As reported in Shim (2011), advanced learners of Korean as a second language (L2) mostly produced background information by using various tense markers while foreground was dominantly described in past tense by learners of low proficiency. Why would proficient learners largely produce background information? This question is addressed in my paper. Unlike foreground, background information must include a description as well as views from an objective perspective, including a commentary and an explanation. It is suggested that, within the framework of Fauconnier and Turner (2002, 93-94), the perspective of the speaker as a writer in a ‘mental space’ must be linked and blended with that of the other in another space by the ‘Change’ and the ‘Identity’ vital relations, and that the blending must be learned by the L2 learners. Viewed from this blending account, productivity of background is likely to be associated with sensitivity of these vital relations