Visual Illusions

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Visual Illusions
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Visual Illusions
Definition Illusions occur when what we see does
not correspond to what is physically present in
the world
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Brightness After Effect
Please Stare for a while
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Colour After Effect
Please Stare for a while
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Negative Colour After Images

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Motion Contrast
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The Zöllner Illusion (Orientation Contrast)
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The Zöllner Illusion (Orientation Contrast)
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Size-Distance Relationship
Object size is inferred from perceived distance
and retinal image size If 2 objects have the
same retinal image size (i.e., are the same real
size), the object appearing further away is seen
as larger
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Size-Distance Relationship
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The Ponzo Illusion
Gregorys theory The visual system makes
hypotheses about distance to objects based on
evidence in the image. Interpretation of size
follows.
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Müller-Lyer Illusion
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Müller-Lyer Illusion
Objectively equal in separation, perceptually
different
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Müller-Lyer Illusion
Perceptually equal in separation, objectively 30
different
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Müller-Lyer Illusion
Perspective cues set up false interpretations of
distance
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Ames Room
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Ames room
Ames room sets up false distance cues Objects
that are different distances appear the same
distance
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Reversible Figure and Ground
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Necker cube
Look at the red dot It can be either on a near
corner or a far corner
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Ambiguous figures
Old woman looking down/young woman looking away
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Ambiguous figures
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Ambiguous figures
Rabbit
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Ambiguous figures
Duck
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How many dolphins?
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Penrose Triangle
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Eschers prints
The brain cannot compute 3-D structure from all
parts at once, each part looks plausible in
isolation
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Eschers prints
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The Thatcher Illusion
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This is the same stimuli but 1 looks more strange
than other