Object Attention Flashcards
What information is required to identify distal stimuli?
Light sources
Reflectance
Surface orientation
Viewing position
What are primary light sources?
Sun, lightbulb
What are secondary light sources?
Moon, walls
What is surface orientation?
Position of surface causes different amount of light to fall on it/reflect off it
What is viewing position?
Scene appears different from different viewing angles
What is the inverse projection problem?
How do you go from the proximal stimulus to identifying the distal stimulus?
What is underdetermination?
Any 2D image may have many potential 3D sources that created it
What is a contour?
Border between light and dark areas in an image
What is Ganzfeld?
Sensory deprivation developed to test for telepathic communication
Some observers blank out or halluinate
Sharp luminance contours are important for visual system
What are microsaccades?
Minute, involuntary, almost imperceptible eye movements that occur during fixations
Purpose is to change the position of the image on the retina
What did Pritchard find about microsaccades?
Observers wore contact lenses with an attached device and a constant image was projected onto the retina
The image disappeared within 3 seconds so eyes respond best to changing stimuli and a static pattern will quickly fade from view
What are illusory contours?
Contours not present on the retina, still affect contour perception
What are the characteristics of figures?
Appear to be in front
Are smaller
Have well-defined shape
Are meaningful
Have more detail
Differ from background in lightness
What is the law of proximity?
Things near to each other tend to be grouped together
What is the law of similarity?
Similar things tend to be grouped together
What is the law of good continuation?
Points that, if connected, would result in either straight or smoothly curving lines, tend to be seen as belonging together; and lines follow the smoothes path
What is the law of closure?
A space enclosed by a contour tends to appear as a figure
What is the law of common fate?
Things that are moving in the same direction tend to be grouped together
What is the law of meaningfulness/familiarity?
Things that are meaningful or familiar tend to form groups
What is the law of Pragnanz?
Every stimulus pattern is seen in such a way that the resulting structure is as simple as possible
What are the pros of Gestalt?
Holistic approach
What are the cons of Gestalt?
Operates post hoc; not good for predictions
Not good at explanations
Vague definitions
What is recognition?
Perceiving something as previously known
What is identification?
Naming or classifying an object
What are the pros of template theories?
Successfully used by machines
What are the cons of template theories?
Intolerant to variations in a stimulus
Too many templates requires
Cannot handle novel stimuli
Cannot handle context
What are template theories?
Compare input to a model or template stored in memory
Stimulus categorized by exact match
What are the stages of the feature-based theory, Pandemonium?
Stage 1 = image demon gets sensory input
Stage 2 = future demon analyzes input in terms of features
Stage 3 = cognitive demon determines which groups of features are present
Stage 4 = decision demon = identifies pattern by listening to the cognitive demon that is shouting the loudest
What are the pros of feature-based theories?
Feature-detectors physiologically relate to cells in the visual system
Can identify wide range of stimuli - just specify component features
What are the cons of feature-based theories?
Doesn’t define “feature”
Cannot handle Gestalt organizational principles
Cannot handle context
What about 3D objects?
What is the computational approach to object perception?
Multi-stage approach that applies precise mathematical formulas
What is a primal sketch?
Image analyzed to determine primitives like contours and object edges
Is based on natural constraints = universal, consistent properties of the world
What is a 2 1/2 D sketch?
Primitives are grouped via Gestalt principles and processed using depth perception
Structured with reference to the observer’ point of view
What is a 3D model representation?
3D component parts and their relations are determined, and matched to stored knowledge to identify an object
Is independent of viewing point
Only this last stage is available to consciousness
What are the pros of the computational approach to object perception?
Can be highly accurate
Takes world knowledge into account
What are the cons of the computational approach to object perception?
Difficult to identify neural circuits for this processing
What is recognition by components?
There is a BASIS in which a visual scene can be decomposed into basic elements that are constant
Components are called GEONS which are 36 basic volumetric shapes that can be modified but still remain identifiable
What is the principle of componential recovery?
If an object’s geons can be determined, then the object can be identified even if the object is partially obscured
What are the pros of recognition by components?
Has well-defined features
Can handle variation and novel stimuli
What are the cons of recognition by components?
Cannot handle context
May be too broad, objects also differ in their details
Not all 3D objects are easily decomposed into their parts
What is shape constancy?
Perceived shape of an object remains constant despite variations in orientation
Knowledge of depth is important, as is assumption of rigidity
What is objective view?
What is the real shape of the object?
What is projective view?
What is the shape of the image on the retina?
What was Thouless’ experiment?
Observers viewed a circle at different angles
Their task was to match the retinal image with given ellipses
Observers never produced correct projective view; there was always some shape constancy at work
A critical factor in shape constancy is knowing you viewing angle of the object
What was Biderman’s experiment?
Observers cued to a location on a screen and then a scene is presented
The task was to identify object at cued location
The observers did worse identifying familiar items in an impossible location than in an unlikely location or normal location
What is perceptual priming?
Perceiving and identifying an object is affected by previous experience with that object
What is a perceptual set?
Predisposition to interpret a stimulus in a particular way, based on past experience or knowledge
What are schemas?
Mental structures that help us organize the world into a coherent, meaningful whole
Are learned, thus affected by content, culture, and experience
What might you do if you had little exposure to photos?
Misinterpret depth cues in orientation
What is pareidolia?
Illusion or misconception involving a vague or obscure stimulus being perceived as something clear and distinct
-like a face
-used in ink blots
What is telepathy?
Direct mind-to-mind communication
What is clairvoyance?
Perception of distant events, beyond the range of vision
What is precognition?
Perception of future events
What is telekinesis/psychokinesis?
Acting upon objects directly with the mind
What is parapsychology?
The scientific study of phenomena produced by living beings that cannot be explained by known scientific laws and forces
Who established the first lab dedicated to psi?
J.B. Brine
What percent of the population believes in ESP?
41%
