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Burkhard C. Schipper - One of the best experts on this subject based on the ideXlab platform.
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Discovery and Equilibrium in Games with Unawareness
SSRN Electronic Journal, 2018Co-Authors: Burkhard C. SchipperAbstract:Equilibrium notions for games with Unawareness in the literature cannot be interpreted as steady-states of a learning process because players may discover novel actions during play. In this sense, many games with Unawareness are ``self-destroying'' as a player's representation of the game may change after playing it once. We define discovery processes where at each state there is an extensive-form game with Unawareness that together with the players' play determines the transition to possibly another extensive-form game with Unawareness in which players are now aware of actions that they have discovered. A discovery process is rationalizable if players play extensive-form rationalizable strategies in each game with Unawareness. We show that for any game with Unawareness there is a rationalizable discovery process that leads to a self-confirming game that possesses a self-confirming equilibrium in extensive-form rationalizable strategies. This notion of equilibrium can be interpreted as steady-state of both a discovery and learning process.
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Self-confirming Games: Unawareness, Discovery, and Equilibrium
Electronic Proceedings in Theoretical Computer Science, 2017Co-Authors: Burkhard C. SchipperAbstract:Equilibrium notions for games with Unawareness in the literature cannot be interpreted as steady-states of a learning process because players may discover novel actions during play. In this sense, many games with Unawareness are "self-destroying" as a player's representation of the game must change after playing it once. We define discovery processes where at each state there is an extensive-form game with Unawareness that together with the players' play determines the transition to possibly another extensive-form games with Unawareness in which players are now aware of actions that they have previously discovered. A discovery process is rationalizable if players play extensive-form rationalizable strategies in each game with Unawareness. We show that for any game with Unawareness there is a rationalizable discovery process that leads to a self-confirming game that possesses an extensive-form rationalizable self-confirming equilibrium. This notion of equilibrium can be interpreted as steady-state of a learning and discovery process.
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TARK - Self-confirming Games: Unawareness, Discovery, and Equilibrium
2017Co-Authors: Burkhard C. SchipperAbstract:Equilibrium notions for games with Unawareness in the literature cannot be interpreted as steady-states of a learning process because players may discover novel actions during play. In this sense, many games with Unawareness are "self-destroying" as a player's representation of the game must change after playing it once. We define discovery processes where at each state there is an extensive-form game with Unawareness that together with the players' play determines the transition to possibly another extensive-form games with Unawareness in which players are now aware of actions that they have previously discovered. A discovery process is rationalizable if players play extensive-form rationalizable strategies in each game with Unawareness. We show that for any game with Unawareness there is a rationalizable discovery process that leads to a self-confirming game that possesses an extensive-form rationalizable self-confirming equilibrium. This notion of equilibrium can be interpreted as steady-state of a learning and discovery process.
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does exposure to Unawareness affect risk preferences a preliminary result
Theory and Decision, 2017Co-Authors: Burkhard C. SchipperAbstract:One fundamental assumption often made in the literature on Unawareness is that risk preferences are invariant to changes of awareness. We study how exposure to Unawareness affects choices under risk. Participants in our experiment choose repeatedly between varying sure outcomes and a lottery in three phases. All treatments are exactly identical in phase 1 and phase 3, but differ in phase 2. There are five different treatments pertaining to the lottery faced in phase 2: The control treatment (i.e., a standard lottery), the treatment with awareness of Unawareness of lottery outcomes but known number of outcomes, the treatment with awareness of Unawareness of outcomes but with unknown number of outcomes, the treatment with Unawareness of Unawareness of some outcomes, and the treatment with an ambiguous lottery. We study both whether behavior differs in phase 3 across treatments (between subjects effect) and whether differences of subjects’ behavior between phases 1 and phase 3 differ across treatments (within subject effects). We observe no significant treatment effects.
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does exposure to Unawareness affect risk preferences a preliminary result
Social Science Research Network, 2017Co-Authors: Burkhard C. SchipperAbstract:One fundamental assumption often made in the literature on Unawareness is that risk preferences are invariant to changes of awareness. We study how exposure to Unawareness affects choices under risk. Participants in our experiment choose repeatedly between varying sure outcomes and a lottery in 3 phases. All treatments are exactly identical in phase 1 and phase 3, but differ in phase 2. There are five different treatments pertaining to the lottery faced in phase 2: The control treatment (i.e., a standard lottery), the treatment with awareness of Unawareness of lottery outcomes but known number of outcomes, the treatment with awareness of Unawareness of outcomes but with unknown number of outcomes, the treatment with Unawareness of Unawareness of some outcomes, and the treatment with an ambiguous lottery. We study both whether behavior differs in phase 3 across treatments (between subjects effect) and whether differences of subjects' behavior between phases 1 and phase 3 differs across treatments (within subject effects). We observe no significant treatment effects.
