This piece is one of many color plates from Albers' educational text, Interaction of Color, which aims to impart the rules Albers discovered through his experimentation. Albers was very interested in how people perceive light intensity/value between different hues, and would regularly ask his students which of two colors seemed darker.^1 This painting shows the effects of that consideration. The reds to either side of the yellow band are the same from top to bottom, but where they overlap it, they mix with it more and more going down the canvas. The topmost bar seems to hover in front of the yellow, while the bottommost appears to pass beneath it (though the yellow is somewhat translucent). At what point does it switch? Why does it seem that way? Do they merge at some point in the middle? These questions are useful for learning artists to ponder, as they help relate the components of an image to the perception of it as a whole. Even changing just the blue of the background can change where the other objects appear to fall in relation to one another. For me the bars seems to be receding as my eye goes down the canvas, an effect I would have to attribute to the visual cue of occlusion, though in this case neither object completely obscures the other. 

1 Source: http://elizabethahunt.wordpress.com/2013/01/13/interaction-of-color-by-josef-albers/