The study by Hillyard, Hink, Schwent, and Picton (1973) investigates the electrical signs of selective attention in the human brain. Using auditory evoked potentials, they recorded responses from subjects listening selectively to tone pips in one ear while ignoring those in the other. The negative component (N1) of the evoked potential was significantly larger for attended tones, indicating a stimulus set mode of selective attention. A late positive component (P2) reflected response set processing for infrequent, higher-pitched tones in the attended series. These findings suggest that selective attention is associated with distinct neural mechanisms, with N1 reflecting attentional direction and P2 indicating response preparation. The study also highlights the role of selective attention in filtering sensory input, allowing individuals to focus on relevant auditory information in a noisy environment. The results demonstrate that changes in evoked potential components can specifically reflect selective attention rather than nonselective preparatory states. The experiments involved randomized sequences of tone pips presented to both ears, forcing subjects to focus on one ear at a time. The N1 component was significantly larger for tones in the attended ear, indicating that selective attention enhances neural responses to attended stimuli. The study contrasts with earlier research that failed to show significant effects of selective attention on N1. The current findings suggest that selective attention involves two distinct processes: a stimulus set that favors one ear over the other and a response set that facilitates recognition of specific task-relevant signals. These processes are supported by the differential effects on N1 and P2 components, with N1 reflecting attentional direction and P2 indicating response preparation. The results have implications for understanding the neural mechanisms underlying selective attention and its role in processing sensory information.The study by Hillyard, Hink, Schwent, and Picton (1973) investigates the electrical signs of selective attention in the human brain. Using auditory evoked potentials, they recorded responses from subjects listening selectively to tone pips in one ear while ignoring those in the other. The negative component (N1) of the evoked potential was significantly larger for attended tones, indicating a stimulus set mode of selective attention. A late positive component (P2) reflected response set processing for infrequent, higher-pitched tones in the attended series. These findings suggest that selective attention is associated with distinct neural mechanisms, with N1 reflecting attentional direction and P2 indicating response preparation. The study also highlights the role of selective attention in filtering sensory input, allowing individuals to focus on relevant auditory information in a noisy environment. The results demonstrate that changes in evoked potential components can specifically reflect selective attention rather than nonselective preparatory states. The experiments involved randomized sequences of tone pips presented to both ears, forcing subjects to focus on one ear at a time. The N1 component was significantly larger for tones in the attended ear, indicating that selective attention enhances neural responses to attended stimuli. The study contrasts with earlier research that failed to show significant effects of selective attention on N1. The current findings suggest that selective attention involves two distinct processes: a stimulus set that favors one ear over the other and a response set that facilitates recognition of specific task-relevant signals. These processes are supported by the differential effects on N1 and P2 components, with N1 reflecting attentional direction and P2 indicating response preparation. The results have implications for understanding the neural mechanisms underlying selective attention and its role in processing sensory information.