As soon as consumption became apart from its functional value and gained different meta values through the discourses of media and culture mediators, sociological and psychological reasons behind consumption phenomenon has become more questionable. The point of view indicating that consumption is just the function of income collapsed and the point of view indicating that irrational different factors can be determinant in consumption phenomenon has become dominant. In the explanation of this irrational condition in consumption, the interdisciplinary approach where the concepts in sociology and psychology literature are used can be instructive. In this work, the place of Diderot effect and Zeigarnik effect thought to be psychological reasons behind irrational consumption activities in consumption phenomenon and marketing discipline was examined. As a result of literature review made within the study, it was determined that departure products and the products bought as a result of symbolic values could be effective in forming new Diderot unities. In addition,it was determined that the advertisements prepared by using Zeigarnik effect and provided incomplete receive audiences’ attention more, arouse audiences’ interest, and stick in audiences’ mind.