Spyros Galanis - One of the best experts on this subject based on the ideXlab platform.
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Speculation under Unawareness
Games and Economic Behavior, 2018Co-Authors: Spyros GalanisAbstract:“No trade” theorems establish that, in various trading environments, investors who share a common prior will not engage in speculation, as long as expected utility, Bayesian updating and full awareness are imposed. We relax the last assumption by allowing for asymmetric Unawareness and examine under which conditions speculative behaviour emerges. We find that if common knowledge is assumed (as in the settings of Aumann, 1976 and Milgrom and Stokey, 1982), Unawareness cannot generate speculation. This is not true, however, in settings where no common knowledge is assumed, such as speculation in equilibrium (Geanakoplos, 1989) and betting that is always beneficial (Morris, 1994), unless stronger conditions on awareness are imposed.
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The value of information under Unawareness
Journal of Economic Theory, 2015Co-Authors: Spyros GalanisAbstract:The value of information is examined in a single-agent environment with Unawareness. Although the agent has a correct prior about events he is aware of and has a clear understanding of his available actions and payoffs, his Unawareness may lead him to commit information processing errors and to behave suboptimally. As a result, the value of information can be negative, contrasting what is true in the standard model with partitional information and no Unawareness. We show that the source of the agent's suboptimal behavior is that he misunderstands the information revealed by his varying awareness, treating it asymmetrically.
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Unawareness of theorems
Economic Theory, 2011Co-Authors: Spyros GalanisAbstract:This paper provides a set-theoretic model of knowledge and Unawareness. A new property called Awareness Leads to Knowledge shows that Unawareness of theorems not only constrains an agent’s knowledge, but also can impair his reasoning about what other agents know. For example, in contrast to Li (J Econ Theory 144:977–993, 2009), Heifetz et al. (J Econ Theory 130:78–94, 25 2006) and the standard model of knowledge, it is possible that two agents disagree on whether another agent knows a particular event. The model follows Aumann (Ann Stat 4:1236–1239, 1976) in defining common knowledge and characterizing it in terms of a self-evident event, but departs in showing that no-trade theorems do not hold.
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Unawareness of Theorems
SSRN Electronic Journal, 2011Co-Authors: Spyros GalanisAbstract:This paper provides a set-theoretic model of knowledge and Unawareness. A new property called Awareness Leads to Knowledge shows that Unawareness of theorems not only constrains an agent's knowledge, but also, can impair his reasoning about what other agents know. For example, in contrast to Li (2006), Heifetz et al. (2006) and the standard model of knowledge, it is possible that two agents disagree on whether another agent knows a particular event. The model follows Aumann (1976) in defining common knowledge and characterizing it in terms of a self evident event, but departs in showing that no-trade theorems do not hold.
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Syntactic foundations for Unawareness of theorems
Theory and Decision, 2010Co-Authors: Spyros GalanisAbstract:We provide a syntactic model of Unawareness. By introducing multiple knowledge modalities, one for each sub-language, we specifically model agents whose only mistake in reasoning (other than their Unawareness) is to underestimate the knowledge of more aware agents. We show that the model is a complete and sound axiomatization of the set-theoretic model of Galanis (University of Southampton Discussion paper 709, 2007) and compare it with other Unawareness models in the literature.
Piero Amodio - One of the best experts on this subject based on the ideXlab platform.
