exam 2 Flashcards
what are the senses (5 senses we typically think of + senses beyond these 5)
typical:
1) smell
2) see
3) taste
4) hear
5) touch
5 senses beyond:
1) temperature
2) pain
3) hunger
4) thirst
5) full bladder
6) time
sensation vs perception ( + lightbulb example) (+ transduction)
SENSATION: nervous system detects/encodes information from the environment
- concerned with identifying environmental energy/information
- ex. - input stimulus of light -> sensory cells detect the light information -> sensory neurons/action potentials activate a brain response
PERCEPTION: how we interpret/give meaning to nerve sensations
- concerned with identifying objects
- ex. - what is the light? how bright is it? what colour is it? where is it?
TRANSDUCTION: converts external stimulus/physical energy into electrical signals within neurons
- ex. sensory neurons transduce the physical energy of the light into nervous system activity
people vs commonalities (basics of perception)
perceptions are private experiences, unique to each of us, but there are some commonalities
- ex. some people see a blue box, some people see a purple box
physical events that we miss (basics of perception)
- We do not perceive everything in the physical world
- There are physical events that we miss
- We see stuff that aren’t physically present all the time because our nervous system reconstructs what we see
- Ex. you won’t always detect/have perception of bug crawling up you’re leg
- Ex. illusory images
does perception reflect our reality?
no, perception does not reflect our reality
** Perceptions are RECONSTRUCTIONS, not REPRODUCTION of the physical world**
Perception is all about constructing the reality that we’re seeing
perception is not a faithful construction of our reality
three themes of perception
1) perception depends on context
2) perception is about objects
3) perception is multimodal (multi-sensory)
theme 1: perception depends on context
- ex. dress debate
electromagnetic spectrum + visible light + reflect + refract (theme 1: perception depends on context)
- visible light is a small sliver of the electromagnetic spectrum
ELECTROMAGNETIC SPECTRUM: the range of electromagnetic radiation in wavelengths/frequencies
- VISIBLE LIGHT is electromagnetic energy that can be perceived by the eye (only a sliver of the EM spectrum)
- humans are sensitive to wavelengths between 400 and 700 nanometers
light REFLECTS when it bounces off of objects (which is the reason we see objects)
light REFRACTS when it passes through objects and bends (bending waves)
lens + retina + ciliary muscle (theme 1: perception depends on context)
LENS: bends light
- focuses light waves on the retina
RETINA:
- innermost layer of the eye
- contains sensory cells that transduce/convert incoming light into action potentials
CILIARY MUSCLE: changes the shape of the lens to control accommodation (focusing on objects at different distances)
lens focusing (accommodation + unaccommodated lens + accommodated lens) (theme 1: perception depends on context)
ACCOMMODATION: changing the shape of the lens to focus on objects near or far
UNACCOMMODATED: relaxed ciliary muscle, see far-away objects
- thinner, flatter lens which bends the light rays properly so they focus/converge right on the retina itself
ACCOMMODATED: contracted ciliary muscle, see close-up objects
- ciliary muscle bending the lens, making it thicker/fatter
- making sure the light is bending appropriately so you can see objects properly in focus
lens correction (myopia + hyperopia) (theme 1: perception depends on context)
LENS CORRECTION: when eyeball is too big relative to the size of the lens
MYOPIA (near-sightedness):
- objects focus IN FRONT of the retina/sensory neurons, not on the retina/sensory neurons
- can see up close easily
- CONCAVE LENS: fixes myopia; bends light OUTWARDS to get focus properly on the retina itself (thinner in the middle, fatter on the ends)
HYPEROPIA (far-sightedness):
- objects focus BEHIND the retina/sensory neurons, not on the retina/sensory neurons
- can see far away easily
- CONVEX LENS: fixes hyperopia; bends light INWARDS so focus is properly on the retina itself (fatter in the middle)
light transduction (macula + rods + cones) (theme 1: perception depends on context)
TRANSDUCTION: process of converting an external energy into electrical acitivyt within neurons
MACULA: centre of retina/vision
- composed of an array of sensory cells: rods and cones
RODS & CONES: sensory cells that transduce light energy into neural signals
RODS:
- detect dark vs light
- detect motion
- located in the visual periphery (the brain is always filling in information about your peripheral/surroundings because it doesn’t provide fine detail)
CONES:
- provides rich colour
- provides detail information
- there are three kinds
- located in the visual centre
trichromatic theory of colour vision (cone response to wavelengths) (theme 1: perception depends on context)
TRICHROMATIC THEORY: colour vision is influenced by the output of all 3 cone types
3 cone types:
- cones respond to wavelengths
- short and high frequency waves (red & yellow)
- long and low frequency waves (violet & blue)
- medium wavelengths (cyan & green)
the COMBINATION of ALL cone activity influences colour vision, not the activity of a single cone type
- to see any singular cone colour, you you need all 3 cones to be active/operating at the same time
- each cone type is giving a different colour code to tell you what you’re seeing
- Any given wavelength corresponds to a different set of cone activation
- Every cone is gonna respond to a different light, but to different levels
- Ex. if i see the colour red, im not seeing it just because the red cone is activated, but because all cones are activated at different levels
colour contrast (colour contrast + colour constancy +illuminant)
COLOUR CONTRAST: colours are more vivid when they contrast with their background
- i.e. CONTRAST!
