Sensation & Perception: Vision Flashcards
Parts of the Eye
Cornea Pupil Iris Lens Retina
Cornea
The clear, dome-like window in the front of the eye. It gathers and focuses on incoming light.
Pupil
The hole in the iris. It contracts in bright light and focuses on incoming light.
Iris
The colored part of the eye. It has involuntary muscles and autonomic nerve fibers. It also control the size of the pupil, therefore the amount of light entering the eye.
Lens
Lies right behind the iris. It helps control the curvature of the light coming in and can focus near or distant objects on the retina.
Retina
The back of the eye and is filled with neural elements and blood vessels. It detects images.
Duplicity Theory of Vision
The idea that retina have 2 kinds of photoreceptors. Cones and Rods
Cones
A photoreceptor that see color and fine detail. They are most effective in bright light.
Rods
A photoreceptor that do well in low light and black and white images
Fovea
A point in the retina that contains only 1 cone. Moving away from the fovea, there are more rods than cones. You can see detail straight on and peripheral vision is blurrier.
Neurons between the Photoreceptors and the Optic Nerve
Horizontal
Amacrine
Bipolar Cells
Ganglion Cells
Path from Photoreceptors to Optic Nerve
Rods and Cones are respectfully connected to BIpolar Cells and a group of Bipolar Cells are connected to the Ganglion Cells. Layers of Ganglion Cells become the Optic Nerve.
Visual Pathway
- Optic Chiasm
2. Disperse Visual Information
Optic Chiasm
When the nasal fibers (the fibers closest to the nasal) cross paths and the temporal fibers (the fibers closest to the temples) don’t cross paths. Both fibers arrive in different regions of the brain to deliver the information.
Regions of the Brain for Visual Processing
Lateral Geniculate Nucleus of the Thalamus
Visual Cortex of the Occipital Lobe
Superior Colliculus
Hubel & Wiesel
Discovered Feature Detection Theory
Feature Detection Theory
The idea that certain cells in the cortex are maximally sensitive to certain features of stimuli.
3 Different Types of Cells
Simple
Complex
Hypercomplex
Simple Cells
Give information about orientation and boundaries of objects
Complex Cells
Give more advanced information about orientation such as movement
Hypercomplex Cells
Give information about abstract concepts such as object shape.
Single Cell Recording
A research method that involves placing a microelectrode in the cortex so sensitive that it could record responses of a single cell.
Illumination
A physical objective measurement that is simply the amount of light falling on a surface.
Brightness
The subjective impression of the intensity of a light stimuli.
Factors to Measuring Brightness
Adaptation
Simultaneous Brightness Contrast
Dark Adaptation
A type of adaptation where the light “bleached” the rods when entering a dark space. The rod only have one photopigment that must adjust to the darkness.