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Chapter 7 Sensation and Perception

Chapter 7 Sensation and Perception
The study of the relationship between physical stimulation and its psychological effects.
How we recognize, interpret, and organize our sensations.
The act of sensing a stimulus
absolute threshold
The minimal amount of stimulation needed to detect a stimulus and cause the neuron to fire 50% of the time.
signal detection theory
This theory takes into consideration that there are four possible outcomes on each trial in a detection experiment: hit, miss, false alarm, and correct rejection.
The signal was present, and the participant reported sensing it.
The signal was present, but the participant did not sense it.
false alarm
The signal was absent, but the participant reported sensing it.
correct rejection
The signal was absent, and the participant did not report sensing it.
difference threshold (also just noticeable difference- JND)
The minimum amount of distance between two stimuli that can be detected as distinct.
Ernst Weber
He noticed that at low weights (like 1oz) it was easy to notice a 0.5oz increase or decrease in weight; but at higher weights (like 32oz) participants were not able to judge 0.5oz differences.
Weber's Law
This law states that the greater magnitude of the stimulus, the larger the differences must be noted.
subliminal perception
a form of preconscious processing that occurs when we are presented with stimuli so rapidly that we are not consciously aware of them.
receptor cells
specialized cells designed to detect specific types of energy.
receptive field
the area from which our receptor cells receive input.
The term describing the process which the form of the input is converted into the electrochemical form of communication used by the nervous system. Takes place at the level of the receptor cells.
contralateral shift
the switch of sensory input from one side of the body to the opposite side of the brain.
the sense of smell.
sensory coding
the process by which receptors convey such a range of information to the brain.
single cell recording
a technique by which the firing rate and pattern of a single receptor cell can be measured in response to varying sensory input.
visual sensation
when the eye receives light input from the outside world.
distal stimulus
the object as it exists in the environment.
proximal stimulus
the image of the object on the retina- it is later inverted and the brain interprets the image correctly.
a protective layer on the outside of the eye.
the transparent structure behind the pupil that changes shape to help focus images on the retina
located at the back of the eye and covered with receptor cells (rods and cones)
located on the periphery of the retina and are sensitive to low light.
located in the center of the retina (or fovea) and are sensitive to bright light and color vision.
bipolar cells
specialized cells which connect rods and cones to the ganglion cells of the optic nerve.
amacrine cells
Between the ganglion cells and the bipolar cells.
optic nerves
nerves that carry visual information from the eyes to the brain.
optic chiasma
the crossing of the optic nerves from the two eyes at the base of the brain.
feature detector neurons
"see" different parts of the pattern such as a line set at a specific angle to background.
Young-Helmoltz or trichromatic theory
According to this theory, the cones in the retina of the eyes are activated by light waves associated with blue, red, and green. We see all colors by mixing these three colors.
opponent process theory
The theory contends that cells within the thalamus respond to opponent pairs of receptor sets- namely black/white, red/green, and blue/yellow. If one color of the set is activated, the other is essentially turned off.
if you stare at a red dot on a page and turn away to a blank piece of white paper, you will see a green dot on the blank piece of paper- this is known as the ________.
people who cannot distinguish between the red/green or blue/yellow continuums.
people who see only in shades of black and white.
auditory input
the form of sound waves that enters the ear by passing the outer ear and into the ear canal.
tympanic membrane
the membrane in the ear that vibrates to sound; known as the eardrum.
