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Cost-sensitive Bayesian control policy in human active sensing.

ABSTRACT: An important but poorly understood aspect of sensory processing is the role of active sensing, the use of self-motion such as eye or head movements to focus sensing resources on the most rewarding or informative aspects of the sensory environment. Here, we present behavioral data from a visual search experiment, as well as a Bayesian model of within-trial dynamics of sensory processing and eye movements. Within this Bayes-optimal inference and control framework, which we call C-DAC (Context-Dependent Active Controller), various types of behavioral costs, such as temporal delay, response error, and sensor repositioning cost, are explicitly minimized. This contrasts with previously proposed algorithms that optimize abstract statistical objectives such as anticipated information gain (Infomax) (Butko and Movellan, 2010) and expected posterior maximum (greedy MAP) (Najemnik and Geisler, 2005). We find that C-DAC captures human visual search dynamics better than previous models, in particular a certain form of "confirmation bias" apparent in the way human subjects utilize prior knowledge about the spatial distribution of the search target to improve search speed and accuracy. We also examine several computationally efficient approximations to C-DAC that may present biologically more plausible accounts of the neural computations underlying active sensing, as well as practical tools for solving active sensing problems in engineering applications. To summarize, this paper makes the following key contributions: human visual search behavioral data, a context-sensitive Bayesian active sensing model, a comparative study between different models of human active sensing, and a family of efficient approximations to the optimal model.

SUBMITTER: Ahmad S

PROVIDER: S-EPMC4253738 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Cost-sensitive Bayesian control policy in human active sensing.

Ahmad Sheeraz S Huang He H Yu Angela J AJ

Frontiers in human neuroscience 20141203

An important but poorly understood aspect of sensory processing is the role of active sensing, the use of self-motion such as eye or head movements to focus sensing resources on the most rewarding or informative aspects of the sensory environment. Here, we present behavioral data from a visual search experiment, as well as a Bayesian model of within-trial dynamics of sensory processing and eye movements. Within this Bayes-optimal inference and control framework, which we call C-DAC (Context-Depe ...[more]

PMID: 25520640

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Project description:BackgroundThe increasing cost on healthcare exposes China's healthcare budgets and system to financial crisis. To control the excessive growth of healthcare expenditure, China's healthcare reforms emphasize the control of the global budget for healthcare, which leads to the release of relevant policy and a series of cost-control actions implemented by different hospitals. This work aims to identify the effects brought by the cost-control policy and actions via surveying and analysing feedback from clinicians.MethodsQuestionnaires on the cost-control policy and actions were designed for surveying 110 clinicians in hospitals from different regions of China. The data on the implementation of the cost-control actions and doctors' feedback on these actions were analysed using descriptive statistics. Pearson's chi-squared tests were performed to detect associations between doctors' opinions and specific cost-control actions. A value of p < 0.05 was considered statistically significant. Association relationships between doctors' opinions and cost-control actions were modelled into network models, and key factors were identified in a multi-variate framework. Last, we visualized our resultant data using a network model, and further multi-variate analysis was performed.ResultsThere were three main findings. (1) The cost-control policy has been widely implemented in the sampled hospitals in different regions of China, with more than 80% of those surveyed acknowledging that their hospitals take actions of reducing average prescription fees for outpatients, drug costs, and in-hospitalization durations. (2) Most doctors have a negative view of some cost-control actions; this is mainly due to concerns about the effects of these actions on the doctors' own healthcare performance and patient satisfaction. (3) Cost-control actions that had a significant impact on doctors' performance included limiting average prescription fees for outpatients and limiting the use of examinations/drugs/surgeries. Decreased patient satisfaction was associated with fewer admissions of critically ill patients, reduced use of brand-name drugs, and increased total costs to patients due to increased frequencies of visits to the hospitals.ConclusionsCost-control actions implemented in hospitals in response to the government's policy to reduce its national healthcare budget affect both doctors and patients in several ways. Moreover, the cost-control policy and actions can be improved.

Project description:Purpose of review:Kidney Failure is highly prevalent and uses a disproportionate amount of health care funding. In Canada (excluding Quebec), 37 647 people were living with kidney failure in 2016. The single-payer Canadian health care system spends approximately 1.2% of their annual budget on kidney failure. In 2016, 58.4% of patients with kidney failure in Canada (excluding Quebec) were on dialysis as opposed to living with a functioning kidney transplant. Home dialysis modalities including peritoneal dialysis (PD) and home hemodialysis (HD) were used by 18.9% and 4.7% of these patients, respectively. In-center HD and home dialysis (PD and home HD) are often considered equally efficacious and have similar impacts on quality of life. Despite cost minimization analyses suggesting that home dialysis offers cost savings over in-center HD, there has been a slow uptake of home dialysis in developed nations over time, suggesting that controversies and barriers to implementation currently exist. The primary objective of this health policy briefing article is to introduce and address some of the major controversies surrounding the cost effectiveness in supporting advocacy for a "Home Dialysis First" policy with a primary focus on single-payer systems in a developed nation such as Canada. Sources of information:Canadian Agency for Drugs and Technologies in Health (CADTH), Canadian and US epidemiologic databases, national/international conference presentations, primary literature review, and discussion with experts within the field of home dialysis. Methods:We have conducted a focused primary literature review alongside individuals with expertise in the field of home dialysis to discuss the cost controversies surrounding the implementation of a "Home Dialysis First" policy. Key findings:First, the primary literature is limited to mostly observational studies which are highly variable in study design and content. Local economic assessments, however, have provided convincing data for home dialysis cost savings in Canada. Second, the cost of delivering dialysis differs significantly throughout the world, explained by differing costs of labor and supplies in developing nations. Third, the indirect patient costs of water, energy, and home modifications are often barriers to implementation and may be overcome by introducing cost reimbursement programs. Fourth, home dialysis requires upfront training costs. We explore the impact of premature switches from home dialysis to in-center HD or a functioning kidney transplant on overall cost savings. Fifth, we discuss the effect of physician financial incentives and program funding on the uptake of home dialysis. Finally, we introduce the controversial topic of comparing the societal value of freedom of modality choice against the societal cost savings of a "Home Dialysis First" policy. Limitations:Narrative reviews, due to their inherently reduced methodological quality in comparison with systematic reviews, may expose our collected literature to selection bias. We have attempted to compose a diverse collection of available literature alongside consensus expertise to provide a fair and concise review of home dialysis cost controversies. Implications:Implementation of a "Home Dialysis First" policy would be a disruptive change to kidney failure care in Canada. To make informed policy decisions, we should recognize the cost savings associated with home dialysis in developed nations, the significance of patient-borne costs as a barrier to implementation, the impact of training costs and early modality switching in home dialysis, the lack of evidence regarding physician financial incentives, and the importance of program funding. Ultimately, we must consider the societal value of freedom of patient modality choice in comparison with the potential cost savings of a "Home Dialysis First" policy.

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Cost-sensitive Bayesian control policy in human active sensing.

Publications

Cost-sensitive Bayesian control policy in human active sensing.

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