Chapter 4 Flashcards
Sensation and perception
Explain the details of the case of Dr. P? What was different about him?
- Dr. P - music instructor - he was a little strange - would talk to parking meters, tilt head to students
- Dr. Sacks - shown images - focus on certain items but not the bigger picture.
◦ not perceiving things they was you usually would
◦ prosopagnosia - a visual issue with faces
‣ perceptual issue - stage were brain is selecting information
What is sensation?
- Sensation= stimulation of sense organs (lightwaves by sensory receptors)
What is perception?
- Perception = selection, organization, and interpretation of sensory input (brain does this and recognizes)
What is psychophysics?
- Psychophysics = Study of how physical stimuli are translated into psychological experience
What did Gustav Fechner discover?
Sensory thresholds Concept of the threshold - enough stimulation to detect it. (how bright does the light need to be to see it, when do we cross the threshold?) ex. night lights turn on automatically as you cross that threshold the light turns on.
What is a threshold?
a dividing point between energy levels that do and do not have a detectable effect
What is an absolute threshold?
for a specific type of sensory input is the minimum amount of stimulation that an organism can detect. (50% of the time.)
What are some examples of absolute thresholds?
- Vision - A candle flame seen at 50 km on a dark clear night (50% of the time you should detect it)
- Hearing - The tick of a watch under quiet conditions at 6 metres
- Taste - One tsp (5 ml) of sugar in 7.5 litres of water
- Smell - One drop of perfume diffused into the entire volume of a six-room apartment
- Touch - The wing of a fly falling on your cheek from a distance of 1 cm
What is the JND? (Just noticeable difference?)
- two weights to compare, how big of a different needs to exist to notice a difference
- JND = smallest different detectable
What is weber’s law?
- Weber’s Law - Size of JND is proportional to size of initial stimulus (ex. lighter weights could detect a smaller difference more easily)
- Weights: 1/30 - if standard=30 oz
What are the four quadrants of signal detection theory?
When the actual stimulus condition is present and…
Your response is present: Hit
Your response is not present: Miss
When the actual stimulus is not present and…
Your response is present: False alarm
Your response is not present: Correct rejection
What is signal detection theory?
proposes that the detection of stimuli involves decision processes as well as sensory processes, which are both influenced by a variety of factors besides stimulus intensity.
◦ not just sensory information but also a decision
What is perception without awareness called?
◦ Subliminal perception - the registration of sensory input without conscious awareness.
◦ ex. popcorn at the movie theatre
◦ are we actually influenced by subliminal perception?
What is sensory adaptation?
◦ decline in sensitivity (ex. water is very cold then you get used to it, socks are skratchy then you don’t notice)
‣ The gradual decline in sensitivity due to prolonged stimulation
◦ perfume, skunk, stinky socks (you adapt to the smells)
What is synaesthesia?
= condition in which perceptual/cognitive activities trigger special experiences (ex. shapes associated with tastes, hear things and see) - joined sensation! (Coloured hearing, you are more likely to have other types)
‣ it is a trait not a disorder - it’s good for memory! Pairing remain fixed for life.
What is the key stimulus for vision?
light waves and electromagnetic radiation
How does the amplitude of wavelengths affect vision?
- greater amplitude = brighter
- smaller amplitude = dim light
How do varies on wavelength effect what we see?
- varies in wavelength - perception of colour (long wavelengths - red, medium - green, short - blue)
What is purity?
mixture of wavelength in the light
What is saturation?
richness of the colours (amount of whiteness in a colour)
Can humans see the same waves as other animals?
- we can only experience certain types of waves
- some insects can detect other rays (Ultraviolet rays)
- reptile can use infrared rays
What are the two purposes the eye?
- channel light to the neural tissue that receive it (called the retina)
- and they house that tissue
What does the sclera do?
- sclera (white portion) makes sure the rest of the eye is dark, only light passes through that part
What does the cornea do?
- cornea - light where it enter the eye. Light enters the eye through a transparent “window” at the front, the cornea.
