scholarly journals Salience-driven value construction for adaptive choice under risk

2018 ◽  
Author(s):  
Mehran Spitmaan ◽  
Emily Chu ◽  
Alireza Soltani
Keyword(s):  
Reward Magnitude ◽  
Human Subjects ◽  
Real Life ◽  
Individual Outcomes ◽  
Single Piece ◽  
Differential Weighting ◽  
Adaptive Choice ◽  
Plausible Mechanism ◽  
Reward Information ◽  
Adaptive Decision Making

Decisions we face in real life are inherently risky and can result in one of many possible outcomes. However, most of what we know about choice under risk is based on studies that use options with only two possible outcomes (simple gambles), so it remains unclear how the brain constructs reward values for more complex risky options faced in real life. To address this question, we combined experimental and modeling approaches to examine choice between pairs of simple gambles and pairs of three-outcome gambles in male and female human subjects. We found that subjects evaluated individual outcomes of three-outcome gambles by multiplying functions of reward magnitude and probability. To construct the overall value of each gamble, however, most subjects differentially weighted possible outcomes based on either reward magnitude or probability. These results reveal a novel dissociation between how reward information is processed when evaluating complex gambles: valuation of each outcome is based on an integrated value whereas combination of possible outcomes relies on a single piece of reward information. We show that differential weighting of possible outcomes enabled subjects to make decisions more easily and quickly. Together, these findings reveal a plausible mechanism for how salience, in terms of possible reward magnitude or probability, can influence the construction of subjective values for complex gambles. They also point to separable neural mechanisms for how reward value controls choice and attention in order to allow for more adaptive decision making.

scholarly journals Crowd behaviour during high-stress evacuations in an immersive virtual environment

2016 ◽  
Vol 13 (122) ◽  
pp. 20160414 ◽  
Author(s):  
Mehdi Moussaïd ◽  
Mubbasir Kapadia ◽  
Tyler Thrash ◽  
Robert W. Sumner ◽  
Markus Gross ◽  
...  
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Human Subjects ◽  
High Stress ◽  
Three Dimensional ◽  
Real Life ◽  
Social Conventions ◽  
Emergency Situations ◽  
Crowd Behaviour ◽  
The Individual

Understanding the collective dynamics of crowd movements during stressful emergency situations is central to reducing the risk of deadly crowd disasters. Yet, their systematic experimental study remains a challenging open problem due to ethical and methodological constraints. In this paper, we demonstrate the viability of shared three-dimensional virtual environments as an experimental platform for conducting crowd experiments with real people. In particular, we show that crowds of real human subjects moving and interacting in an immersive three-dimensional virtual environment exhibit typical patterns of real crowds as observed in real-life crowded situations. These include the manifestation of social conventions and the emergence of self-organized patterns during egress scenarios. High-stress evacuation experiments conducted in this virtual environment reveal movements characterized by mass herding and dangerous overcrowding as they occur in crowd disasters. We describe the behavioural mechanisms at play under such extreme conditions and identify critical zones where overcrowding may occur. Furthermore, we show that herding spontaneously emerges from a density effect without the need to assume an increase of the individual tendency to imitate peers. Our experiments reveal the promise of immersive virtual environments as an ethical, cost-efficient, yet accurate platform for exploring crowd behaviour in high-risk situations with real human subjects.

scholarly journals Physical Context Detection using Wearable Wireless Sensor Networks

2008 ◽  
Vol 4 (3) ◽  
pp. 191 ◽  
Author(s):  
Muhannad Quwaider ◽  
Subir Biswas
Keyword(s):  
Markov Model ◽  
Hidden Markov Model ◽  
Hidden Markov ◽  
Human Subjects ◽  
Real Life ◽  
Sensor Data ◽  
Physical Context ◽  
Significant Extension ◽  
The Individual ◽  
Stochastic Identification

This paper presents the architecture of a wearable sensor network and a Hidden Markov Model (HMM) processingframework for stochastic identification of body postures andphysical contexts. The key idea is to collect multi-modal sensor data from strategically placed wireless sensors over a human subject’s body segments, and to process that using HMM in order to identify the subject’s instantaneous physical context. The key contribution of the proposed multi-modal approach is a significant extension of traditional uni-modal accelerometry in which only the individual body segment movements, without their relative proximities and orientation modalities, is used for physical context identification. Through real-life experiments with body mounted sensors it is demonstrated that while the unimodal accelerometry can be used for differentiating activityintensive postures such as walking and running, they are not effective for identification and differentiation between lowactivity postures such as sitting, standing, lying down, etc. In the proposed system, three sensor modalities namely acceleration, relative proximity and orientation are used for context identification through Hidden Markov Model (HMM) based stochastic processing. Controlled experiments using human subjects are carried out for evaluating the accuracy of the HMMidentified postures compared to a naïve threshold based mechanism over different human subjects.

