2 - Theses

Across cultures and historical epochs, body-altering practices—ranging from decorative tattoos to permanent modifications—have been employed to convey aesthetic values, mark group affiliations, and many subfunctions. As these practices evolve, so too does the need to understand the psychological, anthropological, social, and aesthetic motivations that underpin them. This dissertation presents a comprehensive exploration of body alterations through the lens of three interconnected studies. Together, they investigate the mental functions of body-altering behaviors, the conceptual structure of tattoo aesthetics, and the mechanisms underlying aesthetic appreciation of tattoos across diverse populations. By synthesizing insights from psychology, anthropology, sociology, and empirical aesthetics, these studies contribute to a deeper understanding of why individuals engage in body alterations and how these practices are perceived in modern society. The first study examines the mental functions of body-altering behaviors, emphasizing the dual roles of aesthetics and group affiliation. It identifies the aesthetic drive as the primary mental function, supported by secondary functions. The second study shifts focus to the conceptual structures of tattoo aesthetics, examining how internalized social norms and expertise shape aesthetic judgments. Finally, the third study provides an empirical investigation of how tattoos influence the aesthetic appreciation of human stimuli, revealing variations in perception influenced by expertise, age, and the extent of tattoo coverage. The abstracts for each of these studies can be found underneath, where they are presented in detail. Together, they offer a multidimensional perspective on the phenomenon of body modification, addressing not only the motivations behind these practices but also the intricate ways they are perceived, appreciated and understood by individuals with varying social and cultural norms. The findings have significant implications for understanding human aesthetic preferences, social identity, and cultural evolution in the context of body-altering practices. Study 1. Decorating the body as well as (semi-)permanent bodily modifications are a longstanding human practice, together with spending a great amount of time and effort on such body alterations. The present article reviews the mental functions of body-altering behavior. The primary aim is to identify and elucidate the predominant mental function underpinning these body alterations. Following several guidelines for reviews, we synthesized the literature, including several categories of body-altering entities from different eras. We argue that there are two crucial commonalities for individuals engaging in body-altering behavior that comprise the mental functions for doing so: aesthetics and group affiliation (dynamics), including the latter’s subfunctions of supporting individuality, resistance, personal narrative, physical endurance, and sexual motivation. Incorporating the existing literature, we find that aesthetic motivation takes precedence over group affiliation, thereby establishing aesthetics as the primary mental function of body-altering behavior; factors substantiating this conclusion are explored in detail within the article. Study 2. While body modifications have increasingly gained acceptance and popularity, how different subpopulations aesthetically appreciate tattoos remains unclear. The present study aimed to investigate the conceptual structure underlying tattoo aesthetics, focusing on the effects of internalized social norms and expertise. Using a timed free-listing task, three groups (≤49 years, ≥50 years, and experts) comprising 497 participants were asked to write down adjectives that could describe tattoo aesthetics. Statistical analyses of frequency, cognitive salience indices, co-occurrence dimensions, semantic dimensions, similarity measures, and valences were applied and, to directly compare the three groups, a generalized Procrustes analysis was applied. The variance and complexity with which individuals verbally expressed their perceived aesthetic appeal of tattoos were highlighted. However, the results do not reveal a unified concept of beauty, nor do they present a clear bipolar dimension of beautiful/ugly for two of the three groups. Nevertheless, the concept of beauty was found to be prominent in tattoo aesthetics, and aesthetic and descriptive–evaluative dimensions were identified, with terms such as beautiful, ugly, multicolored, and interesting being the most notable adjectives, although not with the highest valence. Possible factors explaining the intracultural differences between the three groups are also discussed. Study 3. Scientific interest in body modifications continues to grow, and tattoos have recently become a subject of empirical aesthetics. While conceptual structures of tattoo aesthetics have been studied, the question of how tattoos are aesthetically appreciated has not yet been studied. In this study, we examined how tattoos influence the aesthetic appreciation of human stimuli and uncovered differences in beauty perceived by individuals older and younger than 50, which we consider indicative of different internalized social norms, experts (tattoo artists) and nonexperts, and tattooed and nontattooed individuals. Images of a male and a female model were manipulated to vary in the amount of tattoo coverage across six manipulation conditions: Baseline (none), Light, Moderate, Heavy, Extreme, and Extreme + Face. N = 487 participants rated the beauty of these stimuli. The results suggest overall group differences (experts vs. nonexperts; tattooed vs. nontattooed; older vs. younger). The perceived beauty of the stimuli decreased as the extent of tattoos increased, with the Extreme + Face condition standing out as the lowest rated condition. These findings confirm that tattoos influence aesthetic appreciation, which is highly dependent on expertise and social norms as indicated by age. We also discuss the generalizability and implications of the findings.

