negative emotional response (Delgado, Labouliere and Phelps), and that avoiding an aversive event can generate rewarding signals in the orbitofrontal cortex (Kim, Shimojo and Doherty). 

  A loss-averse agent maximizes experienced utility before, during and after decision. Similarly, players in the ultimatum game and prisoner’s dilemma also behave rationally: they maximize positive feelings by being fair and minimize negative ones by avoiding or punishing unfairness. A responder (in the ultimatum game) accepting an unfair split would experience moral disgust, and would be happier from punishing the unfair proposer than from accepting the offer. One of the strengths of neuroeconomics is a more accurate description of subjects’ preferences: instead of inferring preferences solely from behavior, imaging and lesion studies allow inferences from brain functioning.

  Are agents hence always internally rational, and always have good reasons (maximizing positive feelings, minimizing negative ones)? As Davidson suggested, accounting for irrationality requires partitioning the mind into subparts with a high degree of internal structures, potentially causing genuine internal conflict between values, judgments or motivations (Davidson "Problems of Rationality"). Explanations of practical irrationality such as akrasia (not acting on one’s own best judgment about what to do) reveal conflicting motivations: I want to finish my homework, I know it is the best thing to do, but instead I watch Casablanca on TV, even though I know it is not the best decision. With the distributed account of utility, one might identify several ways to be irrational. A perfectly rational agent would be an agent whose decision, predicted, experienced and remembered utility would always be in agreement. 

  Any mismatch between these types of utility could be a variety of irrationality, and neuroeconomics could describe the interactions between different utility-maximization mechanisms. When decision utility is higher than predicted utility, for instance, some mechanisms inside the agent value the outcome of the decision more highly than others that predict an inferior utility. Drug addiction works exactly along the lines of this ‘irrational pursuit’ (Berridge): dopaminergic neurons ‘hijacked’ by drugs overvalue the drug rewarding effect, even if prefrontal areas involved in affective prediction do not anticipate a positive hedonic effect. This interaction betweens different processes may explains why addiction often seems internally irrational (its external irrationality is more obvious). John Cheever’s narration of his alcoholism in his Journals illustrates the incoherence between decision and utility, both predicted and experienced: “[d]rink, its implements, environments, and effects all seem disgusting. And yet each noon I reach for the whiskey bottle (Cheever 54). 

  In his case, although the decision utility of drinking does not coincide with its predicted and experienced utility, these two types of utility are here in agreement: Cheever both anticipates and experiences disgust. In other cases, we are irrational when predicted and experienced utility mismatch. Gilbert and Wilson coined the term ‘miswanting’ to describe the shortcomings of affective forecasting (the prediction of emotional impact). A perfectly rational agent, at time t, would choose to do X at t+1 given what she expects her future valuation of X to be. Many studies showed instead that people are subject to many biases that cause miswanting. For instance, people overestimate the length or intensity of the emotional impact of negative events: they recover from tragic incidents faster than they anticipated, and get used to pleasant effects. For instance, almost everybody imagines that being richer implies being happier.

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