I'm struggling with your concept of "literal perception" vs. what people think they perceive. Or is it possible that this work suggests a different way of thinking about perception? That "literal perception" is not a useful way of thinking about how stimuli are interpreted, and that the process of creating interpretations of the sensory world does not involve a "literal perception" step? Perhaps beliefs don't affect "literal perception" because it just refers to the earliest stages of handling stimuli, and that they do affect later stages of interpretation. Then we assign special significance to early stages as "literal perception" because they seem so tightly constrained to us whereas cognition seems less constrained.
Is it possible that the way we intuitively assume perception to work may be what is misleading rather than the role of expectancy and belief on perception?
Read the Article at HuffingtonPost