scholarly journals Dynamic decision policy reconfiguration under outcome uncertainty

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Krista Bond ◽  
Kyle Dunovan ◽  
Alexis Porter ◽  
Jonathan E Rubin ◽  
Timothy Verstynen
Keyword(s):  
Drift Rate ◽  
Environmental Changes ◽  
Optimal Choice ◽  
Decision Boundary ◽  
Policy Changes ◽  
Evidence Accumulation ◽  
Pupillary Responses ◽  
Human Participants ◽  
Decision Policies ◽  
Shed Light

In uncertain or unstable environments, sometimes the best decision is to change your mind. To shed light on this flexibility, we evaluated how the underlying decision policy adapts when the most rewarding action changes. Human participants performed a dynamic two-armed bandit task that manipulated the certainty in relative reward (conflict) and the reliability of action-outcomes (volatility). Continuous estimates of conflict and volatility contributed to shifts in exploratory states by changing both the rate of evidence accumulation (drift rate) and the amount of evidence needed to make a decision (boundary height), respectively. At the trialwise level, following a switch in the optimal choice, the drift rate plummets and the boundary height weakly spikes, leading to a slow exploratory state. We find that the drift rate drives most of this response, with an unreliable contribution of boundary height across experiments. Surprisingly, we find no evidence that pupillary responses associated with decision policy changes. We conclude that humans show a stereotypical shift in their decision policies in response to environmental changes.

scholarly journals Dynamic decision policy reconfiguration under outcome uncertainty

2020 ◽  
Author(s):  
Krista Bond ◽  
Kyle Dunovan ◽  
Alexis Porter ◽  
Jonathan Rubin ◽  
Timothy Verstynen
Keyword(s):  
Drift Rate ◽  
Environmental Changes ◽  
Action Selection ◽  
Optimal Choice ◽  
Quick Recovery ◽  
Selection Policy ◽  
Adaptive Shift ◽  
Decision Dynamics ◽  
Shed Light ◽  
Rate Mechanism

AbstractHumans and other mammals flexibly select actions under noisy and unstable conditions. To shed light on the mechanism driving this flexibility, we evaluated how the underlying decision policy evolves when humans change their minds about the most rewarding action. Participants performed a dynamic variant of the two-armed bandit task that manipulated the certainty in relative reward probabilities (conflict) and the reliability of action-outcome contingencies (volatility). We found that conflict and volatility contributed to shifts in exploratory states by changing both the rate of evidence accumulation (drift rate) and the amount of evidence needed to make a decision (boundary height). Following a switch in the optimal choice, the drift rate and the boundary height reduce, allowing variability in the accumulation process to predominate action selection, leading to a fast exploratory state. These changes facilitate the discovery of the new optimal choice, with a quick recovery of the boundary height to baseline. In parallel, the drift rate gradually returns to its asymptotic value as the belief in the value of the optimal choice stabilizes. Together, these decision dynamics suggest that, in the context of volatile two-choice decisions, humans adopt a combined information-threshold and drift rate mechanism in response to environmental changes. Unlike previous observations, we found no evidence that fluctuations in norepinephrine, as measured by pupillometry, associated with this adaptive shift toward an exploratory policy. We conclude that the multifaceted processes underlying a decision can rapidly reconfigure to adapt action selection policy under multiple forms of environmental uncertainty.

scholarly journals Meta-Omics Reveals Genetic Flexibility of Diatom Nitrogen Transporters in Response to Environmental Changes

2019 ◽  
Vol 36 (11) ◽  
pp. 2522-2535 ◽  
Author(s):  
Greta Busseni ◽  
Fabio Rocha Jimenez Vieira ◽  
Alberto Amato ◽  
Eric Pelletier ◽  
Juan J Pierella Karlusich ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Seawater Temperature ◽  
Holistic Approach ◽  
Gene Families ◽  
Functional Trait ◽  
Marine Phytoplankton ◽  
Functional Biology ◽  
Key Events ◽  
Diverse Groups ◽  
Shed Light

