-A Brain-based skill that is essential to carry out every task varies from the modest to the extreme complex is cognitive ability. In cognitive abilities emphasizes is not on actual knowledge, it is concern with the how to learn, recall, pay attention and solve the problem. Cognitive science learns about the environment, the chores, and the roles of cognition. The purpose of the cognitive science is to study the mind and behavior. Cognitive neuroscience is all about in what way the brain assists the mind. It is the field which deals in systematic learning of the biological developments and traits that motivate cognition, with a precise emphasis on association of neural in the brain which is involved in conceptual processes. Electro encephalography is a reliable biomedical signal that gives approximate estimation of an individual cognitive ability. Many researches are working in the domain of the development algorithm aimed at feature extraction of EEG. In this study, several effective feature extraction algorithms are studied to identify cognitive state.