Published by: Zaya
Published date: 15 Jun 2021
Perceptual illusions are false perceptions. They are the misinterpretations or interpretations of stimuli that do not correspond to the stimulus received by the eye or other senses. For example; the grass looks greener on the other side of the fence. Illusions may occur because of confusion, eye movement, perspectives, emotion, contrast perception, habits, defect of the sense organs, and tendency toward wholes.
Illusions due to physical processes
The illusions are perceived without any existence of the stimulus. Those are things that are not really there. For example; Mirage is an optical illusion in which the image of an object, oasis, or water appears on a dry road. These illusions are something that falsely appears to be real.
Illusions due to cognitive processes
Cognitive illusions occur in the presence of the stimulus but the individual simply misinterprets the situation or the stimulus. Their two categories are:
1. The illusion of size
It occurs because we perceptually distort the length of various lines. Learning also plays an important role in perceiving illusions of size. Examples; Multilayer illusion- both arrowheads and the feather-headed lines are of the same length but the one with feather-headed looks long or bigger.
2. The illusion of shape or area
It suggests that the geometrical stimulus is the other cause to mislead the perception. Examples;
They are abnormal reactions to the perception. They are also regarded as neurotic and psychotic symptoms. The perception is identical to normal persons whereas hallucinations and delusions vary with the individual in illusions.
Delusions are unusual subjectivity-determined beliefs that are out of harmony with an individual’s education and surroundings. It can be classified into:
It is the sensory perception in the absence of external sensory stimuli. For example; an individual hears voices when there is no sound. It is classified into: