Sensation involves transduction of the physical world into neural impulses.
Perception involves binding these sensory impulses into a representation of the world.
*brain neural impulse
-responsible for treating patients who survived
-based on the bullet wound he could tell where the damaged occurred
-discovered the back of the brain was for vision, and it was organized ( scotomas ) blind
-correlated where the damage was and the part if vision affected.
Sensory impulses are processed by distinct brain regions
Physiological response (brain response)-> Sensory experience
Physical stimulus -> Domain of sensory physiology (how activity affects your brain
Psychophysics- the relationship between physical stimuli and the sensations about them
that we experience.
-became physically ill
-can he measure his mind???
-invented a method to measure the mind
-relationship between physical and the sensations we experience
1) Detection (can you detect it)
The quantitative (minimum) amount of a stimulus required to be detected.
absolute threshold-That intensity at which a stimulus is detected 50% of the time
when graphed right shift-higher threshold
-lower sensitivity .
left shift- lower threshold
Hit- in reality yes and in the response was yes
False alarm-in reality no and the response was yes
Miss-reality was yes and response was no
Correct rejection- in reality was no and response was no
2) Discrimination (difference)
By how much must the stimulus intensity vary to just detect a change?
Called Difference Threshold or Just Noticeable Difference (JND)
-Different amount webers law- difference threshold varies to the standard stimulus in a linear way
difference threshold = I K
difference theshold =0.5
threshold = 3
K=difference in threshold/threshold
=664 (4 g candy) ^
webers law For a stimulus to be detected as different from the comparison 50% of the
time, the intensity of a comparison stimulus must change by a fixed proportion of the
standard stimulus. Weber fraction=JND/%magnitude of the standard
Fechner’s Law -Uses Weber’s Law to reveal the relationship between the physical
stimulus and sensation.
--Sensation intensity increases proportional to the logarithm of physical stimulus
- Light is the result of electromagnetic waves.
- Electromagnetic (light) waves can have different wavelengths.
-Visible light takes up only a small amount of the electromagnetic spectrum.
3nm wave length is x-ray
3m wave length is FM radio
nervous system can detect a small amount of the electromagnetic spectrum… visible
nervous system applies the color
-need light to see, light bounces off things
-broad spectrum-light from the sun
-pigment molecules absorb light
-it gets reflected to your eye
black is the absence of reflected light
the white part- sclera
boarder between them-limbus
centre of iris-pupil
can change its size
small-constriction in a bright room
large-dilation in a dim room
pupillary response^ 6 extra ocular muscles
outside of the eye
muscle closest to the nose-medial rectus
lateral rectus other side of eye
muscle attach interior oblique
bottom of eye-inferior rectus
top of eye-superior rectus
muscle attach-superior oblique
in the middle, top, and bottom muscles attach
1-light detecting device (ex. eye)
eyebrow and eyelashes is to keep vision non impaired. keeps away debris and sweat
cornea is transparent
accommodation -shape change
bringing things into focus
close has a fat shape
far away has a thin shape
becomes less flexible as you become older-harder (presbyopia)
strabismus-miss alignment of the eye
esotropia-one eye turns in
exotropia-one eye turns out
could fix by changing muscle length- brain finds a way to ignore it
triangluar part-outter segment
cell body(nuclus)- inner segment
end of the thing-synaptic ending
it can tell when it absorbs light, it changes. communicates to other cells by the synaptic
ending light starts and then goes through
-located in periphery
-respond to dim light
-located in fovea
-respond to bright light
horzontial and amacrine cells
bipolar and ganglion cells
visual receptive field
the region of visual space to which a cell will respond
Colour VisionTrichromatic Theory - Young & Helmholtz (1800)
Opponent-process Theory - Hering (1870)
Dual process Theory - (1998)
- The auditory system is designed to detect sound waves.
- Air molecules are required to generate sound waves.
Compression(top of wave )->refraction(bottom of wave )->compression etc.. produce a
high- waves short and tall
ex. 1 cycle per second= 1Hz , how many cycles pre second
ex. 3 cycles/second= 3Hz
frequency codes –pitch
amplitude codes –loudness
soft 3Hz, distance between peak and trough is smaller
loud 3Hz, distance between peak and trough is greater
0dB is the smallest detectable sound
10dB is 10x smallest detectable sound
140dB=immediate damage simple wave- low frequency + simple wave- high frequency = complex wave
Human can detect all frequencies between 20Hz and 20,000Hz (young adult) 20-
15000Hz (older adult)
Middle ear bones-malleus
eardrum (tympanic membrane)-moves back and forth amplifies the signal
Asound causesthe basilar membrane to wave up and down
Loudness is coded by
(1) the degree of hair cell bending, and by
(2) neurons that are activated only after a threshold level of hair cell bending.
