If the acoustic stimulus is preceded by an optic stimulus, the latencies and amplitudes preceding optic signal elicits a differentiated or diffuse attention to the acoustic stimulus (pistol-shot or click). The parallel and inverse changes of the parameters of the startle blink and the ACER are observed. The differentiated attentive process reduces the latency and amplitude of the peak N1. In all conditions there is a positive correlation between the amplitude of the peak N1 and the subjective startle response (verbal report).