Fill in the blank with an appropriate option.

Illusions are usually related with _______ processes.

visual

The correct option to fill in the blank is visual.

Illusions are usually related with visual processes, as they are caused by the way our brains interpret images. For example, the Müller-Lyer illusion is a visual illusion that makes two lines of equal length appear to be different lengths. This is because our brains interpret the arrows at the ends of the lines as pointing inwards or outwards, which changes the way we perceive the length of the lines.

The other options are not as appropriate:

• Audio illusions are illusions that are caused by the way our brains interpret sound. For example, the Shepard tone is an audio illusion that creates the perception of a continuously rising or falling tone, even though the tone is actually repeating at a fixed frequency.
• Oratory illusions are illusions that are created by the way our brains interpret language. For example, the McGurk effect is an oratory illusion that makes us perceive a different sound than the one that is actually being spoken.
• Digital illusions are illusions that are created by digital technology. For example, the checker shadow illusion is a digital illusion that makes us perceive a checkerboard pattern as having a shadow, even though there is no shadow in the actual image.