The individual's learning process begins with birth and continues with discoveries in the living spaces. The curiosity-driven learning process is the basis of cognitive development, and nowadays, much research is being done to understand this development field. Determining the focal point of research on cognitive development in preschool in Turkey has shed light on the work to be done later. This study consists of theses and articles written in development and education related to the field of cognitive development in children aged 3-6. The study consists of 53 studies chosen randomly from the scientific research published between the years 2008-2018 within the field of cognitive development in 3-6 aged children. The keywords of "cognitive development, mental development, cognition" were applied while searching through the Higher Education Council Theses Center and The Turkish Academic Network and Information Center (ULAKBIM). Twenty-four theses that have been in Higher Education Council Theses Center and 29 articles in The Turkish Academic Network and Information Center (ULAKBIM) were reviewed using content analysis through a form that includes subject areas, data collection tools used in the research, data analysis methods, references, and sample characteristics. In this study, it was found that academic studies of early childhood were focused on 60-72 months. It has been observed that there has been an increase in the number of studies conducted on children aged 0-2 years. The increase in the number of new academic studies on this period, which is critical for brain development, will also prepare a strong ground for understanding and developing the later stages of early childhood.