Abstract Diatoms (Bacillariophyta), one of the most abundant and diverse groups of marine phytoplankton, respond rapidly to the supply of new nutrients, often out-competing other phytoplankton. Herein, we integrated analyses of the evolution, distribution, and expression modulation of two gene families involved in diatom nitrogen uptake (DiAMT1 and DiNRT2), in order to infer the main drivers of divergence in a key functional trait of phytoplankton. Our results suggest that major steps in the evolution of the two gene families reflected key events triggering diatom radiation and diversification. Their expression is modulated in the contemporary ocean by seawater temperature, nitrate, and iron concentrations. Moreover, the differences in diversity and expression of these gene families throughout the water column hint at a possible link with bacterial activity. This study represents a proof-of-concept of how a holistic approach may shed light on the functional biology of organisms in their natural environment.

A Computational Feedforward Model Predicts Categorization of Masked Emotional Body Language for Longer, but Not for Shorter, Latencies

2012 ◽  
Vol 24 (7) ◽  
pp. 1806-1821
Author(s):  
Bernard M. C. Stienen ◽  
Konrad Schindler ◽  
Beatrice de Gelder
Keyword(s):  
Human Performance ◽  
Recognition Performance ◽  
Neural Model ◽  
Stimulus Onset ◽  
Emotional Expressions ◽  
Feedback Processing ◽  
Feedforward Processing ◽  
Human Participants ◽  
Onset Asynchrony ◽  
Shed Light

Given the presence of massive feedback loops in brain networks, it is difficult to disentangle the contribution of feedforward and feedback processing to the recognition of visual stimuli, in this case, of emotional body expressions. The aim of the work presented in this letter is to shed light on how well feedforward processing explains rapid categorization of this important class of stimuli. By means of parametric masking, it may be possible to control the contribution of feedback activity in human participants. A close comparison is presented between human recognition performance and the performance of a computational neural model that exclusively modeled feedforward processing and was engineered to fulfill the computational requirements of recognition. Results show that the longer the stimulus onset asynchrony (SOA), the closer the performance of the human participants was to the values predicted by the model, with an optimum at an SOA of 100 ms. At short SOA latencies, human performance deteriorated, but the categorization of the emotional expressions was still above baseline. The data suggest that, although theoretically, feedback arising from inferotemporal cortex is likely to be blocked when the SOA is 100 ms, human participants still seem to rely on more local visual feedback processing to equal the model's performance.

scholarly journals Boldness and exploration vary between shell morphs but not environmental contexts in the snail Cepaea nemoralis

2019 ◽  
Author(s):  
Maxime Dahirel ◽  
Valentin Gaudu ◽  
Armelle Ansart
Keyword(s):  
Behavioral Ecology ◽  
Environmental Changes ◽  
Thermal Environment ◽  
Thermal Response ◽  
Credible Interval ◽  
Individual Level ◽  
Cepaea Nemoralis ◽  
Selective Pressures ◽  
And Behavior ◽  
Shed Light

Understanding the maintenance of among-individual behavioral variation in populations, and predicting its consequences, are key challenges in behavioral ecology. Studying the association between repeatable behaviors and other traits under selection may shed light on the underlying selective pressures. We used the model snail Cepaea nemoralis to examine whether individual behavior is associated with shell morph, a key trait that has been extensively studied in the context of thermal tolerance and predator avoidance, and which is known to be under strict genetic control in this species. We quantified proxies of boldness and exploration in snails of three morphs coming from two habitats with different thermal contexts. We show that both behaviors were repeatable at the among-individual level (within-state Rboldness = 0.22 [95% credible interval: 0.15, 0.29]; Rexploration = 0.20 [0.15, 0.25]). Behavior was associated with shell morph, with the darker morph (five-banded) being consistently shyer and slower to explore. There was no evidence that thermal environment of origin influenced behavior. Snails became faster when test temperature increased; we found no evidence morphs differed in their thermal response. Boldness and exploration were correlated among individuals, forming a syndrome (r = 0.28 [0.10, 0.46]). We discuss what these results may tell us about the type of selection exerted by predators. We also detail how our results hint to a genetic link between shell morph and behavior, and the evolutionary implications of such a link. Finally, we discuss how our findings combined with decades of evolutionary research make C. nemoralis a very valuable model to study the evolution of behavior in response to environmental changes.

scholarly journals Tax Reform: Is it Welfare-Enhancing or Welfare-Reducing?

