Event-related potential correlates of judgment categories and detection sensitivity in a visual detection task

Event-related potentials were recorded from human subjects performing a visual detection task to find correlates of detection performance (d' and beta) in accordance with the theory of signal detection. Two spatial frequencies of square waves shifted horizontally with three shifting-step varieties were presented to the subjects who reported whether or not the waves were perceived to shift. Although three components of N1, P2, and P3 were observed for all of four response categories of hit, miss, false alarm, and correct rejection, only the amplitudes of the P3 component at vertex and parietal sites highly correlated to the detection sensitivity of d'. It was also found that coefficients of correlation between the P3 amplitudes at these sites and observed hit and false alarm rates were highly significant and a d'-extrapolation value reproduced by the normalized P3 amplitudes and the usual d' indicated a highly linear trend. Results suggest that generation of the P3 component is associated with "threshold-modulating" mechanisms which determine detection sensitivity of a task for each perceptual event.