Ponzo illusion

Much confusion is present about this including many references to a paper that Ponzo published in 1911 on the Aristotle illusion.

One of the explanations for the Ponzo illusion is the "perspective hypothesis", which says that the perspective feature in the figure is produced by the converging lines ordinarily associated with distance; the two oblique lines appear to converge toward the horizon or a vanishing point.

However, prior visual experience seems mandatory to perceive it as demonstrated by the fact that congenitally blind subjects are not sensitive to it.

The Ponzo illusion has been used to demonstrate a dissociation between vision-for-perception and vision-for-action (see Two-streams hypothesis).

[6] In other words, the opening between the index finger and thumb is scaled to the real not the apparent size of the target object as the grasping hand approaches it.