Figure 4.

(A) A 2-by-2 factorial design for independent manipulation of top-down attention and conscious visibility of the stimulus (Watanabe et al., 2011). Subjects are asked to carry out one of two attention tasks while viewing either a visible or invisible target stimulus. At the same time, dependent variables, such as hemodynamic responses in the brain, are measured. Here, we illustrate roughly what participants perceived in each condition (not the physical stimulus) in the study by Watanabe and colleagues. Subjects either had to report the presence of a target letter when it appeared or whether they could see the target grating or not. (B) fMRI responses in V1 is strongly modulated by top-down attention but not by conscious visibility of the grating. Modified based on Figures 2, S2 (n = 7 in total) in (Watanabe et al., 2011). The data was provided by the original author. The area under the curve (7–18 s from the block onset) is normalized to the attended and visible condition. The error bar represents 95% confidence interval.