The purpose of this research is to determine the variables that affect consumer propensity to observe. It was performed in Iran-Shiraz and the effects of these factors on consumers of Nokia cell phone have been studied. 384 consumers participated in the research by integrating questions including measurement of favorite items. Index of observation in decision making for Iranian's consumers was used for measurement of propensity to observe. Effective noticeable factors of propensity to observe include propensity to minimize risk, need for cognition, choosing brand, self-confidence of consumer, and propensity to conform to norms of groups. Additionally, it shows that propensity increases when some presumptions have effect on each other. The result of this research proposes that observation in making decision is a significant controversy and most consumers and retailers should consider consumer propensity to observe when marketing and merchandising products. This research was designed by creating and validating the measurement of propensity to observe and another designing factor of this research is a situation where consumers observe the behavior of other consumers in buying some things before deciding to choose the products they want to buy.