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cognitive neurophysiologic and metabolic sequelae of previous hypoglycemic coma revealed by hyperinsulinemic hypoglycemic clamp in type 1 diabetic patients
Metabolic Brain Disease, 2017Co-Authors: Alberto Maran, Franco Del Piccolo, Lisa Zarantonello, Carlo Crepaldi, Angelo Avogaro, I A Macdonald, Piero AmodioAbstract:To examine the relationship between electroencephalographic (EEG) activity and hypoglycemia Unawareness, we investigated early parameters of vigilance and awareness of various symptom categories in response to hypoglycemia in intensively treated type 1 diabetic (T1DM) patients with different degrees of hypoglycemia Unawareness. Hypoglycemia was induced with a hyperinsulinemic-hypoglycemic clamp in six T1DM patients with a history of hypoglycemia Unawareness previous severe hypoglycemic coma (SH) and in six T1DM patients without (C) history of hypoglycemia Unawareness previous severe hypoglycemic coma. Cognitive function tests (four choice reaction time), counterregulatory responses (adrenaline), and symptomatic responses were evaluated at euglycemia (90 mg/dl) and during step-wise plasma glucose reduction (68, 58 and 49 mg/dl). EEG activity was recorded continuously throughout the study and analyzed by spectral analysis. Cognitive function deteriorated significantly at a glucose threshold of 55 ± 1 mg/dl in both groups (p = ns) during hypoglycemia, while the glucose threshold for autonomic symptoms was significantly lower in SH patients than in C patients (49 ± 1 vs. 54 ± 1 mg/dl, p < 0.05, respectively). In SH patients, eye-closed resting EEG showed a correlation between the mean dominance frequency and plasma glucose (r = 0.62, p < 0.001). Theta relative power increased during controlled hypoglycemia compared to euglycemia (21.6 ± 6 vs. 15.5 ± 3% Hz p < 0.05) and was higher than in the C group (21.6 ± 6 vs. 13.8 ± 3%, p < 0.03). The cognitive task beta activity was lower in the SH group than in the C group (14.8 ± 3 Hz, vs. 22.6 ± 4 vs. p < 0.03). Controlled hypoglycemia elicits cognitive dysfunction in both C and SH patients; however, significant EEG alterations during hypoglycemia were detected mainly in patients with a history of hypoglycemia Unawareness and previous severe hypoglycemic coma. These data suggest that prior episodes of hypoglycemic coma modulate brain electric activity.
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Cognitive, neurophysiologic and metabolic sequelae of previous hypoglycemic coma revealed by hyperinsulinemic-hypoglycemic clamp in type 1 diabetic patients.
Metabolic Brain Disease, 2017Co-Authors: Alberto Maran, Franco Del Piccolo, Lisa Zarantonello, Carlo Crepaldi, Angelo Avogaro, I A Macdonald, Piero AmodioAbstract:To examine the relationship between electroencephalographic (EEG) activity and hypoglycemia Unawareness, we investigated early parameters of vigilance and awareness of various symptom categories in response to hypoglycemia in intensively treated type 1 diabetic (T1DM) patients with different degrees of hypoglycemia Unawareness. Hypoglycemia was induced with a hyperinsulinemic-hypoglycemic clamp in six T1DM patients with a history of hypoglycemia Unawareness previous severe hypoglycemic coma (SH) and in six T1DM patients without (C) history of hypoglycemia Unawareness previous severe hypoglycemic coma. Cognitive function tests (four choice reaction time), counterregulatory responses (adrenaline), and symptomatic responses were evaluated at euglycemia (90 mg/dl) and during step-wise plasma glucose reduction (68, 58 and 49 mg/dl). EEG activity was recorded continuously throughout the study and analyzed by spectral analysis. Cognitive function deteriorated significantly at a glucose threshold of 55 ± 1 mg/dl in both groups (p = ns) during hypoglycemia, while the glucose threshold for autonomic symptoms was significantly lower in SH patients than in C patients (49 ± 1 vs. 54 ± 1 mg/dl, p
Alberto Maran - One of the best experts on this subject based on the ideXlab platform.
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cognitive neurophysiologic and metabolic sequelae of previous hypoglycemic coma revealed by hyperinsulinemic hypoglycemic clamp in type 1 diabetic patients
Metabolic Brain Disease, 2017Co-Authors: Alberto Maran, Franco Del Piccolo, Lisa Zarantonello, Carlo Crepaldi, Angelo Avogaro, I A Macdonald, Piero AmodioAbstract:To examine the relationship between electroencephalographic (EEG) activity and hypoglycemia Unawareness, we investigated early parameters of vigilance and awareness of various symptom categories in response to hypoglycemia in intensively treated type 1 diabetic (T1DM) patients with different degrees of hypoglycemia Unawareness. Hypoglycemia was induced with a hyperinsulinemic-hypoglycemic clamp in six T1DM patients with a history of hypoglycemia Unawareness previous severe hypoglycemic coma (SH) and in six T1DM patients without (C) history of hypoglycemia Unawareness previous severe hypoglycemic coma. Cognitive function tests (four choice reaction time), counterregulatory responses (adrenaline), and symptomatic responses were evaluated at euglycemia (90 mg/dl) and during step-wise plasma glucose reduction (68, 58 and 49 mg/dl). EEG activity was recorded continuously throughout the study and analyzed by spectral analysis. Cognitive function deteriorated significantly at a glucose threshold of 55 ± 1 mg/dl in both groups (p = ns) during hypoglycemia, while the glucose threshold for autonomic symptoms was significantly lower in SH patients than in C patients (49 ± 1 vs. 54 ± 1 mg/dl, p < 0.05, respectively). In SH patients, eye-closed resting EEG showed a correlation between the mean dominance frequency and plasma glucose (r = 0.62, p < 0.001). Theta relative power increased during controlled hypoglycemia compared to euglycemia (21.6 ± 6 vs. 15.5 ± 3% Hz p < 0.05) and was higher than in the C group (21.6 ± 6 vs. 13.8 ± 3%, p < 0.03). The cognitive task beta activity was lower in the SH group than in the C group (14.8 ± 3 Hz, vs. 22.6 ± 4 vs. p < 0.03). Controlled hypoglycemia elicits cognitive dysfunction in both C and SH patients; however, significant EEG alterations during hypoglycemia were detected mainly in patients with a history of hypoglycemia Unawareness and previous severe hypoglycemic coma. These data suggest that prior episodes of hypoglycemic coma modulate brain electric activity.
