# The Gestalt Theory of illusions

• Gestalt Theory of Illusions
• Evaluating the Gestalt Theory of illusions - it provides a good explanation for ambiguous figures. However, it cannot explain any distortions other than the Muller-Lyer illusion. The Gestalt Theory can explain fictions well, although there is a problem - it suggests that we use closure to see it as a whole even though there are parts missing, if we did, we see a six pointed star. But we dont, we see two triangles. The theory seems to use different explanations at different times.
• When explaining fictions - (e.g. Kanizsa Triangle), a 'brighter than white' triangle is perceived in the middle even though the edges of the shape are not physically there.
• Illusions like the Kanizsa Triangle can be explained using the Gestalt Theory. When we see a figure which is incomplete, our perception makes a 'whole' shape using closure. We complete the edges to make regular or familiar shape. This is the 'figure' of the figure-ground relationship.
• In the case of the Kanizsa Triangle, the arrow heads, 'bitten' circles and the space around them become the ground. The triangle illusion changes if the circles are replaced with dots -  then we see two interlocking triangles. Similarity organises the dots and lines and continuity joins the lines to form a triangle.
• Explaining distortions - it can explain the Muller-Lyer distortion illusion. The Muller-Lyer illusion still works when the 'fins' are replaced with circles. This suggests that in perceiving the figure as a whole, we tend to 'add' the fins or circles to the central lines.
• When the fins and circles extend beyond the central line, stretching the whole figure out, it makes the central line look bigger.
• Explaining ambiguous figures -  we identify an object as the 'figure' and we separate it from the 'ground'. If we encounter a situation where something could either be the figure or the ground, it becomes ambiguous, so we see an illusion.
• Rubins Vase illusion - according to the Gestalt Theory, this is an illusion because we cannot tell whether the black or the white area is the figure
• The Gestalt Theory can account for ambiguous figures - e.g. the Leepers Lady illusion. The problem is that there are two alternative figures. Because they are made up of the same parts of the stimulus they cannot be seen at the same time. The perception has to be organised differently to see each face.
• The Gestalt Theory suggests that 'The whole is worth more than the sum of the parts'.