Color appearance models can provide predictions of the perception for color, including visual phenomena such as chromatic adaptation. Color matching of a print with a monitor is one good example in which color appearance models play a significant role. Recently the performance for more complex and higher dynamic range stimuli has come to be required. This paper focuses on the problem of the simultaneous perception of lightness in a bipartite background. The perceived lightness of a pair of stimuli on the bipartite background was measured at various luminance and contrast levels and positions. The results are analyzed by using existing color appearance models. A concept of the global and local lightness is introduced to evaluate the perceived lightness.