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Cognitive, neurophysiologic and metabolic sequelae of previous hypoglycemic coma revealed by hyperinsulinemic-hypoglycemic clamp in type 1 diabetic patients.
Metabolic Brain Disease, 2017Co-Authors: Alberto Maran, Franco Del Piccolo, Lisa Zarantonello, Carlo Crepaldi, Angelo Avogaro, I A Macdonald, Piero AmodioAbstract:To examine the relationship between electroencephalographic (EEG) activity and hypoglycemia Unawareness, we investigated early parameters of vigilance and awareness of various symptom categories in response to hypoglycemia in intensively treated type 1 diabetic (T1DM) patients with different degrees of hypoglycemia Unawareness. Hypoglycemia was induced with a hyperinsulinemic-hypoglycemic clamp in six T1DM patients with a history of hypoglycemia Unawareness previous severe hypoglycemic coma (SH) and in six T1DM patients without (C) history of hypoglycemia Unawareness previous severe hypoglycemic coma. Cognitive function tests (four choice reaction time), counterregulatory responses (adrenaline), and symptomatic responses were evaluated at euglycemia (90 mg/dl) and during step-wise plasma glucose reduction (68, 58 and 49 mg/dl). EEG activity was recorded continuously throughout the study and analyzed by spectral analysis. Cognitive function deteriorated significantly at a glucose threshold of 55 ± 1 mg/dl in both groups (p = ns) during hypoglycemia, while the glucose threshold for autonomic symptoms was significantly lower in SH patients than in C patients (49 ± 1 vs. 54 ± 1 mg/dl, p
Stephanie A Amiel - One of the best experts on this subject based on the ideXlab platform.
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patient experience of hypoglycaemia Unawareness in type 1 diabetes are patients appropriately concerned
Diabetic Medicine, 2012Co-Authors: Helen Rogers, N De Zoysa, Stephanie A AmielAbstract:Diabet. Med. 29, 321–327 (2012) Abstract Objective Risk of severe hypoglycaemia is increased by absence of subjective awareness of hypoglycaemia and reduced by avoidance of minor hypoglycaemia. For many, problems persist despite educational strategies that work for others. We explored psychological factors that might inhibit the efforts of an individual in hypoglycaemia avoidance. Methods People with Type 1 diabetes and hypoglycaemia Unawareness gave semi-structured interviews exploring their perceptions and experiences of their condition. Identified factors were grouped into categories and analysed to establish links and form a grounded theory in a constant comparative analysis. A questionnaire was devised from the qualitative analysis to identify patients with problematic beliefs about their hypoglycaemia. Results Saturation (no new themes emerging) was reached with 17 patients. Responses fell into two groups: high concern and low concern regarding hypoglycaemia Unawareness. Those in the first group described severe hypoglycaemia as aversive and wanted to regain awareness. The second group included three patients in whom Unawareness was not associated with severe hypoglycaemia, nevertheless unhelpful attitudes which inhibited hypoglycaemia avoidance were expressed. Responses from this group fell into categories: (1) normalizing the presence of Unawareness; (2) underestimating its consequences; (3) wanting to avoiding the ‘sick role’; and (4) overestimating the consequences of hyperglycaemia. Conclusions A qualitative analysis of patient interviews identified deficits in education, technology and motivation in hypoglycaemia Unawareness. Interventions can therefore be tailored to target underlying problems that prevent individual patients from regaining awareness. A brief assessment tool was devised to categorize patients’ hypoglycaemia Unawareness accordingly. Psychological interventions should be developed to address the problems of ‘low concern’ regarding hypoglycaemia Unawareness.
