Objective-The development of "common ground," or mutual knowledge of shared information, is belie... more Objective-The development of "common ground," or mutual knowledge of shared information, is believed to require the ability to update a mental representation of another person's thoughts and knowledge based on verbal information and nonverbal social and emotional signals, in order to facilitate economical communication. As in other forms of everyday social communication, the development of common ground likely requires the orchestration of multiple cognitive processes supported by various neural systems. Here, we investigate the contribution of the amygdala to these processes.
Decision-making is a complex process that requires the orchestration of multiple neural systems. ... more Decision-making is a complex process that requires the orchestration of multiple neural systems. For example, decision-making is believed to involve areas of the brain involved in emotion (e.g., amygdala, ventromedial prefrontal cortex) and memory (e.g., hippocampus, dorsolateral prefrontal cortex). In this article, we will present findings related to the amygdala's role in decision-making, and differentiate the contributions of the amygdala from those of other structurally and functionally connected neural regions. Decades of research have shown that the amygdala is involved in associating a stimulus with its emotional value. This tradition has been extended in newer work, which has shown that the amygdala is especially important for decision-making, by triggering autonomic responses to emotional stimuli, including monetary reward and punishment. Patients with amygdala damage lack these autonomic responses to reward and punishment, and consequently, cannot utilize "somatic marker" type cues to guide future decision-making. Studies using laboratory decision-making tests have found deficient decision-making in patients with bilateral amygdala damage, which resembles their real-world difficulties with decision-making. Additionally, we have found evidence for an interaction between sex and laterality of amygdala functioning, such that unilateral damage to the right amygdala results in greater deficits in decision-making and social behavior in men, while left amygdala damage seems to be more detrimental for women. We have posited that the amygdala is part of an "impulsive," habit type system that triggers emotional responses to immediate outcomes.
Previous studies have reported conflicting evidence concerning the contribution of declarative me... more Previous studies have reported conflicting evidence concerning the contribution of declarative memory to advantageous decision-making on the Iowa Gambling Task (IGT). One study, in which the measurement of psychophysiology during the task necessitated a 10-sec delay between card selections, found that six participants with amnesia due to hippocampal damage failed to develop a preference for advantageous decks over disadvantageous decks (Gutbrod et al., Neuropsychologia, Vol. 44, pp. 1315-1324). However, a single case study (where psychophysiology was not measured and no delay between card selections occurred) showed that an amnesic patient developed normal preference for advantageous decks (Turnbull & Evans, Neuropsychologia, Vol. 44, pp. 300-306, 2006). We sought to resolve these discrepant findings by examining IGT performances in five patients with profound amnesia (WMS-III General Memory Index M =63) and bilateral hippocampal damage caused by anoxia (n = 4) or herpes simplex encephalitis (n = 1). In one administration of the IGT, psychophysiology measurements were utilized and a 6-sec delay was interposed between card selections. In a second administration, no delay between card selections was interposed. While age-, sex-, and education-matched healthy comparison participants showed significant learning with a gradual preference for advantageous decks in both conditions, amnesic patients, irrespective of IGT administration condition and extent of medial temporal lobe damage, failed to develop this preference. These findings strongly discount the possibility that the delay between card selections explains why amnesic participants fail to learn in the IGT, and suggest instead a significant role for medial temporal lobe declarative memory systems in the type of complex decision-making tapped by the IGT.
Background-Definite references signal a speaker's belief that a listener can uniquely identify th... more Background-Definite references signal a speaker's belief that a listener can uniquely identify the referent (e.g., the dog, as the only dog among a group of animals). collaborative referencing model provides a way to examine the speaker's display of confidence that his/her reference will be understood by the listener without further clarification. We previously found that amnesia participants, as directors in a barrier task with a familiar partner, used referencing forms that displayed less confidence than forms used by comparison participants. If this is an interactional consequence of managing the memory impairment (as opposed to a language deficit), we should also expect a decrease in definite referencing by their partners.
We incorporate intermediate inputs into a small-union general-equilibrium model and develop the w... more We incorporate intermediate inputs into a small-union general-equilibrium model and develop the welfare economics of preferential trading under the rules of origin. Combining this analysis with the Grossman-Helpman political-economy model, we demonstrate that the rules of origin can improve the political viability of FTAs. Two interesting outcomes are derived. First,
The central question addressed in this paper is whether the presence of the MFA made the NAFTA po... more The central question addressed in this paper is whether the presence of the MFA made the NAFTA politically more acceptable. Assuming that the government maximizes a weighted sum of welfare and producer profits, we derive four key results. First, taking the initial level of trade restriction as exogenously given, it is possible for an FTA to be endorsed by both parties under the MFA-like quota in one country though it is unambiguously rejected under a tariff that provides equal protection. Second, if the initial MFA quota is itself chosen endogenously, as long as all quota rents accrue to exporting countries, the quota is set so as to yield either autarky or free trade. Third, an intermediate outcome can obtain if quota rents are shared between the trading partners as is true, for example, under a tariff quota. Depending on the degree of the government's bias in favor of producers, this outcome may be more or less restrictive than that obtained under a tariff.
