Adaptive Support for Human-Computer Teams: Exploring the Use of Cognitive Models of Trust and Attention

Treur, J. [Promotor]Bosse, T. [Copromotor

Development of Antipsychotic Medications with Novel Mechanisms of Action Based on Computational Modeling of Hippocampal Neuropathology

A large number of cellular level abnormalities have been identified in the hippocampus of schizophrenic subjects. Nonetheless, it remains uncertain how these pathologies interact at a system level to create clinical symptoms, and this has hindered the development of more effective antipsychotic medications. Using a 72-processor supercomputer, we created a tissue level hippocampal simulation, featuring multicompartmental neuron models with multiple ion channel subtypes and synaptic channels with realistic temporal dynamics. As an index of the schizophrenic phenotype, we used the specific inability of the model to attune to 40 Hz (gamma band) stimulation, a well-characterized abnormality in schizophrenia. We examined several possible combinations of putatively schizophrenogenic cellular lesions by systematically varying model parameters representing NMDA channel function, dendritic spine density, and GABA system integrity, conducting 910 trials in total. Two discrete “clusters” of neuropathological changes were identified. The most robust was characterized by co-occurring modest reductions in NMDA system function (-30%) and dendritic spine density (-30%). Another set of lesions had greater NMDA hypofunction along with low level GABA system dysregulation. To the schizophrenic model, we applied the effects of 1,500 virtual medications, which were implemented by varying five model parameters, independently, in a graded manner; the effects of known drugs were also applied. The simulation accurately distinguished agents that are known to lack clinical efficacy, and identified novel mechanisms (e.g., decrease in AMPA conductance decay time constant, increase in projection strength of calretinin-positive interneurons) and combinations of mechanisms that could re-equilibrate model behavior. These findings shed light on the mechanistic links between schizophrenic neuropathology and the gamma band oscillatory abnormalities observed in the illness. As such, they generate specific falsifiable hypotheses, which can guide postmortem and other laboratory research. Significantly, this work also suggests specific non-obvious targets for potential pharmacologic agents

The Discovery and Interpretation of Evidence Accumulation Stages

To improve the understanding of cognitive processing stages, we combined two prominent traditions in cognitive science: evidence accumulation models and stage discovery methods. While evidence accumulation models have been applied to a wide variety of tasks, they are limited to tasks in which decision-making effects can be attributed to a single processing stage. Here, we propose a new method that first uses machine learning to discover processing stages in EEG data and then applies evidence accumulation models to characterize the duration effects in the identified stages. To evaluate this method, we applied it to a previously published associative recognition task (Application 1) and a previously published random dot motion task with a speed-accuracy trade-off manipulation (Application 2). In both applications, the evidence accumulation models accounted better for the data when we first applied the stage-discovery method, and the resulting parameter estimates where generally in line with psychological theories. In addition, in Application 1 the results shed new light on target-foil effects in associative recognition, while in Application 2 the stage discovery method identified an additional stage in the accuracy-focused condition — challenging standard evidence accumulation accounts. We conclude that the new framework provides a powerful new tool to investigate processing stages

Capturing Dynamic Performance in a Cognitive Model:Estimating ACT-R Memory Parameters With the Linear Ballistic Accumulator

The parameters governing our behavior are in constant flux. Accurately capturing these dynamics in cognitive models poses a challenge to modelers. Here, we demonstrate a mapping of ACT-R's declarative memory onto the linear ballistic accumulator (LBA), a mathematical model describing a competition between evidence accumulation processes. We show that this mapping provides a method for inferring individual ACT-R parameters without requiring the modeler to build and fit an entire ACT-R model. Existing parameter estimation methods for the LBA can be used, instead of the computationally expensive parameter sweeps that are traditionally done. We conduct a parameter recovery study to confirm that the LBA can recover ACT-R parameters from simulated data. Then, as a proof of concept, we use the LBA to estimate ACT-R parameters from an empirical dataset. The resulting parameter estimates provide a cognitively meaningful explanation for observed differences in behavior over time and between individuals. In addition, we find that the mapping between ACT-R and LBA lends a more concrete interpretation to ACT-R's latency factor parameter, namely as a measure of response caution. This work contributes to a growing movement towards integrating formal modeling approaches in cognitive science