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hypoglycemia Unawareness is associated with reduced adherence to therapeutic decisions in patients with type 1 diabetes evidence from a clinical audit
Diabetes Care, 2009Co-Authors: Charlotte B Smith, Pratik Choudhary, A Pernet, D L Hopkins, Stephanie A AmielAbstract:OBJECTIVE Hypoglycemia Unawareness increases severe hypoglycemia risk. Hypoglycemia avoidance restores awareness, but it is difficult to sustain. We compared adherence to treatment changes by awareness status. RESEARCH DESIGN AND METHODS Case notes of 90 type 1 diabetic patients were analyzed retrospectively, identifying awareness status and insulin regimens over four visits. The proportion of patients adhering to advice and percent advice taken were calculated. RESULTS A total of 31 patients with hypoglycemia awareness and 19 patients with hypoglycemia Unawareness were identified, with insulin regimens available in 23 and 13, respectively. Patients with hypoglycemia Unawareness were older ( P = 0.001) and had longer diabetes duration ( P = 0.002) and lower A1C ( P = 0.007). More patients with hypoglycemia Unawareness reported severe hypoglycemia ( P = 0.002) and fewer were adherent (53.8 vs. 87.0%, P = 0.046), with lower adherence scores (42.5 ± 24.7 vs. 75.3 ± 27.5%, P = 0.001). CONCLUSIONS Reduced adherence to changes in insulin regimen in hypoglycemia Unawareness is compatible with habituation to hypoglycemic stress. Therapies aimed at reversing repetitive harmful behaviors may be useful to restore hypoglycemia awareness and protection from severe hypoglycemia.
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attenuation of amydgala and frontal cortical responses to low blood glucose concentration in asymptomatic hypoglycemia in type 1 diabetes a new player in hypoglycemia Unawareness
Diabetes, 2007Co-Authors: Joel Dunn, Iain Cranston, Paul Marsden, Stephanie A Amiel, Laurence ReedAbstract:OBJECTIVE—Loss of ability to recognize hypoglycemia (hypoglycemia Unawareness) increases risk of severe hypoglycemia threefold in insulin-treated diabetes. We set out to investigate the cerebral correlates of Unawareness in type 1 patients. RESEARCH DESIGN AND METHODS—Regional changes in brain glucose kinetics were measured using [ 18 F]-fluorodeoxyglucose (FDG) positron emission tomography (PET), in 13 men with type 1 diabetes—6 with hypoglycemia awareness and 7 with hypoglycemia Unawareness—at euglycemia (5 mmol/l) and hypoglycemia (2.6 mmol/l), in random order. RESULTS—Epinephrine responses to hypoglycemia were reduced in hypoglycemia Unawareness ( P P P = 0.007), and robust increase in bilateral ventral striatum during hypoglycemia (region of interest analysis hypoglycemia Unawareness 3.52 ± 1.02 vs. awareness 6.1 ± 0.53; P = 0.054). Further analysis at the statistical threshold of P CONCLUSIONS—Ventral striatal, amygdala, brain stem, and orbitofrontal responses to hypoglycemia indicate engagement of appetitive motivational networks, associated with integrated behavioral responses to hypoglycemia. Reduced responses in these networks in hypoglycemia Unawareness, particularly failure of amygdala and orbifrontal cortex responses, suggest habituation of higher behavioral responses to hypoglycemia as a basis for Unawareness. New approaches may be needed to restore awareness effectively in practice.
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Hypoglycaemia Unawareness and the brain.
Diabetologia, 2002Co-Authors: D Smith, Stephanie A AmielAbstract:The intention of this paper is to critically review the current state of knowledge of the role of the brain in the syndrome of hypoglycaemia Unawareness. Both the role of the brain in the detection of hypoglycaemia and initiation of the counterregulatory responses and the function of the cerebral cortex during acute hypoglycaemia are considered. The evidence for and against the brain as the primary site of mammalian hypoglycaemia sensing and the mechanisms whereby such sensing may occur and change in hypoglycaemia Unawareness are discussed. Current evidence supports a major role for the central nervous system in hypoglycaemia sensing and there is increasing understanding of the mechanisms of counterregulatory failure and cognitive dysfunction in hypoglycaemia Unawareness. More needs to be done to expand this understanding and translate it into therapeutic strategies to defend against severe hypoglycaemia in diabetes therapy.
