PSYC1101 - Sensation & Peception

sensation

• process of detecting information from the environment via sensory receptors

peception

•  how the brain interprets and gives meaning to sensory information

electromagnetic spectrum

• humans can only detect a small portion of electromagnetic spectrum (400-700 nm)

• there is no colour in light energy; the brain creates our colour peception

cones vs rods

• cones: works in good lightning, sensitive to fine detail & colour

• rods: works in dim lighting & sensitive to movement, but not fine detail or colour

photoreceptors

• convert light energy into neural signals

dominant vision

• the fovea is the centre of vision

• contains a high no. of cones & produces the sharpest vision / high acuity

peripheral vision

• dominated by rods = lower detail

blind spot

• the location where the optic nerve exits the eye

• contains no photoreceptors; no info is processed

optic nerve

• nerve that carries visual information from the retina in the eye to the brain

how visual info travels

optic nerve → retina → brain

colour contrast

• the same colour can look more or less vibrant depending on surrounding colours

colour constancy

• the tendency of a surface to appear the same colour under a fairly wide range of illuminants (lightning) due to awareness of the true colour

visual processing

information from the left fixation is processed in the right hemisphere (and vice versa)

first stage of cortical processing

detecting lines & edges in the visual scene

figure ground segregation

 segmenting images between the central/main figure and the background

proximity

objects close together are grouped together

similarity

objects that look alike are grouped together

linear continuity

 the brain prefers smooth lines

prior context

• the brain uses prior knowledge & probabilities to overcome contradictory visual information

linear perspective

• we know lines are closer when they are further away

occlusion

• when one thing blocks another thing, we know its closer

clarity

• we know things are more blurry when they are far away

height

• we know objects higher in our visual field are far away

relative size

• we know small things are far away

motion parallax

• we know things far away move faster

binocular depth cues

depth cues in two eyes

each eyes sees a slightly diff image - thus we can process 3d images

binocular disparity

• the small difference between what the left and right eye sees

sound

pressure waves in the air, water or another medium

frequency

no. of sound waves per second

amplitude

 the vertical size of sound waves

decibels

a measure of the physical pressures that occur at the eardrums

sound processing

• soundwave pressure distorts the eardrum, causing physical movement in the ear

• these bones push on the cochlear, causing fluid inside to move

cochlea

• a fluid filled, spiral shaped structure in the inner ear containing hair cells that converts sound waves to neural signals

frequency theory

• we sense sound frequency depends on the fluid movement. (e.g. hair cells move a little = we sense little frequency, and vice versa)

place theory

• we sense frequency according to the location of the fluid activity in the cochlear.

• different frequencies stimulate different locations (high frequency = stiff base of cochlea responds, low frequency = apex of cochlea responds)

locating sound

• sounds will be percieved first and loudest by the closest ear

sense of balance

• dizziness is caused by the vestibular system in the ear

what happens during dizziness

• the semicircular canals in your ear are filled with fluid

• when you spin, the fluid starts moving & bending the hair cells

• when you stop, the fluid still keeps moving due to the momentum - but the visual information coming into your eye have stopped moving.

how taste and smell is connected

• both work together (explains why food is less tasty when we have a cold/blocked nose)

• both can evoke emotional responses in the amygdala  (helps us perceive threats/danger e.g. yucky food = might be dangerous)

gustation

• taste buds on the surface of the tongue react to the chemical compounds in food

• sweet, sour, bitter, salty, umami

• processed in the gustatory cortex

smell

• chemicals bind to receptor cells (cilia in the lining of our nasals)

• each receptor binds to a specific chemical

• processed in the olfactory cortex

pheromones

• odourless chemicals that signal sexual behaviour

  • during ovulation, females secrete these "pheromones"

• detected via vomeronasal organ in the nose

touch receptors location

 embedded in the outer layer / epidermis and underlying lyer (dermis) of our skin

kinesthetic receptors

• mechanoreceptors in muscles, tendons and joints that tell us where limbs are without awareness

labelled lines

• we have separate receptors for things like pressure, vibration, hot, cold, pain, etc

somatotopic representation

adjacent areas on the skin connect to adjacent areas in the brain

pain

•  associated with evolutionary processes & survival complex

• triggers rapid & reflexive withdrawal from harmful situations

• two components; sensation of pain & emotional response

miss c

• was born with insensitivity to pain (no sneezing, gagging reflex etc)

• died at 29 from infections that could have been prevented if she sensed pain

analgesia

• decreasing pain sensation using conscious experience

endorphins

neurotransmitters that inhibit pain

phantom pain

• you can feel pain, even when theres nothing there

• somatotopic centre attributes random activity o stimulation from the missing limb, thus feeling pain

• treated using mirror therapy