The background of the painting, behind the girl, shows nothing recognizable. It’s like she’s surrounded by a random pattern of squares, cubes, rectangles and other geometric shapes. Since Picasso has rendered the girl the same way as the background, it's a little difficult to tell which shapes belong to the background and which shapes belong to the girl. It’s like figure and ground are one surface.
Girl with a Mandolin is a good example of why it’s a challenge, even for a sighted viewer, to look at a Cubist painting and clearly see the figure as distinct from the background.
It is possible to identify the figure of the girl because she is in slightly lighter tones than the background. These lighter colors make her body parts visible,
Also, it’s easy to recognize the pear-shaped body of the mandolin. It’s oval curved lines stand out starkly against all the straight lines and angles of the geometric forms.