2021 ◽  
Vol 21 (3) ◽  
pp. 1101-1112
Author(s):  
Roshaiza Taha ◽  
Norsiah Ahmad ◽  
Wan Anisah Endut ◽  
Saeed Rabea Ali Baatwah
Keyword(s):  
Tax Reform ◽  
Consumer Welfare ◽  
Price Effect ◽  
Policy Changes ◽  
The Public ◽  
Goods And Services ◽  
Negative Effect ◽  
The Government ◽  
The Impact ◽  
Shed Light

The ongoing tax reform in Malaysia has triggered our motivation to understand the effect of such reform on the public since the government has continuously emphasised that the changes would not burden the consumer. Whether this is a myth or reality is deemed interesting to ponder upon. Thus, this study aims to provide evidence concerning Malaysian tax reform on consumer welfare by looking at the price effect, consumer burden, and inflation. Price observations of the pre-, during and post-reformation period were conducted to provide meaningful evidence. Interestingly, the outcome of the observation rules out the public accusation that the tax reform would boost the price of goods and services and further result in a welfarereducing event. Also, a review of the recent statistics on poverty incidence does not show a negative effect of tax policy changes on society’s welfare. It is hoped that the discussion provided in this paper will shed light on the impact of tax reformation in Malaysia, albeit a further thorough examination might be required. 

scholarly journals Neural encoding of task-dependent errors during adaptive learning

2020 ◽  
Author(s):  
Chang-Hao Kao ◽  
Sangil Lee ◽  
Joshua I. Gold ◽  
Joseph W. Kable
Keyword(s):  
Adaptive Learning ◽  
Posterior Parietal Cortex ◽  
Environmental Changes ◽  
Environmental Stochasticity ◽  
Anterior Cingulate ◽  
Dependent Manner ◽  
Neural Encoding ◽  
Stochastic Fluctuations ◽  
Human Participants ◽  
Reward Contingencies

AbstractEffective learning requires using errors in a task-dependent manner, for example adjusting to errors that result from unpredicted environmental changes but ignoring errors that result from environmental stochasticity. Where and how the brain represents errors in a task-dependent manner and uses them to guide behavior are not well understood. We imaged the brains of human participants performing a predictive-inference task with two conditions that had different sources of errors. Their performance was sensitive to this difference, including more choice switches after fundamental changes versus stochastic fluctuations in reward contingencies. Using multi-voxel pattern classification, we identified task-dependent representations of error magnitude and past errors in posterior parietal cortex. These representations were distinct from representations of the resulting behavioral adjustments in dorsomedial frontal, anterior cingulate, and orbitofrontal cortex. The results provide new insights into how the human brain represents errors in a task-dependent manner and guides subsequent adaptive behavior.

Towards optimal seeding for the synthesis of ordered nanoparticle arrays on alumina/Ni3Al(111)

2015 ◽  
Vol 17 (42) ◽  
pp. 28154-28161 ◽  
Author(s):  
Jimena A. Olmos-Asar ◽  
Erik Vesselli ◽  
Alfonso Baldereschi ◽  
Maria Peressi
Keyword(s):  
Transition Metals ◽  
Experimental Evidence ◽  
Optimal Choice ◽  
Nanoparticle Arrays ◽  
P Adsorption ◽  
Supported Nanoparticles ◽  
Shed Light

