Sensation and Perception Flashcards
Elements of a sensory system and the flow of info from a stimulus in the environment
Thalamus - processes signals and relays to cortex.
Transduction
The process of converting incoming energy into nerual activity.
Neural receptors
Specialized cells that detect certain forms of energy and transduce them into nerve cell activity
Transduction and encoding
- Codes are usually intense - coded by the frequency of neural firing or number of neurons.
- Quality - coded by the type or location or pattern of specific neurons.
- Principles 1- anatomical feature for gathering, focusing, filtering stimuli. 2. sensory receptors - detect physical energy, translate physical stimulation into neural signals.
Photoreceptors
At the back of the retina = rods and cones
Ganglion cells
On the surface of retina, generates action potentials, edge detectors
Interneurons
Pass signals from photoreceptors to ganglion cells
common features across senses
- accessory strucutres - anatomics features = gathering,focusing and filtering stimuli
- Sensory receptors - detect physical enegy and translate physical stimulation into neural signals (Transduction)
- Each system - minimum energy to activate it
- Sensation = attention, decision making
- Perception is complex interpretive process.
Spectrum of electromagnetic energy - visible light
Small part of the electromagnet spectrum , 400 to 750 nanometers, light intensity vs wavelength.
https://www.notion.so/Sensation-Perception-448442fce81d49a9a731672d8049f13c?pvs=4#85ae4509f3f8469f9a2f7b85618916c3
Psychological dimensions of light
Hue - colour
Colour saturation - purity
Brightness - intensity
Trichromatic - young helmholtz theory of colour vision
- Mixing pure lights of blue, green, red = any colour
- Short wavelength = sensitive to blue
- Medium wavelength = sensitive to green
- Long wavelength - sensitive to reddish yellow
https://www.notion.so/Sensation-Perception-448442fce81d49a9a731672d8049f13c?pvs=4#dabe2d42e2bc4e13af6a8701cd2e4016
Audition/hearing
- Vibration of air molecules due to objects, travels through air as waves at 340 m/s, travels around and through objects, enter the ear and are transduced.
Dimensions of sound
Frequency - cycles per sec, Hz, psychological experiences of pitch
Amplitude - sound pressure, psychological experience of loudness, decibels, dB
Complexity - spectrum and transients, timbre or “quality”
Structure of the ear
Outer ear - pinna - collects, shapes sound, ear canald
Middle ear - tympanic membrane , ossicles including malleus (hammer), incus (anvil), stapes (stirrup)
Inner ear - cochlea, semicircular canals
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Structures of inner ear
https://www.notion.so/Sensation-Perception-448442fce81d49a9a731672d8049f13c?pvs=4#3c4de02657eb4597b9e7dcf15ed16e37
Cochlea structure
https://www.notion.so/Sensation-Perception-448442fce81d49a9a731672d8049f13c?pvs=4#bdb9bfdd718e493e9b3d87b15da4f09b
Cochlea info
Vibrations stimulate inner and outer hair cells. The stereocilia bens on the hair cells releasing neurotransmitters = nerve impulses
Projections to the brain come from inner hair cells = outer hair cells amplify and control membrane vibrations.
Fusion
Two primary tones of the roughly the frequency fuse. The amplitude changes depending on phase primary tone 1, primary tone 2 and fused tones.
Beats
Tones separated by less than 1/4 a critical band beat. This results in a frequency and amplitude modulated at a rate equal to the difference in primary frequencies = unpleasant - sensory dissonance
Roughness
Beats faster than 20Hz, not individually processed but rough and nasty sounding. 300/320 roughness, 300 Hz primary tone, 320Hz primary tone.
Disappears when tones are far apart in separate critical bands = 400 Hz primary tone, swept primary tone and combined tone
Absolute pitch
The ability to identify the musical notes associated with specific sound frequencies.
Timbre
The mixture of frequencies and amplitudes that make up the quality of the sound
Psychophysics
Scientific study of - elationship between physical attributes and psychological experience by gustav fechner
- Frechner method - original methods - limits, adjustments, constant stimuli, modern enhancements, staircase methods, PEST.
