EEG correlates of different ways of information processing in response selection

The lateralized readiness potential as a measure of response tendencies has become a relevant method in experimental psychology within the last decade. This measure delivers information about response preparation long before the overt response. Applying the method of measuring event-related lateralizations (ERL) of the EEG to posterior sites, correlates of processing of spatial information and of response selection have been found. The present study investigated the topographical distribution of asymmetries at the moment of response selection. Response selection was assumed to be reflected in a discrete peak of parietal asymmetries. At this time point two distinct topographies were found that might reflect two different types of information processing. If response selection was based on spatial information a parieto-occipital maximum was found. In contrast, if centrally presented symbolic stimuli were used for response selection, lateralizations were largest at central (motor areas) and at parietal sites.