Over the last several decades, spatial attention has been shown to influence the activity of neurons in the visual cortex in a number of different ways. These observations have inspired different theories of how attention influences perception and behavior. We used measures of brain activity (electroencephalography or EEG) to assess steady-state visual evoked potentials (SSVEPs) in human subjects. Our data show that different patterns of neural modulation do not reflect fundamentally different neural mechanisms, but instead reflect changes in how people distribute their attention. This finding confirms predictions made by the normalization model of attention (NMA) that changes in the size of the stimulus and the distribution of attentional focus explain neural responses in visual cortex.
