Visual processing of different race and great ape faces in the context of spatial frequency

Basic classification in the visual system is a fast and efficient classification procedure, mostly based on low and unfiltered spatial frequency. Whether the process of classifying the faces of other races and species in the human visual system depends on the early basic-level classification in the visual system has not been revealed in the literature. In this context, with this thesis, it is aimed to reveal the role of different spatial frequencies in the visual system according to a basic visual classification tasked with "I saw/did not see a face", and to reveal whether there is a difference in early visual processing of scramble faces at the same spatial frequency. When the P100, N170, and N250 ERP components were analyzed, it was observed that while no other race effects were observed in the basic classification, monkey faces were different processing hierarchy than human faces, and it was more dependent on high spatial frequency. In early visual processing, scrambled faces of monkey faces have been observed to have a similar processing hierarchy as faces in many cases, whereas human faces have been observed to be processing more specifically. The findings are discussed based on the hierarchical model in the visual system.