scholarly journals Orthogonal Representations of Reward Magnitude, Certainty, and Volatility in the Macaque Orbitofrontal Cortex

2018 ◽  
Author(s):  
Tianming Yang ◽  
Elisabeth A. Murray
Keyword(s):  
Reward Magnitude ◽  
Orbitofrontal Cortex ◽  
Stimulus Presentation ◽  
Two Dimensions ◽  
Foraging Strategies ◽  
General Role ◽  
Decision Variables ◽  
Categorical Knowledge ◽  
Reward Information ◽  
The Brain

AbstractCategorical knowledge about the probabilistic and volatile nature of resource availability can improve foraging strategies, yet we have little understanding of how the brain represents such knowledge. Neurons in the orbitofrontal cortex (OFC) of macaques encode several decision variables (e.g., reward magnitude, probability) that could influence choice behavior. Here we investigated whether OFC neurons also represent two aspects of reward predictability: certainty and volatility. Rhesus monkeys performed a visual stimulus-reward association task in which a set of simple shapes preceded the delivery of reward, and they learned the nature of each shape’s reward association along two dimensions. One involved the certainty of a reward outcome; rewards can be either deterministic (and therefore certain) or probabilistic (uncertain). A second dimension reflected the volatility of an outcome; reward schedules can be either stable over time or volatile. During stimulus presentation, the activity of OFC neurons reflected both categorical certainty and categorical volatility, in addition to reward magnitude. These three characteristics were represented orthogonally by three distinct neural populations of similar size. These findings point to a more general role for OFC in processing reward information than one restricted to encoding parametric valuations such as reward magnitude and probability.

scholarly journals Sunburn Protection by Sunscreen Sprays at Beach

2017 ◽  
Author(s):  
Hao Ou-Yang ◽  
Richard Bradley Rzendzian
Keyword(s):  
Environmental Conditions ◽  
Healthy Subjects ◽  
Human Subjects ◽  
Real Life ◽  
The Body ◽  
Single Center ◽  
Human Behaviors ◽  
Actual Usage ◽  
Neck Area ◽  
The Face

Background: The efficacy of sunscreen is evaluated by SPF values, which are quantitatively determined in laboratories on the backs of human subjects according to a standardized procedure. However, SPF cannot be directly translated to sunburn protection under real-life situations because actual efficacy depends on various factors related to human behaviors and environmental conditions. This study clinically evaluated the efficacy of two sunscreen sprays (SPF 30 and SPF 70) under natural sunlight exposure on healthy subjects at the beach. Methods: Twenty subjects were divided into two cells for the two sunscreen sprays (SPF 70 and SPF 30) in a single-center, actual usage test. The primary endpoint of the study was sunburn protection on the dorsal arms and the secondary endpoint was protection on the face and neck. Subjects stayed at the beach for 4 h after application of the sunscreens with normal beach activities. Subjects’ behavior at the beach, the amounts of sunscreen applied and reapplied, and environmental conditions were all recorded. Results: There was no significant sunburn for a majority of the subjects in either cell. However, neither sunscreen completely blocked the sunburn, especially for the face/neck area. We found that the SPF 70 sunscreen was more effective than the SPF 30 sunscreen. Conclusion: Modern sunscreen sprays, applied liberally, are effective in providing sunburn protection for the body in a beach setting.

scholarly journals The caudate nucleus controls coordinated patterns of adaptive, context-dependent adjustments to complex decisions

2019 ◽  
Author(s):  
Takahiro Doi ◽  
Yunshu Fan ◽  
Joshua I. Gold ◽  
Long Ding
Keyword(s):  
Basal Ganglia ◽  
Caudate Nucleus ◽  
Decision Process ◽  
Visual Motion ◽  
Electrical Microstimulation ◽  
Visual Evidence ◽  
Sensory Evidence ◽  
Reward Information ◽  
Adaptive Decision Making ◽  
The Brain

AbstractOur decisions often need to balance what we observe and what we desire. However, our understanding of how and where in the brain such decisions are made remains limited. A prime candidate for integrating sensory observations and desired rewards, and a focus of many modeling studies, is the basal ganglia pathway, which is known to make separate contributions to perceptual decisions that require the interpretation of uncertain sensory evidence and value-based decisions that select among outcome options 1-16. Here we report direct evidence for a causal role for a major input station of the basal ganglia, the caudate nucleus, in incorporating reward context and uncertain visual evidence to guide adaptive decision-making. In monkeys making saccadic decisions based on visual motion evidence and asymmetric reward-choice associations 17, single caudate neurons encoded information about both the visual evidence and the asymmetric rewards. Electrical microstimulation at caudate sites with task-modulated activity during motion viewing affected how the visual and reward information was used to form the decision. The microstimulation effects included coordinated changes in multiple computational components of the decision process, mimicking the monkeys’ voluntary adjustments in response to the asymmetric reward contexts. These results imply that the caudate nucleus plays key roles in coordinating the deliberative decision process that balances external evidence and internal preferences to guide adaptive behavior.

