Sensing and Perceiving Flashcards
sensation
awareness resulting from the stimulation of a sense organ
perception
the organization and interpretation of sensations
transduction
the conversion of stimuli detected by receptor cells to electrical impulses that are then transported to the brain
Psychophysics
branch of psychology that studies the effects of physical stimuli on sensory perceptions and mental states.
Gustav Fechner
absolute threshold of a sensation
the intensity of a stimulus that allows an organism to just barely detect it.
Signal detection analysis
a technique used to determine the ability of the perceiver to separate true signals from background noise
sensitivity
measure of subjects true ability to detect presence or absence of signals in psychophysics experiment
response bias
behavioral tendency to respond yes to the trials in in psychophysics experiment
difference threshold (or just noticeable difference [JND])
the change in a stimulus that can just barely be detected by the organism.
Weber’s Law
Ernst Weber law in psychophysics
just noticeable difference of a stimulus is a constant proportion of the original intensity of the stimulus
if you have a cup of coffee that has only a very little bit of sugar in it (say 1 teaspoon), adding another teaspoon of sugar will make a big difference in taste. But if you added that same teaspoon to a cup of coffee that already had 5 teaspoons of sugar in it, then you probably wouldn’t taste the difference as much
subliminal stimuli
events that occur below the absolute threshold and of which we are not conscious
can still have an impact on our behavior if if below threshold and not conscious
blindsight
a condition in which people are unable to consciously report on visual stimuli but nevertheless are able to accurately answer questions about what they are seeing
cornea
a clear covering that protects the eye and begins to focus the incoming light
pupil
a small opening in the center of the eye
iris
the colored part of the eye that controls the size of the pupil by constricting or dilating in response to light intensity.
lens
a structure that focuses the incoming light on the retina
retina
the layer of tissue at the back of the eye that contains photoreceptor cells
Visual accommodation
the process of changing the curvature of the lens to keep the light entering the eye focused on the retina
optic nerve
a collection of millions of ganglion neurons that sends vast amounts of visual information, via the thalamus, to the brain
light passes through retina, it activates rods and cones, then spreads to bipolar cells then to the ganglion cells/optic nerve
Rods
visual neurons that specialize in detecting black, white, and gray colors.
particularly active in peripheral vision
help in dim light
Cones
visual neurons that are specialized in detecting fine detail and colors
best in bright light
fovea
the central point of the retina, where rods and cones are located
pathway of vision
sensory information received by the retina is relayed through the thalamus to corresponding areas in the visual cortex, which is located in the occipital lobe at the back of the brain
the left and right eyes each send information to both the left and the right hemisphere, and the visual cortex processes each of the cues separately and in parallel
feature detector neurons
specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus
help to create perception by activating specific feature detectors then comparing with other memories of feature to create recognition
color perception
human visual system can detect and discriminate among 7 million color variations
all created by the combinations of the three primary colors: red, green, and blue
visual cortex then detects and compares the strength of the signals from each of the three types of cones, creating the experience of color
Young-Helmholtz trichromatic color theory
what color we see depends on the mix of the signals from the three types of cones (one for blue red and green)
opponent-process color theory
proposes that we analyze sensory information not in terms of three colors but rather in three sets of “opponent colors”: red-green, yellow-blue, and white-black
e.g., afterimage
gestalt
a meaningfully organized whole
we recognize form by trying to create a whole from component parts
Figure and ground
We structure input such that we always see a figure (image) against a ground (background).
Similarity
Stimuli that are similar to each other tend to be grouped together.
Proximity
We tend to group nearby figures together.
Continuity
We tend to perceive stimuli in smooth, continuous ways rather than in more discontinuous ways.
Closure
We tend to fill in gaps in an incomplete image to create a complete, whole object.
