© 2014 IEEE. This paper presents a developed experimental system using an eye-tracking device, by which we can control displayed visual stimuli flexibly like visual trick. Using this system, comparisons between two faces with different expressions are experimented in a specific condition as one face is always forced to display as in the subject's central field of view, while another face is always displayed in his/her peripheral field of view. The results have proved that ability of discriminate faces in the peripheral field of view is quite poor. In addition, the experimental results indicate how we could live our daily lives more peacefully.