4 - Sensation and Perception Flashcards
Sensation
simple stimulation of a sense organ; basic registartion of light, sound, pressure, odor, or taste as parts of your body interact with the physical world
Perception
the organization, identification, and interpretation of a sensation in order to form a mental representation
transduction
when many sensors in the body convert hysical signals from the environment into encoded nerual signals sent to the central nervous system
Psychophysics
methods that measure the strength of a stimulus and the observer’s sensitivity to that stimulus
Absolute threshold
minimal intensity needed to just barely detect a stimulus in 50% of the trials; a boundary
JND
just noticable difference; the minimal change in a stimulus that can just barely be detected
Weber’s Law
The JND of a stimulus is a constant proportion despite vatriations in intensity. ex: 1 ounce envelope vs 2 counce envelope, will be felt; 20 pound package and 20 pound 1 ounce package, will not be felt
Signal detection theory
the respones to a stimulus depends both on a person’s sensitivity to the stimulus in the presnse of noise and on a person’s decision criterion
hit, miss, false alarm, correct rejection
light + yes = hit
light + no = miss
no light + yes = false alarm
no light + no = correct rejection
perceptual sensitivity
how effectively the perceptual system represents sensory events
selective attention
only percieving what;s currently relevant to you
why can’t you text and drive?
selective attention, multitasking; phone conversations require memory retrieval, deliberation, planning, emotion, and take much more attention than, say, listening to the radio. impairing of texting has been found to be equal to alcohol consumption and greater than marjuana
sensory adaption
sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current conditions
visual acuity
ability to see fine detail
length of light
hue/colour
amplitude
brightness
purity
(number of distinct wavelenghts that make up the light) saturation/richness
Cornea
clear, smooth outer tisue, bends light wave and sends it through the pupil
pupil
hole in coloured part of eye
iris
coloured part of the eye, translucent, doughnut shaped muscle, controls the size of the pupil
retina
light sensitive tissue lining the back of the eyeball
accommodation
the process by which the eye maintains a clear image on the retina
myopia
eyeball is too long, images are focused in front of the retina, nearsightedness
hyperopia
eyeball is too short, images are focused behind the retina, farsightedness
photoreceptor cells
cones, rods
cones
colour, operate under normal daylight conditions, allow us to focus on fine detail, 6 million
rods
active under low light onditions for nightvision, more sesntive to cones, provide no information about colour, only shades of grey, 120 million
fovea
an area of the retina where vision is clearest and there are no rods at all
explain how the fovea affects how we see
night sky
bipolar cells
collect neural signals from the rods and cones and transmit them to the outermost layer of the retina
RGCs
retinal ganglion cells, organize the signals and send them to the brain
blind spot
a location in the visual field that produces no sensation on the retina
colour deficiency
colour blindness, genetic, one or more of the cone types is missing
colour afterimage
staring too long at one colour fatigues the cones that respond to that colour, producing a form of sensory adaption that results in an afterimage
colour opponent system
pairs of visual neruons work in oppositive, red senstivie against green sensitive; blue sensitive cells agianst yellow sensitive
LGN
lateral geniculate nucleus, located in the thalamus
area V1
part of the occipital lobe that ocntains the primary visual cortex
two visual pathways
ventral (what) and dorsal (where)
ventral stream
occipital lobe –> lower levels of temporal lobe; “what” path
dorsal stream
occipital lobe –> parietal lobes (including some of the middle and upper levels of the temporal lobes), connecting brain with areas taht identify the location and motion of an object; “where” path
“where” vs “how” path
scientists argue that the dorsal stream is crucial for guiding movements like aiming, reaching, or tracking with the eyes, thus the “where’ pathway should be called the ““how” pathway
visual form agnosia
the inability to recognize objects by sight
binding provelm
how features are linked together so we can see unified objects in our visual world rather than free-floating or miscombined features
illusory conjunction
a perceptual mistake where features from multple objects are incorrectly cobined
feature-integration theory
focused attention is not required to detect the individual features that comprise a stimulus, such as the colour, shapre, size, and location of letter, but it required to bind those individual features together
modular view
specialized brain areas or modules detect and represeent faces or house or body parts
distributed representation
pattern of activity acoross multiple brain regions that identies any viewed object, including faces
perceptual constancy
even as aspects of sensory signals change, perception remains consistent
princples of perceptual organization
gestalt; simplicity, colosure, continuitiny, similiarity, proximity, common fate
simplicity
the simplest explanation is usually the best
closure
we tend to fill in missing elements of a visual scene, allowing us to percieve edges that are separated by gaps as belonging to compltete objects
continuinity
edges or contors that have the same orientation tend toward good coninuation, we tend to group them together perceptually
similarity
regions that are similar in colour, lightness, shape, or texture are percieved as belonging to the same object
proximity
objects that are close together tend to be grouped togehter