Alice in Wonderland syndrome (AIWS), or micropsia, is a disorienting neurological condition which affects human visual perception.

Sufferers perceive objects (including animals and other humans, or parts of humans, animals, or objects) as appearing substantially smaller than in reality. Generally, the object appears far away at the same time. For example, a family pet, such as a dog, may appear the size of a mouse, or a normal car may look shrunk to scale. This leads to another name for the condition, namely, Lilliput sight or Lilliputian hallucinations. The condition is in terms of perception only; the mechanics of the eye are not affected, only the brain's interpretation of information passed from the eyes.

The syndrome is associated with, and perhaps in part caused by, the classical migraine headache. Occasionally, Alice in Wonderland syndrome is named as one of the first symptoms of mononucleosis. Micropsia can also be caused by complex partial epilepsy, and the actions of various psychoactive drugs (notably dextromethorphan).

Small children, usually between the ages of five and ten, form a large proportion of those afflicted by spontaneous temporary micropsia. Micropsia tends to occur during darkness, when the brain lacks visual size references.

Micropsia does not only affect visual perception, but also one's hearing, sense of touch, and sometimes one's own body image; the syndrome continues even when the eyes are closed. Peripheral symptoms include anxiety, apraxia, and agnosia.

The disorder is named after Lewis Carroll's Alice's Adventures in Wonderland, where the title character experiences many situations similar to those of micropsia and macropsia. Since it is known that Carroll suffered from migraines, there is some speculation that he might have written that work from direct experience.

See also

• macropsia
• metamorphopsia
• visual disorder
• Epstein-Barr virus