Frequency theory states that the frequency of nerve impulses sent to the brain match the
frequency of the sound.
Place Theory states that sound frequencies are coded at different positions along the
Interaural Time Difference - difference in the time it takes a sound! to reach each ear.!
-- When a sound reaches both ears at the same time it is perceived to originate from a
source directly ahead.
-- When the sound reaches the right ear first it is perceived to originate from a source to
-- As the interaural time difference increases, the source of the sound is perceived to
deviate increasingly from center.
Taste smell touch
papillae- little bumps on your tounge, not taste buds
the taste buds are on the sides of them.
-tastants molecules flow across the surface of the tounge and go into the grooves formed
by the papillae
-inside the taste bud it is made of a lot, complicated machine. collection of cells.
-support cells, -chemoreceptor cells, air like things called microvilli
surface of microvilli are receptors, bind tastes
-combines and 2 nerves facial and glossopharyngeal
with great affinity, produces a response
-produces activity across the tounge, the brain communicates it.
-50 % of our taste comes from smell -taste buds small number around on your mouth
approx. 9 thousand taste buds
odorant molecule is what creates the sensation of the smell, outer smell.
get sucked up into the nasal cavity.
nasal cavity-inner smelling
olfactory epithelium- a lot of blood vessels. very quick recovery.
cells are called olfactory sensory neurons- they patrood out to the nasal cavity in to the
cilia, called mucosa.(tips of cilia)
-there for the sensation of smell, contains a lot of enzymes and stuff to protect your form
-provides of opportunity for odorant to become solubilizes. not all molecules will be
olfactory receptors- 350 different receptors- suited to a particular odor
40million receptors- allows us to detect about 10 thousand odors
defactory bulb-make connections with olfactory bulb neurons and their axons form what
is called a olfactory nerve. many different receptors.
starts to put it back together, pattern of activity.
skin is the largest organ in the body.
layers of skin
teeth nails hair and brain dont have touch neurons. cannot feel if people touch it
some parts are more sensitive then other parts- inhomogeneous of the receptors
converting physical stimuli into neural impulses
start out with pigment (rhodopsin)
light is made up of photons
1)photon is absorbed by pigment (rhodopsin)
2)as it absorbs light, it changes it structure.
causes a protein inside the cell to become activated( TRANSDUCTION)
one can active 800 trandsucin
70 can be activated
4)CGMP (goes down)
eat up or clean break apart (broken down)
because of the channels of the side
inward-only when CGMP is bound to it, if none it will close
removed from the cell because of the CGMP-it is blocked, so no positive going in.
so positive ions are going out, so the cell becomes more negative.
so neurones become more positive.
outward channel-all the positive changes inside the cell go out of the cell though this
Brain activity of the orgin of our perception
-attention shapes your perception
dr. newsome- he did an experiment
got a monkey to look at a computer screen that contained 100 dots
trained him to look at the screen and fixate on the screen
some of the dots would move left or right, and all the other dots would move
certain collection of neurons prefer certain movement of the dots.
is our perception a result of brain activity?
brain says left, eyes say right. the neurons produce a signal stronger then the stimulus.
scientific evidence that shows that
-Attention to particular sensations permits filtering of less important sensations.
-Attention can be consciously directed, or guided by features inherent within sensory
shadowing- left and right people talking get tested on only one, you are able to ignore the
one side your not paying attention to. can turn your attention to one way or the other.
some stimulus can shift your attention
top down is the interpation of the binding of the information
binding sensory input for perception
-similarty (our brains group like objects)
-proximity (grouped together)
-closure (wanting to close objects)
Perceptual errors result when our perceptual system applies Gestalt principles incorrectly.
Our moment to moment awareness of ourselves and our surroundings.
It is (1) subjective, (2) dynamic, (3) and self-reflective.
-Conscious -Preconscious -Subconscious
-Conscious – Unconscious
-Controlled andAutomatic Processes are harmonious
- emotional state influenced by unconscious events