Abstract
Covert attention aids us in monitoring the environment and optimizing performance in visual tasks. Past behavioral studies have shown that covert attention can enhance spatial resolution. However, electroencephalography (EEG) activity related to neural processing between central and peripheral vision has not been systematically investigated. Here, we conducted an EEG study with 25 subjects who performed covert attentional tasks at different retinal eccentricities ranging from 0.75° to 13.90°, as well as tasks involving overt attention and no attention. EEG signals were recorded with a single stimulus frequency to evoke steady-state visual evoked potentials (SSVEPs) for attention evaluation. We found that the SSVEP response in fixating at the attended location was generally negatively correlated with stimulus eccentricity as characterized by Euclidean distance or horizontal and vertical distance. Moreover, more pronounced characteristics of SSVEP analysis were also acquired in overt attention than in covert attention. Furthermore, offline classification of overt attention, covert attention, and no attention yielded an average accuracy of 91.42%. This work contributes to our understanding of the SSVEP representation of attention in humans and may also lead to brain-computer interfaces (BCIs) that allow people to communicate with choices simply by shifting their attention to them.
Highlights
Our eyes are constantly subjected to a complete image of the visual world that contains large amounts of information than we can process at once
To investigate the subjects’ state visual evoked potentials (SSVEPs) response with eccentricity under different visual angles, we compared the relationship between the synthetic correlation parameter ρ and both the horizontal distance (Figure 4) and vertical distance (Figure 5)
The subjects generated similar characteristics of SSVEPs
Summary
Our eyes are constantly subjected to a complete image of the visual world that contains large amounts of information than we can process at once. One mechanism that limits these processing resources to the most relevant aspects of the environment is selective attention, which optimizes our visual processing through trade-offs in which the representations of attended locations or features of our environment are enhanced, while those of unattended locations or features are diminished. This attention can be further categorized as overt when we move our eyes to a relevant location and the focus of attention coincides with the movement of the eyes or as covert when attention is deployed to a relevant location without accompanying eye movements (Carrasco and Yeshurun, 2009). It has been shown that information about visual targets accrues faster at attended than at unattended locations (Carrasco and McElree, 2001; Carrasco et al, 2006)
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