Lecture 1: Sensation Vs Perception Flashcards
1
Q
What is the difference between sensation and perception
A
- Sensation: real /collection of information
- Perception: interpretation of reality based on individual
- Pathway of sensation to perception:
3a. Sensory stimulus->sensory receptors->neural impulses->interpretation
2
Q
Psychophysics
A
- Attempts to quantify the relationship between sensation and perception
- Has 3 elements
2a. Simple responses by the subject
2b. Extensive data collection from each subject
2c. Precise manipulation of experimental stimuli
3
Q
Top down vs bottom up processing
A
- Top down (old situations): uses prior knowledge/experience to influences answers which can lead to bias (ex: pattern recognition)
- Bottom up processing (new situations): perception is created by sensory stimuli, is data driven and happens in real time
- Need both to be effective
4
Q
Perceptual organization
A
- When the brain makes inferences to organize sensory information from vision (in the form of electromagnetic waves)
5
Q
Perceptual organization: depth perception: Binocular cues
A
- Depth perception that requires 2 eyes
- Types
2a. Retinal disparity: 2 retina each make a slightly different image (due to coming in from different angles), eyes compare these images creating depth perception
2b. Convergence: when we focus on an image, we cross our eyes slightly (greater convergence for closer images): our brain registers how much our eyes turn in which tells us how close the image is
6
Q
Perceptual organization: depth perception: Monocular cues
A
- Relative size: larger images look closer
- Relative height: objects higher look distant
- Overlap/interposition: object overlapped in front=looks closer
- Shading/contour: darker(contour)= closer , lighter(shaded)=farther
- Motion parallax: more distant objects move slower as we pass them
7
Q
Perceptual organization: Subjective Constancy
A
- Subjective constancy: people assume size, Color and shape of things remains constant
1a. Size constancy: perception that object has a fixed size regardless of the size of its in the retina
1b. Color constancy: perception that object doesn’t change colour
1c. Shape constancy: perception that object has a fixed shape, no matter its position (ex: closed vs open door)
8
Q
Perceptual organization: Gestalts grouping principles: main principles
A
- Emergence: we put things into patterns without realizing it
- Reification: perception has more information than sensation (abstract is perceived as real)
- Invariance: simple objects are perceived in the same way regardless of their direction, rotation, scale etc.
- Multistability: tendency for ambiguous perceptual experiences to alternate in unstable fashion
9
Q
Perceptual organization: Gestalts basic principles
A
- Figure ground: multistability/ Humans organize their perceptions into figures and backgrounds
- Pragnanz: Brain interprets images in the simplest manner possible
- Law of proximity: close=grouped
- Law of similarity: similar=grouped
- Law of closure: gaps=closed
- Law of continuity: aligned objects=continue behind obstructions (weird lines)
- Law of symmetry: objects create symmetry
- Law of past experience: objects based on past experience
- Law of common fate: objects that move together=grouped
- Law of common region: objects in same region=grouped
- Law of parallelism: objects aligned parallel to one another=grouped
- Law of connectedness: objects connected=grouped
10
Q
Sensory processing: Absolute threshold of sensation
A
- Definition: Minimal intensity of stimulus that is detected (detected 50% of the time)
- Subliminal stimulus: stimulus below absolute threshold
2a. has no effect on conscious perception, but still affects brain activity
11
Q
Sensory processing: Just noticeable difference (JND)
A
- Definition: the smallest noticeable difference in intensity of a stimulus while its being experienced
- Webers law=K=(^I)/I
2a. ^I: just noticeable difference
2b. I: first stimulus - Higher intensity of original sound, the greater the difference needed to notice it
12
Q
Signal detection theory (SDT)
A
- How individuals differentiate signals (important stimuli) from a noise (unimportant stimulus)
- 4 possibilities
2a. Hit (good): correct identification of signal
2b. Miss: identification of signal as noise
2c. False alarm: identification of noise as signal
2d. Correct rejection (good): identification of noise
13
Q
Unbiased SDT in histogram
A
- If put noise and signals in a histogram:
1a. Criterion in middle: unbiased criterion
1b. Anything less intense than criterion=no response
1c. Anything more intense than criterion=response
14
Q
Biased SDT histogram
A
- Conservative/+/strict: move criterion to right (histograms shift to left)
1a. Reduce hit/false alarms: good if brave/thirsty
1b. Increase miss/correct rejection: bad bc likely to get eaten
1c. Increases specificity: positive identification is more likely correct
1d. Conservative strategy: prefers correct rejection over hits - Liberal/-/relaxed: move criterion to left
2a. Increase hit/false alarm
2b. Decrease miss/correct rejection
2c. Increases sensitivity: negative identification is more likely correct
2d. Liberal strategy: prefer hits over correct rejection
15
Q
Sensory Receptor types
A
- Free nerve ending : dendrites embedded in tissues
- Encapsulated endings: dendrites encapsulated by connective tissue that enhances their sensitivity
- Receptor cell: distinct cells (not neurons) that activate neurons. Each kind of receptor cell is designed to recieve and transducer a specific type of physical stimulus
16
Q
Sensory Receptor location
A
- Exteroceptor: located near external environment (skin)
