Perceiving and Recognizing Objects Flashcards
texture segmentation
Carving an image into regions of common texture properties.
global superiority effect
The finding in various experiments that the properties of the whole object take precedence over the properties of parts of the object.
viewpoint invariance
- A property of an object that does not change when observer viewpoint changes. 2. A class of theories of object recognition that proposes representations of objects that do not change when viewpoint changes.
fusiform face area (FFA)
A region of extrastriate visual cortex in humans that is specifically and reliably activated by human faces.
agnosia
A failure to recognize objects in spite of the ability to see them. Agnosia is typically due to brain damage.
homologous regions
Brain regions that appear to have the same function in different species.
recognition-by-components model
Biederman’s model of object recognition, which holds that objects are recognized by the identities and relationships of their component parts.
symmetry
A rule for figure-ground assignment stating that symmetrical regions are more likely to be seen as figure.
congenital prosopagnosia
A form of “face blindness” apparently present from birth, as opposed to “acquired prosopagnosia,” which would typically be the result of an injury to the nervous system.
Necker cube
An outline that is perceptually bi-stable. Unlike the situation with most stimuli, two interpretations continually battle for perceptual dominance.
heuristic
A mental shortcut.
middle (midlevel) vision
A loosely defined stage of visual processing that comes after basic features have been extracted from the image (low-level, or early, vision) and before object recognition and scene understanding (high-level vision).
middle temporal area (MT)
An area of the brain thought to be important in the perception of motion.
structuralism
A school of thought believing that complex objects or perceptions could be understood by analysis of the components.
Bayesian approach
A way of formalizing the idea that our perception is a combination of the current stimulus and our knowledge about the conditions of the world—what is and is not likely to occur. The Bayesian approach is stated mathematically as Bayes’ theorem—P( A|O) = P( A) × P(O| A)/P(O)—which enables us to calculate the probability (P ) that the world is in a particular state ( A) given a particular observation (O).
extrastriate body area (EBA)
A region of extrastriate visual cortex in humans that is specifically and reliably activated by images of the body other than the face.
figure-ground assignment
The process of determining that some regions of an image belong to a foreground object (figure) and other regions are part of the background (ground).
double dissociation
The phenomenon in which one of two functions, such as hearing and sight, can be damaged without harm to the other, and vice versa.
feed-forward process
A process that carries out a computation (e.g., object recognition) one neural step after another, without need for feedback from a later stage to an earlier stage.
Gestalt
In German, literally “form.” In perception, a school of thought stressing that the perceptual whole could be greater than the apparent sum of the parts.
accidental viewpoint
A viewing position that produces some regularity in the visual image that is not present in the world (e.g., the sides of two independent objects lining up perfectly).
parallelism
A rule for figure-ground assignment stating that parallel contours are likely to belong to the same figure.
Gestalt grouping rules
A set of rules describing which elements in an image will appear to group together. The original list was assembled by members of the Gestalt school of thought.
lesion
- (n) A region of damaged brain. 2. (v) To destroy a section of the brain.
structural description
A description of an object in terms of the nature of its constituent parts and the relationships between those parts.
ambiguous figure
A visual stimulus that gives rise to two or more interpretations of its identity or structure.
good continuation
A Gestalt grouping rule stating that two elements will tend to group together if they seem to lie on the same contour.
similarity
A Gestalt grouping rule stating that the tendency of two features to group together will increase as the similarity between them increases.
geon
In Biederman’s recognition-by-components model, any of the “geometric ions” out of which perceptual objects are built.
naïve template theory
The proposal that the visual system recognizes objects by matching the neural representation of the image with a stored representation of the same “shape” in the brain.
prosopagnosia
An inability to recognize faces.
parahippocampal place area (PPA)
A region of extrastriate visual cortex in humans that is specifically and reliably activated more by images of places than by other stimuli.
extrastriate cortex
The region of cortex bordering the primary visual cortex and containing multiple areas involved in visual processing.
inferotemporal (IT) cortex
Part of the cerebral cortex in the lower portion of the temporal lobe, important in object recognition.
relatability
The degree to which two line segments appear to be part of the same contour.
illusory contour
A contour that is perceived even though nothing changes from one side of it to the other in an image.
entry-level category
For an object, the label that comes to mind most quickly when we identify it (e.g., “bird”). At the subordinate level, the object might be more specifically named (e.g., “eagle”); at the superordinate level, it might be more generally named (e.g., “animal”).
surroundedness
A rule for figure-ground assignment stating that if one region is entirely surrounded by another, it is likely that the surrounded region is the figure.
proximity
A Gestalt grouping rule stating that the tendency of two features to group together will increase as the distance between them decreases.
nonaccidental feature
A feature of an object that is not dependent on the exact (or accidental) viewing position of the observer.
