Appraises current explanations of how visual processing occurs. Highlights the basics of simultaneous and serial levels of processing. Discusses the results of a series of experiments on visual-search tasks and also on the role of prior knowledge in processing. (ML)

A general model of conceptual change which is largely derived from current philosophy of science, but which can illuminate learning as well, is described. Some features of this model are illustrated by interviews with students studying special relativity in physics. Finally, some pedagogical implications are presented. (Author/PB)