Mechanisms of selective attention in adults and children as reflected by evoked potentials to warning stimuli

Abstract

Components of evoked potentials to stimuli differing in size and warning about the necessity of subsequent recognition of an image at the global or local level were analyzed to identify the specific features of selective attention in adults and seven-year-old children. In both age groups, components were found that were related to selective attention aimed at processing a warning stimulus (the P1, N1, and P2 components) and producing a response to the subsequent test stimulus. Both age groups exhibited similar dependences of changes in the P1 component (40–110 and 110–220 ms in the adults and children, respectively) on the type of the warning stimulus. The children displayed a greater increase in the amplitude of the P1 component of the response to the global versus the local key than the adults did. The P1 component is suggested to reflect not only the sensory features of the stimulus but also the selective attention associated with its sensory processing. The amplitude of the P2 component of the response to the global key (190–240 and 330–410 ms in the adults and children, respectively) was higher in both age groups. This component is believed to indicate evaluation of the signal importance of the warning stimulus. In the adults, late components of event-related potentials (ERPs), i.e., P3-N3 (300–450 ms), were associated with the global or local level of recognition of a test hierarchical stimulus that was presented after the key, with the greatest differences in the central and posterior associative areas of the right hemisphere and in the frontocentral areas of the left hemisphere. In the children, the N3 component (530–600 ms) in the left parietal area, as well as the late ERP phases, i.e., Ps (680–950 ms) and Ns (1030–1130 ms), during which the frontal cortical areas are involved in preparing the subsequent response, was shown to depend on the type of the warning stimulus.