What is the pupil? What does it do?
- pupil is the black circle - is the opening in the centre of the iris that helps regulate the amount of light passing into the rear chamber of the eye. (pupil changes depending on how much light is coming into the eye._
◦ pupil will get larger when it’s dimmer to let more light in
What is the lense?
Transparent eye structure that focusses the light rays falling on the retina. (cristaline structure that changes - maintains good eye health when you see a variety of length things)
◦ Made up of relatively soft tissue - capable of adjustments that facilitate a process called “accomodation” where the curvature of the lens adjusts to alter visual focus.
What is the iris? What does it do?
- Iris - colourful part - coloured muscle helps with pupil
What is the Fovea? What does it do?
Fovea - is the tiny spot in the center of the retina that contains only cones, visual acuity is the greatest at this spot. Gives us the crisp vision, (rose - light waves refelcting off the rose and are refracted to back on eye on fovea - and see rose is upsidedown
What is the vitrious humour?
- Vitrious humour - jelly substance - floaters - particles that float
What is the aqueous humour?
- Aqueous humour - liquid that flows through the channels, increase pressure - glatcoma
◦ concerned about the pressure! Can lead to damage.
What is the retina?
- Retina - health of retina - neural tissue are very important to our vision. The retina is the neural tissue lining the inside back surface of the ye, it absorbs light, processes images, and send visual information to the brain.
What is the optic disk?
- Optic disk - is a place in the retina where the optic nerve fibres exit the eye. clump together and exit
What are visual receptors?
Visual Receptors: Rods and Cones Located within the inner most layer of the retina
What are cones?
- Cones: are specialized visual receptors that play a key role in daylight vision and colour vision. (daytime vision, provide visual acuity (sharpness and precise detail) (stubbier)
What are rods?
- Rods: the specialized visual receptors that play a key role in night vision and peripheral vision. (elongated)
What occurs in Nearsighteness?
- Nearsighteness - football shaped eye - focus point fall in place of the eye and blurry for things that are far away. Corrective lenses reflect the light where it should
What occurs in farsightedness?
- Farsightedness - Shortened eyes - focus point is behidn the retina. Things that are close are blurry. Far away are clear.
What are receptive field?
Receptive Fields = Retinal area that affects firing of cell.
◦ The collection of rod and cone receptors that funnel signals to a particular visual cell in the retina makes up the cell’s receptive field.
What occurs in receptive fields when there is A) no light, B) Light in center, C) Light surrounding?
‣ A) No light: normal baseline rate of firing
‣ B) Light in centre: increased rate of firing
‣ C) Light surround: decrease rate of firing
What are ganglion cells?
- Ganglion Cells: responds to light in certain spots (constrast, light and darkness)
- Receptive field: 1 tiny portion of ganglion cell that are being responded to.
- Baseline activity
What is optic chiasm?
the point at which the optic nerves from the inside half of each eye cross over and then project to the opposite half of the brain.
◦ Axons on the left side of the brains and axons on the right half of each retina carry information to the right side of the brain.
What are the two different visual pathways in the brain?
‣ 2 Different pathways:
* Magnocellular (brightness)
* Parvocellular (colour)
What did hubel and wiesel say about cells in the visual cortex?
◦ 1) Simple - width and orientation of lines when right position
◦ 2) Complex - width, orientation, in any position
What are the two visual processes?
- Ventral pathway (Temporal) “what” an object is
- Dorsal pathway (Parietal) “where” an object is and how to use it
◦ Damage to the what system - the case of DF (couldn’t recognize what he was looking at.)
What is the trichromatic theory of colour vision? Why is this theory by?
- Trichromatic theory (Young & Helmholtz)
◦ Receptors: 3 different photopigments
‣ Sensitive to long, medium or short wavelengths
‣ waves: short - blue, medium - green and long -red.
‣ Eye does it’s own colour mixing
‣ Different levels of neural activation translated into different colours.