- ex. Ex. bright green and bright orange traffic cones are vivid because they contrast with their background
COLOUR CONSTANCY: objects appear the same colour despite changes in lighting conditions
- ex. we perceive square A and square B to be different because of the surrounding context and our brain is constructing a reality based on what is plausible (we can see that the cylinder is casting a shadow across the checkerboard)
- the dress debate of 2015 !
- ILLUMINANT: the light
- one type of context
perception of colour depends on context
- ex. casting the shadow, changing the filter, etc.
the dress perception debate
best answer: colour constancy
- people imagine different illuminants
- some people imagine a warm illuminant (black and blue) and others a cool illuminant (white and gold)
- based on how you imagine the illuminant, you can get two perceptual answers
context matters for perception
- just because different imaginations for what the context is, it doesn’t invalidate your perception
- What the actual answer is is immaterial to your perception
theme 2: perception is about objects
- the brain “fills in” missing perceptual information to complete objects in your mind
- often based on what we experienced in the past
experience is a determinant of perception
gestalt laws of organization (theme 2: perception is about objects)
GESTALT LAWS OF ORGANIZATION: let us group and combine visual features into coherent objects based on past experiences
- we see the world as whole, organized objects, not individual lines, curves, shapes, etc.
- ex. seeing phone as a phone and not a rectangle, through experience
GESTALT PRINCIPLES OF:
1) PROXIMITY: perceive objects NEAR each other as groups
- ex. grouping the circle, square, and triangle as one group because they’re close to each other
2) SIMILARITY: perceive SIMILAR objects in groups
- group together objects with similar properties
- ex. blue team goes together cause theyre all wearing blue shirts
- ex. a row of white circles, a row of black circles, rather than a column
3) CONTINUITY: perceive stimuli as single, UNINTERRUPTED objects
- filling in gaps when something is blocking parts of it and seeing it as a whole object rather than an object with separate broken off parts
- ex. drawing an inference that train tracks continue underneath the bridge even if you can’t see it
- ex. seeing the circle as one continuous loop just with breaks in between, even though physically whats actually happening is that it’s three different objects
4) CLOSURE: perceive stimuli as a WHOLE entity
- illusory contours and negative space
- has a little bit of continuity
- perceiving an object that is not there to complete the shape
- ex. we perceive a white triangle even though it’s not physically there
- ex. perceiving an image of peacock in the NBC logo
monocular depth cues (theme 2: perception is about objects)
MONOCULAR DEPTH CUES: let us perceive visual depth (3D) with one eye
- uses context and ability to form things into specific objects
1) LINEAR PERSPECTIVE: parallel lines converge in the distance, and diverge closer to us
- ex. looking at the beginning vs the end of train tracks
2) RELATIVE HEIGHT: faraway objects are higher in our field of view than closer objects
- comparing heights of objects
- ex. tulips in a field that are closer to you appear lower than tulips further away
3) RELATIVE SIZE: nearby objects appear larger than objects at greater distance
- comparing size of objects
- ex. tulips that are closer seem bigger and tulips that are far away seem smaller
4) FAMILIAR SIZE: prior knowledge about the size of the object and how it should appear relative to other objects
-not comparing physical objects
5) AERIAL PERSPECTIVE: distant objects appear more hazy because light is scattered by the atmosphere
- depends on the wavelength
- ex. stuff that’s further away has blue smearing/haze because of the light thats reflected off that object and short wavelengths
6) MOTION PARALLAX: distance estimated when viewing objects from two different lines of sight
- objects that are closer to you to appear to move faster and objects that are further away seem to move slower
- the parallax is greater for objects that are closer to us than objects that are further away
