Understanding the learners' cognitive characteristics and designing the personalized learning environments accordingly is quite a challenging task. Although various models and frameworks have been proposed when designing adaptive environments, it is less understood how these cognitive characteristics are determined and how different personal characteristics change when exposed to various media and design choices. Therefore, this chapter first aims to introduce neuropsychological tests and their potential uses in determining cognitive profiles. Secondly, existing research will be reviewed to discuss how those individual cognitive characteristics yield different results while interacting with the content. Finally, some recommendations will be made for further research.