Sensory Perception and Visual Cues

Sensory Perception

• Sensory perception involves processing the environment through visual cues, binocular cues, and monocular cues.
• Sensory adaptation occurs when our perception of stimuli changes with prolonged exposure.

Visual Cues

• Visual cues encompass depth, form, motion, and constancy

Binocular Cues

• Retinal disparity is a binocular cue where each eye (2.5 inches apart) receives a slightly different image
• Convergence, another binocular cue, reflects how relaxed our eyes are when viewing distant objects, and how contracted they are when viewing close objects.

Monocular Cues

• Monocular cues include relative size, interposition (overlap), relative height (higher objects seem farther), shading and contour, and motion parallax (farther objects move slower).
• Constancy, also a monocular cue, ensures our perception of an object remains stable regardless of changes on the retina, including size, shape, and color.

Sensory Adaptation

• Sensory adaptation includes: hearing (inner ear muscle contracts with higher noise), touch (temperature receptors desensitize), smell (receptors desensitize to molecules), proprioception (adaptation over time), and sight (pupils constrict, cone/rod desensitization or pupils dilate).

Weber's Law

• Weber's Law explains how we perceive differences in stimuli, using weight perception as an example.
• A 2 lb weight feels similar to a 2.05 lb weight, but a 2.2 lb weight difference is noticeable.
• The just noticeable difference (JND) represents the threshold for perceiving change.
• For a 5 lb weight, a 5.2 lb difference is subtle, while a 5.5 lb difference is noticeable.
• The intensity of the stimulus (I) and the change needed for JND (delta I) have a constant ratio: Delta I / I = k (Weber's Law).
• Rearranging Weber's Law reveals a linear relationship between incremental threshold and background intensity, shown by Delta I = Ik.
• Plotted, I against delta I, gives a constant.

Absolute Threshold of Sensation

• Absolute threshold is the minimum stimulus intensity needed for detection 50% of the time
• Detection varies among individuals and within an individual
• Absolute threshold differs from the difference threshold (JND), which is the smallest detectable difference 50% of the time.
• Expectations, experience, motivation, and alertness influence absolute threshold
• Subliminal stimuli are below the absolute threshold

The Vestibular System

• The vestibular system contributes to balance and spatial orientation
• It relies on the inner ear's semicircular canals (posterior, lateral, and anterior), which are filled with endolymph
• Endolymph movement helps detect head direction and rotation strength.
• Otolithic organs (utricle and saccule) detect linear acceleration and head positioning, using calcium crystals attached to hair cells in a viscous gel.
• Endolymph continues spinning and results in dizziness and vertigo

Signal Detection Theory

• Signal detection theory explores decision-making amidst uncertainty, distinguishing between important stimuli and noise.
• Used to determine when we can detect a signal, like a small fish versus a large whale or words on lists
• Has real-world applications, such as interpreting traffic lights
• Signal strength is variable (d'), and strategy is (c)
• Strategies range from conservative (always say no unless 100% sure) to liberal (always say yes)
• Noise distribution: For any signal
• Signal distribution: Second graph
• d' = difference between means of the two
• d' big: signal shifted to right, be big and easy to detect.
• d' very small: signal shifted to left and would more difficult to detect.
• The strategy C can be expressed via choice of threshold
• If we use B strategy use this threshold – 2: probability of hit is yellow and false alarm pink
• d= d'-B in an example d'=1, so 2 -1= 1 Y

Ideal Observer

• ideal observer, minimizes miss and false alarm.
• C = B – d'/2 example anthing above a 1.5
• C = 0, participant is ideal observer <1 liberal >1 conservative
• Beta value of threshold to the ratio of height of signal distribution to height of signal
• Inbeta is d' x C = 1. 5

Bottom-Up vs. Top-Down Processing

• Bottom-up processing is stimulus-driven, sensory information processing from basic sensory pieces
• Top-down processing uses background knowledge and cognition to perceive and fill in blanks

Gestalt Principles

• Gestalt Principles highlight how we perceive organized patterns and wholes
• Similarity involves grouping similar items, proximity involves grouping close objects, and pragnanz prioritizes simplest forms
• Continuity shows lines following a smooth path, closure perceives objects as complete and whole, and things are perceived as parts of a group

Sight (Vision)

• Conjunctiva: First layer light
• Cornea: Transparent, anterior 1/6th of tissue
• Anterior chamber: Space with aqueous humor, maintains eye ball
• Pupil: Determines eye color, iris holes
• Lens: Light goes to back eyeball
• Suspensory ligaments: Attched to ciliary muscle, secrets aqueous humor
• Posterior chamber: Is area behind the ciliary muscle, also with aqueous humor
• Vitreous chamber: Filled with vitreous humor, pressure to eyeball
• Retina: Contains photoreceptors
• Macula: Special part of retina rich in cones(color)
• Fovea: Is completely covered in cones, no rods
• Choroid: Pigmented black in humans, a network of blood vessels bc of reflection
• Sclera: Whites of the eye, thick fibrous tissue that covers posterior of eye, and includes the attachment point for muscles

