Consistent Implementation of Decisions in the Brain

Despite the complexity and variability of decision processes, motor responses are generally stereotypical and independent of decision difficulty. How is this consistency achieved? Through an engineering analogy we consider how and why a system should be designed to realise not only flexible decision-making, but also consistent decision implementation. We specifically consider neurobiologically-plausible accumulator models of decision-making, in which decisions are made when a decision threshold is reached. To trade-off between the speed and accuracy of the decision in these models, one can either adjust the thresholds themselves or, equivalently, fix the thresholds and adjust baseline activation. Here we review how this equivalence can be implemented in such models. We then argue that manipulating baseline activation is preferable as it realises consistent decision implementation by ensuring consistency of motor inputs, summarise empirical evidence in support of this hypothesis, and suggest that it could be a general principle of decision making and implementation. Our goal is therefore to review how neurobiologically-plausible models of decision-making can manipulate speed-accuracy trade-offs using different mechanisms, to consider which of these mechanisms has more desirable decision-implementation properties, and then review the relevant neuroscientific data on which mechanism brains actually use.     

Ballast Blockade: Stopping Aquatic Immigrants

This article emphasizes not only an important environmental issue for the Great Lakes but also the importance of decision-making skills in scientific thinking. The activity allows students to acquaint themselves with current Great Lakes topics while simultaneously partaking in decision-making processes that could affect them. As students work through the outlined steps of making a decision, they also participate in cooperative learning, scientific reasoning, and interdisciplinary processing. Students are presented with six ballast water treatment methods that they must evaluate on the basis of provided criteria. They assess the treatments using the decision-making skills of rating, weighing, and discussing.     

Consistency and use of information about threats in the participatory process for identification of priority conservation areas in the Brazilian Amazon

Despite the increasing number of scientific papers on the subject, conservation planning has failed to actively prioritise the creation of new protected areas. Strategies proposed to increase the creation of new protected areas based on conservation plans include broad stakeholder participation in decision-making processes in order to include their concerns and facilitate social acceptance of proposed actions. However, there are controversial views about the effectiveness of stakeholder participation. The quality of the decision depends both on the information used by stakeholders and on how it is used, so it is necessary to evaluate both these aspects of a decision-making process. Threats are intrinsically related to conservation decisions because they are more easily understood by people than biodiversity values, and they can affect both decisions and outcomes of conservation actions. This article analyses how information about threats was used in the decision-making process conducted by the Brazilian Government in 2006 to indicate priority areas for the conservation of the Amazon biome. We first verified the consistency of the information on threats attributed by stakeholders to these new priority areas, and then assessed whether the existence, levels and types of threats influenced the choice of areas for conservation. The results showed that there were some successes in recognising threats, but also many inconsistencies, especially in assigning levels of intensity for some types of threats such as fishing. The decision-making process also did not fully use available information to indicate areas for conservation. The lack of understanding on the motivation behind these inconsistencies could suggest the presence of political opportunism. A more quantitative approach to assigning priorities is needed: one that is less dependent on the individual input of stakeholders and more accurately reflects the actual emergency status of proposed areas. This indicates that greater effort should be allocated to combining a participatory approach with a robust decision support system.     

Noise in attractor networks in the brain produced by graded firing rate representations

Representations in the cortex are often distributed with graded firing rates in the neuronal populations. The firing rate probability distribution of each neuron to a set of stimuli is often exponential or gamma. In processes in the brain, such as decision-making, that are influenced by the noise produced by the close to random spike timings of each neuron for a given mean rate, the noise with this graded type of representation may be larger than with the binary firing rate distribution that is usually investigated. In integrate-and-fire simulations of an attractor decision-making network, we show that the noise is indeed greater for a given sparseness of the representation for graded, exponential, than for binary firing rate distributions. The greater noise was measured by faster escaping times from the spontaneous firing rate state when the decision cues are applied, and this corresponds to faster decision or reaction times. The greater noise was also evident as less stability of the spontaneous firing state before the decision cues are applied. The implication is that spiking-related noise will continue to be a factor that influences processes such as decision-making, signal detection, short-term memory, and memory recall even with the quite large networks found in the cerebral cortex. In these networks there are several thousand recurrent collateral synapses onto each neuron. The greater noise with graded firing rate distributions has the advantage that it can increase the speed of operation of cortical circuitry.     

