Isolation
While elements that are grouped together may carry more visual weight, isolating or separating a key object or shape from the rest of a composition will make it stand out.
In At the Moulin Rouge (1892-95), Henri De Toulouse-Lautrec uses isolation to guide our attention.
The group of people at the table are placed near the centre of the painting but our eyes are drawn to the woman who sits alone at the right edge of the frame.
The way she stares directly out of the painting as if looking at the viewer increases the emphasis on her. More emphasis is created by the unusual green and blue tones of her skin.
When we look at Apples and Oranges (Paul Cezanne, 1895–1900) the placement of the apple in the centre of the painting draws our eyes to it.
While the other fruit is all arranged in groups, this single apple is isolated from its surroundings by the white of the table cloth.
In Karasaki Pines at Night (Unknown Artist, c.1900-20) the boat is emphasised because it is isolated from the larger shape of the island by a large area of negative space.
The line of smoke helps lead the viewer's eye to the boat, particularly through the use of colour.
Red stands out against the blue-grey and black background, and it becomes more intense closer to the boat.