Visual Sensory Information

• Sensation requires light turned into neural impulse by photoreceptor
• Light is an electromagnetic wave within a large spectrum
• EM spectrum contains everything from gamma rays to AM/FM waves. Visible light is in the middle
• Violet (400nm) – Red (700nm)
• Sun is source of light
• Light enters pupil and retina contains Rods and cones, which gives night vision
• Light in and goes through pupil to hit rod, which light is then turned off
• Once rod off it turns on bipolar cell and turns on retinal ganglion, which turns optic nerve in to brain
• 6-7 million - Cones.
• There are 3 types: green, red, blue, and they area all centered in fovea
• Phototransduction Cascade – light into neural impulse
• Disc stack, proteins: 7 discs-rhodopsin (retinal). Shape change changes the molecules shape
• Transducin breaks from rhodopsin, goes to breaks PDE
• As cGMP decreases, hyperpolarize, Glutamate channels on, signals to bipolar and finally to optic nerve in brain

Photoreceptors

• Rods better in dark, cones better in color (photopsin)
• Differences of 120 million rods vs. 6 million cones
• Cones are in fovea
• Rods x1000 cones
• Cones are less sensitive better resolution
• Rods have slow recovery/cones have very fast recovery

Photoreceptor Distribution in Retina

• Blind spot no have rods or cones at all
• Rods are on the periphary
• Cones are within the whole retina
• If zoom into fovea will reach higher resolution and will see more clearly.

Visual Field Processing

• Brain makes sense:
• Right of body and right visual in L side of brain. L visual to R side

Feature Detection and Parallel Processing

• Color-triarchic, Form-parvo temporal, Motion- mango high tempo, no color
• Parallel processing see the same thing but different

Sound (Audition)

• Preserved waves to hair cells
• With air molecules around.
• Sound waves
• Farther=close=frequency
• Noise have different length. If are together it will strange
• Pinna, hits eardrum, 3 bones to vibrate, oval window back to cochlea
• Fluid goes to around where can back. Round window
• Organ of corti
• Little strands, hair, kinocilium connect
• Ca cells ap spirial ganglion, then auditory
• Cochlea=differentiate base is low and apex is high.
• Brain takes all then says what happening.

Cochlear Implants

• Narrow deafness where sounds are waves through to brain Transmiter stimulator back

Somatosensation

• Somatosensation is types intensity location. Types of thermos and propio and mech. timing can non adapt slow or fast

Vision/Downreulation

• Hands to together, cells no longer fire
• Improtant if have pain cell, cells will fire
• If lights enters cells ap can be connected

Soma/homunculus

• Brain body map and the senosory cortex where cortex can be taken
• If the there the brain parts and people can give stimulate then feel.

Propio

• Walk pitch sense. Sensory muscle stretches
• Muscle stretch it so we know if in the bodies know what it looks like
• If more we know movement more behavior cognitive process

Pain

• Thermocetpion rely on TRPV receptor for change that breaks molecule
• Thousand breaks bind cell same shape, causes AP Brain to make for you

3 type

• AB fibers fast thick myelin
• Ad fibers small and less myelin
• C fibers linger

Olfactory

Structure to have old then won’t eat things will in together taste, nose all together you can even.

Functions

• Knows which is smell called oilFactory area with epithelium
• Separately where it goes through and projects to each one
• Then goes to to olfactory lobe
• If binds there the it projects to cells one the one cell and they and all to glomerulus
• then are mit/tufted with brain.

More things

• G protein dissociate and binders 

Pheromones are urinating.

• The special oilFactory to acessory olfactory
• Also accessary with basial cells on activate,
• Triangle activate for amagldya like mating things..

Gust

• Have five: localize
• On tip, circle and side
• Each to certain section of things can be teste, mostly to brain label lines model

Ex

• Glucose hits sweet cell so it depolarizer

Channel binds

• Salt receptor in cell axon will say is sweet signal
• Conscinous = area alertless/sleep

Alertness

• Drowsly before sleep meditation state

Frequency

• Beta - concentrate alerts..

###Sleep

• stages through the patterns, 90 cycle what your you

####Movement stages Stage one through waves sensation seeing and not

Effects

• Dangers
• Can get back and will be certain to be

Dream

theories

• Freud: The ocean and what they look iceberg/ ocean The what meaning content
• what it can't Synthesis Lots pulses interprets it

Problems

• Deprivation make them worse and could dangerous drive worse
• More can be the hunger ones bad more Can back and sleep

other end

• Sleepness and to sleep fits like 2000

Sleep

walking

• and talking the have more and harmless

Air through in airway

problems

• May block the nose area of air-sleep stop breathing problems
• Brain no longer sends signal right

Lungs

• Vent could hyper low from heart

Hyp

• Hynopis relax alpha in state suggest and try

• Help remember and try

• Meditation

Med

• Train regulart mind delta

• Help Ad and age Psycho to oipiates
• Down functions more alcohol is the sleep memory

• To anxiety
• They neuron negatively charge