‣ Colour blidness - deficiency in ability to distinguish among colours. 3 cones = normal, other = colour blind.
What is the opponents processing theory of colour vision?
- Opponent processing theory
◦ 3 pairs of antagonistic colours.
◦ Red/Green, blue/yellow, black/white.
◦ Acros from one another is a pairing
What is a perceptual set?
◦ Perceptual set - readiness to perceive in a particular way
‣ ex. examples of reversible (ambiguous) figures
What is inattentional blindness?
◦ Selective attention: Inattentional blindness = Failure to see visible objects or events because attention is focused elsewhere
What is change blindness?
‣ Change blindness: involves the failure to notice a seemingly obvious change in a visual display. Not able to see large changes unless your aware of it.
What is feature analysis?
‣ Process of detecting specific (basic) elements in visual input & assemble into more complex form
‣ Starts in components of a form (lines, edges, and corners) and you build them into perceptions.
What is gestalt theory?
◦ An influencial school of thought that emerged out of Germany during the first half of the 20th century. Gestalt = german for “form” or “shape”. Demonstrates that:
‣ Whole can be greater than the sum of its parts
Relates to “figure and ground”
How is figure and ground? How does it relate to gestalts theory?
◦ Figure and ground - do you see a vase or two faces? Dividing visual displays into figure and ground is a fundamental way people organize visual perceptions.
◦ Gestalts theory relates to how these elements are groups into higher-order figures:
‣ Proximity - elements that are close to one another tend to be grouped together
‣ Closure - Viewers tend to supply missing elements to close or complete a familiar figure
‣ Similarity - Elements that are similar tend to be grouped together
‣ Simplicity - Viewers tend to organize elements in the simplest way possible
‣ Continuity - Viewers tend to see elements in ways that produce smooth continuation
What is Distal a principle of perception?
- Distal - stimuli outside the body (the actual thing)
What is proximal a principle of perception?
- Proximal - stimulus energies impinging on sensory receptors (the image projected by your retina)
What is the context effect?
- “The CHT” your brain may fill in that information for you
- Contextual information
What are perceptual constancies?
- Perceptual constancies: stable perceptions maid changing stimuli
◦ Closet door will be recognized no matter how open it is. eg. size and shape
What are binocular cues?
- Binocular cues - cues form both eyes (take info form one eye if needed)
◦ retinal disparity - difference between the 2 images projected on each retina
◦ finger hasn’t moved but where it is in space cast from your eye.
◦ Magic eye images - roses
What is the difference between convergence and divergence?
- Covergence - eyes turn toward each other to focus near objects
- Divergence - eyes turn less for objects that are further away
What are monocular cues?
Monocular cues - the clues about distance based on the image in either eye alone.
What is the motion parallax?
- Motion parallax - things that move appear difference
◦ daisy moved more than cow and tree
◦ Things that are far away move more slowly than things that are close
◦ close move across visual scene more quickly
What is accomodation?
- Accommodation - The eye changes its focus to see objectives clearly at different distances. (adjustment to maintain clear vision at different distances)
What are pictoral cues?
monocular cues that give us an idea of where things are in space.
◦ linear perspective - a depth cue reflecting the fact that lines converge in the distance
◦ relative size - cue because closer objects appear larger
◦ texture gradient - can provide information about depth because the detais are too small when they are far away
◦ light and shadow - effects of shadowing make it useful for judging distance.
◦ interposition - cue when an object comes between you and another object, it must be closer to you.
◦ height in plane - reflects the fact that distant objects appear higher in a picture.
What are optical illusion?
- something of kilter on what we are experiencing and the reality
- Inexplicable discrepancy between appearance and reality
◦ Muler-Lyer Illusion (lines)
◦ The Ames room (room looks different from different perspectives.)
What are the two ways our ears hear sound?
- Amplitude (dB) decibels - sound pressure (ket lifitng off 130 - loud sound!)
- Frequency (Hz) cycles per second *also prosody - aprosodia
◦ Dogs can hear lower Hz/pitch
What is the pinna?
