Which part of the composition do you look at first and why? Despite the sometimes shocking and graphic nature of the subject matter it is primarily a formal game of contrasting visual elements that allows Goya to achieve visual dominance in one region and not another. Wherever the greatest contrast exists (contrast of Scale, Shape, Placement, Orientation, Value, Edge, Pattern/Texture) the viewer's eye will look first. Most of us can agree on where we look first but we could also probably agree on where we look second and third (as contrast slowly diminishes). The artist can choose to reduce attention to a given area by reducing contrast and increase contrast elsewhere. More on Francisco Goya here.