Strategy Switching Research Articles

Executive control by fronto-parietal activity explains counterintuitive decision behavior in complex value-based decision-making

In real life, humans make decisions by taking into account multiple independent factors, such as delay and probability. Cognitive psychology suggests that cognitive control mechanisms play a key role when facing such complex task conditions. However, in value-based decision-making, it still remains unclear to what extent cognitive control mechanisms become essential when the task condition is complex. In this study, we investigated decision-making behaviors and underlying neural mechanisms using a multifactor gambling task where participants simultaneously considered probability and delay. Decision-making behavior in the multifactor task was modulated by both probability and delay. The behavioral effect of probability was stronger than delay, consistent with previous studies. Furthermore, in a subset of conditions that recruited fronto-parietal activations, reaction times were paradoxically elongated despite lower probabilistic uncertainty. Notably, such a reaction time elongation did not occur in control tasks involving single factors. Meta-analysis of brain activations suggested an interpretation that the paradoxical increase of reaction time may be associated with strategy switching. Consistent with this interpretation, logistic regression analysis of the behavioral data suggested a presence of multiple decision strategies. Taken together, we found that a novel complex value-based decision-making task cause prominent activations in fronto-parietal cortex. Furthermore, we propose that these activations can be interpreted as recruitment of cognitive control system in complex situations.

The impairment of continuous malnutrition on larval fish swimming performance at the mouth-opening stage

Nutritional status at the mouth-opening stage is critical for fish development and fitness due to the nutritional strategy switch from endogenous to exogenous feeding. In the present study, we explored the impairments of continuous malnutrition on larval development and swimming performance. Results showed that larval survival and body growth were reduced from 5 days post fertilization (dpf) to 14 dpf under malnutrition, and the swimming performance of moved distance, velocity, motility, maximum duration of movement, highly mobile and mobile states were significantly suppressed. As to the transcripts analyses, the mRNA expression of gh1 distinctly downregulated with the compensatory effect of increased expression of ghrb, and the ghrelin expression responded fast with upregulation to the malnutrition. The downregulated mRNA expressions of neurodevelopment related genes (nes, neurog1, gap43, syn2a, manf, hirip3) meant the disturbed neuronal functions that account for the swimming response and suggest the vulnerable molecular marker of Neurog1 responsible for the alternation of swimming behavior. And the upregulated mRNA expressions of apoptotic genes (bax, casp3, casp9) signified cellular injury in the malnutrition-treated larvae. Besides, the decreased mitochondrial DNA copy number indicated the mitochondrial dysfunction, which might be responsible for the reduced larval development and swimming performance that link to the potential chronic impairments throughout the lifespan. Collectively, current works discussed the specific impairments of malnutrition on swimming capability and its potentially chronic adverseness to remind the larval management in the aquaculture industry.

Unified load flow calculation for flexible interconnected AC-MTDC distribution system considering control strategy switching with high penetration of DGs

A new unified algorithm is proposed in this paper to solve the power flow problem of AC distribution systems incorporating voltage-sourced converter (VSC) based multi-terminal direct current (MTDC) grids. In this method, the VSC modulation indices, mode changes, power losses as well as MTDC control strategy switching are all considered. Active power mismatch equations of VSC boundary buses in AC side have been modified to eliminate VSC power injection items. Various VSC control strategies are demonstrated in both active power function of DC boundary buses and reactive power function of AC boundary buses. In this way, only few modifications are required for existing AC load flow to incorporate the MTDC models. Moreover, the change of VSC operation mode and the switch of MTDC control strategies can be easily realized. The power flow calculation of AC and DC subgrids is solved simultaneously by Newton-Raphson (NR) method using a modified Jacobian matrix. Two case studies have been presented to demonstrate that the proposed algorithm is fast, flexible and effective in solving power flow of AC-MTDC distribution systems with various control strategies and can easily accommodate any changes in VSC control modes with high convergence performance.

Team of rivals: How should original equipment manufacturers cooperate with independent remanufacturers via authorisation?

