In fact, some psycholinguistic and empirical research of Heurley (1997) and Hearst (1997) indicates that paragraph breaks do not always occur at the same locations as the thematic boundaries.
experiments of Bruder and Wiebe (1990) and Wiebe (1994) show that paragraph breaks help readers to interpret private-state sentences in narratives, i.e., sentences about psychological states such as wanting and perceptual states such as seeing.