- Interoceptors: located internally (organs sensing blood pressure)
- Proprioceptor: located in moving body part because they sense position and movement (muscle movement)
17
Q
Sensory Receptor functions
A
- Mechanoreceptors: touch such as pressure, distraction or vibration
1a. Pacinian corpuscles: vibration and heavy touch
1b. Meissner corpuscles: light touch - Thermoreceptors: temperature change
- Nociceptors: pain
- Photoreceptors: light
- Chemoreceptors: taste, small, blood chemistry
18
Q
Transient receptor potential (TRP) channels
A
- Receptors that respond to pain and changes in temperature
- TRP channels are located on the surfaces of Nociceptors and thermoreceptors: if damaged by a stimulus they undergo conformational changes which activate action potentials that travel 3 types of nerve fibres
2a. AB (A-beta) nerve fibres: high diameter, thick myelination, fastest signal conduction
2b. A-delta nerve fibers: medium all
2c. C nerve fibers: smallest, unmyelinated, slowest conduction speed
19
Q
Tonic vs phasic receptors
A
- Tonic receptors: when receptors adapt slowly to stimuli and fire as long as stimulus is present
- Phasic receptor: quickly adapt to stimuli and dire when intensity or rate of stimulus changes
20
Q
Primary somatosensory cortex (PSC)
A
- Sensory receptors->primary somatosensory cortex (PSC) in post central gyrus of parietal lobe
- Homounculus: representation of how much space different areas of the body take up in PSC
21
Q
Sensory adaptation
A
- Occur in response to short continuous exposure to stimuli
- Temporary
22
Q
Structure of eye
A
- Path of light:
1a. Cornea->anterior chamber->lens->vitreous chamber->retina->fovea - Assisting parts:
2a. anterior chamber & posterior chamber: filled with aqueous humor (nutrients, maintains inocular pressure) from ciliary bodys leaked out of the canal of Schlemm
2b. Accommodation: ciliary muscle contract=lens sphere=brings focal point close to lens
2c. vitrous chamber: has vitrous humor that focuses light to be projected on retina
2d. Choroid: blood vessels
2e. Sclera: white of eye
23
Q
Rods and cones
A
- Rods: rhodopsin is the pigment in rods which is a form of vitamin A (light/dark)
- Cones in fovea of retina:
2a. 3 types for Color: trichromatic theory of vision
24
Q
Iris and autonomic control
A
- Creates opening called pupil
1a. Sympathetic /dark: contracts radical muscles of iris, dilates pupil
1b. Parasympathetic/light: contracts circular muscles of iris, constricts pupils
25
Q
Types of sight
A
- Nearsighted: myopia
1a. Can’t see far
1b. Image is in front of retina - Farsighted: hyperopia
2a. Can’t see close
2b. Image is behind retina - Just right: image is on retina
26
Q
Phototransduction cascade
A
- Light->ganglion cells->bipolar cells-> rods/cones (photoreceptors)
1a. Ganglion cells become optic nerve - Photoreceptors at rest (polarized): releases glutamate (excitatory)
2a. Photons activate retinal from cis to trans retinal in rhodopsin->GPCR activated ->activates phosophodiesterase->hyperpolarizes->no glutamate->active
27
Q
Visual processing
A
- When signal crosses optic chiasm ->LGN in thalamus ->primary visual cortex in occipital lobe
28
Q
Parallel processing /feature detection
A
- Parallel processing is efficient, allows specialization, integration, and redundancy
- Cell types
2a. Parvocellylar pathway: responds to fine detail, Color, size, shape
2b. Magnocellular: location, speed, direction of movement
29
Q
Feature detection
A
- Describes how brain perceives external world by dividing it into specific features
30
Q
Structure and function of the ear
A
- Outer ear
1a. Auricle/pinna directs sound into external auditory canal which carries wave to tympanic membrane/eardrum - Middle ear has 3 bones (ossicles)
2a. Malleus, incus, stapes which translate wave into physical vibration which is conveyed into oval window - Inner ear:
3a. Oval window -> scala vestibuli -> cochlea -> scala tympanic -> round window ->movement of wave causes organ of corti to vibrate (organ of corti sits on basilar membrane)
3b. Hair cells in organ of corti have stereocilia which cause action potentials to be fired ->auditory nerve ->brain
31
Q
Inner ear: vestibular system
A
- semicircular canals: detect angular acceleration (twist of head)
- otoliths: linear acceleration: up down or tilt
32
Q
Auditory processing
A
- Hairs in organ of corti are mechanoreceptors…when they depolarize after binding they release a neurotransmitter that causes electrical signal to go to brain
1a. Sound information: auditory nerve->cochlear nuclei in medulla ->inferior colliculus -> Medial geniculate nucleus of thalamus ->auditory cortex in temporal lobe
33
Q
Basilar tuning
A
- Humans hear from 20 Hz to 20 000 Hz
- We distinguish high and low frequencies from high frequency waves stimulating the narrow cochlear base and low frequency waves stimulating the wider cochlear apex
34
Q
Gustation
A
- Relies on chemoreceptors calledgustatory cells in taste buds
- There are 5 tastes: bitter, sour, salty, sweet, umami (savoury) and each gustatory cell detects all 5 tastes
35
Q
Olfaction
A
- Relies on chemoreceptors that bind to odorants
- Axons of olfactory chemoreceptors form olfactory nerve and when it’s GPCR binds to chemicals it triggers AP to be sent from olfactory nerve to olfactory bulb ->piriform (olfactory) cortex in temporal lobe ->orbitofrontal cortex
- Only sense that doesn’t relay into thalamus
36
Q
Pain
A
- Detected by nociceptors
1a. Bottom up processing detects pain
1b. Top down processing: impacts how people experience pain
37
Q
Kinesthetic sense
A
- Knowing bodies position and motion
- Ex: muscle memory
38
Q
Vestibular sense
A
- Feeling of balance and spatial orientation
- Located in inner ear