Authorisation is a commonly used strategy for OEMs who do not have remanufacturing capability but still want to extract some benefits from the remanufacturing market. In this paper, we analyse two authorisation strategies: one is dealer authorisation, i.e., the OEM turns the independent remanufacturer (IR) into an authorised dealer selling both new and remanufactured products; the other is remanufacturing authorisation, i.e., the OEM authorises the IR to remanufacture used products by charging an authorisation fee. A stylised model is developed to compare the three scenarios: competition, cooperation with dealer authorisation and cooperation with remanufacturing authorisation. Our results show that cooperation depends on the effect of authorisation on the improvement of customers’ willingness-to-pay for remanufactured products. Although remanufacturing authorisation is preferred by the OEM, only dealer authorisation is achievable under certain conditions. Interestingly, while the OEM’s profit decreases in new product cost in general, it may increase when higher cost causes a strategy switch from competition (dealer authorisation) to remanufacturing authorisation. Furthermore, we analyse the environmental and social impact of cooperation and identify the conditions under which cooperation benefits the environment and consumers. While cooperation can achieve a win-win-win situation on the triple bottom line, the choice of authorisation mode always presents a conflict between environmental and consumer benefit.

The anterior cingulate cortex directs exploration of alternative strategies

The ability to adjust one's behavioral strategy in complex environments is at the core of cognition. Doing so efficiently requires monitoring the reliability of the ongoing strategy and, when appropriate, switching away from it to evaluate alternatives. Studies in humans and non-human primates have uncovered signals in the anterior cingulate cortex (ACC) that reflect the pressure to switch away from the ongoing strategy, whereas other ACC signals relate to the pursuit of alternatives. However, whether these signals underlie computations that actually underpin strategy switching or merely reflect tracking of related variables remains unclear. Here we provide causal evidence that the rodent ACC actively arbitrates between persisting with the ongoing behavioral strategy and temporarily switching away to re-evaluate alternatives. Furthermore, by individually perturbing distinct output pathways, we establish that the two associated computations-determining whether to switch strategy and committing to the pursuit of a specific alternative-are segregated in the ACC microcircuitry.

The Role of the Inhibition of Natural Number Based Reasoning and Strategy Switch Cost in a Fraction Comparison Task

Previous research amply showed the importance of a good fraction understanding but also people’s lack of fraction understanding. It is therefore important to investigate the cognitive processes that underlie reasoning with fractions. The present study investigated the role of inhibition and switch costs in fraction comparison tasks. Participants solved a fraction comparison task that alternated between 4 items congruent and 4 items incongruent with natural number reasoning. This allowed to not only investigate congruency switch effects, but also inhibition, given that inhibition was experimentally increased by the prolonged exposure to incongruent trials. Based on data of seventh graders, the present study showed that inhibition does not only play a role in learners’ general mathematics achievement, but also in specific areas of mathematics, such as fractions. Moreover, a switch cost was found in the lower accuracy rates and higher reaction times needed to correctly solve switch items compared to non-switch items.

Research on Multi-mode Operation Control Strategy of Feeder Flexible Interconnection in Distribution Network Based on Flexible Multi-State Switch

Aiming at the problems of multi-mode operation and switching, unbalanced feeder load and heavy load of main transformer in flexible interconnection system of distribution network based on Flexible Multi-State Switch(FMSS), a multi-mode operation control strategy of feeder interconnection in distribution network based on Virtual Synchronous Generator (VSG) is proposed,which includes load balancing control strategy and heavy load main transformer automatic control strategy. Firstly, according to the feeder and main transformer load status, the operation mode of system is divided.Then, through the analysis power transmission and switching logic of different operating mode, active power control instructions of FMSS under multi-mode operation are obtained. So that multi-mode stable operation and free switching of the system, the feeder load balancing and main transformer heavy load automatic regulation are realized. In addition, there is no need for control strategy switching. Simulation verifies the rationality and effectiveness of the proposed control strategy.

