Lost in time : a neurophilosophical quest to understand the perception of time in MCI patients

Tese de doutoramento, Ciências Biomédicas (Neurociências), Universidade de Lisboa, Faculdade de Medicina, 2017Introduction: Mild cognitive impairment (MCI) patients often complaint about difficulties in dealing with time questions, an issue that compromises their daily planning and orientation. The conscious experience of duration has been the most studied time experience and is generally assessed through duration judgments and passage of time judgments. This temporal experience may also impact other aspects of human life, namely intertemporal decision making. In the same vein, the connexion between time and memory has long been debated among neuroscientists, psychologists and philosophers. Among these scholars, Bergson, a 20th century French philosopher, was the leading proponent of a strong bond between time and memory, through the concept of duration. Time, for Bergson, is also interwoven with other dimensions of human consciousness, such as will. Thus, mild cognitive impairment can offer us a human disease model to see if and how memory impairments affect human time perception and to explore their broader effects upon subjects’ lives. Bergson seems to favour the idea of an affective and qualitative time experience interlinked with memory issues, akin of the situation of judging time passage. These ideas contrast with an Aristotelian idea of counting time intervals, similar to interval length judgments and currently conveyed by internal clock models, which neglects the role that feelings may play in time experience. In the case that the results obtained support Bergson’s intuitions, further avenues of work will be open to explore the relation between memory deficits and affective time experience. Objectives: This study aims to investigate the perception of time in patients with Mild Cognitive Impairment. The experience of time duration, with respect to both interval length judgments and passage of time judgments, and the consequences for decision making, using an intertemporal choice, are assessed. We intend to see how the results obtained fit into a philosophical framework that interlink memory and time and make suggestions regarding future work. Methods: Fifty-five MCI patients and fifty-seven healthy controls undergo an experimental protocol for time perception on interval length, a questionnaire for the subjective passage of time, an intertemporal choices questionnaire and a neuropsychological evaluation. In the experimental protocol for interval Length judgements, participants have to estimate and produce the duration of short time intervals of 7 s, 32 s, 58 s, following a prospective paradigm (they are told in advance that they will have to estimate and produce time intervals). They also have to estimate a duration of the time to draw a clock and the duration of the neuropsychological interview, following a retrospective paradigm (they are not told that they will have to estimate time intervals). In the passage of time judgments protocol, participants are inquired about their subjective impressions about the speed of time course and have to rate their impressions into a scale ranging from the very fast to the very slow. To check decision-making, participants are submitted to an intertemporal choice questionnaire where they have to choose between small and immediate reward or a larger but delayed reward. Finally, participants undergo a neuropsychological evaluation, where they are submitted to tests of cognitive functions, particularly memory and executive functions, as well as scales to evaluate their emotional state, namely depressive and anxiety symptoms. Results: Patients with MCI present no changes in the perception of interval length. However, they report the time passing slower than controls. This experience is significantly correlated with memory deficits, but not with performance in executive tests, depressive or anxiety symptoms. Patients with MCI have no alterations in temporal preferences in comparison with the healthy controls. These results from a study in neuroscience, put into a philosophical framework, suggest that Bergson and Aristotle, at the end, consider different aspects of time perception, in the first case referring to feelings of time passage and in the second case to the estimation of time intervals. However, both philosophers highlight the connexions of different aspects of time perception with different types of memory. Thus, passage of time judgements is linked to long-term memory and interval length judgements is associated with working memory. Conclusions: Memory deficits do not affect either the perception of interval length or temporal preferences, but are associated with alterations in the subjective experience of time. Following Bergson’s footsteps, we may say that memory is associated with an affective and qualitative experience of time. Future works investigating time perception in patients with memory deficits should careful consider this dimension when designing the experimental protocols

