Electrophysiological evidence for temporal dynamics associated with attentional processing in the zoom lens paradigm

Abstract

BackgroundVisuospatial processing requires wide distribution or narrow focusing of attention to certain regions in space. This mechanism is described by the zoom lens model and predicts an inverse correlation between the efficiency of processing and the size of the attentional scope. Little is known, however, about the exact timing of the effects of attentional scaling on visual searching and whether or not additional processing phases are involved in this process.MethodElectroencephalographic recordings were made while participants performed a visual search task under different attentional scaling conditions. Two concentric circles of different sizes, presented to the participants at the center of a screen modulated the attentional scopes, and search arrays were distributed in the space areas indicated by these concentric circles. To ensure consistent eccentricity of the search arrays across different conditions, we limited our studies to the neural responses evoked by the search arrays distributed in the overlapping region of different attentional scopes.ResultsConsistent with the prediction of the zoom lens model, our behavioral data showed that reaction times for target discrimination of search arrays decreased and the associated error rates also significantly decreased, with narrowing the attentional scope. Results of the event-related potential analysis showed that the target-elicited amplitude of lateral occipital N1, rather than posterior P1, which reflects the earliest visuospatial attentional processing, was sensitive to changes in the scaling of visuospatial attention, indicating that the modulation of the effect of changes in the spatial scale of attention on visual processing occurred after the delay period of P1. The N1 generator exhibited higher activity as the attentional scope narrowed, reflecting more intensive processing resources within the attentional focus. In contrast to N1, the amplitude of N2pc increased with the expansion of the attentional focus, suggesting that observers might further redistribute attentional resources according to the increased task difficulty.ConclusionThese findings provide electrophysiological evidence that the neural activity of the N1 generator is the earliest marker of the zoom lens effect of visual spatial attention. Furthermore, evidence from N2pc shows that there is also a redistribution of attentional resources after the action of the zoom lens mechanism, which allows for better perform of the search task in the context of low attentional resolution. On the basis of the timing of P1, N1, and N2pc, our findings provide compelling evidence that visuospatial attention processing in the zoom lens paradigm involves multi-stage dynamic processing.

Behavioural and electrophysiological evidence for the effect of target-distractor separation in a tactile search task

“…When the homogenous distractor was delivered in between the target and the singleton distractor (non-contiguous trials), participants may have broadened their attentional focus attending all the ipsilateral stimuli in order to identify the target frequency and select its location. Evidence from visual search studies has indicated that the amplitude of the N2pc can reflect the size of the attentional focus, with larger N2pc amplitudes when participants were explicitly instructed to broaden their attentional focus to cover a larger portion of visual space (Zhang, Liang, Zhang, Fu & Wu, 2018). Furthermore, increasing the number of task-relevant targets within a visual search array resulted in increased N2pc amplitudes (Pagano & Mazza, 2012).…”

Prolonged neural encoding of visual information in autism

“…Alongside MVPA analysis, with the aim to explore potential differences in the observed effects between univariate (i.e., ERPs) and MVPA techniques of EEG data, we performed univariate ERPs analyses both in cue-and target-locked time windows. Cue-and target-locked ERPs components were identified based on previous literature that investigated the neuroelectric correlates of attentional zooming mechanisms in the TD population (Luo et al, 2001;Fu et al, 2005;Song et al, 2006;Zhang et al, 2018), through visual inspection of the ERPs waveform and topographical scalp maps. Following previous studies, to investigate the modulation of early visual evoked potentials by the scale effect of the spatial attention, P1 and N1 components were calculated, choosing, respectively, time windows of 100-150 ms and 200-250 ms after cue onset (cue-locked analysis; large vs. small cue) and time windows of 140-190 ms and 220-270 ms after target onset (target-locked analysis; target location following large vs. small cue trials).…”

“…Following previous studies, to investigate the modulation of early visual evoked potentials by the scale effect of the spatial attention, P1 and N1 components were calculated, choosing, respectively, time windows of 100-150 ms and 200-250 ms after cue onset (cue-locked analysis; large vs. small cue) and time windows of 140-190 ms and 220-270 ms after target onset (target-locked analysis; target location following large vs. small cue trials). These analyses were computed on the central posterior ROI (for a graphical representation, see Supplementary Figure 2), which was the most representative clusters of electrodes to investigate ERPs components associated to cue-size modulation, based on previous literature (Luo et al, 2001;Fu et al, 2005;Song et al, 2006;Zhang et al, 2018) and to visual inspection of topographical scalp maps. Regarding cue-locked analysis, we performed separated repeated measures ANOVA on the peak latency and mean amplitude, separately, of P1 and N1 components with the aim of testing whether ERPs modulations are influenced by the Cue-Size (within-subjects factor: large and small), using as between-subjects factor the Group (ASD and TD).…”

An EEG Study of the Influence of Target Appearing in the Upper and Lower Visual Fields on Brain Attention Resource Allocation

“…As one of the most important cognitive functions of humans, visuospatial selective attention can focus attention on a certain spatial area and allocate attentional resources rationally during the perception of the visual target. The “spotlight theory” of attention also suggests that attention, like a spotlight, can be “focused” on a region of visual space at any given moment, and only stimuli in this area can be effectively perceptually analyzed [ 1 , 2 ]. However, most stroke patients have spatial attention disorder, so their spatial attention distribution and spatial attention fineness will be affected.…”