This fMRI study investigated top-down letter processing with an illusory letter detection task. Participants responded whether one of a number of different possible letters was present in a very noisy image. After initial training that became increasingly difficult, they continued to detect letters even though the images consisted of pure noise, which eliminated contamination from strong bottom...

If we are to understand how human perception occurs, then we must first identify the mechanisms that drive perception. It is commonly believed that perception is influenced by both bottom-up processes (raw sensory input), and top-down processes (expectationdriven matching). What is not fully understood is how the human mind uses expectations and assumptions to manipulate what we call conscious ...