Chapter 5 Flashcards
What is the inverse projection problem?
The task of determining the object responsible for a particular image on the retina because it involves starting with the retinal image and extending rays out from the eye
What parts of object identification do machines struggle with?
Blurred images and objects looked upon from a different angle
What is viewpoint invariance?
The ability to recognize an object seen from different viewpoints
Difficult for computers
What is perceptual organization?
The process by which elements in a person’s visual field become perceptually grouped and segregated to create a perception
What is grouping?
The process by which elements in a visual scene are put together into coherent units or objects
What is segregation?
The processing of separating one area or object from another
What is apparent movement?
Movement that is perceived even though nothing is actually moving
What are the components of apparent movement?
One light flashes, there is a short period of darkness and another flash
We don’t see the darkness and instead interpret an image moving through the space between the flashing lights
What did Wertheimer draw from the apparent movement phenomenon?
Apparent movement cannot be explained by sensations alone
The whole is different than the sum of its parts because the perceptual system creates perception of movement when there is actually none
What are illusory contours?
Seeing edges when there are no actual physical edges present
What is the principle of common fate?
Things that are moving in the same direction appear to be grouped together
What is the principle of common region?
Elements that are within the same region of space appear to be grouped together
What is the principle of uniform connectedness?
A connected region of the same visual properties, such as lightness, color, texture, or motion, is perceived as a single unit
What is figure-ground segregation?
Figures tend to stand out from the background
What is a reversible figure-ground?
An image that can be viewed two ways
What are figural cues?
Cues within an image that determine which area are perceived as a figure
What did Vecera’s experiment conclude?
That there is a preference for seeing objects lower in the display as a figure
How did Gestalt ideas feel about the role of meaning in determining figure-ground segregation?
It plays a minor role in perception
The figure must stand out from the ground before it can be recognized, this must happen before we can assign meaning
What did Gibson’s and Peterson’s experiments show?
Picture that can perceived one of two ways: black area = woman, white area = meaningless figure
More likely to say the meaning of the image is a standing woman = meaning plays a role in perception
What is the recognition by components theory?
Objects that are comprised of individual geometric components called geons, and we recognize objects based on the arrangement of those geons
What are geons?
3D shapes
36 of them
What does recognition by components theory not account for?
Grouping or organization, some objects simply cannot be represented by assemblies of geons
Doesn’t allow for distinguishing between objects within a given category
What is a scene?
A view of a real-world environment that contains background elements and multiple objects that are organized in a meaningful way relative to each other and the background
How can we distinguish between objects and scenes?
Objects are compact and acted upon
Scenes are extended in space and are acted within
What is the gist of the scene?
The ability to identify the most important properties of scenes very rapidly
How long does it take to perceive the gist of a scene?
About 250 ms
What is persistence of vision?
The perception of a visual stimulus continues for 250 ms after the stimulus is extinguished
What is the point of masking?
A random pattern covers a stimulus so the image is only perceived for the desired time
Solution for the persistence of vision
What are global image features?
Features that are perceived rapidly and are associated with specific types of scenes
Holistic = properties of the scene as a whole and do not depend on time-consuming processes
Contain information about a scene’s structure and spatial layout
What are some examples of global image features?
Degree of naturalness
Degree of openness
Degree of roughness
Degree of expansion
Colour
What are regularities in the environment?
Characteristics of the environment that occur frequently
What are physical regularities?
Regularly occurring physical properties of the environment
What is the light-from-above assumption?
We assume light is coming from above because most light (the sun, artificial light) comes from above
What are semantic regularities?
Characteristics associated with activities that are common in different types of scenes
What did Helmholtz propose?
The theory of unconscious interference
What is the likelihood principle?
We perceive the object that is most likely to have caused the pattern of stimuli we received
What is unconscious interference?
Our perceptions are the result of unconscious assumptions, or interferences, that we make about the environment
What is Bayesian inference?
Our estimate of probability is determined by prior probability and the likelihood of the outcome
What is prior probability?
Our initial estimate of the probability of an outcome
What is predictive coding?
A theory that describes how the brain uses our past experiences to predict what we will perceive
Where is the lateral occipital complex?
In the ventral pathway of the brain
When does the lateral occipital complex activate?
When a person views any kind of object
Activates regardless of their size, orientation, position, or other basic features
Does not differentiate between types of objects but plays a role in object perception
What is the fusiform face area?
Area of the brain that responds to faces
What does damage to the fusiform face area cause?
Prosopagnosia = difficulty recognizing faces
What does the extrastriate body area respond to?
Responds to pictures of bodies and parts of bodies but not to faces or other objects
What does the parahippocampal place area respond to?
Responds to places but not faces or objects
What is the spatial layout hypothesis?
Proposes that the PPA/PHC responds to the surface geometry or geometric layout of a scene
What is binocular rivalry?
When the two eyes receive totally different images, the brain cannot combine the two images and the observer can perceive the left-eye image or the right-eye image but not both
What is neural mind reading?
Refers to using a neural response (fMRI), to determine what a person is thinking or perceiving
What is multivoxel pattern analysis?
The pattern of activation across multiple vowels
The pattern depends on the task and the nature of the stimulus being perceived
What is a decoder?
A computer program that can predict the most likely stimulus based on the voxel activation patterns observed in the calibration phase
What is the expertise hypothesis?
The idea that our proficiency in perceiving faces, and the large phase response in the FFA, can be explained by the fact that we have become experts in perceiving faces because we have been exposed to them for our entire lives
