Based on the hierarchical activation model (Haider et al., 1982) the impact of brain DC potentials on performance and ERPs analysed. Twenty-two persons participated in a 40 min lasting cognitive task. Performance was determined on the basis of response times of four 10 min epochs and persons were grouped as quick and slow responders by cluster analysis. The resting DC potential was more negative in persons with a quick response time than in slow responders independent of location indicating some evidence of the impact of a general energetic level (activation) on performance. The slow positive component (SPC) of the event-related potential (ERP) was enhanced in quick responders which was interpreted as a sign of motivation and/or attention. While cognitive information processing, as indicated by SPC, was not affected by task preceding slow potential shifts (pSPS) in quick responders, slow responders showed a prolonged information processing time after specific pSPS indicating an unsteadiness or irregularity of information processing depending on phasic activation changes. Results suggest that cognitive performance is related to the resting DC potential as well as to the impact of pSPS on the SPC which may be seen as an electrophysiological sign of some energetic aspects of information processing often discussed in terms of attention and motivation.