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Lecture

PSYCH 1XX3 Lecture Notes - Critical Period, Visual Acuity, Prosopagnosia


Department
Psychology
Course Code
PSYCH 1XX3
Professor
Joe Kim

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Form Perception
Introduction to Form Perception
Form perception – manage to make sense of things so quickly and easily
The Gestalt Philosophy
Gestalt psychologists - studied how people perceive the world around them
oBelieved the whole is greater than the sum of its parts
oBelieved that people perceive the whole stimulus rather than each individual part
oBelieved that people tended to perceive the whole stimulus rather than just
putting together a collection of the stimulus’ discrete parts
The Gestalt movement was in part reaction to the structuralist approach in vogue at the
time, which suggested that everything could be reduced to basic elements
oExample – perception of movement you experience when watching a movie
made by flashing slightly different static pictures every
oExample - Isn’t continuous movement in or across any of these frames
Still perceive continuous movement as we watch the rapid sequence of
still pictures
Motion is an emergent property of the sequence of pictures
The perception of movie in its entirety – including all the complex
movements is more than a collection of still photographs
Would never provide same rich experience that would get from
watching the movie itself
Gestalt Principle – laws that describe how we organize visual input
Proposed laws of organization that described how we group visual input in certain ways
Innate/acquire them rapidly
Six Gestalt Principles:
Figure-Ground
Ability of a visual scene is part of the object itself and what is part of the background
Example – viewing a vase of flowers against a flowery wallpaper

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The Snowman Example
oSmall enclosed region that is completely surrounded by a larger region
(background)
oFigure tend to have distinct borders/edges - give it a perceptible form, is
perceived as being in front of the background, which is typically be formless or
made up of multiple forms
Example – optical illusions(faces and wine glass)
Proximity
Helps with grouping
Elements that are close together in space tend to belong together
Example - more likely to group together the X’s that are close together than the X’s
that are far apart
Example – daisies: regions of high daisy density as one group of daisies because of
their proximity to each other rather than grouping together some daisies from one
cluster with some from another
Closure
If there are gaps in the contours of a shape, we tend to fill in those gaps and perceive a
whole object
Example – broken truck
Example – your eyes will automatically perceive the shape as a rectangle
Similarity
Tendency for us to group together elements that are physically similar
Example – sunflowers vs. corns (groups together vegetation of same type) and
alternating XO’s (rather than grouping row of XOXO, group columns of X’s)
Continuity
Perceive a simple continuous form rather than a combination of awkward forms
Example – the letter X (rather than a combination of two v’s joined in the middle) and the
flower stems in a vase of flowers (continuous line as a stem even though they cross)
Common Fate

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Idea that things that change in the same way should be grouped together
A perception of the group of elements as a kind of object on its own
Example – school of fish
Example – camouflaged moth – moving elements with a common fate allow the contour
of the moth’s shape to be perceived and suddenly, the moth seems to pop out against
the tree
Pattern/Object Recognition
Expectations
What a person expects to see can influence what they do see
Processes of Object Recognition
Preliminary steps in object recognition involve
oIdentifying what aspect of the scene is the figure
oWhat is the background
Once it is established, parts of the figure are identified and grouped together into a
single object
Bottom-Up Processing
Combination of two processes required in order to recognize an object
First is bottom-up processing
oThe features that are present in the stimulus itself guides object recognition
Recognize what you see by analyzing the individual features and comparing those
features to things with similar features that you have in memory
Stimulus driven
Pizza – must eat toppings before you get to crust
oFeatures
Top-Down Processing
Where your own beliefs or expectations are the primary influence for determining what
youre seeing
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