Given the importance of correctly perceiving and remembering faces for successful social interaction, face processing is one of the most widely studied cognitive domain in behavioral, neurophysiological and neuroimaging research, particularly, based on a group-mean approach. However, above mean differences, inter- and intra-individual variability in face processing provide valuable information for investigating the underlying mechanisms and binding the behavioral and neural substrates for better understanding of face processing.. In my dissertation I investigated the biological mechanisms underlying face cognition from an inter- and intra-individual variability perspective at the genetic, neural, and behavioral levels. The neural activities related to face processing are measured by event-related potentials (ERPs) and their trial-by-trial latency variability are estimated using a novel and well-established method, Residue Iteration Decomposition (RIDE).. Study 1 demonstrates the reliability of RIDE in extracting single-trial parameters of the P3b component, which is used in the investigation of the neural basis of intra-subject variability (ISV) in face processing speed in Study 2. In the Study 2, individual differences in ISV of face processing speed, measured at both behavioral and neural levels during a face processing task, are studied in their genetic variation. The results suggest that individual differences in ISV are related not only to the COMT Val158Met polymorphism, but also to the type of cognitive processing (e.g., memory domain). Moreover, we showed that ISV in reaction time can be partially explained by ISV in the speed of central cognitive processes.. Furthermore, the individual differences approach in Study 3, provided valuable and novel information beyond the common group-mean approach applied in the N1/N170-related research. Based on this approach, not only we could replicate previous findings that the N170 predicts individual differences in face cognition abilities, but also we could decompose individual differences in the N170 into a domain-general and a face-specific part with different predictive powers. Moreover, we showed that top-down modulations on the N170 have separable and qualitatively different relationships to face cognition abilities.. In summary, the integrated results from different studies in my dissertation demonstrate the psychological importance of the information provided by inter- and intra-individual variability in face processing in the investigation of its underlying biological mechanisms.
|01 January 2016
|Nowparast Rostami, Hadiseh
|HKBU Institutional Repository
|Hong Kong Baptist University
|Open Access Theses and Dissertations
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