Chapter 4 Recognizing Visual Objects Pg 117 Flashcards
Object variety
the world contains an enormous variety of objects
*Flexibility, without restrictions
Variable views
Different retinal images that can be projected by the same object or category of objects
Representation
Pattern of neural activity in brain that contains information about a stimulus and give rises to subjective perceptual experience of that stimulus
Recognition
Process of matching the representation of a stimulus to a representation store in long-term memory based on previous encounters with that stimulus or with similar stimuli
Perceptual organization
- Represent edges- abrupt, elongated changes in brightness and/or color
- Represent uniform regions bounded by edges
- Divide regions into figure and ground, and assign border ownership
- Group together regions that have similar properties (e.g. color). Groups consisting of “figure” regions are represented as candidate objects; other groups of regions are represented as background.
- Fill in missing edges and surfaces- that is, edges and surfaces that are partly occluded- to obtain more complete representations of candidate objects.
Object recognition
Use higher-level processes to represent object fully enough to recognize them by matching their representations stored in memory
Figure
Region of an image that is perceived as being part of an object
Ground
Region of an image that is perceived as part of background
Border ownership
Perception that an edge, or border, is “owned” by a particular region of retinal image
Perceptual grouping
Process by which the visual system combines separate regions of the retinal image that “go together” based on similar properties
Perceptual interpolation
Process by which the visual system fills in hidden edges and surfaces in order to represent the entirely of a partially visible object.
Edge extraction
visual system determines the location, orientation, and curvature of edges in retinal image, based on patterns of responses from neurons in area V1, V2, V4-> “What” pathway
Uniform connectedness
Characteristic of regions of the retinal image that have approximately uniform properties.
Depth
Front (Figure)
Back (ground)
Surrounding
surround region (owning borders, figure)
Symmetry
Region with symmetrical borders ->figure
Convexity
Convex borders, outward-bulging region(figures)
Concave, inward-going region (background)
Meaningfulness
Figure-ground organization precedes object recognition
- Regions perceived as figure are meaningful- they correspond to object shapes store in memory
- Recognizes object shapes prior to assignment of border ownership and determination of figure-ground organization
Simplicity
Number and placement of shapes composing image
Proximity
Elements that are close together group more easily than elements that are far apart
*Things that are near to each other are grouped together
Similarity
Similar elements tend to group together
*Similar things are grouped together
Common motion (Common fate)
Elements that move in unison are likely to be perceptually grouped
*Things moving in same direction are grouped together
Symmetry and Parallelism
symmetrical/parallel tend to group together
Good continuation
two edges that would meet if extended are perceived as single edge that has been partially occluded, like the top and bottom edges of horizontal bar.
- Edges that are aligned, or follow the smoothest or straightest path, are seen as part of the same contours.
- Points that, when connected, result in contours. These contours follow the smoothest path.
Synchronized neural oscillations
Those neurons could indicate that the regions belong together by synchronizing their oscillations- by producing clumps of spikes at the same time
*Similarity of orientation, good continuation, common motion