Reaching a Consensus: Terminology and Concepts Used in Coordination and Decision-Making Research

Research on coordination and decision-making in humans and nonhuman primates has increased considerably throughout the last decade. However, terminology has been used inconsistently, hampering the broader integration of results from different studies. In this short article, we provide a glossary containing the central terms of coordination and decision-making research. The glossary is based on previous definitions that have been critically revised and annotated by the participants of the symposium “Where next? Coordination and decision-making in primate groups” at the XXIIIth Congress of the International Primatological Society (IPS) in Kyoto, Japan. We discuss a number of conceptual and methodological issues and highlight consequences for their implementation. In summary, we recommend that future studies on coordination and decision-making in animal groups do not use the terms “combined decision” and “democratic/despotic decision-making.” This will avoid ambiguity as well as anthropocentric connotations. Further, we demonstrate the importance of 1) taxon-specific definitions of coordination parameters (initiation, leadership, followership, termination), 2) differentiation between coordination research on individual-level process and group-level outcome, 3) analyses of collective action processes including initiation and termination, and 4) operationalization of successful group movements in the field to collect meaningful and comparable data across different species.     

Studying Knowledge, Culture, and Behavior in Applied Medical Anthropology

In this article we argue that the concept of knowledge, as utilized by public health professionals, is best regarded as cultural belief as defined in anthropology. The implications of this position are explored, particularly as it relates to the development of a decision-making approach to the understanding and analysis of health care behavior. The methodological challenges posed by the new theoretical perspective that has emerged from the emphasis on decision making is discussed from the perspective of applied research. The role of focused ethnographic studies is examined and contrasted with ethnomedicine and survey approaches. Some main features of focused ethnographic methods are described and illustrated with a case example of acute respiratory infection (ARI) in Gambia. [knowledge and cultural beliefs, decision-making approaches, health behavior, focused ethnographic studies]     

MORAL EXPERTISE: A PROBLEM IN THE PROFESSIONAL ETHICS OF PROFESSIONAL ETHICISTS

Philosophers, particularly moral philosophers, are increasingly being involved in public decision-making in areas which are seen to raise ethical issues. For example, Dame Mary Warnock chaired the ‘Committee of Inquiry into Human Fertilization and Embryology’ in the UK in 1982–4; the Philosophy Department at Auckland was commissioned by the Auckland Regional Authority to report on the ethical aspects of fluoridating the public water supply in 1990; and many of us are serving on ethics committees of various sorts. Not only are philosophers actually being called on or consulted, but many of us would argue that a philosophical contribution in such areas is essential. The involvement of moral philosophers in public policy decisions raises a question of professional ethics, viz, what role should a philosopher's own moral perspective or judgements play in the advice s/he gives, or contribution s/he makes, to public decision-making on ethical issues. Like most problems in professional ethics, this prompts reflection on the nature of the profession, and in particular on the expertise we take moral philosophy to offer. It also prompts reflection on how processes of public decision making in ethically problematic areas should be understood. I explore these issues in this paper.     

Variation in primate decision-making under uncertainty and the roots of human economic behaviour

Uncertainty is a ubiquitous component of human economic behaviour, yet people can vary in their preferences for risk across populations, individuals and different points in time. As uncertainty also characterizes many aspects of animal decision-making, comparative research can help evaluate different potential mechanisms that generate this variation, including the role of biological differences or maturational change versus cultural learning, as well as identify human-unique components of economic decision-making. Here, we examine decision-making under risk across non-human primates, our closest relatives. We first review theoretical approaches and current methods for understanding decision-making in animals. We then assess the current evidence for variation in animal preferences between species and populations, between individuals based on personality, sex and age, and finally, between different contexts and individual states. We then use these primate data to evaluate the processes that can shape human decision-making strategies and identify the primate foundations of human economic behaviour.This article is part of the theme issue ‘Existence and prevalence of economic behaviours among non-human primates’.     

Music and Video Gaming during Breaks: Influence on Habitual versus Goal-Directed Decision Making

Different systems for habitual versus goal-directed control are thought to underlie human decision-making. Working memory is known to shape these decision-making systems and their interplay, and is known to support goal-directed decision making even under stress. Here, we investigated if and how decision systems are differentially influenced by breaks filled with diverse everyday life activities known to modulate working memory performance. We used a within-subject design where young adults listened to music and played a video game during breaks interleaved with trials of a sequential two-step Markov decision task, designed to assess habitual as well as goal-directed decision making. Based on a neurocomputational model of task performance, we observed that for individuals with a rather limited working memory capacity video gaming as compared to music reduced reliance on the goal-directed decision-making system, while a rather large working memory capacity prevented such a decline. Our findings suggest differential effects of everyday activities on key decision-making processes.     