MLD-Based Thermal Behavior Analysis of Traction Converters Under Faulty Conditions

The existing thermal behavior analysis mainly focuses on the normal condition of converter but lacks investigation in the cases of faulty condition and modulation strategy switching. This further leads to inaccuracy and incomprehensive thermal management. In order to address this issue, in this article, a mixed-logical-dynamic (MLD)-based electrothermal model is proposed for a fast observation of the thermal behavior of power devices within converters under both normal case and open-circuit (OC) fault cases. It also has the advantage of applicability to various modulation strategies. To be specific, the switching-logic-mixed (SLM) and transition-logic-mixed (TLM) variables are first defined to analyze the generating conditions of power loss in power modules, where the power loss models considering the normal and OC fault cases are built, after which the MLD-based electrothermal model is established to calculate the junction temperature of power modules, which will be used to obtain the thermal behaviors of converters. Finally, under various OC fault cases, the thermal behavior of traction converters is analyzed by hardware-in-the-loop (HIL) real-time simulation test. The HIL-based results show that the proposed model can be used to analyze the thermal behaviors under various scenarios in real time, which can further offer guidance for thermal management under faulty conditions.

Strategies for Speeding Up Manipulator Path Planning to Find High Quality Paths in Cluttered Environments

AbstractIn many manufacturing applications, robotic manipulators need to operate in cluttered environments. Quickly finding high-quality paths is very important in applications that require high part fix and frequent setup changes. This paper presents a point-to-point path planning framework for manipulators operating in cluttered environments. It uses a bi-directional tree-search to find path and facilitates finding a balance between path quality and planning time. The framework dynamically switches between search strategies based on the search progress to produce high-quality paths quickly. This paper three main contributions. First, we extend a previously developed sampling-based modular tree-search. Specifically, we present a strategy that can sample effectively in challenging regions of the search-space by using local approximations of the configuration space. Second, we add new strategies and scheduling logic that decreases the failure rate as well as the planning time compared to the prior work. We also present an inter-tree connection strategy that adapts to collision information gathered over time. We introduce a scheduling rule that regulates the exploitation of focusing hints derived from the workspace obstacles. Third, we present theoretical reasoning behind strategy switching and how it can help decrease planning times and increase path quality. Together, these new features the reduce average failure rate by a factor of 4 and improve the average planning time by 22% over the previous work.

Solving the Multi-Functional Heterogeneous UAV Cooperative Mission Planning Problem Using Multi-Swarm Fruit Fly Optimization Algorithm.

The complexity of unmanned aerial vehicle (UAV) missions is increasing with the rapid development of UAV technology. Multiple UAVs usually cooperate in the form of teams to improve the efficiency of mission execution. The UAVs are equipped with multiple sensors with complementary functions to adapt to the complex mission constraints. Reasonable task assignment, task scheduling, and UAV trajectory planning are the prerequisites for efficient cooperation of multi-functional heterogeneous UAVs. In this paper, a multi-swarm fruit fly optimization algorithm (MFOA) with dual strategy switching is proposed to solve the multi-functional heterogeneous UAV cooperative mission planning problem with the criterion of simultaneously minimizing the makespan and the total mission time. First, the multi-swarm mechanism is introduced to enhance the global search capability of the fruit fly optimization algorithm. Second, in the smell-based search phase, the local search strategies and large-scale search strategies are designed to drive multiple fruit fly swarms, and the dual strategy switching method is presented. Third, in the vision-based search stage, the greedy selection strategy is adopted. Finally, numerical simulation experiments are designed. The simulation results show that the MFOA algorithm is more effective and stable for solving the multi-functional heterogeneous UAV cooperative mission planning problem compared with other algorithms.

Bumblebees Learn a Relational Rule but Switch to a Win-Stay/Lose-Switch Heuristic After Extensive Training.

