<p>This study investigates the conceptualization of need unfulfillment as a neutral experience distinct from need satisfaction and need frustration. It further examines the unique roles that the satisfaction, frustration, and unfulfillment of autonomy, competence, and relatedness play in relation to positive, negative, and neutral affect, as well as other emotional indicators. Across two studies involving Italian adult participants (Study 1: <i>n</i> = 328, ages 18–67 years; Study 2: <i>n</i> = 1,062, ages 18–39 years), trait-level and scenario-based measures evaluated how distinct need states map onto positive, negative, and neutral affect, alongside specific emotional indicators (vitality, depression, anger, and apathy, assessed in the Study 2 only). A Bayesian bifactor model was employed to examine whether items associated with need unfulfillment load onto unique factors separate from those describing need satisfaction and frustration. Furthermore, using structural equation modeling and comparing four hypothetical scenarios, the analysis assessed how need satisfaction, frustration, and unfulfillment are differentially associated with positive, negative, and neutral affect, along with the various emotional indicators. The results provide robust evidence for need unfulfillment as a distinct, neutral experience related to autonomy, competence, and relatedness. Participants clearly distinguished between these need experiences, with unfulfillment being associated with neutral affect and apathy. In conclusion, a neutral experience toward the three basic psychological needs manifests as an unpleasant, energy-deflating sensation that something vital is missing, thereby supporting the essential nature of basic psychological needs as claimed by Self-Determination Theory.</p>