Objective-The development of "common ground," or mutual knowledge of shared information, is belie... more Objective-The development of "common ground," or mutual knowledge of shared information, is believed to require the ability to update a mental representation of another person's thoughts and knowledge based on verbal information and nonverbal social and emotional signals, in order to facilitate economical communication. As in other forms of everyday social communication, the development of common ground likely requires the orchestration of multiple cognitive processes supported by various neural systems. Here, we investigate the contribution of the amygdala to these processes.
Decision-making is a complex process that requires the orchestration of multiple neural systems. ... more Decision-making is a complex process that requires the orchestration of multiple neural systems. For example, decision-making is believed to involve areas of the brain involved in emotion (e.g., amygdala, ventromedial prefrontal cortex) and memory (e.g., hippocampus, dorsolateral prefrontal cortex). In this article, we will present findings related to the amygdala's role in decision-making, and differentiate the contributions of the amygdala from those of other structurally and functionally connected neural regions. Decades of research have shown that the amygdala is involved in associating a stimulus with its emotional value. This tradition has been extended in newer work, which has shown that the amygdala is especially important for decision-making, by triggering autonomic responses to emotional stimuli, including monetary reward and punishment. Patients with amygdala damage lack these autonomic responses to reward and punishment, and consequently, cannot utilize "somatic marker" type cues to guide future decision-making. Studies using laboratory decision-making tests have found deficient decision-making in patients with bilateral amygdala damage, which resembles their real-world difficulties with decision-making. Additionally, we have found evidence for an interaction between sex and laterality of amygdala functioning, such that unilateral damage to the right amygdala results in greater deficits in decision-making and social behavior in men, while left amygdala damage seems to be more detrimental for women. We have posited that the amygdala is part of an "impulsive," habit type system that triggers emotional responses to immediate outcomes.
Previous studies have reported conflicting evidence concerning the contribution of declarative me... more Previous studies have reported conflicting evidence concerning the contribution of declarative memory to advantageous decision-making on the Iowa Gambling Task (IGT). One study, in which the measurement of psychophysiology during the task necessitated a 10-sec delay between card selections, found that six participants with amnesia due to hippocampal damage failed to develop a preference for advantageous decks over disadvantageous decks (Gutbrod et al., Neuropsychologia, Vol. 44, pp. 1315-1324). However, a single case study (where psychophysiology was not measured and no delay between card selections occurred) showed that an amnesic patient developed normal preference for advantageous decks (Turnbull & Evans, Neuropsychologia, Vol. 44, pp. 300-306, 2006). We sought to resolve these discrepant findings by examining IGT performances in five patients with profound amnesia (WMS-III General Memory Index M =63) and bilateral hippocampal damage caused by anoxia (n = 4) or herpes simplex encephalitis (n = 1). In one administration of the IGT, psychophysiology measurements were utilized and a 6-sec delay was interposed between card selections. In a second administration, no delay between card selections was interposed. While age-, sex-, and education-matched healthy comparison participants showed significant learning with a gradual preference for advantageous decks in both conditions, amnesic patients, irrespective of IGT administration condition and extent of medial temporal lobe damage, failed to develop this preference. These findings strongly discount the possibility that the delay between card selections explains why amnesic participants fail to learn in the IGT, and suggest instead a significant role for medial temporal lobe declarative memory systems in the type of complex decision-making tapped by the IGT.
Background-Definite references signal a speaker's belief that a listener can uniquely identify th... more Background-Definite references signal a speaker's belief that a listener can uniquely identify the referent (e.g., the dog, as the only dog among a group of animals). collaborative referencing model provides a way to examine the speaker's display of confidence that his/her reference will be understood by the listener without further clarification. We previously found that amnesia participants, as directors in a barrier task with a familiar partner, used referencing forms that displayed less confidence than forms used by comparison participants. If this is an interactional consequence of managing the memory impairment (as opposed to a language deficit), we should also expect a decrease in definite referencing by their partners.
We incorporate intermediate inputs into a small-union general-equilibrium model and develop the w... more We incorporate intermediate inputs into a small-union general-equilibrium model and develop the welfare economics of preferential trading under the rules of origin. Combining this analysis with the Grossman-Helpman political-economy model, we demonstrate that the rules of origin can improve the political viability of FTAs. Two interesting outcomes are derived. First,
The central question addressed in this paper is whether the presence of the MFA made the NAFTA po... more The central question addressed in this paper is whether the presence of the MFA made the NAFTA politically more acceptable. Assuming that the government maximizes a weighted sum of welfare and producer profits, we derive four key results. First, taking the initial level of trade restriction as exogenously given, it is possible for an FTA to be endorsed by both parties under the MFA-like quota in one country though it is unambiguously rejected under a tariff that provides equal protection. Second, if the initial MFA quota is itself chosen endogenously, as long as all quota rents accrue to exporting countries, the quota is set so as to yield either autarky or free trade. Third, an intermediate outcome can obtain if quota rents are shared between the trading partners as is true, for example, under a tariff quota. Depending on the degree of the government's bias in favor of producers, this outcome may be more or less restrictive than that obtained under a tariff.
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