Frank Tong and colleagues superimposed a house onto a face and asked participants to make judgments about what they saw. What were the participants' brain responses?
(a) The brain noticed both equally, meaning that eventually everything becomes conscious.
(b) The unconscious brain became confused, and thus the participants were unable to see either the house or the face.
(c) The brain emitted large slow-wave activity equally for both images.
(d) The brain activity changed depending on whether participants reported seeing a house or a face.