[Concepts underlying the analysis of late evoked potentials applied to the study of information processing and its disturbances in psychopathology].

This paper gives a rapid overview of the information processing approach taken when recording and analysing endogenous event-related potentials (ERPs) with psychiatric patients, and its theoretical framework, born from information theory and cognitive psychology. The triarchic model of P 300 amplitude recently proposed by Johnson (1986) is given as an example of a particularly coherent framework that should help determine the various sources of the P 300 amplitude reduction usually observed in psychiatric patients, probably related to the impairment of a number of different processes. The concept of "functional component" is underlined and some examples are given concerning different ERP components reflecting normal and abnormal attention processes of either automatic or controlled mode of processing. The difference between this information processing approach of the cognitive electro-physiologist, aiming at shedding some light on the strategies utilized by patients in order to cope with the experimental situation, and the electro-clinical approach seeking chiefly for a diagnostic, is emphasized.