This thesis explores the role of what has traditionally been considered as neural “noise”, specifically BOLD signal variability and aperiodic neural activity, in human cognitive functions,... Show moreThis thesis explores the role of what has traditionally been considered as neural “noise”, specifically BOLD signal variability and aperiodic neural activity, in human cognitive functions, particularly in metacontrol. The metacontrol model assumes that individuals vary in their cognitive styles between "persistence" and "flexibility." Persistence emphasizes focused goal pursuit, while flexibility allows for easy task switching and consideration of diverse possibilities. Through three empirical studies, this thesis investigates the relationship between two specific forms of neural "noise" – BOLD signal variability and aperiodic neural activity – and metacontrol biases (i.e., persistence vs. flexibility). Chapter 2 emphasizes the importance of resting-state BOLD signal variability in understanding individualized cognitive control styles. Chapter 3 highlights the importance of the aperiodic component of the EEG power spectrum in reflecting demand-specific metacontrol states. Notably, Chapter 4 illuminates the functional significance of aperiodic activity in creative thinking. Overall, the research presented in this thesis highlights the importance of resting-state BOLD signal variability and aperiodic activity in the EEG power spectrum for understanding the neural underpinnings of cognitive functions. Show less