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PS262 Study Guide - Midterm Guide: Binocular Rivalry, Inattentional Blindness, Visual Search

Course Code
Elizabeth Olds
Study Guide

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October 6, 2012
Chapter 5: Object Perception
Perceptual Organization
Grouping: gestalt approach
o Strucutalism
Add up perception of each bit of scene to get perception of while scene
o Gestalt
The whole is more than the sum of its parts
Perception of one part of stimulus depends on the nature of other parts of
Not purely bottom-up
Whole vs. sum of parts
Laws of perceptual organization
o Grouping of elements in an image to create larger objects
o Good continuation
Points that when connected result in straight or smooth curving lines are seen
as belonging together, lines tend to be seen a way as to follow the smoothest
o Proximity
Things that are near each other appear to be grouped together
o Common Region
o Uniform Connectedness
o Synchrony
o Common Fate
o Meaningfulness
Perceptual Segregation
o Problem of figure-ground segregation
When we see a separate object, it is usually seems a and figure that stands out
from its background which is called the ground
o Reverse figure ground
Perceiving image as two different ways
o Regions in the lower part of a display are more likely to be seen as figures that in the
Recognition-by- Components theory
o How do we recognize objects ?
o Our recognition of objects is based on features called geons

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o NAPs (non-accidental properties)
Properties of edges in the retinal image that correspond to the properties of
edges in the three-dimensional environment
Edges that are only seen from certain viewpoints
o Principle of Componential Recovery
Identify objects even when parts of the objects are hidden by other objects
Based on small number of geons
o Naturalness
o Openness
o Roughness
o Expansion
o Colour
Regularities of the Environment
o Physical regularities
Regularly occurring physical properties of the environment
o Semantic
Meaning of a scene
Characteristics associated with the functions carried out in different types of
Theory of Unconscious Inference
o Some of our perception are the result of unconscious assumptions we make about the
o Account for our ability to create perceptions from stimulus information that can be seen
in more than one way
Likelihood Principle
o We perceive the object that is most likely to have caused the pattern of stimuli we have
Contextual Modulation
o The effect of stimuli that fall outside of the neuron`s receptive fields bg
o Similarity
o Meaningfulness
Problems with gestalt
o Laws describe, don’t predict
What happens when two conflict
o Simplicity
o Similarity
Overall contribution
o Pay attention to overall stimulus pattern
o Doesn’t explain mechanisms of how visual system groups portions

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Perceptual Figure-ground segregation
o Transition from perceptual grouping to perceptual segregation
o Depends on object recognition
Neurons and
o Perceptual groping
Neural response to grouping by
Similarity of orientation
Good continuation
Response is affected by stimuli outside of its RF
o Figure-ground segregation
Early neural representation = affected by overall context
Identifying the Object
What object has produced this portion of the retinal image
Recognition by Components
o Recognize 3-D object by decomposing image of object into its basic Components
o Binocular rivalry
Perception alternating between 2 images
o Report of perceptual experience and activity in the brain are correlated
Apparent Movement
o No movement, just two stationary stimuli flashing on and off
Chapter 6:Attention
o Places where the eyes pause to take in information about specific parts of the scene
o Lines connecting the dots are eye movements called saccades
o About 3 per second
o People fixate on few objects that were irrelevant to the task and that eye movements
and fixations were closely linked to the actions they were about to take
Stimulus Salience
o Characteristics of the environment that stand out because of physical properties such as
as colour, brightness, contrast, or orientation
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