From the first intention movement to the last joiner: macaques combine mimetic rules to optimize their collective decisions

Mechanisms related to collective decision making have recently been found in almost all animal reigns from amoebae to worms, insects and vertebrates, including human beings. Decision-making mechanisms related to collective movements-including pre-departure and joining-have already been studied at different steps of the movement process, but these studies were always carried out separately. We therefore have no understanding of how these different processes are related when they underlie the same collective decision-making event. Here, we consider the whole departure process of two groups of Tonkean macaques (Macaca tonkeana), using a stochastic model. When several exclusive choices are proposed, macaques vote and choose the majority. Individuals then join the movement according to a mimetism based on affiliative relationships. The pre-departure quorum and the joining mimetic mechanism are probably linked, but we have not yet identified which transition mechanism is used. This study shows that decision-making related to macaque group movements is governed by a quorum rule combined with a selective mimetism at departure. This is the first time that transition mechanisms have been described in mammals, which consequently helps understand how a voting process leads to social amplification. Our study also provides the first complete proof that there is continuity in the decision-making processes underlying collective movements in mammals from the first intention movement right through to the last joiner.     

Modeling hunter-gatherer decision making: complementing optimal foraging theory

While optimal foraging theory has been of considerable value for understanding hunter-gatherer subsistence patterns, there is a need for a complementary approach to human foraging behavior which focuses on decision-making processes. Having made this argument, the paper proposes the type of modeling approach that should be developed, using decision making during encounter foraging as an example. This model concerns the individual decision maker attempting to improve his foraging efficiency, rather than maximize it, under the constraint of limited information and with conflicting goals. This is illustrated by applying it to the Valley Bisa hunters using computer simulation.     

The brain and the law

Much has been written about how law as an institution has developed to solve many problems that human societies face. Inherent in all of these explanations are models of how humans make decisions. This article discusses what current neuroscience research tells us about the mechanisms of human decision making of particular relevance to law. This research indicates that humans are both more capable of solving many problems than standard economic models predict, but also limited in ways those models ignore. This article discusses how law is both shaped by our cognitive processes and also shapes them. The article considers some of the implications of this research for improving our understanding of how our current legal regimes operate and how the law can be structured to take advantage of our neural mechanisms to improve social welfare.     

Neural basis of quasi-rational decision making

Standard economic theories conceive homo economicus as a rational decision maker capable of maximizing utility. In reality, however, people tend to approximate optimal decision-making strategies through a collection of heuristic routines. Some of these routines are driven by emotional processes, and others are adjusted iteratively through experience. In addition, routines specialized for social decision making, such as inference about the mental states of other decision makers, might share their origins and neural mechanisms with the ability to simulate or imagine outcomes expected from alternative actions that an individual can take. A recent surge of collaborations across economics, psychology and neuroscience has provided new insights into how such multiple elements of decision making interact in the brain.     

Preference suppression caused by misattribution of task-irrelevant subliminal motion

It is well known that subjects tend to misattribute task-irrelevant signals, incorporating them into the information on which a decision is made. Such misattribution has been reported to originate only from a social or a cognitive stage of information processing. However, we provide the initial evidence that misattribution also originates at a lower, visuomotor stage. This type of misattribution occurs only when subjects do not notice a visuomotor conflict. Misattribution at a social or a cognitive stage facilitates decision-making if the misattributed information is consistent with the decision and impedes decision-making if the information is in conflict with the decision. However, misattribution originating at a visuomotor stage only impedes decision-making, suggesting a fundamental difference between the mechanisms for the two types of misattribution. Furthermore, misattribution effects that originate in a visuomotor interaction stage also affect subjective preference ratings, suggesting that the misattribution exerts an influence on global brain processing.     

Limbic justice--amygdala involvement in immediate rejection in the Ultimatum Game

Imaging studies have revealed a putative neural account of emotional bias in decision making. However, it has been difficult in previous studies to identify the causal role of the different sub-regions involved in decision making. The Ultimatum Game (UG) is a game to study the punishment of norm-violating behavior. In a previous influential paper on UG it was suggested that frontal insular cortex has a pivotal role in the rejection response. This view has not been reconciled with a vast literature that attributes a crucial role in emotional decision making to a subcortical structure (i.e., amygdala). In this study we propose an anatomy-informed model that may join these views. We also present a design that detects the functional anatomical response to unfair proposals in a subcortical network that mediates rapid reactive responses. We used a functional MRI paradigm to study the early components of decision making and challenged our paradigm with the introduction of a pharmacological intervention to perturb the elicited behavioral and neural response. Benzodiazepine treatment decreased the rejection rate (from 37.6% to 19.0%) concomitantly with a diminished amygdala response to unfair proposals, and this in spite of an unchanged feeling of unfairness and unchanged insular response. In the control group, rejection was directly linked to an increase in amygdala activity. These results allow a functional anatomical detection of the early neural components of rejection associated with the initial reactive emotional response. Thus, the act of immediate rejection seems to be mediated by the limbic system and is not solely driven by cortical processes, as previously suggested. Our results also prompt an ethical discussion as we demonstrated that a commonly used drug influences core functions in the human brain that underlie individual autonomy and economic decision making.     

