Post on 02-Dec-2014
Perceptual OrganizationPerceptual ConstanciesDepth and DimensionPerceptual SetThe World of Illusions
Perception
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Which center circle is larger?
Here are the same circles again.
Gestalt Principles of Visual Perception
Gestalt Principles of Visual Perception
Gestalt – Movement in experimental psychology which began prior to WWI.
We perceive objects as well-organized patterns rather than separate components.
“The whole is greater than the sum of it’s parts.”
Based on the concept of “grouping”.
Gestalt Principles of Visual Perception
We impose visual organization on stimuli
W.E. Hill, 1915 German postcard, 1880
Gestalt Principles of Visual Perception
Illusory Contours
The Kanisza triangle as figure-ground illusory contours
Gestalt Principles of Visual Perception
Three Main Principles:
Grouping (proximity, similarity, continuity, closure)
Goodness of figuresFigure/ground relationships
Gestalt Principles of Visual Perception
Grouping:
Law of Proximity
Gestalt Principles of Visual Perception
Grouping:
Law of Similarity
Gestalt Principles of Visual Perception
Grouping: Law of Similarity: Shape, Scale, Color
Gestalt Principles of Visual Perception
Law of Good Continuation, or Continuity
Objects arranged in either a straight line or a smooth curve tend to be seen as a unit.
Gestalt Principles of Visual Perception
Law of Closure
Gestalt Principles of Visual Perception
Law of Common Fate
Chapter 7 - Perception 18
The Law of Common Fate
Finally, elements of visual perception that move togetherare seen as forming a common object.
This law is best imagined in terms of those animals yousee on nature shows that seem to perfectly blend intotheir background, until they move. Then suddenly theyappear visible.
As an example though ...
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Common Fate Example - 1
Chapter 7 - Perception 20
Common Fate Example - 2
Chapter 7 - Perception 21
Common Fate Example - 3
Chapter 7 - Perception 22
Common Fate Example - 4
Gestalt Principles of Visual Perception
Goodness of Figure, or the Law of Pragnanz
(Pragnanz is German for Pregnant, but in the sense of pregnant with meaning, not with child!)
Gestalt Principles of Visual Perception
Figure/Ground relationships
Figure – seen as the foreground
Ground – seen as the background
Contours – “belong” to the figure
Gestalt Principles of Visual Perception
Reversible Figure/Ground
relationship
Gestalt Principles of Visual Perception
Reversible Figure/Ground
relationship
Can be affected by the principle of smallness:
Smaller areas tend to be seen as figures against a larger background.
Gestalt Principles of Visual Perception
Reversible Figure/Ground
Relationship:
Tessellation – interlocking figure/ground
M.C. Escher
Gestalt Principles of Visual Perception
Gestalt laws of Grouping organize the visual scene into units
The Law of Pragnanz, or Goodness of Figure creates the simplest most meaningful pattern
Figure/Ground relationships define important parts of the scene
Gestalt Principles of Visual Perception
Problems with Gestalt theory:
It is a phenomenological approach
Some of the terms are vague
(e.g. what is the “simplest” organization?)
Drawings that one can perceive in different ways by reversing figure and ground.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Perceptual Organization Reversible Figures
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Proximity Seeing 3 pair of lines in
A Similarity
Seeing columns of orange and red dots in B
Continuity Seeing lines that
connect 1 to 2 and 3 to 4 in C
Closure Seeing a horse in D
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Perceptual Organization Gestalt Laws of Grouping
Geons (geometric icons) are simple 3D component shapes.
A limited number are stored in memory.
Geons are combined to identify essential contours of objects.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Perceptual OrganizationIdentifying Objects
Size Constancy The tendency to view an object as
constant in size despite changes in the size of the retinal image.
Shape Constancy The tendency to see an object as
keeping its form despite changes in orientation.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Perceptual Constancies
Perceptual Constancies The Ames
Room A specially-built room that makes people seem to change size as they move around in it
The room is not a rectangle, as viewers assume it is.
A single peephole prevents using binocular depth cues.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Even though these images cast shadows of different shapes, they still are seen as round.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Perceptual Constancies Shape Constancy
Depth Perception The use of visual cues to estimate
depth and distance. Convergence
A binocular cue involving the turning inward of the eyes as an object gets closer.
Binocular Disparity A binocular cue whereby the closer an
object is, the more different the image is in each retina.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Depth and Dimension
Distance cues that enable the perception of depth with one eye. Relative Image Size Linear Perspective Interposition Atmospheric Perspective Relative Elevation Familiarity
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Depth and DimensionMonocular Depth Cues
Chapter 7 - Perception 39
Depth Perception
In order for us to figure out where an objects is, we need someway of judging depth in our visual environment.
In turns out that we use a fairly large range of cues to helpin our perception of depth, and the fall under two generalclasses.
