This is a research about the design of reward systems on interactive contemporary interfaces of communication. After a research made on User Experience (UX) and Human-Computer Interaction (HCI) theory fields, it was possible to identify some particular kind of interface component which was, according to this study, capable of accomplishing several UX and HCI objectives related to affection and complex interaction relations on the generation of a valuable experience. This particular kind of component is the primal object of this study, which was designated by the author as Reward Systems , in a metaphorical meaning, besides the original conception of reward systems in neuroscience. These are components that allows user to appreciate some kind of content retrieving status to it. Facebook is widely discussed, because it was a pioneer in handling the interface of reward systems, where these components have reached a high level of development so far. This research is particularly relevant due to two factors: first, the lack of meaningful content in the current related literature. Secondly, the remarkable expansion of systems designed for this purpose, as will be demonstrated in the study. The project goal is to understand how the design of reward systems influence the flow of interactions and behavior of users today. In order to accomplish this, the research seeks to ascertain how certain theoretical aspects of design - dedicated to understanding the dynamics of interactive processes - apply to real interaction experiences in the contemporary world. For example, several models and frameworks in areas of HCI (Human Computer Interaction) and UX (user experience) highlight concepts consistent with those identified in reward systems which are in process of constant development, guided by commercial tendencies almost in a intuitive manner. Little attention has been paid in literature on neuroscience bases which make this process work.