The Job Demands-Resources (JDR) model provides a well-established framework for examining workplace antecedents and outcomes. This dissertation extends the JDR model by investigating how personal resources interact with work location in hybrid and remote settings. Four empirical studies explore whether remote work serves as a resource or a demand and how personal resources, both stable traits and daily states, moderate this relationship. Part A focuses on core self-evaluations (CSE) and remote work intensity among hybrid leaders (N = 370), showing that remote work can enhance health outcomes over time, particularly for those with lower personal resources. However, no effect on work-life balance was found. Part B comprises two diary studies (N = 63 and N = 98) on daily character strength application, demonstrating its benefits for performance and self-efficacy. These effects were stronger on office days, indicating a potential enhancement role of the office environment for state-like personal resources. Part C validates the German version of the “Thriving from Work” (TfW) questionnaire using item response theory (N = 567), establishing a reliable short form for future diary research. Part D uses this measure in a five-day diary study (N = 408), revealing that daily remote work is associated with higher daily thriving. Findings underscore the complex role of remote work within the JDR model: it can act as both a resource and a demand, depending on the individual’s personal resources and context. This dissertation advances the theoretical understanding of hybrid work and offers practical implications for supporting employee well-being and performance in flexible work environments.

This dissertation investigates the nexus of speech features and perceived transformational leadership through computational paralinguistic and phonetic approaches across three studies, bridging leadership theory and vocal. Study 1, an integrative review, leverages computational advancements to explore acoustic features like pitch, jitter, and formant dispersion beyond human perception. It synthesizes early research with modern tools like Mel-Frequency Cepstral Coefficients (MFCCs), showing how lower pitch and features like speech pauses predict dominance and charisma (Cullen & Harte, 2018). This sets the stage for empirical analyses using machine learning to dissect vocal cues. Study 2 employs a computational paralinguistic approach, analyzing 122 speakers’ recordings by evaluated by 122 raters via the German Multifactor Leadership Questionnaire (MLQ)—with OpenSMILE. Focusing on fundamental frequency, intensity, and voicing probability, it uses Sequential Minimal Optimization (SMO) regression in WEKA. Results highlight fundamental frequency’s predictive power for inspirational motivation (R²=0.31) and idealized influence (R²=0.45), with intensity driving individualized consideration (R²=0.35). This approach quantifies paralinguistic features’ impact, revealing their nuanced roles across leadership dimensions. Study 3 shifts to a phonetic approach, using Praat on the same dataset to extract fundamental frequency (F0), intensity, speech duration, and formants (F1-F5). SMO regression identifies speech duration as key for individualized consideration (R²=0.40) and F0 for inspirational motivation (R²=0.43). The implications amplify these findings: a wider F0 range and steeper slopes enhance dynamism and charisma; lower F1, F2 frequencies and narrower F3, F4 bandwidths boost authoritative resonance and clarity; longer duration and pauses, paired with slower rates, project control; and dynamic intensity modulation strengthens emotional impact. These phonetic insights complement Study 2’s paralinguistic focus, offering a dual-lens framework. The dissertation integrates explainable AI (XAI) to balance predictive accuracy with interpretability, linking computational paralinguistic features (e.g., voicing probability) and phonetic traits (e.g., formant bandwidths) to psychological constructs like enthusiasm and authority. The paralinguistic approach excels in broad feature extraction, while the phonetic method provides granular physiological insights, together advancing psychoacoustics and leadership studies. This synergy enables practical vocal optimization- varying pitch, modulating intensity, and pacing delivery- for authentic leadership projection in business contexts, demonstrating the power of computational and phonetic methodologies in decoding vocal influence.

The focus on electrification in urban public transit has been strengthened by the global shift towards sustainable transportation. A promising solution to reduce emissions and dependence on fossil fuels is electric buses. However, the widespread implementation of electric buses requires a robust charging infrastructure capable of meeting the operational demands. This work addresses many challenges and limitations facing the spread of electric buses using optimization methodologies. It includes varies parameters, which affect the planning of the required charging infrastructure such as available area, charging capacity, and optimum total costs. Also, this work examines the robustness of the charging infrastructure, where many possible failure scenarios of the components are considered. In this part, potential effects on planned routes and buses are used as an indicator for the severity of failures. Additionally, the ability of bus depots to supply ancillary services is analyzed. In this context, the advantages of implementing either load management or stationary batteries or even both are evaluated.