Adsorption and nucleation of different transition metals on alumina/Ni3Al(111) have been studied to shed light on the first stages of the synthesis of supported nanoparticles, rationalizing the experimental evidence that Pd seeding is the optimal choice to give rise to highly ordered patterns.

scholarly journals The importance of food systems and the environment for nutrition

2020 ◽  
Vol 113 (1) ◽  
pp. 7-16
Author(s):  
Jessica Fanzo ◽  
Alexandra L Bellows ◽  
Marie L Spiker ◽  
Andrew L Thorne-Lyman ◽  
Martin W Bloem
Keyword(s):  
Food Systems ◽  
Food System ◽  
Environmental Changes ◽  
Food Policy ◽  
Sociocultural Factors ◽  
System Transformation ◽  
Policy Changes ◽  
Local Food System ◽  
Nutrition Research ◽  
Global And Local

ABSTRACT Global and local food system transformation is necessary in order to ensure the delivery of healthy, safe, and nutritious foods in both sustainable and equitable ways. Food systems are complex entities that affect diets, human health, and a range of other outcomes including economic growth, natural resource and environmental resiliency, and sociocultural factors. However, food systems contribute to and are vulnerable to ongoing climate and environmental changes that threaten their sustainability. Although there has been increased focus on this topic in recent years, many gaps in our knowledge persist on the relation between environmental factors, food systems, and nutritional outcomes. In this article, we summarize this emerging field and describe what innovative nutrition research is needed in order to bring about food policy changes in the era of climate disruption and environmental degradation.

scholarly journals Value-based attentional capture affects multi-alternative decision making

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Sebastian Gluth ◽  
Mikhail S Spektor ◽  
Jörg Rieskamp
Keyword(s):  
Decision Making ◽  
Original Data ◽  
Complex Interplay ◽  
The Third ◽  
Relative Preference ◽  
Choice Sets ◽  
Human Participants ◽  
Alternative Decision ◽  
Positive Effect ◽  
Shed Light

Humans and other animals often violate economic principles when choosing between multiple alternatives, but the underlying neurocognitive mechanisms remain elusive. A robust finding is that adding a third option can alter the relative preference for the original alternatives, but studies disagree on whether the third option’s value decreases or increases accuracy. To shed light on this controversy, we used and extended the paradigm of one study reporting a positive effect. However, our four experiments with 147 human participants and a reanalysis of the original data revealed that the positive effect is neither replicable nor reproducible. In contrast, our behavioral and eye-tracking results are best explained by assuming that the third option’s value captures attention and thereby impedes accuracy. We propose a computational model that accounts for the complex interplay of value, attention, and choice. Our theory explains how choice sets and environments influence the neurocognitive processes of multi-alternative decision making.

scholarly journals Novelty is not surprise: Human exploratory and adaptive behavior in sequential decision-making

2021 ◽  
Vol 17 (6) ◽  
pp. e1009070
Author(s):  
He A. Xu ◽  
Alireza Modirshanechi ◽  
Marco P. Lehmann ◽  
Wulfram Gerstner ◽  
Michael H. Herzog
Keyword(s):  
Decision Making ◽  
Environmental Changes ◽  
Free Action ◽  
Human Action ◽  
Sequential Decision Making ◽  
Sequential Decision ◽  
World Model ◽  
Model Free ◽  
The World ◽  
Human Participants

Classic reinforcement learning (RL) theories cannot explain human behavior in the absence of external reward or when the environment changes. Here, we employ a deep sequential decision-making paradigm with sparse reward and abrupt environmental changes. To explain the behavior of human participants in these environments, we show that RL theories need to include surprise and novelty, each with a distinct role. While novelty drives exploration before the first encounter of a reward, surprise increases the rate of learning of a world-model as well as of model-free action-values. Even though the world-model is available for model-based RL, we find that human decisions are dominated by model-free action choices. The world-model is only marginally used for planning, but it is important to detect surprising events. Our theory predicts human action choices with high probability and allows us to dissociate surprise, novelty, and reward in EEG signals.

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