chapter 4 Flashcards
sensation
the process of detecting external events with sensory receptors producing electrical impulses that travel to the brain and represent our internal or external experiences. (physical process)
perception
act of attending to, organizing, and interpreting sensory experience (psychological process)
transduction
when specialized receptors transform the physical energy of the outside world into neural impulses
neural impulses involved in transduction
travel into the brain and influence the activity of different brain structures
organizing perception involves
organizing the different vibrations of the eardrum in a way that allows you to recognize them as a voice and linking together the stimulation of groups of receptions in the eye into visual experience
sensory adaptation
reduction of activity in sensory receptors with repeated exposure to a stimulus
vision stimuli and type of receptor
light waves.
light-sensitive structures are the back of the eye.
hearing stimuli and type of receptor
sound waves.
hair cells that respond to pressure changes in the ear.
touch stimuli and type of receptor
pressure, stretching, warming, cooling, or piercing of the skin surface.
different types of nerve endings that respond to pressure, temperature changes, and pain.
taste stimuli and type of receptor
chemicals on the tongue and in the mouth.
cells lining the taste buds of the tongue.
smell stimuli and type of receptor
chemicals contacting mucus lined membranes of the nose.
nerve endings that respond selectively to different compounds.
from stimulus to perception
stimulus (light, sound, smell, etc) - sensory receptors (eyes, ears, nose, etc) - transduction - neural impulses - perception (visual, auditory, olfactory areas)
all of our senses
use the same mechanism for transmitting information in the brain: the action potential
doctrine of specific nerve energies
different senses are separated in the brain
- proposed in 1826 by Johannes Müller
the orienting response
describes how we quickly shift our attention to stimuli that signal a change in our sensory world
sensory adaptation provides
the benefit of allowing us to adjust to our surroundings and shift our focus to other events that may be important
drawback to sensory adaptation
we get used to listening to loud music in our earbuds, which can eventually damage the auditory system. we also stop noticing how polluted and loud city life can be.
psychophysics
the field of study that explores how physical energy such as light and sound and their intensity relate to psychological experience.
thresholds
amount of stimulus or amount of change need to be detected
absolute threshold
minimum stimulation needed to detect the presence of a particular stimulus 50% of the time
difference threshold
the smallest difference between stimuli that can be reliably detected at least 50% of the time
weber’s law
states that the just noticeable difference between two stimuli changes as a proportion of those stimuli
signal detection theory
states that whether a stimulus is perceived depends on both the sensory experience and that judgment made by the subject
signal detection theory is designed
to deal with response biase
- emphasizes process of making a judgment about the presence or absence of a stimuli
signal detection theory requires us to examine
two processes: a sensory process and a decision process
sensory process
reflects observers sensitivity to the strength of the stimulus
decision process
reflects observers response bias
priming
previous exposure to a stimulus can influence that individuals later responses either to the same stimulus or to one that is related to it
gestalt psychology
an approach to perception that emphasizes that “the whole is greater than the sum of its parts”
(understood only when viewed as organized, structured wholes, and not when broken down)
one basic gestalt principle is that
objects or “figures” in our environment tend to stand out against a background
- referred to as the figure-ground principle
there are two different stimuli involved in perception
proximal stimulus and distal stimulus
proximal stimulus
the optical image on the retina (anything close to you)
distal stimulus
the physical object in the world (distant things)
illusions occur when
perceptual systems deceive you into experiencing a stimulus pattern in a manner that is demonstrably incorrect
gestalt laws of grouping
similarity continuity proximity closure figure-ground
divided attention
paying attention to more than one stimulus at the same time
selective attention
focusing on one particular event or task to the exclusion of others
inattentional blindness
a failure to notice clearly visible events or objects because attention is directed elsewhere
wavelength
distance from peak of one wave to peak of next
amplitude
vertical distance from peak to trough
hue
dimension of colour determined by wavelength of light
intensity
amount of energy in wave determined by amplitude (brightness)
