© 2017 IEEE.Reaction time that is the period between the emerging of the target stimulus and the subject's motor response is an important and informative tool in the study of cognitive ability in psychology and other disciplines. In this study we proposed to evaluate attention level of students before and after an exam via a designed stimulus system. The study conducted on 30 individuals that are studying at first class at Erciyes University department of Biomedical Engineering. The participants were responded to press a button in target stimuli in a block diagram prepared in Labview. The experiment repeated before and after exam. Reaction time evaluated between groups via statistical analysis. The RT was faster, before exam compared to after exam results. In conclusion we assume that the alertness and focusing are higher before exam as an effect of positive stress compared the after exam condition.