Experience of family members with the decision concerning artificial nutrition and hydration in people with dementia in nursing homes

The purpose of this study is to investigate how relatives of nursing home patients with dementia, for whom the decision whether to start or forgo artificial nutrition and hydration (ANH) was made, assess the decision-making process. Furthermore we evaluated the information given by the nursing home staff to the relatives and the care provided by them to the patient. The study was an observational study based on written questionnaires. Relatives of 99 nursing home patients with dementia filled in a questionnaire at the time of the decision-making and 6 weeks after the decision was made or 6 weeks after the patient had died. Almost all relatives assessed the 4 aspects of the decision-making process (number of consults, content of the consults, carefulness of the decision-making and there own part in the decision-making process) at both times as 'good' or 'satisfactory'. Furthermore it appeared that they judged the carefulness of the decision-making process significantly more often as 'good' when they also assessed the other three aspects as 'good'. Especially their own influence on the decision-making process appeared to play a part in this matter. Information about the possible consequences of starting ANH as well as about the condition of the patient were experienced sufficient by almost all relatives. This was also the case for the care offered to the patient. In general almost all relatives reported satisfaction with the decision and with the carefulness of the decision-making process. This satisfaction did not differ between the moment of the decision and afterwards. For this it did not make any difference whether the patient had or had not died.     

A functional difference in information processing between orbitofrontal cortex and ventral striatum during decision-making behaviour

Both orbitofrontal cortex (OFC) and ventral striatum (vStr) have been identified as key structures that represent information about value in decision-making tasks. However, the dynamics of how this information is processed are not yet understood. We recorded ensembles of cells from OFC and vStr in rats engaged in the spatial adjusting delay-discounting task, a decision-making task that involves a trade-off between delay to and magnitude of reward. Ventral striatal neural activity signalled information about reward before the rat''s decision, whereas such reward-related signals were absent in OFC until after the animal had committed to its decision. These data support models in which vStr is directly involved in action selection, but OFC processes decision-related information afterwards that can be used to compare the predicted and actual consequences of behaviour.     

A system dynamics model of clinical decision thresholds for the detection of developmental-behavioral disorders

Background

Clinical decision-making has been conceptualized as a sequence of two separate processes: assessment of patients’ functioning and application of a decision threshold to determine whether the evidence is sufficient to justify a given decision. A range of factors, including use of evidence-based screening instruments, has the potential to influence either or both processes. However, implementation studies seldom specify or assess the mechanism by which screening is hypothesized to influence clinical decision-making, thus limiting their ability to address unexpected findings regarding clinicians’ behavior. Building on prior theory and empirical evidence, we created a system dynamics (SD) model of how physicians’ clinical decisions are influenced by their assessments of patients and by factors that may influence decision thresholds, such as knowledge of past patient outcomes. Using developmental-behavioral disorders as a case example, we then explore how referral decisions may be influenced by changes in context. Specifically, we compare predictions from the SD model to published implementation trials of evidence-based screening to understand physicians’ management of positive screening results and changes in referral rates. We also conduct virtual experiments regarding the influence of a variety of interventions that may influence physicians’ thresholds, including improved access to co-located mental health care and improved feedback systems regarding patient outcomes.

Results

Results of the SD model were consistent with recent implementation trials. For example, the SD model suggests that if screening improves physicians’ accuracy of assessment without also influencing decision thresholds, then a significant proportion of children with positive screens will not be referred and the effect of screening implementation on referral rates will be modest—results that are consistent with a large proportion of published screening trials. Consistent with prior theory, virtual experiments suggest that physicians’ decision thresholds can be influenced and detection of disabilities improved by increasing access to referral sources and enhancing feedback regarding false negative cases.

Conclusions

The SD model of clinical decision-making offers a theoretically based framework to improve understanding of physicians’ behavior and the results of screening implementation trials. The SD model is also useful for initial testing of hypothesized strategies to increase detection of under-identified medical conditions.