Lecture 5 Flashcards
define Sensation
Energy from the environment is absorbed by a sensory organ (e.g., your
eyes; your ears) and converted to a neural impulse
define Perception
The sensed information (neural impulse) is interpreted as something meaningful by the brain
is everyone susceptible to the mcgurk effect
no
what is different between people who are and are nor susceptible to the mcgurk effect
¤ Compared brain activity for people who experienced the McGurk effect and those people who did not experience this effect
¤ The left superior temporal sulcus is important for audiovisual integration during speech perception and is more active for people who experienced the McGurk effect
¤ Individual differences are seen in the brain
what is Akinetopsia
World is like a series of snapshots (motion pathway (dorsal) is damaged)
Damage to the visual processing areas (the what pathway) of the brain that result in selective problems recognizing what
objects
what is Visual agnosia
Damage to the visual processing areas (the what pathway) of the brain that result in selective problems recognizing objects
with Visual agnosia, are brain systems intact
yes– Supports a dissociation between being able to see visual
features and interpreting those visual features
what is damaged with Visual agnosia
The specific area of the brain that is damaged determines which types(or features) of objects cannot be recognized
¤ Supports higher level functional specialization
what is Prosopagnosia
¤ A form of visual agnosia
¤ An inability to recognize faces while still
being able to recognize other visual objects
where is the damage to the brain in Prosopagnosia
Damage to fusiform face area
what are some Subtypes of Prosopagnosia
¤ Problem perceiving faces
¤ faces look contorted
¤ Problem attaching meaning to faces
¤ faces cannot be identified
what are the causes of Prosopagnosia
¤ Acquired (brain injury) ¤ Congenital (genetic)
what is Apperceptive visual agnosia
A failure recognizing objects due to problems perceiving objects
is Apperceptive visual agnosia a deficit in sensory processing
no
¤ Visual features can be detected
¤ The ability to copy a line drawing is intact
what is the main problem with Apperceptive visual agnosia
A problem grouping visua lfeatures into something meaningful
whats Associative visual agnosia
An inability to associate visual forms (what you see) with the intended meaning (Inability to determine if an visual object is a possible or impossible object such as a lion with wings)
with Associative visual agnosia, cannot access memories of objects leads to problems such as
¤ Drawing objects from memory ¤ Naming objects
¤ Indicating the functions objects
do illusions provide evidence for topdown or bottom up processing
Evidence that top-down processing support vision¤ Since information is lost as it moves from the eyes to the brain, we
have to use pre-existing knowledge to help guess what you are seeing ¤ Schemas or Heuristics
was JJ Gibson against or for the idea of top down processes needed for vision
Against the idea that ‘top-down’ processes are
needed for perception
what did JJ Gibson argue
Argued that there is enough information in our visual environment to perceive
¤ We don’t have to ‘transform’ sensory information
what approach did jj gibson take to perception
A passive bottom-up approach to perception
¤ Information from the visual environment (the bottom – light arrays) guides perception
what are Gibson’s View: Two points
¤ Information that directs perception (cues) is in real-world environment, so perception must be studied in the real world
¤ The match between a person’s action and the environment will determine perception
gibson believed “Cues in the ‘optic array’ (visual input) determine what we see” what are the 3 main optic array
¤ Texture gradients
¤ Topological breakages
¤ Scatter-reflection (i.e., how widely light scatters)
explain Texture gradients
The density of a texture (gradient) carries information about orientation and distance of an object
¤ In this ‘rug’, the circles that appear closer together (denser) are those that are farther apart
explain Topological breakages
¤ When two textures intersect
¤ Discontinuity
¤ Signals edges between objects
¤ Important for defining objects
explain Scatter reflection
How widely light scatters off an object’s surface provides cues about the nature of the objects surface
Smooth surface: Light is less scattered
Rough surfaces: Light will scatter more widely
Gibson’s View: Perception and action interact, explain this
We perceive based upon to-be-carried out actions or functions of an object
according to Gibson’s View, we perceive based upon to-be-carried out actions or functions of an object– what re these determined by
affordances
what are affordances
¤ Visual cues in our environment
¤ Perceived directly and immediately
¤ Provides information on the potential function of an object
according to gibson, we ‘see’ based on what
We ‘see’ based on what we can/need to do in the environment
we need a slot and we know to put something in it
what is Visual object recognition
Perception involves processing basic visual elements of an input that are added up for object recognition
what are the two types of visual object recognition
¤ Passive views
¤ Gibson’s view
¤ Active views: Pattern recognition
¤ We compare patterns from visual input to patterns in our mind (memory) ¤ Incorporates top-down processing
what is Pattern recognition theories
Identifying something (a pattern) as an instance of a category
Find a pattern in visual input and match it to existing patterns
¤ Like scanning a bar code
¤ How is this pattern recognition happening
what are the patter recognition theories
¤ Template-based approaches ¤ Prototype-based approaches ¤ Feature-based approaches
how do patern recognition theories work
We must recognize configurations from the environment
¤ A percept (visual input) has to mingle with our memories to be able to
recognize an object
what is Template matching theory
Match the pattern you see to templates of previous objects you have encountered that is stored in memory
what are the problems with template matching theory
¤ We can recognize new objects that don’t match a template ¤ We can recognize objects from different viewpoints
¤ Inefficient
what is Prototype theory
Compare the configuration of the current visual input with prototype
¤ Allows for ‘flexible’ object identification
¤ A good enough match (resemblance) can support object recognition
what is a prototype:
The average representation of the object in memory
formed from what is common among all encountered instances
what is an issue with prototype theory (experiment that identified it)
¤ Participants studied a series of faces related to a prototype face
¤ Did NOT study the prototype
¤ Participants completed a recognition memory test that included the studied faces, the prototype face, unstudied faces
¤ People remembered the studied faces and they falsely remembered studying the prototype face
whats Feature detection theories
¤ W first decompose what we see into a set of features
¤ A simple element that can appear in combination with other visual elements to
form objects
¤ We then match this set of features to feature sets stored in memory.
