For neurological purposes we developed a new method for eliciting P300-waves: Using two different kinds of checkerboard stimuli that were randomly flashed on a TV screen we obtained, besides the well-known usable primary complex, prominent PF-P300-complexes consisting of a marked negative potential (= N250), the PFP300a and the N400 peaks. These components could be related to different cognitive processes such as floating versus selective sustained attention and stimulus evaluation. N250 especially was shown to be closely related to different degrees of difficulty in visual discrimination. Further, the PFP300 components are test-retest reliable and sex-independent. Since they have relative small interindividual variabilities, we consider the N250- and PFP300a-latencies especially as well as the ascending PFP300a-amplitudes to be appropriate parameters for investigating diseases with cognitive disorders objectively.