PSYCH 1XX3 Lecture Notes - Lecture 9: Brain Injury, Retina, Microelectrode
Form and Perception 1
Gestalt Principles
The Gestalt Philosophy
- The whole is greater than the sum of its parts
o 1920s and 1930s, German psychologists
o Believed that people perceive the whole stimulus rather than each individual part
o A reaction to the structuralist approach (everything could be reduced to basic elements)
- Example: A movie is a collection of still pictures
o There aren’t continuous movements in the frames, but we still perceive continuous motion
o Motion is an emergent property of a sequence of pictures
- Gestalt Principles: Laws that describe how we organize visual input
o 1. Figure-Ground
▪ The ability to distinguish an object from most background in a visual scene
o 2. Proximity
▪ The tendency to group elements that are close together in space
▪ We are more likely to group objects that are closer together than far apart
o 3. Closure
▪ The tendency to fill in gaps in a contour to perceive a whole object
o 4. Similarity
▪ The tendency to group together elements that are physically similar
o 5. Continuity
▪ The ability to perceive a simple, continuous form rather than a combination of awkward
forms
o 6. Common Fate
▪ The tendency to group elements that change in the same way
Pattern/Object Recognition
Expectations shapes what we see
Processes of Object Recognition
- Establishing figure from background is the first step to object recognition
o Top-down processing and bottom-up processing work together to influence object recognition
o Bottom-Up Processing
▪ Object recognition is guided by the features that are
present in the stimulus
▪ Involves comparing every feature (physical
categorization) to memory
o Top Down Processing
▪ Object recognition is guided by your own beliefs or
expectations
▪ Recognition can be primed in top-down processing.
Processing of a word is more efficient if the participant is primed to expect the word of a
certain category
▪ Top-down processing need some input form the stimulus to work
o Bidirectional Activation
▪ Using past experiences and things from the present
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- Theories of Object Recognition
o Object recognition can rely on varying degrees of processing
o Biederman’s Geon Theory
▪ Theory suggests that we have 36 different geons, or
simple geometrical forms, stored in memory. We use
these 36 forms to recognize over 150 million objects
▪ Cons
• Its difficult to imagine the geons used in more
complicated objects
• Brain injury can affect recognition for only certain types of objects. They could
recognize tools but not fruits
• A weakness of the theory is that slight changes in lighting conditions make it
difficult to discern geons necessary for object identification.
o Template Theory
▪ Suggests that we store many different templates in memory, and when we come across an
object, we compare that object to all the templates in memory. If a match is found, then
it’s a familiar object and the person could name it by activating connections to brain. If
the object is unfamiliar then a new template is formed.
▪ Cons: too many different stimuli exist to store in memory
o Prototype Theory
▪ We store the most ideal example of an object, the perceived average. More flexible since
you don’t need an exact match. Likely that we have more than one type of representation
for each object
▪ Prototype theory helps overcome the storage problem of the template theory, as an exact
match is not required when comparing novel objects to examples.
▪ Cons: we can categorize bizarre objects seen only once
- Parallel Processing
o Much of the neural processing of object information is done in parallel, so different brain
systems process stimuli simultaneously
o No theory can precisely explain why we can process objects
Perceptual Constancies
We retain perceptual constancy despite variation in visual stimuli
Perceptual Constancy
- Our ability to perceive an object as unchanging even though the visual image produced by the object is
constantly changing
- 1.Shape Constancy
o An object is perceived to have a constant shape despite the shape of its retinal image changing
with shifts in point of view or change in object position
- 2. Location Constancy
o An object is perceived to be stationary despite changing location on our retina due to our body
movements
- 3. Size Constancy
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Example: a movie is a collection of still pictures: there aren"t continuous movements in the frames, but we still perceive continuous motion, motion is an emergent property of a sequence of pictures. Gestalt principles: laws that describe how we organize visual input: 1. Figure-ground: the ability to distinguish an object from most background in a visual scene, 2. Proximity: the tendency to group elements that are close together in space, we are more likely to group objects that are closer together than far apart, 3. Closure: the tendency to fill in gaps in a contour to perceive a whole object, 4. Similarity: the tendency to group together elements that are physically similar, 5. Continuity: the ability to perceive a simple, continuous form rather than a combination of awkward forms, 6. Common fate: the tendency to group elements that change in the same way.
