Keeping track of time is a fundamental challenge the brain needs to accomplish to successfully interact with the environment. However, perceived time is not equivalent to physical time. Disentangling influencing factors and quantifying resulting distortions of time and duration perception gives important insights into underlying computational and neural mechanisms. This thesis focuses on the modulation of short interval duration estimates by the internal temporal structure of the interval. Chapter 1 introduces contemporary models, research paradigms and findings, and outlines distortions due to temporal structure as a promising research direction. The experiments described in Chapter 2, 3 and 4 use psychophysics to systematically investigate the influence of the temporal arrangement of interval fillers. It is shown that temporal regularity and predictability lead to a robust overestimation of duration. This may be explained via a logarithmic accumulation of perceived over physical time or increased neural response magnitudes toward regular stimulation due to neural entrainment. Chapter 5 reports an experiment using electroencephalography (EEG) which gives evidence for a neural response magnitude account by showing a direct relationship between the overestimation of regularity and entrainment strength. Chapter 6 summarizes the findings and puts them into a broader context of temporal and general perceptual processing.