NEPA stands for "Novelty, Experienced Pleasantness, Pre-existing Attitude" and is a tripartite model of affective evaluation that is used to describe how people evaluate new stimuli (novelty), how they experience pleasure or displeasure in response to the stimuli (experienced pleasantness), and how their prior knowledge or beliefs about the stimuli (pre-existing attitude) influences their affective evaluation.
For example, a person might encounter a new food (novelty) and initially find it to be unpleasant (experienced pleasantness), but after learning that it is a popular dish in a particular culture, they might revise their evaluation and find it more appealing (pre-existing attitude). Another example could be a person encountering a new technology (novelty) and initially finding it exciting and innovative (experienced pleasantness), but after learning that it is not user-friendly (pre-existing attitude), they may revise their evaluation and find it less appealing.
NEPA might also refer to The National Environmental Policy Act (NEPA), which is a 1970 environmental law of the United States.