In the first 150 milliseconds of looking at a picture, those elements draw the eye. That's bottom-up seeing. Then, top-down spotlighting takes over: "Of special significance are images of biological relevance -- like fear, sex, gender, aggression -- which are much more dependent on training and culture," Koch says.
Tests have shown, for example, that East Asians' interpretations of facial expressions depend heavily on the expressions of people surrounding the subject in an image. For Mexicans the color blue, not black, signals mourning. These judgments happen quickly, often without conscious thinking. Such cultural norms dictate not only the way we interpret images but the unconscious motion of our eyes when looking at them.