Mapping animal performance in a behavioral task to underlying cognitive mechanisms and strategies is rarely straightforward, since a task may be solvable in more than one manner. Here, we show that bumblebees perform well on a concept-based visual discrimination task but spontaneously switch from a concept-based solution to a simpler heuristic with extended training, all while continually increasing performance. Bumblebees were trained in an arena to find rewards on displays with shapes of different sizes where they could not use low-level visual cues. One group of bees was rewarded at displays with larger shapes and another group at displays with smaller shapes. Analysis of total choices shows bees increased their performance over 30 bouts to above chance. However, analyses of first and sequential choices suggest that after approximately 20 bouts, bumblebees changed to a win-stay/lose-switch strategy. Comparing bees’ behavior to a probabilistic model based on a win-stay/lose-switch strategy further supports the idea that bees changed strategies with extensive training. Analyses of unrewarded tests indicate that bumblebees learned and retained the concept of relative size even after they had already switched to a win-stay, lost-shift strategy. We propose that the reason for this strategy switching may be due to cognitive flexibility and efficiency.

Cognitive effort investment and opportunity costs in strategic decision-making: An individual differences examination

People are often more likely to persist with a strategy when more resources have been invested in this course of action, a phenomenon known as the ‘sunk cost’ effect. This effect has been difficult to demonstrate in the domain of real (non-hypothetical) effort investment, and this may be due in part to individual differences in the decision processes. We designed a decision-making task, where a cognitive effort investment is required to enact a strategy, to examine the extent to which individual differences in Need for Cognition (NFC), Lack of Premeditation, and subjective effort perception bear upon decisions to persist with a suboptimal strategy under varying levels of effort investment and opportunity cost—i.e. the difference in utility between persisting with versus switching strategies. We found that NFC and (Lack of) Premeditation predicted the extent to which strategy switch decisions were driven by opportunity costs. While we did not find an overall effect of past behavioral investment effect, self-reported effort (Temporal Demand) appeared to predict susceptibility to sunk cost. We also found a decrease in decision times with increasing sunk costs, but this effect did not appear to differ as a function of the individual differences examined.

Sensitive and selective photoelectrochemical immunosensing platform based on potential-induced photocurrent-direction switching strategy and a direct Z-scheme CdS//hemin photocurrent-direction switching system

Herein, we develop a novel ultrasensitive and selective photoelectrochemical (PEC) immunosensor based on a potential-induced photocurrent-direction switching of the CdS-chitosan nanoparticles (CdS-CS NPs) and a direct Z-scheme CdS/hemin photocurrent-direction switching system. Taking the detection of Prion (PrPC) as example, the CdS-CS NPs served as photoactive materials showed a cathodic photocurrent by the potential-stimulated switching of the photocurrent direction strategy, after immobilization of the captured antibody of PrPC (Ab1) onto the surface of CdS-CS NPs, nitrogen-doped porous carbon (NPC)-hemin polyhedra labelled with secondary antibody of PrPC (Ab2) were subsequently introduced onto the immunosensing interface due to the antigen−antibody specific recognition, and could act as a photocurrent-direction converter of CdS-CS NPs to produce a big anodic photocurrent which was opposite to that of CdS-CS NPs, owe to the well-matched energy levels between CdS and hemin to form a direct Z-scheme CdS/hemin system. By coupling the potential-stimulated switching of the photocurrent direction strategy and direct Z-scheme photocurrent-direction switching system, PrPC was detected sensitively with a wide linear response range from 4 to 1000 aM and a low detection limit of 0.53 aM. Also, the developed PEC immunosensing platform showed excellent selectivity. Going beyond the conventional “signal-off” or “signal-on” driven immunosensor, this strategy may has promising applications in bioanalysis, disease diagnostics, and clinical biomedicine.