Depth perception
ability to perceive three-dimensional space and to accurately judge distance
partially innate, partially learned
depth cues
messages from our bodies and the external environment that supply us with information about space and distance
Binocular depth cues
depth cues that are created by retinal image disparity—that is, the space between our eyes, and thus which require the coordination of both eyes
convergence
binocular depth cue ; the inward turning of our eyes that is required to focus on objects that are less than about 50 feet away from us
Monocular depth cues
depth cues that help us perceive depth using only one eye
Position Relative size Linear perspective Light and shadow Interposition Aerial perspective
phi phenomenon
we perceive a sensation of motion caused by the appearance and disappearance of objects that are near each other
perceiving motion
The brain detects motion partly from the changing size of an image on the retina (objects that look bigger are usually closer to us) and in part from the relative brightness of objects.
pinna
the external and visible part of the ear, which is shaped like a funnel to draw in sound waves and guide them into the auditory canal
tympanic membrane (or eardrum)
At the end of the canal, the sound waves strike the tightly stretched, highly sensitive membrane
vibrates with the waves
ossicles
three tiny bones, the hammer (or malleus), anvil (or incus), and stirrup (or stapes), through which the vibrations are relayed into the middle ear to the cochlea
cochlea
a snail-shaped liquid-filled tube in the inner ear, covered by the oval window
the vibrations disturb the liquid inside the cochlea
the movement of the liquid bend the cilia/hair cells of the inner ear, which trigger nerve impulses in the attached neurons
oval window
the membrane covering the opening of the cochlea
loudness
degree of sound volume
determined by the number of hair cells vibrating
pitch
the perceived frequency of a sound
detected by two different mechanisms
frequency theory and place theory
frequency theory of hearing
whatever the pitch of a sound wave, nerve impulses of a corresponding frequency will be sent to the auditory nerve
place theory of hearing
different areas of the cochlea respond to different frequencies
Lower tones excite areas near the narrow tip of the cochlea, at the opposite end.
Conductive hearing loss
caused by physical damage to the ear (such as to the eardrums or ossicles) that reduce the ability of the ear to transfer vibrations from the outer ear to the inner ear.
Sensorineural hearing loss
caused by damage to the cilia or to the auditory nerve, is less common overall but frequently occurs with age
six different tastes
sweet, salty, sour, bitter, piquancy (spicy), and umami (savory)
tongue
covered with 2,000 to 10,000 taste buds, each bud contains between 50 and 100 taste receptor cells
smelling
airborne chemical molecules, re detected by the 10 million to 20 million receptor cells embedded in the olfactory membrane of the upper nasal passage.
olfactory receptor cells
topped with tentacle-like protrusions that contain receptor proteins.
When an odor receptor is stimulated, the membrane sends neural messages up the olfactory nerve to the brain
1,000 types of odor receptor cells
receptors come in many different shapes and respond selectively to different smells.
skin
nerve endings in the skin respond to four basic sensations: Pressure, hot, cold, and pain
only the sensation of pressure has its own specialized receptors. Other sensations are created by a combination of the other four
proprioception
the ability to sense the position and movement of our body parts
accomplished by specialized neurons located in the skin, joints, bones, ears, and tendons, which send messages about the compression and the contraction of muscles throughout the body.
vestibular system
a set of liquid-filled areas in the inner ear that monitors the head’s position and movement, maintaining the body’s balance
also helps keep track of where the body is moving
gate control theory of pain
proposes that pain is determined by the operation of two types of nerve fibers in the spinal cord
One set of smaller nerve fibers carries pain from the body to the brain, whereas a second set of larger fibers is designed to stop or start (as a gate would) the flow of pain
sensory interaction
the working together of different senses to create experience
taste, smell, and texture combine to create the flavor we experience in food
synesthesia
an experience in which one sensation (e.g., hearing a sound) creates experiences in another (e.g., vision)
selective attention
the ability to focus on some sensory inputs while tuning out others
sensory adaptation
a decreased sensitivity to a stimulus after prolonged and constant exposure.
e.g., cold water in a pool
eyes are constantly moving that is why we can see an image continuously, rather than adapting to that light and no longer seeing it
perceptual constancy
The ability to perceive a stimulus as constant despite changes in sensation
e.g., a door opening, with its shape changing
Human factors
field of psychology that uses psychological knowledge, including the principles of sensation and perception, to improve the development of technology
