The forgotten effects theory has been widely developed by different researchers because of its wide applications and validity for decision-makers in the decision-making process. In this paper we develop the application of this theory in the case of consumer decision-making in search of the best choice based on their characteristics. For this, we located our research in the city of Barcelona (Spain), because it is a cosmopolitan city and a reference at European level. We have carried out a research for which we have had the assistance of four experts in the field. The main advantage of this model is that it allows second-generation effects to be considered in decision-making, which could go unnoticed by the decision-maker at first, thus reducing the uncertainty associated with the process.