Sensation and Perception
Chapter 3
Sensation
The process of detecting a physical stimulus, such as light, sound, heat, or pressure.
Perception
The process of integrating, organizing, and interpreting sensation.
Sensory Receptors
Specialized cells unique to each sense organ that respond to a particular form of sensory stimulation
Transduction
The process by which a form of physical energy is converted into a coded neural signal that can be processed by the nervous system
Absolute Threshold
The smallest possible strength of a stimulus that can be detected half the time.
Difference Threshold
The smallest possible difference between two stimuli that can be detected half the time; also called just noticeable difference.
Weber’s Law
A principle of sensation that holds the size of the just noticeable difference will vary depending on its relation to the strength of the original stimulus
Sensory Adaption
The decline in sensitivity to a constant stimulus
Subliminal perception
The perception of stimuli that are below the threshold of conscious awareness
Wavelength
The distance from on wave peak to another
Cornea
A clear membrane covering the visible part of the eye that helps gather and direct incoming light
Pupil
The opening in the iris that change size to let in different amounts of light
Iris
The colored part of the eye, which is the muscle that controls the size of the pupil
Iridology
A pseudoscience based on the unproven notion that the physical and psychological functioning of an individual is represented in marking of the iris
Lens
A transparent structure located behind the pupil that actively focuses, or bends, light as it enters the eye
Accommodation
The process by which the lens changes shape to focus incoming light so that it falls on the retina
Retina
A thin, light-sensitive membrane located at the back of the eye that contains the sensory receptors for vision.
Rods
The long, thin light-sensitive membrane located at the back of the eye that contains the sensory receptors for vision and night vision
Cones
The short, thick, pointed sensory receptors of the eye that detect color and are responsible for color vision and visual acuity
Fovea
A small area in the center of the retina, composed entirely of cones, where visual information is most sharply focused.
Optic Disk
Area of the retina without rods or cones where the optic nerve exits the back of the eye
Blind spot
The point at which the optic nerve leaves the eye; producing a small gap in the field of vision
Ganglion cells
In the retina, the specialized neurons that connect to the bipolar cells, the bundled axons of the ganglion cells form the optic nerve
Bipolar cells
In the retina, the specialized neuron that connects the rods and cones with the ganglion cells.
Optic nerve
The thick nerve that exits from the back of the eye and carries visual information to the visual information to the visual cortex in the brain
Optic Chiasm
Point in the brain where the optic nerve fibers from each eye meet and partly cross over to the opposite side of the brain
Trichormatic theory of color vision
The theory that the sensation of color results because of the cones in the retina are especially sensitive to either red light, green light,or blue light
Color blindness
One of several inherited forms of color deficiency or weakness in which an individual cannot distinguish between certain colors
Afterimage
A visual experience that occurs after the original source of stimulation is no longer present
Opponent-process theory of color vision
The theory that color vision is the product of opposing pairs of color receptors, red/green, blue/yellow, and black/white; when one member of color pair is stimulated the other is not
Audition
The technical term for hearing
Loudness
The intensity (or amplitude) of a sound wave, measured in decibels
Amplitude
The intensity or amount of energy of a wave, reflected In the height of the wave; the amplitude of a sound determines loudness
Decibel
The unit of measurement for loudness
Pitch
The relative highness or lowness of a sound, determined by the frequency of a sound wave.
Frequency
The rate of vibration, or the number of sound waves per second
Timbre
The distinctive quality of a sound, determined by the complexity of a sound wave
Outer Ear
The part of the ear that collects sound waves; consists of the pinna, the ear canal, and the eardrum
Eardrum
A tightly stretched membrane at the end of the ear canal that vibrates when hit by sound wave
Middle ear
The part of the ear that amplifies sound waves, consist of three small bones, the hammer, the anvil, and the stirrup
Inner Ear
The part of the ear where sound is transduced into neural impulses; consist of the cochlea and semicircular canals
Cochlea
The coiled, fluid-filled inner-ear structure that contains the sensory receptors for sound
Basilar Membrane
The membrane within the cochlea of the ear that contains the hair cells
Hair cells
The hair like sensory receptors for sound, found in the basilar membrane of the cochlea
Frequency theory
The view that the basilar membrane vibrates at the same frequency as the sound wave
Place theory
The view that different frequencies cause larger vibrations at different locations along the basilar membrane
Olfaction
Technical name for the sense smell
Gustation
Technical name for the sense of taste.
Olfactory bulb
The enlarged ending of the olfactory cortex at the front of the brain where the sensation of smell is registered
Pheromones
Chemical signals released by an animal that communicates information and affect the behavior of other animals of the same species
Taste buds
The specialized sensory receptors for taste that are located on the tongue and inside the mouth and throat
Pain
The unpleasant sensation of physical discomfort or suffering that can occur in varying degrees of intensity
Gate-control theory
The theory that pain is a product of both physiological and psychological factors that cause spinal gates to open and relay patterns of intense stimulation to the brain, which perceives them as pain.
Substance P
A neurotransmitter that is involved in the transmission of pain messages to the brain
Kinesthetic sense
The technical name for the sense of location and position of body parts in relation to one another
Proprioceptros
Sensory receptors, located in the muscles and joints, that provide information about body position and movement.
Vestibular sense
The technical name for the sense of balance, or equilibrium.
ESP (extrasensory perception)
Perception of information by some means other than through the normal process of sensation
Parapsychology
The scientific investigation of claims of paranormal phenomena and abilities
Bottom-up processing
Information processing that emphasizes the importance of the sensory receptors in detecting the basic features of a stimulus in the process of recognizing a whole pattern; also called data-driven processing
Top-down processing
Information processing that emphasizes the importance of the observer’s knowledge, exceptions, and other cognitive processes, in arriving at meaningful perception; analysis that moves from the whole parts; also called conceptually driven processing
Gestalt psychology
a school of psychology founded in Germany in the early 1900s that maintained that our sensations are actively processed according to consistent perceptual rules that result in meaningful whole perceptions
Figure-ground relationship
A Gestalt principle of perceptual organization that states that we automatically separate the elements of a perception into the feature that clearly stands out and its less distinct in the background
Depth perception
The use of visual cues to perceive the distance or three-dimensional characteristics of objects
Monocular cues
Distance or depth cues that can be processed by either eye alone
Binocular cues
distances or depth cues that require the use of both eyes
Perceptual cues
The tendency to perceive objects, especially familiar objects, as constant and unchanging despite changes in sensory input
Size constancy
The perception of an object as maintaining the same shape regardless of the image produced on the retina
Shape constancy
The perception of an object as maintaining the same shape regardless of the image produced on the retina
Brightness constancy
The perception that the brightness of an object remains the same even though the lighting conditions change
Perceptual illusion
The misperceptions of the true characteristics of an object or an image
Muller-Lyer Illusion
A famous visual illusion involving the misperception of the identical length of two lines, one with an arrow pointed inward, one with an arrow pointed outwards
Moon illusion
A visual involving the misperception that the moon is larger when it is on the horizon than when is directly overhead
Perceptual set
the influence of prior assumptions and exceptions on perceptual interpretations.
KEY PEOPLE
Karl Duncker
German Gestalt psychologist who is best known for his studies on the perception of motion; also studies the perception of pain and the effect of past experience on perception.
Max Wertheimer
German psychologist who founded Gestalt psychology in the early 1900s, immigrated to the United States in 1933, studied the optical illusion of apparent movement, and described principles of perception