The majority of vision specialists concur that newborn infants briefly experience the world as being upside-down. Although the precise duration of this is unknown, some people think it only lasts a few hours.
This phenomenon is caused by the fact that the retina of the human body really records an image that is reversed from what the eye perceives. It is believed that newborn infants have a short period of time to get used to the fact that the eye must learn the mechanism by which the image is flipped right-side up in the brain.
A disorder known as “Print Inverted Reading,” or “PI Reading,” affects some people and causes them to be able to read only when the text is placed upside-down. It is believed that the eye is unable to correctly process the image as a result.