Lexical cohesion and specialized knowledge in science and popular science texts

Scientific journal articles written for specialist audiences and popularized accounts of the same research differ in their cohesive patterns. This difference can be related to different uses of readers' knowledge in the two kinds of texts. In general, readers of scientific texts must have a knowledge of lexical relations to see the implicit cohesion of the text, while readers of popularizations must see the explicitly marked cohesive relations to infer lexical relations, and to link the semantic field of the specialized domain to those of everyday life. An attempt to develop a computational model of cohesion, a procedure that would not have to draw on domain knowledge, has produced a number of examples of the kinds of knowledge required to link sentences in scientific texts. It has also highlighted some of the devices through which this knowledge is conveyed in popular texts. Examples are drawn from texts selected from a corpus of specialized and popular articles on one discovery in molecular genetics. The introductions to one scientific article and one popularization are discussed in detail.