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Perception vs. Reality

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Eric Wieringa

on 16 November 2014

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Transcript of Perception vs. Reality

An optical illusion is characterized by visually perceived images that differ from objective reality. The information gathered by the eye is processed in the brain to give a perception that does not tally with a physical measurement of the stimulus source.

Does an illusion itself disprove an objective reality?

Perception is the act or facility of perceiving. Apprehending by means of the scenes or of the mind; cognition; understanding.

Sensory information is meaningless unless we understand how the information is perceived.
The eye perceives form and color from light.
Our understanding of color and form is determined by both biological and psychological precepts.
Does what we see influence what we believe? or does what we believe influence what we see?

Philosophy of Perception
The philosophy of perception is concerned with the
nature of perceptual experience and the status of perceptual data, in particular how they relate to beliefs about, or knowledge of the world.

This philosophical study of reality is called Ontology, under a larger branch of philosophy called metaphysics.
There are several categories that philosophers distinguish, and explain the perception of objects.
refers to the belief that an explanation can be given of any subject by pointing to things which are internal to the person or their mind which is considering them. (Proponents include: idealists )
Hold that it is things about the world which motivate us, justify our beliefs, determine meaning (Proponents include: direct and indirect realists, skeptics and materialist)
Direct Realism:
is a philosophy of mind rooted in a theory of perception that claims that the senses provide us with direct awareness of the external world.
Indirect Realism:
the philosophical position that our conscious experience is not of the real world itself but of an internal representation, a miniature virtual-reality replica of the world. Indirect realism is broadly equivalent to the accepted view of perception in natural science that states that we do not and cannot perceive the external world as it really is but know only our ideas and interpretations of the way the world
This illusion is known as the Herman Grid
Grey dots appear at the intersection of lines because of the inhibitory response which occurs as a result of the increased dark surround.
The Herman Grid is known as a disappearing effect illusion in which the eye is tricked into seeing something that isn't there.
How do we know it isn't there?
This is known as the Cafe Wall Illusion.
The hor­i­zon­tal lines are straight, even though they do not seem straight. In this illu­sion, the ver­ti­cal zigzag pat­terns dis­rupts our hor­i­zon­tal perception.
In what ways do we determine our external reality?
Are the horizontal lines straight or crooked?
Do you see gray dots where the lines inter­sec­t?
Look at each word and speak out the colors, not the word.
This is known as the color word test.
This chart tests the associations between color and language. The brain tries to identify the colors while another part of your brain reads the word. This regional brain conflict can produce errors in perception.
Do mental associations effect our perception of the world?
Will the man fall into the crevasse?
This images is known as a Trompe l' oeil painting creating the illusion of depth based on the principles of perspective.
You must have a knowledge of reality to prove something is an illusion, but what if we only ever see the illusion?
Does Lincolns face look normal?
This is call a processing illusion.
Some neu­rons in the brain seem spe­cial­ized in pro­cess­ing faces. Faces are usu­ally seen upright. When pre­sented upside down, the brain no longer rec­og­nizes a pic­ture of a face as a face, but rather, as an object.
If our minds are altering visual data, how much correct information do we miss in our daily lives?
What is really real?... Really?
Color is Relative
Joseph Albers was one of the first to theorize the relativity of color. Meaning that our perception of color is altered by surrounding colors and values.
Various contrasts and color relationships change the appearance of color.
The relationship of values, saturation and the warmth or coolness of respective hues can cause noticeable differences in our perception of color.
Our perception of color changes depending on its context, how do we utilize the illusion of color?
Stare at the color dots in the girls nose for 3o seconds, than look away and blink fast.
This is known as an After image.
Negative afterimages are caused when the eye's photoreceptors, primarily those known as cone cells, adapt from over stimulation and lose sensitivity.
The mind uses previous experiences and adapts the negative space to the additive color model.
Does the eye always correctly perceive what really exists?
Are the green squares the same color?
Simultaneous contrast refers to the way in which two different colors affect each other. One color can change the tone and hue of another when placed side by side. The colors themselves don't change, but we see them as altered.
The green squares are the same, but because of their context they appear to intensify and diminish because of surrounding colors.
What other ways can the context of color alter its appearance?
Values appear to change based on mental association between lights and shadow.
Reverse backgrounds
Complements intensify
Is the middle square transparent?
Known as a transparency illusion.
The picture looks like four different colored squares with a transparent folded square on top of them. The transparency is actually just different blocks of color that are just slightly different then their surroundings, placed on top of the squares.
Colors are interacting to create suggestions.
Is color itself an illusion?

The background color "subtracts" itself from the color it surrounds, causing the surrounded color to appear lighter or darker, and sometimes changing the appearance of hue.
Are the horizontal lines straight?
One color looks like two, two colors look like one.
Any color will change appearance when put in proximity of another color.
The grey patches in the colored field are identical. However, there appears to be variations between them. In the next example, the identical blue-violet squares shift color even more dramatically.
You will notice that the colored rectangles of the background between the two samples show a change in intensity. The colored squares interact with their colored backgrounds, creating a perceived difference between the backgrounds of the samples.
Dark colors and dark values look darker when exhibited against light colors and light values, and visa verse.
The difference between each hue pair is in the luminance/lightness measurements, one is lighter than the other is. For instance, when comparing the light blue squares, the one on the left will appear lighter. When comparing the dark yellow squares show the one on the right to appear darker.
Any color will influence an adjacent color’s hue in the direction of its own compliment.
An adjacent color will be pushed toward the other colors direct compliment. Above, the light blue bars tend toward the compliment of the field color. The bar in the orange field picks up a slight bluish tint while the bar in the green field picks up a slight reddish tint.
Any color will appear to gain intensity, and appear lighter, when exhibited against a black ground.
To get the most intensity from a color, show it on a black background. To reduce the intensity of colors, show them on a white background. A mid grey background is used to show the image off in a neutral manner.
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