Formal cognitive models of episodic memory assume that during encoding list items become associated with a changing context representation. However, this representation is recency-biased and thus can not account for primacy effects under conditions that prevent rehearsal. In this paper, it is hypothesized that one source underlying primacy effects is the detection of novelty. In three experiments, it is shown how novelty at the perceptual and semantic level can explain the full serial position function of first recall probabilities, including primacy effects. It is proposed that an item becomes distinctive due to increase in the change within a distributed episodic context representation, induced by novelty detection. The theory makes three assumptions. First, items become associated with a distributed context representation. Second, the context representation changes with item presentation. Third, the rate of contextual change is related to the perceptual and conceptual difference computed between the presented item and the previous item (or items in the buffer). This theory captures primacy effects in first recall probabilities without recourse to a rehearsal process and provides a mechanistic account of distinctiveness.