This reader combines contributions from researchers from different fields of cognitive neuroscience under the unifying perspective to focus on the study of brain functions underlying individual variations in psychological performance. A common denominator for these different approaches is the general goal of progressing from an understanding of basic mechanisms to an understanding of how differences in the functioning of these mechanisms relate to individual differences in cognitive function and performance. According to this idea the contributions of this volume cover the whole spectrum from molecular biology, event related potentials (ERP) and functional imaging (FMRI) work to experimental and cognitive neuropsychology and to methodological approaches. With respect to the degree of development and standardization of methods in different fields of cognitive neuroscience, the contributions include both studies aiming at collecting comprehensive data bases for the purpose of relating psychological test results to neurophysiological activation, and studies in fields where methods are less standardized and where the preferred research strategy is to compare brain activation for the same subjects performing the same task under different conditions. <engl.>