Week 7 - Sensation, Perception Flashcards
Sensation
physical processing of environmental stimuli by the sense organs.
(sense organs engage in transduction to convert sensations into electrical stimulation to be understood by the brain)
Perception
the psychological process that makes sense of the stimuli.
differential threshold, “just noticeable difference” (JND)
the smallest difference needed in order to differentiate between two stimuli.
Weber’s Law
the JND is proportional to the magnitude of the initial stimulus; larger stimuli require larger differences to be noticed (i.e. differentiating between a 1 and 2 lb weight vs. a 10 and 11 lb weight).
bottom-up processing
build up to perceptual experience from the individual pieces.
top-down processing
stimuli we’ve experienced in the past influence how we process new stimuli
Vision
light bouncing off of an object and into our eye.
Light enters through the pupil, which regulates the amount of light by either contracting or dilating in bright or dim environments respectively.
It is then passed through the lens, which focuses an image on the retina.
binocular disparity
result of our two eyes processing slightly different images provides us with the ability to perceive 3D space and depth through binocular vision.
rods
sensitive to low levels of light (black, grey, white)
- found more in the periphery
- more rods than cones
cones
sensitive to colour and allow us to see fine detail (concentrated in the fovea (the central region of focus))
Dark adaptation
the adjustment of our eyes to low levels of light (night vision).
- takes about 10 minutes to occur, due to our rods becoming bleached in normal light conditions.
light adaptation
adjustment of our eyes to high levels of light (entering the daylight after being in a dark room).
-occurs when a large number of rods and cones, which have been adjusted to the dark, become bleached at once, and can cause brief blindness.
trichromatic theory
proposes that colour vision is influenced by three different cones that respond preferentially for red, green, and blue.
opponent-process theory
proposes that our cones send information to retinal ganglion cells, which respond to pairs of colours. This is what causes after-images to occur when we shift our eyes away from something we have been staring at.
hearing
Sound waves are funneled by the pinna into the auditory canal, where they reach the tympanic membrane (eardrum). The eardrum vibrates against the malleus (hammer), incus (anvil), and stapes (stirrup), collectively known as the ossicles.
The ossicles amplify the sound waves entering the cochlea by striking the oval window.
sound waves
- The amplitude of a sound wave changes the volume of a stimulus.
- The frequency of a sound wave changes the pitch of a stimulus.
- The complexity of a sound wave changes the timbre of a stimulus.
somatosensation
ability to sense touch, pain, and temperature. This process transduces physical stimuli into electrical potentials to be processed by the brain.
cutaneous
senses of the skin
kinesthesis
sense of bodily movement
proprioception
sense of the position of our body
nociception
ability to sense pain and discomfort
mechanoreceptors
tranduce tactile stimuli in skin
- merkel’s disks
- meissner’s corpuscles
- ruffini corpuscles
- pacinian corpuscles
Olfaction (Smell)
Odorants in our environment bind with olfactory receptors in the olfactory epithelium.
gustation (taste)
Taste receptor cells, found in the taste buds of the tongue, respond to chemicals known as tastants.
Interaural time differences (ITDs)
differences in the time at which a sound is received between the two ears. A sound originating from your left will reach the left ear first.
We are most sensitive to ITDs at low frequencies.
Interaural level differences (ILDs)
differences in the intensity of a sound received between the two ears. A sound originating from the left will sound louder to the left ear than to the right.
ILDs are most useful at high frequencies.
A-fibers
highly myelinated (fast-conducting) sensory nerves, project to the somatosensory cortex to locate the source of the pain and propel you to remove the source.
C-pain fibers
convey information to the insular cortex, which processes emotion. This causes a longer, aching pain that conditions us to avoid the source in the future.
C-tactile fibers
respond to gentle touch, with their firing rate correlating with how pleasant the touch feels.
analgesia
loss of sensation of pain (expecting pain relief from a medical treatment contributes to the placebo effect)
allodynia
pain occurs as a result of a stimulus that does not normally provoke it.