Chapter 4: Perceiving and Recognizing Objects Flashcards
extrastriate cortex
The region of cortex bordering the primary visual cortex and containing multiple areas involved in visual processing.
lesion
In reference to neurophysiology,
- (n) A region of damaged brain.
- (v) To destroy a section of the brain.
agosia
A failure to recognize objects in spite of the ability to see them. Agnosia is typically due to brain damage.
inferotemporal (IT) cortex
Part of the cerebral cortex in the lower portion of the temporal lobe, important in object recognition.
homologous regions
Brain regions that appear to have the same function in different species.
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.
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).
illusory contour
A contour that is perceived even though nothing changes from one side of it to the other in an image.
structuralism
A school of thought believing that complex objects or perceptions could be understood by analysis of the components.
Gestalt
In German, literally “form”. In reference to perception, a school of thought stressing that the perceptual whole could be greater than the apparent sum of the parts.
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.
good continuation
A Gestalt grouping rule stating that two elements will tend to group together if they seem to lie on the same contour.
closure
In reference to perception, closure is the name of a Gestalt principle that holds that a close contour is preferred to an open contour.
texture segmentation
Carving an image into regions of common texture properties.
similarity
A Gestalt grouping rule stating that the tendency of two features to group together will increase as the similarity between them increase.
proximity
A gestalt grouping rule stating that the tendency of two features to group together will increase as the distance between them decreases.
parallelism
A rule for figure-ground assignment stating that parallel contours are likely to belong to the same figure.
symmetry
A rule for figure-ground assignment stating that symmetrical regions are more likely to be seen as figure.
ambiguous figure
A visual stimulus that gives rise to two or more interpretations of its identity or structure.
Necker cube
An outline that is perceptually bi-stable. Unlike the situation with most stimuli, two interpretations continually battle for perceptual dominance.
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.)
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).
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.
relatability
The degree to which two line segments appear to be part of the same contour.
heuristic
A mental shortcut.
nonaccidental feature
A feature of an object that is not dependent on the exact (or accidental) viewing position of the observer.
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.
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) x 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).
subtraction method
In functional magnetic imaging, brain activity is measured in two conditions: one with and one without the involvement of the mental process of interest. Subtracting the two conditions shows regions of brain specifically activated by that process.
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.
fusiform face area (FFA)
A region of extrastriate visual cortex in human that is specifically and reliably activated by human faces.
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.
naive template theory
The proposal that the visual system recognizes object by matching the neural representation of the image with a stored representation of the same “shape” in the brain.
structural description
A description of an object in terms of the nature of its constituent parts and the relationships between those parts.
geon
In Biederman’s recognition-by-components model, any of the “geometric ions” out of which perceptual objects are built.
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.
viewpoint invariance
- A property of an object that does not change when observer viewpoint changes.
- A class of theories of object recognition that proposes representations of objects that do not change when viewpoint changes.
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”).
prosopagnosia
An inability to recognize faces.
double dissociation
The phenomenon in which one of two function, such as hearing and sight, can be damaged without harm to the other, and vice versa.
congenital prosopagnosia
A form of “face blindness” apparently present from birth, as opposed to “acquired prospagnosia,” which would typically be the result of an injury to the nervous system.