Modelling job crafting behaviours: Implications for work engagement

In this study among 206 employees (103 dyads), we followed the job demands–resources approach of job crafting to investigate whether proactively changing one’s work environment influences employee’s (actor’s) own and colleague s (partner’s) work engagement. Using social cognitive theory, we hypothesized that employees would imitate each other’s job crafting behaviours, and therefore influence each other’s work engagement. Results showed that the crafting of social and structural job resources, and the crafting of challenge job demands was positively related to own work engagement, whereas decreasing hindrance job demands was unrelated to own engagement. As predicted, results showed a reciprocal relationship between dyad members’ job crafting behaviours – each of the actor’s job crafting behaviours was positively related to the partner’s job crafting behaviours. Finally, employee’s job crafting was related to colleague’s work engagement through colleague’s job crafting, suggesting a modelling process

The undervalued potential of positional therapy in position-dependent snoring and obstructive sleep apnea—a review of the literature

PURPOSE: Research during the past 10–20 years shows that positional therapy (PT) has a significant influence on the apnea–hypopnea index. These studies are predominantly performed as case series on a comparably small number of patients. Still, results have not found their way into the daily diagnostic and treatment routine. An average of 56 % of patients with obstructive sleep apnea (OSA) have position-dependent OSA (POSA), commonly defined as a difference of 50 % or more in apnea index between supine and non-supine positions. A great deal could be gained in treating patients with POSA with PT. The aim of this paper was to perform a thorough review of the literature on positional sleep apnea and its therapy. METHODS: A broad search strategy was run electronically in the MEDLINE and EMBASE databases using synonyms for position and sleep apnea. RESULTS: Sixteen studies were found which examined the effect of PT on OSA. In this literature review, we discuss the various techniques, results, and compliance rates. CONCLUSION: Long-term compliance for PT remains an issue, and although remarkable results have been shown using innovative treatment concepts for PT, there is room for both technical improvement of the devices and for further research

Mapping EU support for sanitation in Africa

This study addresses a number of key concerns of AMCOW, the European Union (EU) and other donors around the need to increase support to sanitation in order to accelerate the progress of national plans, Africawide goals, and the attainment of the MDG target on sanitation. The purpose of the study is to obtain an overview of the status of the involvement of EU Member States and the European Commission in sanitation-related activities in Africa. It is anticipated that the findings of this work will have the potential to be used for both arguing for greater priority for sanitation within the international architecture and also for individual donors to use in discussing their own Official Development Assistance (ODA). The work is complementary to the report from 2008 on mapping EU development assistance to the water sector in Africa. This earlier report had a much wider remit and as such, the Sanitation Mapping report can be considered as being supplementary to it

European Union support for sanitation in sub-Saharan Africa: aid flows and effectiveness

Within sub-Saharan Africa, 569 million people, amounting to 69% of the population, do not use improved sanitation. This study presents an overview of European Union (EU) donor support to sanitation in sub-Saharan Africa and proposes a method for investigating the effectiveness of national sanitation programmes through linking aid flows to sanitation outcomes in terms of trends in open defecation; this can be used to locate the relative performance of different countries. The work addresses key concerns of the African Ministers' Council on Water and the European donors around the need to increase support to sanitation. Results show that EU donors are the major source of external finance for sanitation in sub-Saharan Africa. Case studies from Mozambique, Uganda and Burkina Faso show that the majority of national planned expenditure on sanitation comes from donor sources, with EU donors being the substantive contributors. National policies on subsidy for sanitation and expenditure allocations vary extremely widely and do not necessarily align with sanitation outcomes. EU member states' donor policies on sanitation are consistent and well-aligned with those of the African Union; this is a major achievement for Europe and Africa. Inadequate national monitoring of sanitation expenditure remains a constraint to determining programme effectiveness

Inaugurating a Dutch Napoleon? Conservative criticism of the 1815 constitution of the United Kingdom of The Netherlands

International audienc