Innovative approaches in investigating inter-beat intervals: Graph theoretical method suggests altered autonomic functioning in adolescents with ADHD

Cardiac inter-beat intervals (IBIs) are considered to reflect autonomic functioning and self-regulatory abilities and are often investigated by traditional time- and frequency domain analyses. These analyses investigate IBI fluctuations across relatively long time series. The similarity graph algorithm is a nonlinear method that analyzes segments of IBI time series (i.e., time windows)—possibly being more sensitive to transient and spontaneous IBI fluctuations. We hypothesized that the similarity graph algorithm would detect differences between Attention-Deficit/Hyperactivity Disorder (ADHD) and control groups. Resting electrocardiogram (ECG) recordings were collected in 10–18-year-olds with ADHD (n = 37) and controls (n = 36). IBIs were converted to graphs that were subsequently investigated for similarity. We varied the criterion for defining IBIs as similar, assessing which setting best distinguished ADHD and control groups. Using this setting, we applied the similarity graph algorithm to time windows of 2–5, 6–13 and 12–25 s, respectively. We also performed traditional IBI analyses. Independent samples t tests assessed group differences. Results showed that a 1.5% criterion of similarity and a time window of 2–5 s best distinguished adolescents with ADHD and controls. The similarity graph algorithm showed a higher number of edges, maximum edges and cliques, and lower edges10+10/edges2+2 in the ADHD group compared to controls. The results suggested more similar IBIs in the ADHD group compared to the controls, possibly due to altered vagal activity and less effective regulation of heart rate. Traditional analyses did not detect any group differences. Consequently, the similarity graph algorithm might complement traditional IBI analyses as a marker of psychopathology.publishedVersio

Variability and similarity of inter-beat intervals of the heart as markers of perceived stress and behavioral regulation

The current dissertation investigated inter-beat interval (IBI) indices of variability and similarity, reflecting autonomic nervous system (ANS) modulation on heart rate. IBI indices of cardiac vagal activity (CVA) are further considered to reflect activity in brain areas involved in self regulation. Yet, it is unclear which specific aspect(s) of self-regulation such IBI indices load most highly on, and their relation to contextual factors. Thus, in a sample of college students (n = 143) in paper I, we investigated how CVA and perceived stress associated with contextual factors of perceived social support and sex. Moreover, we expected indices to load highly on the internal regulation of perceived stress, compared to the external regulation of behavior. This was examined in adolescents with attention-deficit/hyperactivity disorder (ADHD) and controls (n = 67) in paper II. In paper III, we investigated the use of a nonlinear, graph theory-based method for illustrating IBI differences in adolescents with ADHD and controls (n = 73). In all studies, IBI indices were derived from short-term resting electrocardiogram (ECG) recordings, with high frequency-heart rate variability (HF-HRV) as the applied measure of CVA. Self-report questionnaires assessed emotion regulation difficulties (the Difficulties in Emotion Regulation Scale) perceived stress (the Perceived Stress Scale), and perceived social support (The Medical Outcomes Study Social Support Survey). In the moderation analysis of paper I, CVA associated positively with perceived social support in females with intermediate and high, compared to low, perceived stress levels, but not in males. Linear regression analyses in paper II showed that CVA associated negatively with access to emotion regulation strategies in adolescents with ADHD and controls. In paper III, independent samples t-test showed that the similarity graph algorithm illustrated IBI differences between the ADHD and control groups which traditional CVA analyses did not. In sum, the studies suggest that CVA might mark perceived stress regulation, and emphasize the consideration of contextual factors such as perceived social support and sex in the interpretation of this marker. Furthermore, the similarity graph algorithm might increase the sensitivity of IBI markers, possibly also indexing behavioral regulation. Although further research is required, IBI markers might have potential clinical use in the diagnosis, monitoring and treatment of psychiatric disorders.Doktorgradsavhandlin

The Application of Physiological Metrics in Validating User Experience Evaluation on Automotive Human Machine Interface Systems

Automotive in-vehicle information systems have seen an era of continuous development within the industry and are recognised as a key differentiator for prospective customers. This presents a significant challenge for designers and engineers in producing effective next generation systems which are helpful, novel, exciting, safe and easy to use. The usability of any new human machine interface (HMI) has an implicit cost in terms of the perceived aesthetic perception and associated user experience. Achieving the next engaging automotive interface, not only has to address the user requirements but also has to incorporate established safety standards whilst considering new interaction technologies. An automotive (HMI) evaluation may combine a triad of physiological, subjective and performance-based measurements which are employed to provide relevant and valuable data for product evaluation. However, there is also a growing interest and appreciation that determining real-time quantitative metrics to drivers’ affective responses provide valuable user affective feedback. The aim of this research was to explore to what extent physiological metrics such as heart rate variability could be used to quantify or validate subjective testing of automotive HMIs. This research employed both objective and subjective metrics to assess user engagement during interactions with an automotive infotainment system. The mapping of both physiological and self-report scales was examined over a series of studies in order to provide a greater understanding of users’ responses. By analysing the data collected it may provide guidance within the early stages of in-vehicle design evaluation in terms of usability and user satisfaction. This research explored these metrics as an objective, quantitative, diagnostic measure of affective response, in the assessment of HMIs. Development of a robust methodology was constructed for the application and understanding of these metrics. Findings from the three studies point towards the value of using a combination of methods when examining user interaction with an in-car HMI. For the next generation of interface systems, physiological measures, such as heart rate variability may offer an additional dimension of validity when examining the complexities of the driving task that drivers perform every day. There appears to be no boundaries on technology advancements and with this, comes extra pressure for car manufacturers to produce similar interactive and connective devices to those that are already in use in homes. A successful in-car HMI system will be intuitive to use, aesthetically pleasing and possess an element of pleasure however, the design components that are needed for a highly usable HMI have to be considered within the context of the constraints of the manufacturing process and the risks associated with interacting with an in-car HMI whilst driving. The findings from the studies conducted in this research are discussed in relation to the usability and benefits of incorporating physiological measures that can assist in our understanding of driver interaction with different automotive HMIs

Three Risky Decades: A Time for Econophysics?

Our Special Issue we publish at a turning point, which we have not dealt with since World War II. The interconnected long-term global shocks such as the coronavirus pandemic, the war in Ukraine, and catastrophic climate change have imposed significant humanitary, socio-economic, political, and environmental restrictions on the globalization process and all aspects of economic and social life including the existence of individual people. The planet is trapped—the current situation seems to be the prelude to an apocalypse whose long-term effects we will have for decades. Therefore, it urgently requires a concept of the planet's survival to be built—only on this basis can the conditions for its development be created. The Special Issue gives evidence of the state of econophysics before the current situation. Therefore, it can provide excellent econophysics or an inter-and cross-disciplinary starting point of a rational approach to a new era

Proceedings experiencing light 2009 : international conference on the effects of light on welbeing

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Proceedings experiencing light 2009 : international conference on the effects of light on welbeing

no abstrac