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- Autonomes Fahren (1)
- Risikobewertung (1)
- career (1)
In this dissertation the relation between time headway in car following and the subjective experience of a driver was researched. Three experiments were conducted in a driving simulator. Time headways in a range of 0.5 to 4.0 seconds were investigated at 50km/h, 100km/h, and 150km/h under varied visibility conditions and at differing levels of driver control over the car. The main research questions addressed the possible existence of a threshold effect for the subjective experience of time headways and the influence of vehicle speed, forward visibility, and vehicle control on the position of time headway thresholds. Furthermore, the validity of zero-risk driver behavior models was investigated. Results suggest that a threshold exists for the subjective experience of time headways in car following. This implies that the subjective experience of time headways stays constant for a range of time headways above a critical threshold. The subjective experience of a driver is only influenced by time headway once this critical time headway threshold is passed. Speed does not influence preferred time headway distances in self- and assisted-driving, i.e. time headway thresholds are constant for different speeds. However, in completely automated driving preferred time headways are influenced by vehicle speed. For higher speeds preferred time headways decrease. A reduction of forward visibility leads to a shift in preferred time headways towards larger time headways. Results of this dissertation give credence to zero-risk models of driver behavior.
Research in work and organizational psychology frequently conducts studies based on self-report questionnaires. Evidence of the reliability and validity of these measures has to be provided based on thorough research in order to be certain that meaningful conclusions can be reached. Recently, latent variable approaches have been introduced that provide new opportunities to examine the instruments and determine if they are suitable to obtain meaningful results. They also offer new approaches to investigate the relationships between constructs, particularly when assessed over time. The research conducted in this PhD thesis and reported in three papers aims at utilizing these opportunities to examine the measurement properties of a selection of self-report questionnaires and to address conceptual questions regarding the validity of these instruments. In the first paper, the structure of two five-factor personality inventories was examined using Confirmatory Factor Analyses (CFA) and Exploratory Structural Equation Modeling (ESEM). Both methods were applied to construct better-fitting, though more complex models based on data from two questionnaires (NEO PI-R and 16PF) completed by 620 respondents. The impact on the construct validity of the inventories was assessed. Generally, scores derived from either method did not differ substantially. When applying ESEM, convergent validity declined but discriminant validity improved. When applying CFA, convergent and discriminant validity decreased. We conclude that using current personality questionnaires that utilize a simple structure is appropriate. In the second paper, the nature of and reason for the relationship between a presence of a calling and three aspects of career preparation (career planning, decidedness, and self-efficacy) were investigated. Data were collected in three waves of a diverse sample of German university students (N = 846) over one year. Latent growth analyses revealed that calling was positively related with all career preparation measures. The slope of calling was positively related to those of decidedness and self-efficacy but not to planning. Cross-lagged analyses showed that calling predicted a subsequent increase in planning and self-efficacy. Planning and decidedness predicted an increase in the presence of a calling. In the third paper, the measurement properties of an adapted protean career orientation scale were examined. We present a series of studies that (1) establish the scale’s unidimensionality and measurement invariance across gender within separate samples of students and working professionals as well as measurement invariance between both samples; (2) demonstrate measurement invariance and differential stability over six months among students and professionals; (3) show that a protean career orientation partially mediates the relationship between personality dispositions (i.e., proactive personality, core self-evaluations) and proactive career behaviors and career satisfaction among students and employees; (4) demonstrate that a protean career orientation possesses incremental predictive validity regarding proactive career behaviors and career satisfaction beyond personality dispositions among students and employees; and (5) based on a cross-lagged study among employees, we show that career satisfaction predicts a protean career orientation but not vice versa. In summary, the research presented here provides researchers in the field of work and organizational psychology with a thorough assessment of the measurement properties and aspects of validity of these self-report questionnaires. The findings demonstrate their suitability for future research studies conducted in work and organizational psychology as well as for practical applications.
When Libet and colleagues published their results on the temporal order of movement preparation and the reported time of conscious will to move in 1983, they shed some doubt on the existence of free will. This marked the beginning of a controversial and still ongoing debate, not only about the existence of free will, but also about the appropriateness of methods and validity of results from research on free will. Belief in free will was also discovered as psychological research topic. Literature on belief in free will shows some evidence that most laypersons across different cultural backgrounds believe that they have free will and that a person's belief in free will might have an impact on cognition and behavior, tending to positive outcomes with a greater belief in free will. Empirical findings from the German-speaking area are sparse, probably due to a lack of validated measurements assessing belief in free will available in the German language. The aim of this dissertation is to critically examine some aspects in psychological research on free will and the belief in free will. Two studies are reported that aim to generalize the Libet paradigm for a free and voluntary decision with consequences for the acting person, as this was never reported to have been researched in literature before, and to test the critical objection that the measurement of reporting the conscious intention to move has a direct effect on the result in the Libet paradigm. Furthermore, the construction of the first inventory measuring belief in free will in the German language is described. This inventory was also created with the aim of overcoming some methodological problems in the existing instruments in English language. Furthermore, studies on the experimental manipulability of the belief in free will are reported. These findings provide implications in view of the current state of research on free will and belief in free will and its reliability.