Sensory and Motor Systems: Visual System Flashcards
Whether we’re searching for food or scanning the millions of colors displayed by a computer monitor, the process of vision begins with ____.
light
the energy we can see, is one form of electromagnetic radiation produced by the sun.
Visible light
the distance between successive peaks of waves, is decoded by the visual system either as color or as shades of gray.
Wavelength
refers to the height of each wave, which is translated by the visual system as brightness.
Amplitude
Individual, indivisible, very small particles that form waves of electromagnetic energy.
Photons
can also be described as the movement of tiny, indivisible particles known as photons.
Electromagnetic radiation
Electromagnetic radiation can also be described as the movement of tiny, indivisible particles known as ______.
photons
Photons always travel at the same speed (the so-called speed of light), but they can ________.
vary in the amount of energy they possess
The range of electromagnetic energy visible to humans falls between ________.
400 and 700 nanometers (nm)
The ability to retain something rather than reflect or transmit it to another location.
absorption
The bending back of light toward its source.
reflection
The deflection, or changing of direction, of light at a boundary such as that between air and water.
refraction
_____ and _____ determine the colors we see.
Absorption, reflection
The color of an object is not some intrinsic characteristic of the object but, rather, the result of the wavelengths of light that are ______ and ________ by the object.
selectively absorbed, reflected
clothing keeps us cooler because materials perceived as white or _______ reflect more electromagnetic energy.
Light-colored
clothing keeps us warmer because these materials absorb more electromagnetic energy.
Dark-colored
Visual System
Line of Defense
Orbit of the skull
Eyelids
Blink
Tears
can deflect many blows
Orbit of the skull
can be opened and closed either voluntarily or involuntarily.
Eyelids
Involuntary closure of the eyelids protects the eye from incoming objects and moistens and cleans the front of the eye.
Blink
another feature of the eyes’ protective system, are produced in the lacrimal gland at the outer corner of each eye.
Tears
The fluid is composed primarily of _____ and ____ but also contains proteins, glucose, and substances that kill bacteria.
water, salt
Tears flush away ____ and ____ and _____ so that the eyelids don’t scratch the surface during blinks.
dust, debris, moisten the eye
The “white” outer covering of the eye.
sclera
The transparent outer layer of the eye.
cornea
The area of the eye located directly behind the cornea, containing aqueous humor.
anterior chamber
The fluid located in the anterior chamber that nourishes the cornea and lens.
aqueous humor
The opening in the front of the eye controlled by the iris.
Pupil
The circular muscle in the front of the eye that controls the opening of the pupil.
Iris
The clear structure behind the pupil and iris that focuses light on the retina.
lens
The elaborate network of photoreceptors and interneurons at the back of the eye that is responsible for sensing light.
retina
Specialized sensory cell in the retina that responds to light.
photoreceptor
The fiber pathway formed by the axons of the ganglion cells as they leave the eye.
optic nerve
The area in the retina where blood vessels and the optic nerve exit the eye.
optic disk
A 6 mm round area in the retina that is not covered by blood vessels and that is specialized for detailed vision.
macula
The ability to perceive visual stimuli focused on the macula of the retina.
central vision
The ability to perceive visual stimuli that are off to the side while looking straight ahead.
peripheral vision
A small pit in the macula specialized for detailed vision.
fovea
The pigmented layer of cells supporting the photoreceptors of the retina.
epithelium
2 types of Photoreceptors
Rods, Cones
A photoreceptor that responds to low levels of light but not to color. Responsible for scotopic vision, or the ability to see in dim light.
Rods
A photoreceptor that operates in bright conditions and responds differentially to color. Cones are responsible for photopic vision, or vision in bright light.
Cones
is the process of translating a physical stimulus into electrical signals that can be understood and processed by the nervous system.
Transduction
is usually defined as the obtaining of information from the environment and the transmission of that information to the brain.
Sensation
involves the interpretation, or meaningful analysis, of sensory data.
Perception
considered to be the primary colors of light.
Red, Green, and Blue
suggests that human color vision is based on our having three (tri) different color photopigments.
Trichromacy theory
A theory of human color vision based on three antagonistic color channels: red-green, blue-yellow, and black-white.
opponent process theory
(having two cone photopigments) is the most common type of abnormality and results from a missing or abnormal cone pigment. Because genes for the red and green photopigments appear on the X chromosome, this type of dichromacy is sex-linked, Men are about ten times more likely to be colorblind than women
Dichromacy
The ability to see in black and white only.
monochromacy
A condition characterized by having three cone photopigments that respond to slightly different wavelengths than normal.
anomalous trichromacy
people with four different color pigments (Neitz, Kraft, & Neitz, 1998). These individuals match colors in a manner that would be predicted by their having four color pigments rather than three.
tetrachromats
describes the fact that an object’s colors do not appear to change even as the light falling on that object changes.
Color constancy
Lazy eye, or _____, occurs when one eye cannot focus on objects.
amblyopia
result from clouding of the lens of the eye.
Cataracts
Difficulty seeing distant objects. Elongation of the eyeball
Myopia (nearsightedness)
Difficulty seeing close objects, reading. Shortening of the eyeball.
Hyperopia (farsightedness)
A distortion of vision caused by the shape of the cornea.
astigmatism