what model is associated with Feature detection theories
Selfridge’s (1959) pandemonium model
what are the levels of Selfridge’s pandemonium model
bottom
middle
top
what is the key feature of selfeidges pandemonium model
demons
what is the bottom level of selfeidges pandemonium model
Bottom level: data or feature demons ¤ Individual features are represented
what is the middle level of selfeidges pandemonium model
¤ Middle level: cognitive demons
¤ Detects particular patterns of features ¤ If detected the demon ‘shouts’
what is the top level of selfeidges pandemonium model
¤ Top level: decision demons
¤ Selects the ‘loudest’ cognitive demon to identify an object
how does feature detection work on the brain level
¤ Similar to the primary visual cortex which has special cells/areas for processing different visual features (color, lines, etc.)
¤ Parallel processing: Performs many computations at once rather than in serial order
what is Recognition by components a combination of
Combination of feature theory and prototype theory
what is the essence of Recognition by components
¤ All objects are reducible to a set of basic geometric shapes: geons
¤ 36 three-dimensional shapes that can be combined to form any object
according to Recognition by components, Recognizing an object involves what
¤ Mentally separate the object into geons
¤ Comparing the geon arrangement with existing memory representations
what are Geon properties
¤ View invariant and high discriminability
¤ Geons can be identified when viewed from different perspectives or angles
¤ Geons have distinct properties that we can perceive from any angle/view/perspective
¤ Resistant to Noise
¤ We can recognize objects that are covered up if we can see the geons
what re strength of Recognition by components
Accounts for how we are able to recognize objects from different viewpoints and in visual noise
what re weaknesses of Recognition by components
In general, object recognition theories emphasizes bottom- up processing
Recognition by components says we use top down or bottom up processing?
We use top-down processes to recognize objects based on our context
what is Top-down processing in perception
Context, knowledge, and expectations are used to guide visual perception, especially when things are ambiguous
¤ This means our knowledge and thoughts flow down and affect perceptual processing (top-down
what are some common top down processing proofs
¤ A functional illusion: Ames Room
¤ Letter in Context
¤ Color in Context
what is Ames Room
An example of a functional illusion: When expectations used to perceive
how is the ability to read works even when the letters are mixed up an example of top down processing
The ability to read words in sentences even when the letters in the middle of some of the words are mixed up
¤ You expect to see real words in a sentence
¤ Letters in correct positions of jumbled words help with word recognition
You can stlil raed this senetnece even thuogh lettres in the wrods are jubmled.
explain hw Perceiving ‘color’ in context is a top down process
Color perception depends on the wavelengths of light that fall on our retina AND on our past experiences of how objects look under different illumination conditions
what is th Gestalt approach to perception
¤ The whole that is perceived is greater than the sum of its parts ¤ Top-down processing is essential for perception
¤ Holistic versus piecemeal (atomistic) approach to perception
what are bistable figures
gestalt– an image that can take on 2 different images depending on who and how you look at it
what are the six Gestalt organizing principles
- Principle of experience
- Principle of proximity
- Principle of closed forms
- Principle of good contour
- Principle of similarity
- Principle of common movement
what is Principle of experience
We perceptually organize items so that there is an object in the foreground known as
From: www.mitologica.com.br/joomla/images/gestalt/gestalt%20(1).gif and www.nwlink.com/~donclark/
hrd/history/gestalt.gif.
the figure and everything else as the background
what is Principle of proximity
Objects or features that are close to one another in a scene will be judged as belonging together
what is Principle of closed forms
We see a shape in terms of closed forms and we like to see items that enclosed as whole
what is Principle of good contour or continuation
We perceive objects as continuous in cases where it is expected that they
continue
what is Principle of similarity
We organize objects or features of a scene based on similarity
what is Principle of common movement
We group objects together that move together
what is Principle of emergence (not one of gestalts main 6)
things can blend really well but we can see the object if we look hard enough