saturation
variety of wavelengths from the same point (colourfulness)
the primary function of the eye
is to gather light and change it into an action potential
differences in wavelength corresponds to
different colours on the electromagnetic spectrum
long wavelengths correspond to
our perception of reddish colours
short wavelengths correspond to
our perception of bluish colours
low amplitude waves are seen as
dim colours
high amplitude waves are seen as
bright colours
sclera
the white, outer surface of the eye
cornea
the clear layer that covers the front portion of the eye and contributes to the eyes ability to focus and bends incoming light
light enters the eye through
the cornea and passes through an opening called the pupil
pupil
opening in the centre of the iris that regulates the amount of light that enters by changing sizes
- dilates (expands) to allow more light in
- constricts (shrinks) to allow less light in
the changes in the pupils sizes are performed by the
iris
iris
coloured area which is a round muscle that adjusts the side of the pupil
lens
a clear structure that focuses light rays onto the retina
retina
lines the inner surface of the back of the eye and consists of specialized receptors that absorb light and send signals related to the properties of light to the brain
information from the photoreceptors at the back of the retina is transmitted to
the ganglion cells closer to the front of the retina. the ganglion cells gather up information from the photoreceptors. the activity of all the ganglion cells is then sent out of the eye through the optic nerve
optic nerve
a dense bundle of fibres that connect to the brain and transmits impulses to the visual centre of the brain
fovea
the part of the retina where light rays are most sharply focused, the central region of the retina
accommodation
change in shape of lens to focus near objects
there are two general types of photoreceptors
rods and cones
- each responds to different characteristics of light
rods
are photoreceptors that occupy peripheral regions of the retina; they are highly sensitive under low light levels
- particularly responsive to black and grey
cones
are photoreceptors that are sensitive to the different wavelengths of light that we perceive as colour
- cones tend to be clustered around the fovea
dark adaptation
the process by which the rods and cones become increasingly sensitive to light under low levels of illumination
blind spot
point at which optic nerve leaves eye, creating “blind spot” because if no receptor cells there
trichromatic theory (or young-helmholtz theory)
vision is determined by three different cone types that are sensitive to short, medium, and long wavelengths of light.
- suggests there are three types of colour receptors: red, green, blue. all other colours are combinations of the three
opponent-process theory of colour perception
we perceive colour in terms of opposing pairs: red to green, yellow to blue and white to black
optic chiasm
the point at which the optic nerves cross at the midline of the brain
left half of vision =
right half of vision =
left half of vision = right hemisphere of brain
right half of vision = left hemisphere of brain
fibres from the optic nerve first connect with
the thalamus
- the brains “sensory relay station”
the thalamus is made up of over
20 different nuclei with specialized functions
the lateral geniculate nucleus (LGN)
is specialized for processing visual information
fibres from the LGN nucleus send messages
to the visual cortex, located in the occipital lobe, where the processes of visual perception begin
neurone in visual cortex respond to specific features
shake
angle / orientation (feature detection cells)
movement
the ventral stream
extends from the visual cortex to the lower part of the temporal lobe
the dorsal stream
expands from the visual cortex to the parietal lobe
dorsal stream of vision could be referred to as
the “what” and “where” pathway. the dorsal stream locates an object in space and allows you to interact with it
- involved with visually guided movement
perceptual constancy
the ability to perceive objects as having constant shape, size, and colour despite changes in perspective
shape constancy
we judge the angle of the object relative to our position
size constancy
is based on judgments of how close an object is relative to ones position as well as to the positions of other objects
colour constancy
allows us to recognize an objects colour under varying levels of illumination
binocular depth cues
distance cues that are based on the differing perspective of both eyes (require use of two eyes)
convergence
occurs when the eye muscles contract so that both eyes focus on a single object
retinal disparity (binocular disparity)
the difference in relative position of an object seen by both eyes which provides information to the brain about depth
monocular cues
depth cues that we can perceive with only one eye
