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In children exposed to any traumatic experience, a conditional prevalence rate of 15.9% was estimated for posttraumatic stress disorder (PTSD; Alisic et al., 2014). In order to achieve best treatment outcomes, selecting evidence-based treatments is necessary (Durlak & DuPre, 2008). For pediatric PTSD, international guidelines recommend the use of manualized trauma-focused cognitive behavioral therapy (TF-CBT; Forbes, Bisson, Monson, & Berliner, 2020; National Institute for Health and Care Excellence, 2018; Phoenix Australia Centre for Posttraumatic Mental Health, 2013) and many effectiveness studies and initiatives (e.g. Goldbeck, Muche, Sachser, Tutus, & Rosner, 2016; Jensen et al., 2014; National Child Traumatic Stress Network, 2012) disseminated the TF-CBT manual of Cohen, Mannarino and Deblinger (2006, 2017; specific TF-CBT). However, the uptake of evidence-based treatments such as specific TF-CBT into practice is strongly affected by service providers’ attitudes toward evidence-based practice (EBP; Aarons, 2004; Aarons, Cafri, Lugo, & Sawitzky, 2012; Aarons, Sommerfeld, & Walrath-Greene, 2009; Moullin, Dickson, Stadnick, Rabin, & Aarons, 2019). These attitudes can be measured with the Evidence-Based Practice Attitudes Scale-36 (EBPAS-36; Rye, Torres, Friborg, Skre, & Aarons, 2017). In Germany, several effectiveness trials are underway further disseminating specific TF-CBT (Rosner, Barke, et al., 2020; Rosner, Sachser, et al., 2020) but a reliable and validated German version of the EBPAS-36 is missing. In addition, in terms of pooled effect sizes (ES), only one review evaluated specific TF-CBT 10 years ago (Cary & McMillen, 2012). Furthermore, little is known about the stability of its treatment effects, the concordance between children and adolescents’ and their caregivers’ ratings regarding the youths’ symptoms in this context as well as the influence of the heterogeneity of instruments used by individual studies.
Therefore, the aims of this dissertation were fourfold: Publication 1 pooled ES for specific TF-CBT regarding posttraumatic stress symptoms (PTSS) and secondary outcomes to provide an update of the literature. Large improvements were found across all outcomes and results were favorable for specific TF-CBT compared to all control conditions at post-treatment. Publication 2 pooled ES for specific TF-CBT at 12-month follow-up for the same outcomes to evaluate the stability of treatment effects and investigated concordance between participants and caregiver ratings. Again, large improvements were evident across all outcomes and TF-CBT was superior to active treatments and treatment as usual at 12-month follow-up. No significant differences were detected between participant and caregiver ratings with high reliability across almost all outcomes and assessment points. Publication 3 produced a validated German translation of the EBPAS-36 (EBPAS-36D) to facilitate EBP implementation research in Germany. Good psychometric properties and validity of the EBPAS-36D were confirmed. As additional content, this dissertation provides an unpublished report on the pooled ES of publication 1 differentiated by instruments used to assess the outcomes. ES did not differ by the instrument used to assess the respective outcome.
The conclusions that can be drawn from the studies as well as their limitations are discussed in the final section. While the EBPAS-36D was successfully validated and specific TF-CBT was strongly supported, several issues were identified that need further research attention.
Adolescents who have fled to Western host countries show high levels of psychological distress and high risk for mental disorders. During the 2015-17 refugee crisis, Germany emerged as the largest host country for refugees in Europe. Therefore, rapid and valid screenings are needed to ensure assignment to appropriate treatments. However, it is unclear to what extent the situation of these adolescents is comparable to rates of mental health problems from other studies, as long-term studies with validated measures have not yet been conducted in Germany. In addition, procedural challenges exist in the context of valid diagnostics in the field of young refugees, including the question of transcultural validity of screening measures developed in the West and the reliability of interpreter-assisted diagnostics.
