There are no qualia. The phenomenological difference between seeing and visualizing something is that the propositions which the experient begins to believe in the first case are only entertained in the second. We can know what it's like to be a bat by knowing that their echolocation informs them non-inferentially of the shapes, sizes, and directional distances away of nearby surfaces. The terms for secondary qualities like colours, though, are names of the type-properties they designate, tracing back causally to a verbal ‘baptism,’ and so experients don't know the character of colour experiences until they study brain physiology.
