Chapter 6 Flashcards
Perception
The process of creating meaningful patterns from raw sensory information
The brain
Sensation
The experience of sensory perception
The eyes
Parts of the eye
Lens
Fovea
Retina
From eye to brain
Information is transmitted from the retina to the brain via the optic nerve
This creates a blind spot
The blind spot has no rods or cones
Rods
Periphery of retina
Sensitive when low levels of light
Night vision
Cones
Central acuity
Color vision
Transduction
Converting light to neural signals
V1
Primary vision cortex
Striate cortex
Retinotopic organization
Basic image of visual field, boundaries
V2
Prestriate Cortex
Foreground & background
Object segregation
Second major area in the visual cortex, functional properties similar to color
V3
Third visual complex
Scientists unsure what it does
Cortical achromatopsia
V4
Color processing
Color constancy
Damage in v4 results in grayscale vision
V5/MT
Motion & movement
Bilateral damage to this region results in akinetopia (seeing the world as still frames)
Traditional color blindness
An inherited gene produces a photo pigment abnormality
Retina damage
Biological motion
Movement by humans and animals
Some patients w/ akinetopia can discriminate biological movement
Object recognition
Categorizing objects based on certain characteristics
“What” route
Temporal lobes (ventral stream)
What is an object?
“Where” route
Parietal lobe (dorsal stream)
Where is an object in relation to me & other objects?
Pathway from eye to brain
Light -> photoreceptors -> bipolar cells -> ganglion cells -> LGN -> visual cortex
Geniculostriate pathway
Goes via lateral geniculate nucleus (LGN) and terminates in striate cortex (V1)
Lateral geniculate nucleus
Thalamus is primary relay center for sensory information
Primary relay center for visual information received from the retina of the eye
LGN receives information directly from the ascending retinal ganglion cells via the optic tract
Neurons of the LGN send their axons through the optic radiation, a pathway directly to the primary visual cortex
LGN
- each LGN contains info from both eyes
- incoming info is segregated into 6 diff.neuronal layers
Parvocellular/ P layers
Upper 4 layers of LGN
Small cell bodies
Respond to detail & color vision
Mangocellular/ M layers
Lower 2 layers of LGN
Large cell bodies
Sensitive to movement
Respond to larger areas of visual field
1st Stage of object recognition
Visual processing involves basic elements such as edges, contrast, and orientations
2nd Stage of object recognition
Grouping these elements into higher order units that code cues and segregate surface into foreground and background
3rd Stage of object recognition
Observed images are then matched to a memory representation of the 3D structure of objects
Final Stage of object recognition
Meaning is attributed to the stimulus and other information becomes available I.e. name
Law of proximity
Visual elements are likely to be grouped if they are closer together
Law of similarity
Elements will be grouped together if they share visual attributes (I.e. Shape, color)
Law of good continuation
Edges are grouped together to avoid changes or interruptions
Law of closure
Missing parts are filled in
Law of common fate
Elements that move together tend to be grouped together
Recognizing faces is different from other object recognition
Inability to recognize previously familiar faces
Color constancy
The color of a surface is perceived as constant even when illuminated in different lighting conditions.
Why do we have on/off center surround cells?
To emphasize borders & boundaries
