This paper investigates the way in which Rudolf Carnap drew on Gestalt psychological notions when defining the basic elements of his constitutional system. I argue that while Carnap's conceptualization of basic experience was compatible with ideas articulated by members of the Berlin/Frankfurt school of Gestalt psychology, his formal analysis of the relationship between two basic experiences ("recollection of similarity") was not. This is consistent, given that Carnap's aim was to provide a unified reconstruction of scientific knowledge, as opposed to the mental processes by which we gain knowledge about the world. It is this last point that put him in marked contrast to some of the older epistemological literature, which he cited when pointing to the complex character of basic experience. While this literature had the explicit goal of overcoming metaphysical presuppositions by means of an analysis of consciousness, Carnap viewed these attempts as still carrying metaphysical baggage. By choosing the autopsychological basis, he expressed his intellectual depth to their antimetaphysical impetus. By insisting on the metaphysical neutrality of his system, he emphasized that he was carrying out a project in which they had not succeeded.