Our life is full of choices—choices that differ, among others, in the amount of information on which they are based. For instance, when facing a choice between two options that differ on several decision-relevant attributes, one could rely on the most relevant attribute only to make the decision, or one could integrate information from several attributes and base the choice on that combined information. When a decision maker bases her choice on the most relevant attribute only, however, what does this (...) mean with regard to the amount of information this decision maker had processed prior to making the decision: did she process information about the most relevant attribute only and ignored additional information, or did she consider additional pieces of information as well but let her choice nonetheless be guided by only the most relevant attribute? Understanding the cognitive processes underlying those choices that are based primarily on the most relevant attribute is the main subject of this thesis, in particular, the question of whether or not for these choices additional information is ignored, and if additional information is not ignored, how is this information being processed? The empirical results of several experiments reported here show that decision makers do not ignore information when this information is fully shown to them or when decision accuracy is of importance. Moreover, even when information has to be retrieved from memory, information is not completely ignored. Additionally, first evidence was found that decision makers inhibit information when it conflicts with their decisions. Finally, results of one experiment show that the likelihood of relying on only one piece of information increases under ego-depletion. (shrink)