scholarly journals Reading Blood Work is an Art Form: Toward an Embodied Feminist Practice of Veterinary Science and Care

2017 ◽  
Vol 3 (2) ◽  
pp. 1-27
Author(s):  
Christian Gundermann
Keyword(s):  
Knowledge Production ◽  
Animal Studies ◽  
Science Studies ◽  
Human Subjects ◽  
Real Life ◽  
Critical Animal Studies ◽  
Feminist Science ◽  
Art Form ◽  
Advocacy Network ◽  
Clinical Control

What are the advantages of a concrete, embodied relationship between human subjects and their non-human objects of care for the veterinary process of knowledge production? The scientific reductionism that frames formal studies makes much of the knowledge gained in those studies questionable or severely limited, since many important factors of real life illnesses and their causation and cure are excluded from consideration for the sake of clinical control and traditional scientific objectivity. This essay narrates my experience with my mare Lilly who suffered from a rare auto-immune disease; at the same time, it describes and analyzes the history and strategies of the world's largest internet-based equine patient advocacy network on metabolic illness, a network that supported my journey of knowledge acquisition and contribution, through our case history, to a larger alternative veterinary cause of knowledge production. Located between Feminist Science Studies and Critical Animal Studies, this project explores the notion of touch and raises questions about the biomedical field's present-day heavy reliance on visual diagnostics. What is the relation between visual technologies and the detached, disembodied knowledge "from nowhere" that conventional science believes in? How much of the alternative to this way of knowing lies in touch, embodied assistance, relationality, and intuition?And finally, in observing and documenting the relationship at the heart of this venture around knowledge, my essay also suggest that this is a queer project where queerness is understood as the careful but radical reconfiguration of kinship in the context of Haraway’s recent call to “make kin, not babies.” 

scholarly journals Prehospital triage of patients with suspected stroke symptoms (PRESTO): protocol of a prospective observational study

BMJ Open ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. e028810 ◽  
Author(s):  
Esmee Venema ◽  
Martijne H C Duvekot ◽  
Hester F Lingsma ◽  
Anouk D Rozeman ◽  
Walid Moudrous ◽  
...  
Keyword(s):  
Ischaemic Stroke ◽  
Acute Ischaemic Stroke ◽  
Human Subjects ◽  
Real Life ◽  
Clinical Equipoise ◽  
Hospital Data ◽  
Anterior Circulation ◽  
Vessel Occlusion ◽  
Prehospital Triage ◽  
Suspected Stroke

IntroductionThe efficacy of both intravenous treatment (IVT) and endovascular treatment (EVT) for patients with acute ischaemic stroke strongly declines over time. Only a subset of patients with ischaemic stroke caused by an intracranial large vessel occlusion (LVO) in the anterior circulation can benefit from EVT. Several prehospital stroke scales were developed to identify patients that are likely to have an LVO, which could allow for direct transportation of EVT eligible patients to an endovascular-capable centre without delaying IVT for the other patients. We aim to prospectively validate these prehospital stroke scales simultaneously to assess their accuracy in predicting LVO in the prehospital setting.Methods and analysisPrehospital triage of patients with suspected stroke symptoms (PRESTO) is a prospective multicentre observational cohort study in the southwest of the Netherlands including adult patients with suspected stroke in the ambulance. The paramedic will assess a combination of items from five prehospital stroke scales, without changing the normal workflow. Primary outcome is the clinical diagnosis of an acute ischaemic stroke with an intracranial LVO in the anterior circulation. Additional hospital data concerning the diagnosis and provided treatment will be collected by chart review. Logistic regression analysis will be performed, and performance of the prehospital stroke scales will be expressed as sensitivity, specificity and area under the receiver operator curve.Ethics and disseminationThe Institutional Review Board of the Erasmus MC University Medical Centre has reviewed the study protocol and confirmed that the Dutch Medical Research Involving Human Subjects Act (WMO) is not applicable. The findings of this study will be disseminated widely through peer-reviewed publications and conference presentations. The best performing scale, or the simplest scale in case of clinical equipoise, will be integrated in a decision model with other clinical characteristics and real-life driving times to improve prehospital triage of suspected stroke patients.Trial registration numberNTR7595.

