Muller Lyer Illusion

 

Introduction

The Müller-Lyer illusion is an optical illusion consisting of three stylized arrows. When viewers are asked to place a mark on the figure at the midpoint, they invariably place it more towards the “tail” end.It falls into the class of distortion illusion, specifically, this illusion disorts perception of size (Lyer, 1889). A variation of the same effect (and the most common form in which it is seen today) consists of a set of arrow-like figures. Straight line segments of equal length comprise the "shafts" of the arrows, while shorter line segments (called the fins) protrude from the ends of the shaft. The fins can point inwards to form an arrow “head” or outwards to form an arrow "tail". The line segment forming the shaft of the arrow with two tails is perceived to be longer than that forming the shaft of the arrow with two heads.

Illusion 

            An illusion is a distortion of the sense, which can reveal how the human brain normally organizes and interprets sensory stimulation. Though illusions distort reality, they are generally shared by most people.

Types of Illusion

·         Optic illusion

·         Auditory illusion

·         Tactile illusion

·         Visual illusion

Optical Illusion

An optical or visual illusion is a kind of illusion in which the images perceived through the sense of sight tend to be misleading or deceptive, causing errors in perception. An optical illusion is based on the process through which the brain creates a visual world in one's mind using either or both these two sources: previous memory stored in it and the current presentation of the object in the environment(Sincero, 2013)

Auditory Illusion

While optical illusions deceive the eyes through visual images, auditory illusions mislead the ears through sounds. These sounds are usually those that are not really present in the physical stimulus, but is heard by the ears and perceived as a sound related to the stimulus in the environment. There are also auditory illusions that come from "impossible sounds", such as hearing a missing fundamental frequency, provided that there are other portions of the harmonic series, and different psychoacoustic tricks of lossy audio compression (Sincero, 2013).

Tactile Illusion

While optical and auditory illusions are common manifestations of several psychological disorders such as schizophrenia and psychosis, tactile illusion is experienced by patients who have undergone amputation. The phantom limb is a tactile illusion wherein the patient still 'feels' pain on the leg, arm, or digit that has already been removed (Sincero, 2013).

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