The three small bones found in the middle ear (the malleus, the incus, and the stapes) that help to amplify the vibrations from sound waves. The malleus is atached to the tympanic membrane and the stapes is attached to the oval window of the cochlea.
the snail-shaped tube (in the inner ear coiled around the modiolus) where sound vibrations are converted into nerve impulses by the Organ of Corti.
vestibular sacs
Sacs in the inner ear that are responsible for sensing gravitation and forward, backward, and vertical movement.
place theory
theory that asserts that sound waves generate activity at different places along the basilar membrane.
frequency theory
theory that states that we sense pitch because the rate of neural impulses is equal to the frequency of a particular sound.
conductive deafness
damage to the outer or middle ear structure or the neural pathway.
sensorineural deafness
nerve deafness
four basic tastes
sweet, salty, sour, bitter
cutaneous and tactile receptors
receptor cells located in the skin that provide information about pain, pressure, and temperature.
cold fibers
receptor cells that fire in response to cold stimuli
warm fibers
receptor cells that fire in response to warm stimuli
vestibular sense
involves sensation of balance.
found in joints and ligaments, transmits information about the location and position of the limbs and body parts.
an unconscious, temporary change in response to environmental stimuli.
the process by which we become accustomed to a stimulus and notice it less and less over time.
occurs when a change in the stimulus, even a small change, causes us to notice the stimulus again.
the processing through cognition of a select portion of the massive amount of information incoming from the senses and contained in memory.
selective attention
when we try to attend to one thing while ignoring another.
cocktail part phenomenon
our ability to carry on and follow a single conversation in a room full of conversations.
filter theories
these theories propose that stimuli must pass through some sort of screen or filter to enter into attention.
attentional resource theories
these theories posit that we have only a fixed amount of attention and that this resource is divided up as is required in a given situation.
divided attention
trying to focus on more than one task at a time.
perceptual processes
how our mind interprets environmental stimuli.
bottom-up processing
achieving recognition of an object by breaking it down into its component parts. it relies heavily on sensory receptors.
top-down processing
relies on prior experience with an object.
visual perception
how we perceive depth, size, shape and motion.
monocular depth cues
we need only one eye to see these cues.
relative size
refers to the fact that images that are farther from us project a smaller image on the retina than do those that are closer to us.
texture gradient
the patterns of distribution of objects, appear to grow more dense as distance increases.
occurs when a near object partially blocks the view of an object behind it.
linear perspective
a monocular cue based on the perception that parallel lines seem to draw closer together as the lines recede into the distance.
vanishing point
the point at which the two lines become indistinguishable from a single line, and then disappear.
ariel perspective
a perceptual cue based on the observation that atmospheric moisture and dust tend to obscure objects in the distance more than they do nearby objects.
relative clarity
a perceptual clue that explains why less distinct, fuzzy images appear to be more distant.
motion parallax
the difference in the apparent movement of objects at different distances, when the observer is in motion.
binocular depth cues
rely on both eyes viewing an image.
refers to the three-dimensional image of the world resulting from binocular vison.
retinal convergence
a depth cue that results from the fact that your eyes must turn inward slightly to focus on near objects- the closer the object, the more the eye turns inwards
binocular disparity
results from the fact that the closer an object is, the less similar the information arriving at each eye will be.
Eleanor Gibson and RIchard Walk
researchers who developed the visual cliff to test depth perception.
visual cliff
a glass tabletop that appeared to be clear on one side and had a checkerboard design visible on the other side.
Gestalt approach
this view holds that most perceptual stimuli can be broken down into figure-ground relationships.
the tendency to see objects near to each other as forming groups.
the tendency to prefer to group like objects together.
the tendency to perceive preferentially forms that make up mirror images.
the tendency to perceive preferentially fluid or continuous forms, rather than jagged or irregular ones.
the tendency preferentially to close up objects that are not complete.
law of Pragnanz
law that states we tend to see objects in their simplest forms.
feature detector approach
posits that organisms respond to specific aspects of a particular stimulus.
we know that a stimulus remains the same size, shape, brightness, weight, and/or volume even though it does not appear to.
motion detection
we perceive motion through two processes: one records the changing position of the object as it moves across the retina; the other tracks how we movie our head to follow the stimuli.
apparent motion
the appearance of movement
phi phenomenon
an example includes blinking lights on a roadside arrow- they give the appearance of movement.
stroboscopic effect
an example when still pictures move fast enough to imply movement.
autokinetic effect
example: still light that appears to twinkle in darkness.