Chapter 3 Sensation and Perception Flashcards
Sensation
The response of sensory receptors in the sense organs of stimulation and the transmission of that information to the brain
The Retina
Thin membrane lining back of the eyeball; Contains the sensory receptors for vision, the rods and cones
Photoreceptors
Sensory receptors cells that respond to light. Rods and cones are examples
Rods and Cones
Rods cells are much more sensitive to light than cones. Cones cells are sensitive to the different wavelengths that produce the sensation of color. Cones cells are also specialized for seeing fine details.
Fovea
Most of the cones are concentrated in the fovea, which is a region in the very center of the retina.
Optic Nerve and the blind spot
Optic Nerve - The thick nerve that exits from the back of the eye and carries visual information to the visual cortex in the brain.
The blind spot - The point at which the optic nerve leaves the eye, producing a small gap in the field of vision.
Structure of the eye
Cornea, Iris,, Pupil, Lens, Retina, Fovea
Color Vision
Color vision is the ability of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect, emit, or transmit.
Additive Color Mixture
There are 3 primary colors. RGB. When combined, they become white.
Trichromatic Theory of Color Vision
Human eyes can only detect 3 colors. Red, Green, and Blue. When a color other than those strike the retina, it will stimulate a combination of cones.
Afterimages
Afterimage is the visual experience that occurs after the original source of stimulation is no longer present.
Opponent-Process Theory of Color Vision
There are four basic colors which are dvided into two pairs of color-sensitive neurons: red-green and blue-yellow. Each pair can only stimulate one of the other, not both. If you stare at a green, black, yellow flag, it will produce an after image of red/white/blue.
Sound Waves
Physical Stimuli that produce our sensory experience of sound.
Frequency
The rate of vibration, or the number of sounds waves per second
Amplitude
The intensity or amount of energy of a wave, reflected in the height of the wave; the amplitude of a sound wave determines a sound’s loudness
The purpose of the structures in the ear
Sound waves are collected in the outer ear, amplified in the middle ear, and transduced or transformed into neural messages, in the inner ear
Outer Ear
Includes the pinna, the ear canal, and the eardrum. The pinna catches sound waves and funnels them into the ear canal. The ear canal leads to the ear drum vibrates which matches the the vibration of the sound wave in intensity and frequency
Middle Ear
Includes 3 bones: the hammer, anvil, and stirrup. The middle ear almost doubles the amplification of the sound
Inner Ear
The oval window membrane separates the middle and inner ear. Cochlea is a fluid filled tube which ripples and gets transmitted to the basilar membrane.
Basilar Membrane
The basilar membrance contains sensory receptors for sound called hair cells. The hair cell stimulates the cells in the auditory nerve which carries the neural information to the thalamus and auditory cortex of the brain
Top-down vs bottom-up processing
Top-down processing (conceptually driven processing) - Drawing on our knowledge, experiences, expectations, and other cognitive processes to arrive at meaningful perceptions, such as people or objects in a particular context.
Bottom- up processing (data-driven processing) - The flow of sensory data from the sensory receptors to the brain. Trying to figure out the final picture based on ambiguous stimulus.
Perceptual Organization
Our minds have a tendency to organized things in a preferred manner: Proximity Similarity Closure Figure vs. ground Simplicity
Gestalt Psychologists
Gestalt psychology proposes a unique perspective on human perception. According to Gestalt psychologists, we don’t just see the world, we actively interpret what we see, depending on what we are expecting to see.
Figure and Ground
When we vie a scene, we automatically separate the elements of that scene into the figure, which is the main element of the scene, and the ground, which is its background. Example is finding a shape which is part of a white background
Depth Perception
The use of visual cues to perceptive the distance of three-dimensional characteristics of objects
Depth Perception Cues
Relative size - larger objects seem closer
Overlap - the blocked object is farther away
Aerial perspective - faraway objects appear blurred
Texture gradient - surface texture becomes less defined
Linear perspective - parallel lines seem to meet in a distance
Monocular
Require only one eye for depth perception
Binocular
Requires information from two eyes to determine depth.
Convergence - more eye strain means closer
Binocular disparity - if each eye sees it differently, it means it is closer
Ames Room
As a result of the optical illusion, a person standing in one corner appears to the observer to be a giant, while a person standing in the other corner appears to be a dwarf.
It is sufficient to create an apparent horizon (which in reality will not be horizontal) against an appropriate background, and the eye relies on the apparent relative height of an object above that horizon.
Muller-Lyer Illusion
The perception of a line can change by adding additional lines which cause the line to appear shorter or longer.
Ponzo Illusion
The human mind judges an object’s size based on its background. He showed this by drawing two identical lines across a pair of converging lines, similar to railway tracks.
Binocular Disparity
Seeing the difference in relative position in each eye. The closer it is the more disparity.
Binocular Stereopsis
The perception of depth and 3-dimensional structure obtained on the basis of visual information deriving from two eyes by individuals with normally developed binocular vision
Stereogram
A picture that uses the principle of binocular disparity to create the perception of a three-dimensional image.
Autostereogram
A single image that depicts a three-dimensional image
Perceptual constancy and set
Perceptual constancy - The tendency to perceive objects, especially familiar objects, as constant and unchanging despite changes in the sensory input. I.E. SUV stays the same size even though it really does get smaller as it drives away.
Perceptual set - The tendency to perceive objects or situations from a particular frame or reference. I.E. People into UFO’s might think of clouds as a UFO.
