Brain-computer interfaces (BCI) are systems that use signals recorded from the brain to enable communication and control applications. The use of data derived from Brain Computer Interaction (BCI) is a complex process that requires multidisciplinary skills and knowledge in computer science, signal processing, neuroscience, robotics, artificial intelligence, and other related fields. In this study, we propose the quantitative analysis method for feature selection based on descriptive statistics (maximum, minimum, mean and median).The purpose of this paper is to show that different trials of the same individual at the same symbol yield similar brain profiles regardless of their mental state, and that different individuals have different brain profiles at the same visual signals. The obtained data are discussed in the context of studying the nature of brain signals.