Research on human cognition has emphasized the development of integrated and flexibly accessible knowledge base as an important outcome of education. A well-organized and coherent knowledge base initiates inference, conceptualization and the acquisition of principled understanding.

Investigations of the past fifteen years have convincingly shown that a key to developing such an integrated and generative knowledge base is to build upon the learner's prior knowledge. Indeed, new learning is exceedingly difficult when prior informal as well as formal knowledge is not used as a springboard for future learning. It has also become more and more obvious, that in contrast to the traditional measures of aptitude, the assessment of prior knowledge and skill is not only a much more precise predictor of learning, but provides in addition a more useful basis for instruction and guidance.

In order to build on these previous findings, there remains a need for continued research aiming at the development of techniques to diagnose learning reliably and appropriately, and at unravelling the cognitive processes through which prior knowledge affects the learning of new knowledge.

The research reported in this book contributes to these aims by investigates the effects of prior knowledge in a comprehensive way. The author specifies the importance of the problem, especially in the context of (open) higher education. Relevant experimental studies and theoretical work are described in detail and critically discussed. The empirical work carried out contributes to the development of an appropriate methodology for mapping prior knowledge and to assessing the impact of prior knowledge on students' study success. In this respect, so-called 'knowledge profiles' are introduced as potentially useful tools to differentiate between students in terms of their domain-specific prior knowledge.

As a result of this work, the author presents a model of the learning process that integrates prior knowledge tests with progress tests and final tests as integral parts of the learning activities. The integration of assessment and instruction is an important contribution of this work, and points at the same time at a major area for continued research.