This dissertation therefore explored three main questions: Publication 1 traced the natural course of various mental health symptoms in a group of young refugees. It was shown that although symptom severity decreased significantly within one year, a considerable part of the cohort still showed clinically significant symptoms. Publications 2 and 3 addressed the question of valid screening and diagnostics in the group of young refugees. Publication 2 applied smartphone-based Ecological Momentary Assessment in this group for the first time and was able to demonstrate an association between symptom measures assessed in the questionnaires and low-threshold daily-assessed parameters such as low mood and lower sleep duration. This may indicate the transcultural validity of the questionnaires used. Publication 3, on the other hand, examined psychometric parameters of the Child and Adolescent Trauma Screen as a function of interpreter use and showed in a post-hoc analysis that the groups with and without interpreters did not differ statistically. In terms of the reliability of the measurement, the inclusion of lay interpreters, which is common practice, at least did not appear to be disadvantageous.
The implications and limitations of the studies conducted are discussed in the concluding chapter, showing that while promising treatment approaches exist, some research gaps also continue to exist with regard to various issues in the field of clinical research with young refugees.
Reinforcement learning constitutes a valuable framework for reward-based decision making in humans, as it breaks down learning into a few computational steps. These computations are embedded in a task representation that links together stimuli, actions, and outcomes, and an internal model that derives contingencies from explicit knowledge. Although research on reinforcement learning has already greatly advanced our insights into the brain, there remain many open questions regarding the interaction between reinforcement learning, task representations, and internal models. Through the combination of computational modelling, experimental manipulation, and electrophysiological recording, the three studies of this thesis aim to elucidate how task representations and internal models are shaped and how they affect reinforcement learning. In Study 1, the manipulation of action-outcome contingencies in a simple one-stage decision task allowed to investigate the impact of explicit knowledge about task learnability on reinforcement learning. The results highlight the flexible adjustment of internal models and the suppression of central computations of reinforcement learning when a task is represented as not learnable. Using a similar manipulation, Study 2 investigates how this influence of explicit knowledge on reinforcement learning holds under the increasing complexity of a two-stage environment. Again, pronounced neural differences between task conditions indicate separable computations of reinforcement learning and, more importantly, the selective influence of explicit knowledge and internal models on reinforcement learning. Study 3 uses a novel task design which necessitates inference about plausible action-outcome mappings, and thus, credit assignment. The findings suggest that multiple task representations are neurally conceptualized and compete for action selection, thereby solving the structural credit assignment problem. In sum, the studies of this thesis highlight the importance of reinforcement learning as a central biological principle and draw attention to the necessity of flexible interactions between reinforcement learning, task representations, and internal models to cope with the varying demands from the environment.
Today, vehicles already include a wide range of advanced driver assistance systems (ADAS), which will be further developed to specifically address driver needs. Adaptive ADAS present a new form of driver assistance that is based on driver monitoring algorithms and adjusts system parameters according to the driver’s predicted need for support. While it has been suggested that such adaptive systems will improve driving safety and system acceptance, the actual impact of adaptive ADAS on driver behavior and performance remains unclear.
Three studies were carried out to gain knowledge about the potential of adaptive ADAS to minimize the effects of distracted driving while also considering potential adverse behavioral adaptation effects associated with system use. Therefore, this thesis suggests an approach for adaptive forward collision warning (FCW) systems that change warning timing or warning modalities according to driver distraction. Study 1 investigated driver reactions to failures of generic adaptive warning strategies while further examining the influence of awareness on the development of adverse behavioral adaptation. Study 2 extended the approach to a more realistic context and investigated driver reactions to failures of a realistic distraction adaptive FCW system that adjusted warning modalities according to driver distraction in imminent collision situations using a driving simulator. Finally, Study 3 focused on the potential of a distraction adaptive FCW system to induce other forms of adverse behavioral adaptation in terms of riskier driving behavior and increased secondary task engagement. Moreover, in contrast to the previous studies, the presented adaptation strategy in Study 3 was based on a real-time distraction detection algorithm.
In sum, the studies of this doctoral thesis suggest that adaptive FCW systems are generally accepted and have the potential to minimize deficits associated with driver distraction. However, adaptive technologies were found to induce adverse behavioral adaptation in drivers when explicit awareness of system functioning is given. Results demonstrate clear performance and safety impairments for situations in which the adaptive warning strategy fails to present the expected high support. Furthermore, findings show that the mere anticipation of using a distraction adaptive FCW system can adversely affect driving performance. The thesis contributes to traffic research as it provides systematic empirical evidence for the effects of adaptive warnings on driving performance and safety. Both practical implications for the design of adaptive FCWs and methodological implications for future investigations of adaptive technologies based on driver monitoring are discussed.