In this paper the characteristics of the attentional mechanisms in the human brain are analyzed and the P300 component is stimulated using the three basic colors (RGB) and yellow. To define the effect of the color intensity on the human attention, all these colors are tested for two levels of intensity (High-Low). Healthy youth are involved in this study with normal or corrected to normal vision and ensemble averaging is implemented to extract the ERPs from the EEG background noise. The experimental results show a significant effect of the color intensity on the human attention since low responses are captured when the low intensity is presented and P300 responses vary within different color bands. Hence, using proper color combination to design the roads signs may enhance the driver attention and insure a high level of awareness.