Cognitive strategies used in the verbal fluency test by elderly in Sergipe's countryside

To analyze the cognitive strategies used in the verbal fluency test by healthy elderly without current risk of dementia. Method: Participants of the study were active elderly people, living in the countryside of the state of Sergipe, of both sexes. General identification data and health conditions were collected and the Mental State Mini Exam (MSME) and Verbal Fluency Semantics (VFS) test was applied. People with scores below the cut grade for schooling regarding the MSME were excluded from the survey. The results of these tests were analyzed qualitatively (normal or altered) and quantitatively (general score). In the VFS, the analysis was also performed according to the strategies used by the participant to recall the words (number of categories of animals cited, number of clusters performed (Clustering) and number of exchanges of cognitive strategy (Switching). The results were statistically analyzed by the Pearson correlation test. 33 elderly (25 females and 8 males) participated, with a mean age of 71.6 years old. The mean score in the MSME was 23.6 points and in the VFS it was 12.78 points, with a mean number of category used of 2.9, Clustering of 1.8 and Switching of 1.3. Pearson's correlation test identified important correlations between the VFS results and the number of the animals cited, Clustering and Switching categories used by the participants. Conclusion: Good general cognitive performance and language seems to be related to the cognitive strategies used in VFS, evidencing the importance of using this test in cognitive screening, even in cases of active elderly people.

CD36 deficiency reduces chronic BBB dysfunction and scar formation and improves activity, hedonic and memory deficits in ischemic stroke

Ameliorating blood–brain barrier disruption and altering scar formation dynamics are potential strategies that may improve post-stroke recovery. CD36 is a class B scavenger receptor that plays a role in innate immunity, inflammation and vascular dysfunction and regulates post-stroke injury, neovascularization, reactive astrogliosis and scar formation. By subjecting WT and CD36KO mice to different MCAo occlusion durations to generate comparable acute lesion sizes, we addressed the role of CD36 in BBB dysfunction, scar formation and recovery. The majority of stroke recovery studies primarily focus on motor function. Here, we employed an extensive behavioral test arsenal to evaluate psychological and cognitive endpoints. While not evident during the acute phase, CD36 deficient mice displayed significantly attenuated BBB leakage and scar formation at three months after stroke compared to wild-type littermates. Assessment of motor (open field, rotarod), anxiety (plus maze, light-dark box), depression (forced swim, sucrose preference) and memory tests (water maze) revealed that CD36 deficiency ameliorated stroke-induced behavioral impairments in activity, hedonic responses and spatial learning and strategy switching. Our findings indicate that CD36 contributes to stroke-induced BBB dysfunction and scar formation in an injury-independent manner, as well as to the chronic motor and neurophysiological deficits in chronic stroke.

A Simplified Phase-Controlled Switching Strategy for Inrush Current Reduction

High inrush current severely threats the safe operation of the power system and transformers, which may lead to mal-operation of overcurrent protection device, internal short-circuit fault in transformers. Phase-controlled switching technology is an alternative method to reduce inrush current effectively by controlling the front-mounted circuit breaker (CB) to break or make at the predetermined phase angles of current or voltage. In this paper, a new simplified phase-controlled switching strategy is proposed for three-phase unloaded transformer with Y-connected windings in the primary side, which can limit the inrush current under 46.7% of the captured maximum inrush current. Meanwhile, this strategy is independent on the residual fluxes in the iron cores. The optimal making angle is obtained by theoretical analysis based on an equivalent circuit model of unloaded transformer. The comparison of the proposed method and the random switching approach is also presented with considering residual flux. A simulation model is established to calculate the amplitudes of inrush currents against various residual fluxes when using the proposed phase-controlled switching strategy and random switching method. The simulation results show that the proposed strategy can limit the inrush current under a low value. A test platform with high and low voltage instruments is built and some measurements are carried out. The experimental results are in good agreement with the theoretical analysis and simulation results, which verifies the effectiveness and practicability of the proposed strategy.

Neural Correlates of Strategy Switching in the Macaque Orbital Prefrontal Cortex.

