Frustration can be defined as an emotional state generated by the omission or devaluation in the quantity or quality of an expected appetitive reward. Thus reactivity to a reward is affected by prior experience with the different reinforcer values of that reward, a phenomenon known as incentive relativity, which can be studied by different paradigms to induce frustration. In this work we will focus in successive negative contrast (SNC), involving a downshift of the reward, and in the complete omission of the reward, a phenomenon known as extinction. Also, we will discuss the role of the neuroendocrine mechanisms involved in these processes. Specifically, we analyze the action of monoamines, adrenal and sexual hormones.