The article "Electrical Signs of Selective Attention in the Human Brain" by Steven A. Hillyard, Robert F. Hink, Vincent L. Schwent, and Terence W. Picton, published in *Science* in 1973, investigates the neural mechanisms underlying selective attention. The study uses auditory evoked potentials (AEPs) to measure brain responses to tone pips presented to one ear while ignoring those presented to the other. The results show that the negative component of the AEP, peaking at 80 to 110 milliseconds, is significantly larger for attended tones, indicating a stimulus set mode of selective attention. A late positive component, peaking at 250 to 400 milliseconds, reflects the response set for recognizing infrequent, higher-pitched tones in the attended series. The study provides the first clear evidence that changes in AEP components can specifically reflect selective attention, distinguishing it from nonselective preparatory states. The findings suggest that the N1 component indexes the direction of attention, while the P3 component reflects the selective recognition of specific task-relevant signals. These results support the hierarchical modes of attention described by Broadbent, where a stimulus set preferentially admits sensory input to an attended channel, and a response set facilitates the recognition of specific signals.The article "Electrical Signs of Selective Attention in the Human Brain" by Steven A. Hillyard, Robert F. Hink, Vincent L. Schwent, and Terence W. Picton, published in *Science* in 1973, investigates the neural mechanisms underlying selective attention. The study uses auditory evoked potentials (AEPs) to measure brain responses to tone pips presented to one ear while ignoring those presented to the other. The results show that the negative component of the AEP, peaking at 80 to 110 milliseconds, is significantly larger for attended tones, indicating a stimulus set mode of selective attention. A late positive component, peaking at 250 to 400 milliseconds, reflects the response set for recognizing infrequent, higher-pitched tones in the attended series. The study provides the first clear evidence that changes in AEP components can specifically reflect selective attention, distinguishing it from nonselective preparatory states. The findings suggest that the N1 component indexes the direction of attention, while the P3 component reflects the selective recognition of specific task-relevant signals. These results support the hierarchical modes of attention described by Broadbent, where a stimulus set preferentially admits sensory input to an attended channel, and a response set facilitates the recognition of specific signals.