Chapter 5 Flashcards
Why Is It So Difficult to Design a Perceiving Machine
Stimulus on the receptors is ambiguous
Inverse projection problem
image on the retina can be caused by an infinite number of objects
The ability to recognize an object seen from different viewpoints is called
viewpoint invariance
Perceptual organization:
process by which elements in a person’s visual field become perceptually grouped and segregated to create a perception
Grouping:
elements in a visual scene are “put together” into coherent units or objects
Segregation:
separating one area or object from another
The process of perceptual organization involves two components:
grouping and segregation
Structuralism was established by
Established by Wilhelm Wundt
Structuralism distinguished between:
sensations — elementary processes that occur in response to stimulation of the senses— and
perceptions, more complex conscious experiences such as our awareness of objects(how we put those sensations together)
Gestalt psychologists proposed
that ____ depends on a number of principles of perceptual organization, which determine how ___ in a scene
become grouped together
perception, elements
Gestalt Principles of Perceptual Organization
Proximity, Common fate, Common region, Uniform connectedness
Proximity:
things that are near to each other are grouped together
Common fate:
things moving in the same direction are grouped together
Common region:
elements in the same region tend to be grouped together
Uniform connectedness:
connected region of visual properties are perceived as single unit
Figure-ground relationship
Organize scenes to a central figure (focus) and a background
Humans are good at focusing on figures
Perceptual constancies:
stable perceptions amid changing stimuli
Size
Shape
Brightness
Hue
Location in space
Properties of figure and ground
The figure is more “thinglike” and more memorable than the ground
The figure is seen in front of the ground
The ground is more uniform and extends behind figure
The contour separating figure from the ground belongs to the figure (border ownership)
Perceiving the Gist of a Scene
Figures are more likely to be perceived on the convex side of borders
Built-in principles can override experience
Segregation of figure from ground
Gibson and Peterson experiment
Figure-ground formation can be affected by the meaningfulness of a stimulus
principle of pragnanz, also called
the principle of good figure or the principle of simplicity
principle of pragnanz
Every stimulus pattern is seen in such a way that the resulting
structure is as simple as possible
A scene contains
Background elements
Objects organized in meaningful ways with each other and the background
A scene contains
Background elements
Objects organized in meaningful ways with each other and the background
recognition by components
(RBC) theory
objects are comprised of individual geometric components called geons, and we recognize objects based on the arrangement of
those geons.
Difference between objects and scenes:
A scene is acted within
An object is acted upon
Global image features are____and ____perceived
holistic , rapidly
global image features
Degree of Naturalness
Degree of Openness
Degree of Roughness
Degree of Expansion
Colour
Physical regularities
Regularly occurring physical properties of the environment
E.g., more vertical and horizontal orientations in the environment than oblique (angled) orientations
Light-from-above assumption
global image features is that
they contain information about a scene’s ____ and _____
structure, spatial
layout
light-from-above assumption
we usually assume that light is coming from above, because light in the environment, including the sun and most artificial light,
usually comes from above
One of the reasons humans are able to perceive and recognize
objects and scenes so much better than computers
our perceptual system is adapted to respond to physical characteristics of our environment, such as the orientation of objects and the direction of light.
Helmholtz’s Theory of Unconscious Inference
Intended to explain why stimuli can be interpreted in more than one way
Retinal ambiguity:
pattern of stimulation on the retina can be caused by many different possible objects in the environment
Likelihood principle:
objects are perceived based on what is most likely to have caused the pattern
Unconscious inference:
our perceptions are the result of unconscious assumptions, or inferences, that we make about the environment
Estimate of probability of an outcome determined by
Prior probability, Likelihood of the outcome
Prior probability
Our initial estimate of the probability of an outcome
Likelihood of the outcome
Extent to which the available evidence is consistent with the outcome
Predictive coding is a theory that describes
how the brain uses our past
experiences—or our “priors,” as Bayes put it—to predict what
we will perceive
LOC is active when
person views any kind of object—such as an animal, face, house, or tool—but not when they view a texture, or an object with the parts scrambled
Does not differentiate between different types of objects
damage in the fusiform face area (FFA)
Damage to FFA can result in prosopagnosia
prosopagnosia
difficulty recognizing the faces of familiar people, although they can easily identify such people as soon as they hear them speak
Parahippocampal place area (PPA):
located in temporal lobe
Responds to places, but not objects or faces
The first step in understanding corollary discharge theory
is to consider the following three signals associated with
movement of the eyes
motor signal (MS)
corollary discharge signal (CDS)
image displacement signal (IDS)
