Akademik

A false perception; the mistaking of something for what it is not. [L. illusio, fr. il- ludo, pp. -lusus, to play at, mock]

- i. of doubles SYN: Capgras syndrome.

- i. of movement successive stimulation of neighboring retinal points which causes the sensation of movement.

- oculogravic i. apparent movement of the visual field when the body is subjected to acceleration; due to gravity.

- oculogyral i. an i. occurring in angular acceleration in which the position of fixed light appears to drift.

- optical i. a false interpretation of the color, form, size, or movement of a visual sensation.

il·lu·sion il-'ü-zhən n

1) a misleading image presented as a visual stimulus

2 a) perception of something objectively existing in such a way as to cause misinterpretation of its actual nature esp OPTICAL ILLUSION compare DELUSION (2)

b) HALLUCINATION (1)

c) a pattern capable of reversible perspective

il·lu·sion·al -'üzh-nəl, -ən-əl adj

a false perception due to misinterpretation of the stimuli arising from an object. For example, a patient may misinterpret the conversation of others as the voices of enemies conspiring to destroy him. Illusions can occur in quite normal people, when they are usually spontaneously corrected. They may also occur in almost any psychiatric syndrome, especially depression. Compare hallucination.

Optical illusions are perceptions that do not agree with the actual object in the external world. They are produced by deceptive qualities of the stimulus and are in no way pathological.