Neuroeconomics: How Neuroscience Can Inform Economics

Neuroeconomics uses knowledge about brain mechanisms to inform economic analysis, and roots economics in biology. It opens up the "black box" of the brain, much as organizational economics adds detail to the theory of the firm. Neuroscientists use many tools— including brain imaging, behavior of patients with localized brain lesions, animal behavior, and recording single neuron activity. The key insight for economics is that the brain is composed of multiple systems which interact. Controlled systems ("executive function") interrupt automatic ones. Emotions and cognition both guide decisions. Just as prices and allocations emerge from the interaction of two processes—supply and demand— individual decisions can be modeled as the result of two (or more) processes interacting. Indeed, "dual-process" models of this sort are better rooted in neuroscientific fact, and more empirically accurate, than single-process models (such as utility-maximization). We discuss how brain evidence complicates standard assumptions about basic preference, to include homeostasis and other kinds of state-dependence. We also discuss applications to intertemporal choice, risk and decision making, and game theory. Intertemporal choice appears to be domain-specific and heavily influenced by emotion. The simplified ß-d of quasi-hyperbolic discounting is supported by activation in distinct regions of limbic and cortical systems. In risky decision, imaging data tentatively support the idea that gains and losses are coded separately, and that ambiguity is distinct from risk, because it activates fear and discomfort regions. (Ironically, lesion patients who do not receive fear signals in prefrontal cortex are "rationally" neutral toward ambiguity.) Game theory studies show the effect of brain regions implicated in "theory of mind", correlates of strategic skill, and effects of hormones and other biological variables. Finally, economics can contribute to neuroscience because simple rational-choice models are useful for understanding highly-evolved behavior like motor actions that earn rewards, and Bayesian integration of sensorimotor information

The dynamics of ethical product differentiation and the habit formation of socially responsible consumers

In our model of ethical product differentiation two duopolists (a zero profit socially concerned producer and a profit maximizing producer) compete over prices and (costly) socially and environmentally responsible features of their products under a given law of motion of consumer habits. In a continuous time model in which the location of the zero profit social responsible entrant is fixed and the profit maximizing producer (PMP) limits himself to price competition without ethical imitation, we show that the optimal dynamic price is always lower than his optimal static price since the PMP producer knows that, by leaving too much market share to the other producer, he will reinforce the habit of socially responsible consumption and loose further market share in the future. We inspect the properties of equilibria when the PMP can ethically imitate the entrant and when the entrant is free to choose his location. We find that, in the first case, the threshold triggering a PMP strategy of ethical imitation and minimum price differentiation is lower in the dynamic than in the static case, depending on the shadow cost of changes in consumers social responsibility.Socially responsible consumers; ethical product differentiation; profit maximizing producer

Measuring time preferences

We review research that measures time preferences—i.e., preferences over intertemporal tradeoffs. We distinguish between studies using financial flows, which we call “money earlier or later” (MEL) decisions and studies that use time-dated consumption/effort. Under different structural models, we show how to translate what MEL experiments directly measure (required rates of return for financial flows) into a discount function over utils. We summarize empirical regularities found in MEL studies and the predictive power of those studies. We explain why MEL choices are driven in part by some factors that are distinct from underlying time preferences.National Institutes of Health (NIA R01AG021650 and P01AG005842) and the Pershing Square Fund for Research in the Foundations of Human Behavior

Time Inconsistency, Sophistication, and Commitment An Experimental Study

We experimentally study the relationship between time inconsistency, sophistication about time inconsistency, and self-commitment. Previous research has interpreted demand for commitment devices as evidence for the sophistication of a time-inconsistent decision-maker. In our laboratory experiment, we attempt to measure sophistication directly by way of a cognitive test. We then test the hypothesis that people who are both time-inconsistent and show high cognitive capacity take up commitment devices when offered in the strategic game between their current and their future self. For experimental laboratory commitment choices, we cannot detect a moderating effect of cognition on commitment demand of time-inconsistent subjects. However, we find that the existence of time-inconsistent preferences and sophistication (proxied by cognitive performance) can predict the demand for savings commitment in our hypothetical survey vignette question.Series: Department of Strategy and Innovation Working Paper Serie

The role of simulation in intertemporal choices

One route to understanding the thoughts and feelings of others is by mentally putting one's self in their shoes and seeing the world from their perspective, i.e., by simulation. Simulation is potentially used not only for inferring how others feel, but also for predicting how we ourselves will feel in the future. For instance, one might judge the worth of a future reward by simulating how much it will eventually be enjoyed. In intertemporal choices between smaller immediate and larger delayed rewards, it is observed that as the length of delay increases, delayed rewards lose subjective value; a phenomenon known as temporal discounting. In this article, we develop a theoretical framework for the proposition that simulation mechanisms involved in empathizing with others also underlie intertemporal choices. This framework yields a testable psychological account of temporal discounting based on simulation. Such an account, if experimentally validated, could have important implications for how simulation mechanisms are investigated, and makes predictions about special populations characterized by putative deficits in simulating others

The hunt for the perfect discounting function and a reckoning of time perception

Making decisions that factor the cost of time is fundamental to survival. Yet, while it is readily appreciated that our perception of time is intimately involved in this process, theories regarding intertemporal decision-making and theories regarding time perception are treated, largely, independently. Even within these respective domains, models providing good fits to data fail to provide insight as to why, from a normative sense, those fits should take their apparent form. Conversely, normative models that proffer a rationalization for why an agent should weigh options in a particular way, or to perceive time in a particular way, fail to account for the full body of well-established experimental evidence. Here we review select, yet key advances in our understanding, identifying conceptual breakthroughs in the fields of intertemporal decision-making and in time perception, as well as their limits and failings in the face of hard-won experimental observation. On this background of accrued knowledge, a new conception unifying the domains of decision-making and time perception is put forward (Training-Integrated Maximization of Reinforcement Rate, TIMERR) to provide a better fit to observations and a more parsimonious reckoning of why we make choices, and thereby perceive time, the way we do

The effects of background music and sound in economic decision making: Evidence from a laboratory experiment

This paper experimentally studies the effects of background music and sound on the preference of the decision makers for rewards in pairwise intertemporal choice tasks and lottery choice tasks. The participants took part in the current experiment, involving four treatments: (1) the familiar music treatment; (2) the unfamiliar music treatment; (3) the noise treatment and (4) the no music treatment. The experimental results confirm that background noise affects human performance in decision making under risk and intertemporal decision making, though the results do not indicate the significant familiarity effect that is a change of the preference in the presence of familiar background music and sound.Allais-type preferences; choice under risk; intertemporal choice; the familiarity effect

Individuals With Amnesia are not Stuck in Time: Evidence From Risky Decision-Making, Intertemporal Choice, and Scaffolded Narratives

This dissertation investigates the supposition that individuals with amnesia are cognitively stuck in time. In Experiment 1, I used a Galton-Crovitz cueing paradigm to test etiologically diverse amnesic cases on their ability to richly recollect autobiographical episodic memories and imagine future experiences. In Experiment 2, I use two behavioural economics tasks (a risky decision-making task and an intertemporal choice task) to examine whether amnesic cases judgment and decision-making reflects proneness to risky choices or steep disregard for the future. In Experiment 3, I examine the flexibility of amnesics intertemporal choice by testing whether cueing them with personal future events increases their value of future rewards as it does in healthy controls. In Experiment 4, I attempt to decrease the severity of amnesic cases episodic memory and prospection impairment by using structured and personally meaningful cues rather than the single cue words featured in the Galton-Crovitz paradigm. I replicated existing research showing that those with MTL damage have impaired ability to (re)construct rich and detailed narratives of past and future experiences, and I extended this finding for the first time to a lateral dorsal thalamic stroke case (Experiment 1). Despite this impairment in mental time travel, the same amnesic cases made financial decisions that a) systematically considered and valued the future and b) showed normal sensitivity to risk (Experiment 2). The normalcy of intertemporal choice in amnesia extends beyond basic rates of future reward discounting in intertemporal choice. In controls, cues to imagine future experiences can modulate decision-making by increasing the value one places on future rewards. Here, most amnesic cases also retain this modulatory effect, despite having impaired ability to generate detailed representations of future experiences (Experiment 3). Finally, I found that the severity of episodic prospection impairment in MTL amnesia is cue-dependent and likely overestimated in current research: specific, personally meaningful cues lead to an appreciable reduction of episodic prospection impairment over single cue words for those with mild-moderate amnesia (Experiment 4). Collectively, results challenge assumptions that amnesic populations are cognitively confined to the present and call for refinement to simple accounts of limited temporality in individuals with amnesia