- Pinna directs sounds to the auditory canal (some people and cats can move their pinna)
What is amplificaiton?
- Amplificiation as the sound waves move through the canal
◦ Need to be careful with earbuds - 14% of young people are experiencing hearing loss
What are occicles?
- Occicles - tiny bones in the middle of your ear - joined together - pass on sound waves and vibrate move to the cochlea
What is the basilar membrane?
- Basilar membrane - hair cells - strong vibrations move - bang and removes end of hair cells and they don’t always regenerate when damaged.
- Fluid moves hairs - causes electrical signal to the auditory nerve and to the brain.
What is the place theory of hearing?
- Place theory - Von Helmholtz - specific part of the cochlear (1863) - holds that perception of pitch corresponds to the vibration of different portions, or places, along tha basilar membrane.
What is the frequency theory of hearing?
- Frequency theory - rutherford (1886) - the whole cochlear will vibrate but different frequencies will effect. holds that perception of pitch corresponds to the rate, or frequency, at which the entire basilar membrane vibrates
What is the traveling wave theory of hearing?
- Traveling wave theory - Georg von Bekesy (1947)
Basiliar membrane displacement as a function of frequency.
What are the two cues of auditory localization?
- 1) timing of sounds arriving at each ear (different times, if it’s in the middle it would hit at the same time but that’s not always the case)
- 2) Intensity (loudness)
Briefly how does gustation work?
- chemical substances that dissolve within our substance - that allow receptions in taste buds react to soluble chemical substances
- Taste buds -> neural impulse -> thalamus -> cortex
What are the four basic sense of taste? What is the additional 5th?
◦ Four basic tastes: Salty, sweet, sour, bitter and UMAMI flavour (mushrooms, cheese, meats)
What are the three levels of tasters?
◦ Non taster - 25% don’t have that many taste buds
◦ super taster 25% -extra taste buds - sensitive to taste
◦ 50% normal
◦ Females more likely to have super taste profile - so sensitive less likely to enjoy alcohol, spiciy food and cigarettes. Tend to eat bland foods.
What are two other influences on taste?
- Cultural/social influence on preferences (eating blood or bugs) largely learned.
- Perception of taste - multisensory experience - ex. crunchiness matters.
Briefly, how does olfaction (smell) work?
- Olfactory cilia = receptors
◦ substances carried in the air - Olfactory cilia -> neural impulse -> olfactory nerve -> olfactory bulb (brain)
briefly, how does the sense of touch work? What are the types?
- mechanical, thermal, and chemical energy impinging on the skin
◦ hair is a receptive field could leave to excitatory activity - Six types of sensory receptors eg. pressure, temperature, pain
◦ Not clear what the distinction is between them - Sensory receptors -> the spinal column -> brainstem -> thalamus -> somatosensory cortex
What do you know about pain signals?
- the receptors for pain are mostly free nerve endings in the skin. Pain messages are transmitted to the brain via two types of pathways that pass through different areas in the thalamus:
What are the two pathways for pain signals?
◦ Fast pathway: registers localized pain and relays it to the cortex in a fraction of a second. (ex. sharp pain if you cut your finger) uses A-delta fibres.
◦ slow pathway: lags a second or two behind (carries info about temperature, less localized, longer lasting, aching, burning pain after initial injury) uses C-fibres.
What is the kinesthetic sense?
- Kinesthesis - knowing the position of the various parts of the body
◦ Receptors in joints/msucles
What is the vestibular sense?
- Vestibular - equilibrium/balance
◦ Responds to gravity and keeps you informed about your body’s location in space.
◦ The vestibular system shares space in the inner ear with the auditory system. The Semicircular canals make up the largest part of the vestibular system.
What happens after reaching optic chiasm
◦ After reaching the optic chiasm, the optic nerve fibres diverge along two pathways, main pathways projects towards the thalamus. Here about 90% of the axons from the retinas synapse in the lateral geniculate nucleus.
