Processing the Environment Flashcards
Visual Cues
Depth, Form, Motion, & Constancy
Binocular Cues
retinal disparity= eyes are 2.5 inches apart & convergence= things far away, eyes are relaxed. Things close to us, eyes contract
Monocular Cues
relative size, interposition (overlap), relative height (things higher are farther away), shading and contour, motion parallax (things farther away move slower).
Constancy: our perception of object doesn’t change even if it looks different on retina (ex: size constancy, shape constancy, color constancy)
Hearing
inner ear muscles: higher noise= contract
Touch
temperature receptors desensitized
Smell
desensitized to molecules
Proprioception
mice raised upside down would accommodate over time, and flip it over
Sight
down (ex: light adaptation, pupil constrict, rods and cones become desensitized to light) and up regulation (dark adaptation, pupils dilate)
Weber’s Law
2 vs 2.05 lb FEEL the same and 2 vs 2.2 weight difference would be noticeable.
The threshold at which you’re able to notice a change in any sensation is the just noticeable difference
Linear relationship between incremental threshold and background intensity
Vestibular System
balance and spatial orientation
focuses on inner ear –> semicircular canals (posterior, lateral, and anterior)
canal filled with endolymph and causes it to shift and detects what direction our head is moving in and the strength of rotation
contributes to dizziness and vertigo
Absolute threshold of sensation
minimum intensity of stimulus needed to detect a particular stimulus 50% of the time.
low levels of stimulus, some subjects can detect and some can’t
influenced by: expectations, experience, motivation, alertness
Subliminal stimuli: stimuli below the absolute threshold
Otolithic organs
utricle and saccule help detect linear acceleration and head positioning. Lying down to standing up, they move and pull on hair cells which triggers AP
Signal Detection Theory
how we make decision under conditions of uncertainty – discerning between important stimuli and unimportant “noise”
Bottom-Up Processing
stimulus influences our perception
processing sensory information as it is coming in (built from smallest piece of sensory information, memories and experiences)
Top-Down Processing
background knowledge influences perception
Ex: Where’s Waldo.
Driven by cognition (brain applies what it knows and what it expects to perceive and fill in blanks)
Gestalt Principles
Similarity (items similar to one another grouped together), Pragnanz (reality is often organized reduced to simplest form possible), Proximity (objects that are close are grouped together), Continuity (lines are seen as following the smoothest path), Closure (objects grouped together are seen as a whole)
Conjunctiva
first layer light hits
Cornea
transparent thick sheet of tissue
Anterior Chamber
space filled with aqueous humor, provides pressure to maintain shape of eyeball
Pupil
hold made by iris (determines eye color)
Lens
bends the light so it goes to back of eyeball
Suspensory ligaments
attached to a ciliary muscles. these form the ciliary body which secretes the aqueous humor
Posterior Chamber
area behind ciliary muscles, also filled with aqueous humor
Vitreous Chamber
filled with vitreous humor, jelly-like substance to provide pressure to eyeball
Retina
filled with photoreceptors.
Macular= special part of retina rich in CONES
Fovea- completely covered in cones, no rods
Choroid
pigmented black in humans, a network of blood vessels. Bc black all light is reflected
Sclera
whites of the eye, thick fibrous tissue that covers posterior 5/6th of eyeball. Attachment point for muscles
Sensation
light–> neural impulse, by a photoreceptor
Light
electromagnetic wave part of a large spectrum
EM spectrum contains everything from gamma rays to AM/FM waves. Visible light is in the middle (violet (400 nm) and red (700 nm))
Sun is most common source of light
Light enters pupil and goes to retina which contains rods and cones
Rods
120 million rods, night vision
light comes in, goes through pupil, and hits rod. Normally rod is turned on, but when light hits turns off
When rod is off, it turns on a bipolar cell, which turns on a retinal ganglion cell, which goes into the optic nerve and enters the brain
Cones
6-7 million, red, green, blue, covered in fovea
Phototransduction Cascade
when light hits rods and cones
as soon as light is presented, takes light and converts it to neural impulse. Normally turned on but when light hits it is turned off
PTC steps
Inside rod LOTS OF DISKS
Proteins in disks: rhodopsin contains small molecule call retinal. When light hits it can hit the retinal and cause it to change conformation from bent to straight
Retinal changes shape, rhodopsin changes shape
Cascade of events
Transducin= alpha, beta, gamma
Breaks from rhodopsin and alpha part comes to disk and binds to phosphodiesterase
PDE takes cGMP and coverts to regular GMP. Na+ channels allow Na+ ions to come in but for this channel to open, need cGMP bound and as cGMP decreases, Na channels close
Less Na+ enters the cell, rods hyperpolarize and turn off. Glutamate no longer released and no longer inhibits ON bipolar cells (it’s excitatory to OFF bipolar cells)
Bipolar cells turn on and this activates retinal ganglion cell which sends signal to optic nerve to brain
Photoreceptors
specialized nerve that takes light and converts to neural impulse
Inside rod optic discs that are large membrane bound structures and have proteins that fire APs to the brain
Proteins
Rods= rhodopsin and cones= photopsin
Differences b/w rods and cones
120 mil rods vs 6 mil cones
Cones concentrated to fovea
Rods are more sensitive to light than cones and better at detecting light
Cones less sensitive but detect color (60% red, 30% green, and 10% blue)
Rods have slow recovery time, cones have faster recovery time. Takes a while to adjust to dark, rods need to be reactivated
Photoreceptor Distribution in Retina
optic nerve connects to retina at BLIND SPOT- no cones or rods
rods found in periphery and cones in fovea
Zoom in on fovea- no axons in way of light so higher resolution
If light hits periphery, light has to go through bundle of axons and some energy lost. At fovea light hits cones directly
Visual Field Processing
all right visual field goes to left side of brain, all left visual field goes to right side of brain
Feature Detection and Parallel Processing
Color (cones, trichromatic theory of color vision), form (parvocellular pathway- good at spatial resolution but poor temporal), motion (magnocellular pathway, has high temporal resolution and poor spatial resolution, no color)
Parallel processing: see all at same time; simultaneous processing of incoming stimuli that differs in quality
