Gaze.

Gaze is a term used to describe the anxious state that comes with the awareness that one can be viewed;

Kress and van Leeuwen describe a two-valued relation to people depicted: either they look at the viewer, and so make a “demand” for recognition, acknowledgement, response, or they are not looking at the viewer, and in a sense “offer” themselves for viewing as “third persons” ( Reading Images, pp. 121-130.)

Hieronymus Bosch's - The Conjurer.

While the other figures within this painting above observe other objects, the woman in green observes the viewer. The painting thus makes the viewer aware of being on display (the woman in the green is holding an extra-diegetic gaze and the others are displaying an intra-diegetic gaze.)

As a viewer this makes you feel more included in the painting, as well as more aware of the presence of the woman wearing the green drawing much more attention to her than the rest of the women within the image. Perhaps this was a technique used to highlight her importance because it definitely makes her character stand out. In this case, Bosch has successfully managed to establish some-sort of relationship between this character and the viewer. In order to highlight someones importance or role within the narrative of an image this is clearly a successful technique to use...