Some depth information can only be obtained when both eyes are viewing the world … these types of information are termedbinocular cues to depth.
In contrast, monocular cues can be obtained using only one eye.
Chapter 7 - Perception 40
Binocular Cues - ConvergenceBecause the two eyes converge on an object when we areviewing it, the brain can use the angle of convergence as acue to how far away that object is. For example:
The larger the angle, thenearer the object
Chapter 7 - Perception 41
Binocular Cues - Retinal DisparityWhenever we are not focusing on an object, the image of thatobject falls on different points of the two retinas.
The amount of disparity (difference) between the two retinalimages can be used as a cue for distance.
Try holding up two fingers one in front of the other. Focus onthe front one (you should now see two images of the back one).Now move the back one away from, then back towards you, while still focusing on the front one. What happens to the twoimages you see as the back finger moves?
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Monocular Cues - InterpositionWhen one object partially occludes our view of a secondobject, we assume that the first object is closer to us thatthe second.
For example:
Vs.
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Monocular Cues - PerspectiveThings appear to get smaller as they recede into the distanceeven though we know they are not actually getting smaller.
Given this, if the general size ofsome object in the scene is known,the size of the retinal image castby that object can be used to judgeits distance from us.
This can sometimes lead to neat illusions such as the one tothe right.
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Monocular Cues- Shading
We live in a world where our major light sources tend to come from above. As a result, shading has come to be anothersource of depth information such that objects that are shadedlighter on the top are seen as “sticking out towards us”.
Devised by Eleanor Gibson and Richard Walk to test depth perception in infants and animals.
Provides visual illusion of a cliff.
Caregiver stands across the gap.
Babies are not afraid until about the age they can crawl.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Depth and Dimension The Visual Cliff
What is seen in the center figures depends on the order in which one looks at the figures: If scanned from the left, a man’s face is seen. If scanned from the right, a woman’s figure is seen.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Perceptual Set
The same physical stimulus can be interpreted differently depending on perceptual set, e.g., context effects.
When is the middle character the letter B and when is it the number 13?
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Perceptual Set Context Effects
Illusion in which the perceived length of a line is altered by the position of other lines that enclose it
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
The World of Illusions The Müller-Lyer Illusion
Illusion in which the perceived line length is affected by linear perspective cues.
Side lines seem to converge
Top line seems farther away But the retinal
images of the red lines are equal.
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
The World of Illusions The Ponzo Illusion
The Case for ESPThe Case against ESPThe Continuing Controversy
Extrasensory Perception
Extrasensory Perception (ESP) The ability to perceive something
without ordinary sensory information. This has not been scientifically
demonstrated. Parapsychologists distinguish between
three types of ESP: Telepathy – Mind-to-mind communication Clairvoyance – Perception of remote events Precognition – Ability to see future events
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
The Case for ESP
Of course, there is also psychokinesis.
And Levitation Paranormal healing Luminiscent Phenomena (aura) OBE- or sometimes OOBE (An out-of-
body experience )
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
Are they real?
Scientist usually conclude that there is no strong scientific support for these type of phenomena.
Perhaps this is because they defy the establishment in psychology.
Perhaps it is because it is simply a lie… Anyway, there is an amazing instrument
inside our heads that is fascinating enough to start investigating…
J. B. Rhine conducted many experiments on ESP using stimuli such as these.
Rhine believed that his evidence supported the existence of ESP, but his findings were flawed..
Psychology, 4/e by Saul Kassin ©2004 Prentice Hall
The Case against ESPESP Cards
Online tests
http://www.psychicscience.org/esp3.aspx
http://www.psychic-experiences.com/psychic-tests/zener-cards.php
http://www.leotarot.com/test-extrasensorial-percepcion-adivinacion-intuicion-gratis.html
Hallucinations, delusions and illusions
Hallucination: is a perception in the absence of a stimulus. Usually present in severe mental disorder but also in delerium tremens, sleep deprivation and drug use or abuse.
Delusions: an erroneous belief that is held in the face of evidence to the contrary “aliens control my body” “the end of the world is near” “you are cheating on me, the bed is still warm” “I am responsible for last week´s earthquake” “Barak Obama has a crush on me…” “I am Jesus, do you want to be the 13th apostle?” “I have parasites in my eyes, I can see them” “I am the king of England” “The government is conspiring to kill me…”
Illusions:is the mis-perception or misinterpretation of real external stimuli
Example: You recognize a message “hidden” in a
song.
Este tipo de espejismo surge porque las capas de aire junto a la superficie de la Tierra se han vuelto calientes y, por lo tanto, menos densas que las capas más altas. Los rayos de luz junto al suelo se curvan bruscamente hacia arriba y el «agua», que parece mostrar los «reflejos» de objetos distantes, es la imagen del cielo.
Pareidolia
Pareidolia
Pareidolia
http://facesinplaces.blogspot.com/