sensation and perception Flashcards
Kapittel 5
sensation
the stimulus detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain.
perception
making “sense” of what our senses tell us; it is the active process of organizing this stimulus input and giving it meaning.
sensory transduction
the process whereby the characteristics of a stimulus are converted into nerve impulses.
psychophysics
studies that relationship between the physical characteristics stimuli and sensory capabilities.
absolute threshold
the lowest intensity at which a stimulus can be detected 50 percent of the time.
decision criterion
how certain someone must be that a stimulus is present before they will say they can detect it.
signal detection theory
an account of sensory perception that is concerned with the factors that influence humans´ judgements about sensory stimuli.
difference threshold
defined as the smalest difference between two stimuli that someone or som people can perceive 50 percent of the time.
Weber’s law
states that the difference threshold, or JND, is directly proportional to the magnitude of the stimulus with which the comparison is being made.
sensory adaption
the diminishing sensitivity ti an unchanging stimulus.
sensory transduction
the process whereby the characteristics of a stimulus are converted into nerve impulses.
lens
an elastic structure in the eye that becomes thinner to focus on distant objects and thicker to focus on nearby objects.
retina
multilayered light-sensitive tissue at the rear of the fluid-filled eyeball.
rods
function best in dim light, and are primarily black-and white brightness receptors.
cones
color receptors, which function best in bright illumination.
fovea
small area in the centre of the retina that contains no rods but many densely packed cones.
optic nerve
ganglion cells, whose axons are collected into a bundle to form the optic nerve.
visual acuity
ability to see fine detail.
photo-pigments
rods and cones translate light waves into nerve impulses through the action of protein molecules called photo-pigments.
dark adaption
the progressive improvement in brightness sensitivity that occurs over time under conditions of low illumination.
young-helmholtz trichromatic theory
states that there are three types of color receptor in the retina.
Hering’s opponent process theory.
states that each of the three cone types responds to two different wavelengths.
dual-process theory
combines the trichromatic and opponent-process theories to account for the color transduction process.
feature detectors
fire selectively in response to visual stimuli that have specific characteristics.
frequency
the number of sound waves, or cycles, per second.
hertz (Hz)
the measure of cycles per second; 1 hertz equals 1 cycle per second.
amplitude
the vertical size of the sound waves- the depth between the peaks and the troughs in the sound wave.
decibels (dB)
measure of the physical pressures that occur at the eardrum.
cochlea
coiled, snail-shaped tube about 3.5 cm in length.
basilar membrane
sheet of tissue that runs the length of the cochlea.
organ of Corti
contains thousands of tiny hair cells that are the actual sound receptors.
frequency theory of pitch perception
holds that nerve impulses sent to the brain match the frequency of the sound wave.
place theory of pitch perception
suggests that the specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells serves as a frequency coding cue.
conductive hearing loss
involves problems with the mechanical system that transmits sound waves to the cochlea.
sensorineural hearing loss
caused by damaged receptors within the inner ear or damage to the auditory nerve itself.
gustation
sense of taste
olfaction
sense of smell
anosmia
loss of olfaction, the sense of smell.
taste buds
small bodies containing taste receptor cells concentrated along the tip, edges and back surface of the tongue.
olfactory bulb
forebrain structure immediately above the nasal cavity.
pheromones
chemical signals found in natural body scents.
orthonasal olfaction
the sense of smell that comes from odors inhaled up the nostrils from in front of us; orthonasal olfaction is involved in sensing odors in our surroundings and deciding whether or not to ingest something.
retronasal olfaction
the sense of odors that come from the mouth; retronasal olfaction is heavily involved in the perception of flavor while we are eating and drinking.
cutaneous touch
the sense of touch arising from events on the skin surface (including temperature and pressure)
proprioception
sensory input that provide us with information about the layout and movements of our body and limbs.
interoceptive touch
the sense of touch arising from receptors inside the body, typically in blood vessels and organs.
haptics
the active use of touch and movement to explore objects and surfaces within reach.
vestibular system
apparatus in the cochlea that contributes especially to the sense of bodily movement, and orientation with respect to gravity; the vestibular sense plays a crucial role in maintaining balance.
synaesthesia
literally, “mixing of the senses”
bottom-up processing
individual elements of a stimulus are analyzed and then combined to form a unified perception.
top-down processing
sensory information is interpreted in light of existing knowledge, concepts, ideas and expectations.
figure-ground relations
our tendency to organize stimuli into a central or foreground figure and a background.
gestalt laws of perceptual organization
similarity, proximity, close and continuity.
perceptual schema
a mental representation or image containing the critical and distinctive features of a person, object, event or other perceptual phenomenon.
bayesian inference
a statical method for making predictions about what will happen based on information about prior occurrences; it has been used as a basis for explaining how humans perceive the world.
perceptual constancies
allow us to recognize familiar stimuli under varying conditions.
binocular disparity
each eye sees a slightly different image.
convergence
produced by feedback from the muscles that turn your eyes inwards to view a close object.
stroboscopic movement
illusory movement produced when a light is briefly flashed in darkness and then, a few milliseconds later, another light is flashed nearby.
critical periods
periods during which certain kinds of experience must occur if perceptual abilities and the brain mechanisms that underlie them are to develop normally.