We can adapt flexibly to environment changes and search for the most appropriate rule to a context. The orbital prefrontal cortex (PFo) has been associated with decision making, rule generation and maintenance, and more generally has been considered important for behavioral flexibility. To better understand the neural mechanisms underlying the flexible behavior, we studied the ability to generate a switching signal in monkey PFo when a strategy is changed. In the strategy task, we used a visual cue to instruct two male rhesus monkeys either to repeat their most recent choice (i.e., stay strategy) or to change it (i.e., shift strategy). To identify the strategy switching-related signal, we compared nonswitch and switch trials, which cued the same or a different strategy from the previous trial, respectively. We found that the switching-related signal emerged during the cue presentation and it was combined with the strategy signal in a subpopulation of cells. Moreover, the error analysis showed that the activity of the switch-related cells reflected whether the monkeys erroneously switched or not the strategy, rather than what was required for that trial. The function of the switching signal could be to prompt the use of different strategies when older strategies are no longer appropriate, conferring the ability to adapt flexibly to environmental changes. In our task, the switching signal might contribute to the implementation of the strategy cued, overcoming potential interference effects from the strategy previously cued. Our results support the idea that ascribes to PFo an important role for behavioral flexibility.SIGNIFICANCE STATEMENT We can flexibly adapt our behavior to a changing environment. One of the prefrontal areas traditionally associated with the ability to adapt to new contingencies is the orbital prefrontal cortex (PFo). We analyzed the switching related activity using a strategy task in which two rhesus monkeys were instructed by a visual cue either to repeat or change their most recent choice, respectively using a stay or a shift strategy. We found that PFo neurons were modulated by the strategy switching signal, pointing to the importance of PFo in behavioral flexibility by generating control over the switching of strategies.

A cognitive control framework for understanding emotion regulation flexibility.

What are the cognitive processes that allow flexible responses to the changing demands of varying emotional contexts? Previous research suggests that higher levels of cognitive control are linked to successful emotion regulation. In particular, the implementation of emotion regulation strategies has been associated with individual differences in cognitive control, including (a) inhibiting prepotent responses, (b) updating information in working memory, and (c) shifting mental sets. Although most of this work has focused on the relationship between cognitive control and the short-term implementation of regulatory strategies, cognitive control may be even more important for understanding the dynamic adaptation to varying emotional contexts, that is, emotion regulation flexibility. However, cognitive control and emotion regulation flexibility have not been investigated in conjunction, resulting in a lack of a coherent understanding. In this article, we describe a framework outlining the importance of cognitive control for understanding three key components of emotion regulation flexibility: (a) strategy stopping or switching, (b) strategy maintenance, and (c) monitoring. We highlight the relevance of studying each of these components through the lens of cognitive control processes, particularly focusing on the tradeoff between shielding versus shifting goals and goal-directed behavior in various emotional contexts. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Unexpected Rule-Changes in a Working Memory Task Shape the Firing of Histologically Identified Delay-Tuned Neurons in the Prefrontal Cortex

Working memory-guided behaviors require memory retention during delay periods, when subsets of prefrontal neurons have been reported to exhibit persistently elevated firing. What happens to delay activity when information stored in working memory is no longer relevant for guiding behavior? In this study, we perform juxtacellular recording and labeling of delay-tuned (-elevated or -suppressed) neurons in the prelimbic cortex of freely moving rats, performing a familiar delayed cue-matching-to-place task. Unexpectedly, novel task-rules are introduced, rendering information held in working memory irrelevant. Following successful strategy switching within one session, delay-tuned neurons are filled with neurobiotin for histological analysis. Delay-elevated neurons include pyramidal cells with large heterogeneity of soma-dendritic distribution, molecular expression profiles, and task-relevant activity. Rule change induces heterogenous adjustments on individual neurons and ensembles' activity but cumulates in balanced firing rate reorganizations across cortical layers. Our results demonstrate divergent cellular and network dynamics when an abrupt change in task rules interferes with working memory.

Why Have cVDPV2 Outbreaks Increased Globally After the Polio Immunization Strategy Switch: Challenges for the Polio Eradication Endgame

Why Have cVDPV2 Outbreaks Increased Globally After the Polio Immunization Strategy Switch: Challenges for the Polio Eradication Endgame