Abstract: Support theory is a nonextensional theory of subjective probability judgment, which has several arguments: (1) subjective probability is influenced by description, which has description-dependence. (2) subjective probability reflects the relative support for the focal hypotheses. (3) subjective probabilities are complementary in binary case and subadditivity in general case.4 subjective probability judgment has unpacking effect and enhance effect

Key words: support theory, binary complementarity, subadditivity, unpacking effect, enhancement effect