Relationships between stimulus intensity and amplitude of visual and auditory event related potentials

Event related potentials were recorded from subjects presented with separate trains of lights and tones of three intensity levels (75, 240 and 750 fl and 60, 77 and 95 dB respectively). The auditory P1-N1 and N1-P2 components increased linearly with loudness, whereas in visual evoked responses, these components were maximal at an intermediate brightness. There was no correlation between responses to the two modalities. The results are examined in relation to current theories of cortical stimulus processing.