The Model of Service-Quality Expectations Is Based on the Premise

The model of service-quality expectations is based on the premise that customer perceptions and expectations of service quality change over time, but at any one point in time are a function of prior expectations of what will and what should happen during the service encounter, as well as the actual service delivered during the last contact. The researchers' empirically tested model contends that the two different types of expectations have opposing effects on perceptions of service quality. List these two models.