Errors in Perception//Illusion And Hallucination//Educational Psychology//Tnteu B.ed

                                                      

Errors in Perception

Perception may not be always correct and it may go wrong. When a stimulus is interpreted correctly it is called perception and if it is wrongly interpreted it is called misperception or error in perception. 

Errors in perception occur due to internal or external, known or unknown reasons.

There are two types of errors in perception namely

• Illusion 
• Hallucination

Similarity: Both illusion and hallucination are perceptual disturbances. 

Differences:

Illusion	Hallucination
Illusion is a false perception or perception in a wrong manner of a real object. In illusion the person perceives an object differently than it is actually.	Hallucination is a false perception or wrong perception, in the absence of any object. There is no object present, but it is the person who perceives that there is some object
In illusion, there is some external stimulus that is to be seen or heard, but the impression received by the person concerned is misinterpreted.	When there is hallucination, an individual is seen in complete darkness or hears some voices when there is no sound at all.
Illusion means “that which does not really exist”.  Hence illusion is a wrong perception.  Optical illusion can be quoted as an example.	It is only a sense experience in the absence of appropriate external sensory stimuli. Hence it is a misinterpretation based on imaginary experience as real perception.

 Examples of Illusion

• Seeing a rope as a snake is visual illusion. 
• But if one hears the voice of a person without seeing him and comes to a conclusion that the voice is a friend’s voice.  It is auditory illusion.

Muller -Lyer Illusion:

The Muller-Lyer illusion is based on the Gestalt principles of convergence and divergence. It consists of two sticks, one framed by closed fins and one framed by open fins. After seeing the illusion, viewers usually estimate that the stick with two open fins is longer, even though the sticks are actually the same length.

                    
Horizontal Vertical line illusion:

The misperception that vertical lines are longer than horizontal lines when both are actually the same length.

The vertical element of an upper-case letter T, for example, looks longer than the cross bar, even when the lengths are identical.

                Hallucination:

Example when a person sees someone in room but in reality, nobody is the in the room.