scholarly journals On the flexibility of basic risk attitudes in monkeys

2018 ◽  
Author(s):  
Shiva Farashahi ◽  
Habiba Azab ◽  
Benjamin Hayden ◽  
Alireza Soltani
Keyword(s):  
Computational Models ◽  
Weighting Function ◽  
Neural Substrates ◽  
Risk Attitudes ◽  
Economic Choice ◽  
Risky Choices ◽  
Differential Weighting ◽  
Plausible Mechanism ◽  
Linear Probability ◽  
Gains And Losses

ABSTRACTMonkeys and other animals appear to share with humans two risk attitudes predicted by prospect theory: an inverse-S-shaped probability weighting function and a steeper utility curve for losses than for gains. These findings suggest that such preferences are stable traits with common neural substrates. We hypothesized instead that animals tailor their preferences to subtle changes in task contexts, making risk attitudes flexible. Previous studies used a limited number of outcomes, trial types, and contexts. To gain a broader perspective, we examined two large datasets of male macaques’ risky choices: one from a task with real (juice) gains and another from a token task with gains and losses. In contrast to previous findings, monkeys were risk-seeking for both gains and losses (i.e. lacked a reflection effect) and showed steeper gain than loss curves (loss-seeking). Utility curves for gains were substantially different in the two tasks. Monkeys showed nearly linear probability weightings in one task and S-shaped ones in the other; neither task produced a consistent inverse-S-shaped curve. To account for these observations, we developed and tested various computational models of the processes involved in the construction of reward value. We found that adaptive differential weighting of prospective gamble outcomes could partially account for the observed differences in the utility functions across the two experiments and thus, provide a plausible mechanism underlying flexible risk attitudes. Together, our results support the idea that risky choices are flexibly constructed at the time of elicitation and place important constraints on neural models of economic choice.

scholarly journals Luminophonics experiment: A user study on visual sensory substitution device

2015 ◽  
Author(s):  
Shern Shiou Tan ◽  
Tomas Maul ◽  
Neil Mennie
Keyword(s):  
Visually Impaired ◽  
User Study ◽  
Human Subjects ◽  
Sensory System ◽  
Real Life ◽  
Sensory Substitution ◽  
Depth Information ◽  
Daily Lives ◽  
Information Preservation ◽  
Care Givers

Loss of vision is a severe impairment to the dominant sensory system. It often has a catastrophic effect upon the sufferer, with knock-on effects to their standard of living, their ability to support themselves, and their care-givers lives. Research into visual impairments is multi-faceted, focusing on the causes of these debilitating conditions as well as attempting to alleviate the daily lives of affected individuals. One of the methods is through the usage of sensory substitution device. Our proposed system, Luminophonics, focuses on visual to auditory cross modalities information conversions. A visual to audio sensory substitution device a type of system that obtains a continual stream visual inputs which it converts into corresponding auditory soundscape. Ultimately, this device allows the visually impaired to visualize the surrounding environment by only listening to the generated soundscape. Even though there is a huge potential for this kind of devices, public usage is still minimal (Loomis, 2010). In order to promote the adoption from the visually impaired, the overall performance of these devices need to be improved in terms of soundscape interpretability, information preservation and listening comfort amongst other factors. Luminophonics has developed 3 type of prototypes, which we have used to explore different ideas pertaining to visual to audio sensory substitution. In addition to these, one of the prototypes has been converted to include depth information using time of flight camera. Previously, an automated measurement method is used to evaluate the performance of the 3 prototypes (Tan, 2013). The results of the measurement cover the effectiveness in terms of interpretability and information preservation. The main purpose of the experiment reported herein, was to test the prototypes on human subjects in order to gain greater insight on how they perform in real-life situations.

scholarly journals Evaluation of Functional Insoles for Protective Footwear Under Simulated Use Conditions

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Emilia Irzmańska ◽  
Katarzyna Majchrzycka ◽  
Izabella Krucińska ◽  
Michał Puchalski ◽  
Agnieszka Brochocka ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Human Subjects ◽  
Real Life ◽  
Middle Layer ◽  
Climatic Conditions ◽  
Superabsorbent Polymer ◽  
Life Conditions ◽  
Layer Composite ◽  
Foot Model ◽  
Polypropylene Melt

AbstractThe objective of the work was to study the properties of functional insoles for protective footwear using an original methodology by simulating the dynamic real-life conditions. Two insole variants were examined; both are made from a three-layer composite with the middle layer being a polypropylene melt-blown nonwoven. The variants differed in terms of the presence or absence of a superabsorbent polymer (SAP) and a biocide in the middle layer. Insole samples were subjected to pressure and examined in terms of the adsorption and desorption of acidic and alkaline liquids, followed by tear strength experiments. In addition, the insoles were placed in protective footwear and the microclimate existing inside the resulting system was determined using T/RH sensors by means of three complementary methods: under controlled climatic conditions, on a thermal foot model, and on human subjects. The results clearly indicate that insoles containing SAP are more effective than those without SAP in terms of both hygienic and mechanical properties.

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