- ex. in a car, the road is moving faster and the clouds/sky is moving much slower
using two eyes to see depth (binocular disparity + stereopsis) (theme 2: perception is about objects)
BINOCULAR DISPARITY: image on the left retina is different from the image on the right retina
- your two eyes occupy two different positions/spaces in your head and therefore occupy two different images
- Your brain glues both separate images from each retina to form one image
- binocular disparity (difference in images that each eye sees) lets us experience stereopsis (ability to perceive depth)
STEREOPSIS: the ability see depth in the world, using two eyes, because of binocular disparity
theme 3: perception is multimodal
PERCEPTION IS MULTIMODAL: speech is a multimodal phenomenon, nut just auditory
- ex. the McGurk effect
acoustic sound (sound + air pressure vibrations + amplitude + frequency) (theme 3: perception is multimodal)
SOUND: mechanical vibrations we detect with our ears
- Compression and expansion of air molecules
- peak of the wave = compression
- bottom of the wave = expansion
- air pressure vibrations, frequency, and amplitude are related to sound waves and how we perceive them
AIR PRESSURE VIBRATIONS: waves created by air particles vibrating
- sound is air pressure vibrations that can be characterized by their amplitude
AMPLITUDE (dB): related to loudness, measured in decibels (dB)
- the height of the cycle
- loud noise = increased wave amplitude
FREQUENCY (Hz): the number of cycles (of vibration) per second/Hz
- 1 Hz = 1 cycle per second
- long/slow wavelength = low-frequency/pitch
- short/fast wavelength = high-frequency/pitch
CYCLES PER SECOND: frequency (Hz units);
-related to pitch
- One cycle= normal -> compression -> expansion -> normal atmospheric pressure
sound amplitude (dB + dB sound pressure level + example of dB SPL values) (theme 3: perception is multimodal)
SOUND AMPLITUDE: how we talk about sound level
- influences our perception of loudness
DECIBEL (dB): how loud/intense a sound is
- ratio scales
- can be used to describe any ratio of any value
DECIBEL SOUND PRESSURE LEVEL (SPL): measures the strength of sound waves
- sound pressure amplitude measured in dB to weakest sound pressure humans can hear (at 1000 Hz)
- physical energy
- ex. the hearing threshold is 0 dB SPL, and a jet air craft is 140 dB SPL
dB SPL (physical energy) is not the same thing as loudness (mental individual experience)
hearing ranges (4 ranges) (theme 3: perception is multimodal)
HEARING RANGES: frequencies and sound levels we can hear
- frequency= 20 - 20,000 Hz
- level= -10 - ~140 dBSPL (140 is pain threshold)
AUDIBLE RANGE
- everything we can hear in a certain region
- our sensitivity is best from 2,000 Hz to 10,000Hz
SPEECH RANGE
MUSIC RANGE
HIGH RISK THRESHOLD
- close to pain threshold and instantaneous damage
ear anatomy (pinna + ear canal + ear drum + ossicles + cochlea + auditory nerve) (theme 3: perception is multimodal)
1) PINNA:
- collects sound waves and forces them into the ear canal (helps funnel air pressure vibrations into the ear canal)
2) EAR CANAL:
- receives sound waves from pinna
- funnels sound waves in the eardrum
3) EAR DRUM:
- detects sound wave vibrations from the ear canal which sends the ear drum into motion
4) OSSICLES:
- connect the ear drum to the cochlea
- convert air pressure vibrations into mechanical vibrations
- vibrate at the frequency of the sound wave and transmit it from the eardrum to the cochlea
- tiniest ear bones in the body
5) COCHLEA:
- receives sound pressure vibrations from ossicles
- converts the sound-related vibrations into neural activity/action potentials
- acts as a “frequency analyzer” that separates high and low pitches
- separates sounds into high-frequency information (base of cochlea) and low-frequency information (apex of cochlea)
- primary hearing organ (bony, snail-shaped organ inside the inner ear)
6) AUDITORY NERVE/PATHWAY:
- nerve fibre that carries action potential from the cochlea to the brain
- part of the temporal lobe
- visual cortex (V1/V2) influence speech processing in auditory cortex (A1) through multisensory areas (posterior superior temporal sulcus, pSTS)
