Event-related potentials in a lexical stroop task.
In a reaction time (RT) situation the subjects made word/non-word decisions to strings of four letters. The original strings could be either words or non-words when read from left to right. Decisions were made for strings resulting when reading the letters in a different sequence specified on each trial. The 'non-word' RT was longer than the 'word' RT, and RT increased further when the (correct) non-word decision was made to strings which constituted a word in the (traditional) left to right order. Event related potentials (ERPs) following the strings were more negative on the left side (the onset of the negativity was approx. 240 ms). Motor reactions were preceded by an epoch (700-300 ms before the response) where the ERPs of trials with stimulus/response conflict were relatively positive. However, the negativity preceding the response (motor potential) appeared to be independent of the stimulus/response conflict. 'Word' responses were preceded and followed by a positive wave, independent of the motor potential. This positivity is considered to be a very late member of the P3 complex related to lexical memory processes.
Czigler
I
I
Institute for Psychology of the Hungarian Academy of Sciences, Budapest.
Csibra
G
G
D000328:Adult; D003071:Cognition / Q000502:physiology; D004566:Electrodes; D004585:Electrooculography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology