Pronouns, substitutes, elipses, conjunctions, synonyms, antonyms, superordinates and subordinates, and part-whole relations all provide cohesive ties that help a reader understand text. A study at Britain's Open University (England) has revealed the way in which the perception of cohesive ties is achieved as children's reading ability grows. Explanations of the effects of cohesive ties must also take into account the writing of text. Most authors keep their reader's level of knowledge in mind when they write, using this estimate as the basis of how explicit or implicit they make the text. (JL)