Thresholds: absolute threshold; just noticeable difference; magnitude
- Detection threshold - minimum intensity required to detect stimulus 50% of the time
- Varies across persons, but rough averages are often cited
Modality and thresholds
Vison - candle flames at 48km away on a clear night
Hearing - ticking watch or breathing 6m away
taste - 1 stp sugar in 7.5L of water
Fechner’s classical method - signal detection theory
- Sensitivity - intesity of the signal, capacity of sensory systems, affected by noise level.
- Response criterion - willingness to respond to a stimulus, influenced by motivation and expectancies
https://www.notion.so/Perception-6bad362722cd489589e9f7ad16e538cb?pvs=4#05e75c0999594813b10d2ff0e56b6202
Psychophysical “Laws”
Webers law - JND constant proportion of stimulus magnitude , JND = Kl
Fechners law - magnitude of stimulus growth logarithmically as the subjective experience of intensity growths artithmetically
Steven’s power Law - subjective intensity increases linearly as actual intensity grows exponentially and different stimuli/modalities have different exponent.
Fechners Law and stevens law diagam
https://www.notion.so/Perception-6bad362722cd489589e9f7ad16e538cb?pvs=4#adf25e8edd5a4c78a164bfe3102516d0
Key features of the constructivist, computational and ecological approaches to perception
- Computational
- Constructivist
- Ecological
- Perceptual organisation and examples of figure-ground separation and the gestalt grouping principles.
Basic processes in perceptual organisation : Gestalt principles
Proximity, similarity, contnuinty, closure, texture, simplicity, common fate
Palmers grouping principles
Common region, connectedness, synchrony
https://www.notion.so/Perception-6bad362722cd489589e9f7ad16e538cb?pvs=4#683b00c5a6524256a7becc3e9d20fe50
Depth or distance perception
- The organisation of perception in three dimensions
- Two kinds of visual information provide important info about depth and distance
- binocular cues: visual input integrated from the two eyes
- monicular cues - visual input from one eye
Binocular Cues/ cells
Convergence - sensing how “turned” in the eyes are to focus on an object
Monocular cues
Interposition - object blocking anohter
Linear perspective - lines converge
Texture gradient: Distant objects finer
Shaind: 3D objects cast shadows
Aerial persepctive - far objects = blurry
Familiar size - familiar objects are small, distant
Relative size: The smaller object seen as further away
Perception in Emotion
Optical flow cues - motion parallax loming, role of the senses of equilibrium and touch
Stroboscopic illusion - principles of likelihood and simplicity
Perceptual Constancy
https://www.notion.so/Perception-6bad362722cd489589e9f7ad16e538cb?pvs=4#1d83356b1e7f46a8889137b692cfc5e6
Perceptual processing, object superiority effect
https://www.notion.so/Perception-6bad362722cd489589e9f7ad16e538cb?pvs=4#428cf42e90e94ec3bc8c770812a74b5d
Structure of the eye
https://www.notion.so/Perception-6bad362722cd489589e9f7ad16e538cb?pvs=4#ccf4f74b01e34cf195c467164bb7ba19
Rods and cones
Rods - highly light sensitive photoreceptors in the retina that allow vision even in dim light but cannot distinguish colours
Cones - photoreceptors in the retina that help us distinguish colours.
Photoreceptors
Specialised cells in the retina that convert light energy into nerve cell activity and they contain photopigments that respond to light.
Synaesthesia
A blending of sensory experience that causes some people to ‘see’ sounds or ‘taste’ colours, for example
Olfactory perception
Our sense of smell, detects chemicals that are airborne or volatile
Taste perception
Gustatory perception or our senses of taste, detects chemicals in solution that come into contact with receptors inside the mouth.
Olafactory receptors
Odour stimulates these todifferent degrees and the particular patterns of stimuluation create codes for particular odour sensations.
Olfaction and brain structure
Olfactory bulb where processing of olfactory information continues. Information is sent for further processin
tional experience
