WWU Psych 101 Mana: Chapter 4 (Sensation and Perception) Flashcards
Absolute Threshold
minimal intensity need to just barely detect a stimulus in 50% of trials
Accomodation
process by which eye maintains clear image on retina (flatter lens = far away, rounder = nearby)
Binocular Disparity
difference in retinal images of two eyes provides information about depth
Bipolar cells
collect neural signals/transmit to outer layer of retina
Change Blindness
when people fail to detect changes to visual details of a scene
Color Blindness
usually caused by problem with cones, red-green ____________________ most common. Can also be caused by damage to visual cortex.
Color Opponent System
pairs of visual neurons work in opposition (red vs. green, blue vs. yellow)
Cones
detect color, operate under normal daylight conditions/focus on fine detail (6 million in fovea)
Contralateral Vision
Both eyes can see each visual field, but right visual field is perceived by left hemisphere and left visual field is perceived by right hemisphere
Cornea (outer layer of eye)
bends light through pupil (hole)
Dorsal Pathway (Secondary Visual Cortex - V2)
projects into posterior parietal cortex, involved in different high-level perceptual skills and integration, such as perception of the spatial relationships between objects… sometimes called the “where” system
Dorsal Stream
occipital to parietal lobe/mid temporal (motion)
Farsightedness
back of retina (eyeball too short)
Feature-Integration Theory
(Treisman) focused attention not required to detect individual features comprising stimulus, but is required to bind features together
Fovea
area of retina where vision is clearest with no rods
Inattentional Blindness
failure to perceive objects that are not focus of attention
Interposition
blocking objects vs. distance
Iris (colored part of eye)
controls how much light can enter eye
Just Noticeable Difference
minimal change in stimulus that can just barely be detectable
Linear Perspective
parallel lines converge receding in distance
Monocular Depth Cues
aspects of scene that yield information about depth when viewed with only one eye (distance vs. size)
Nearsightedness
front of retina (eyeball too long)
Negative afterimages
occur when visual stimulus overexcites cells sensitive to one color
Optic Chiasm
Where axons from inner half of each retina crossover (allows information from the same visual field to be processed together in the same locations in the brain, making the processing task simpler)
Optic Disc
blind spot at the back of eye where optic nerve leaves (location in visual field that provides no retinal sensation)
Optic Nerve (bundle of RGCs)
where axons of RGCs leave the eye through hole in retina
Parts-based object recognition
deconstructs viewed objects into collection of parts
Perception
organization, identification, interpretation of sensation in order to form mental representation (brain)
Perceptual Constancy
even as aspects of sensory signals change, perception remains consistent
Photoreceptor Cells
cells in eye
Presbyopia
hardening of lens with aging, prevents the lens from changing shape to accommodate to different distances of visual stimuli, you end up near sighted or far sighted
Principles of Perceptual Organization
o Simplicity
Prosopagnosia
can identify individual objects within a subject (such as car parts), but cannot identify what exactly it is (such as what kind of car or brand it is)
Psychophysics
(Gustav Fechner) methods that measure strength of a stimulus to observer’s sensitivity of stimulus to measure individual perceptual experiences, discovered absolute thresholds, and difference thresholds
Purity (# of distinct wavelengths that make up light)
saturation/richness
Retina
light-sensitive tissue lining back of eyeball
Retinal Ganglion Cells
organize signals/send to brain (1.5 million per eye)
Rods
become active under low-light conditions for night vision (more sensitive –> shades of gray, 20 million around retina
Sensation
simple stimulation of sense organ
Signal Detection Theory
response to stimulus depends on both sensitivity to stimulus in presence of noise and decision criterion (internal) –>perceptual sensitivity (hit, miss, false alarm, correct rejection)
Template (Theory of Object recognition)
mental representation directly compared to viewed shape in retinal image
Texture Gradient
size of patterned elements/distance between grows smaller with surface receding
Transduction
when many sensors in body convert physical signals from environment into encoded neural signals sent to CNS (communication between sensory receptors)
Ventral Pathway
projects into the temporal lobe, involved in object recognition (the “what” system). Neurons here are sensitive to complex visual stimuli, representing information from many different parts of the eye.
Ventral Stream
travels across occipital to lower temporal (represent shape/identity)
Visible Light
portion of electromagnetic spectrum we can see
Vision
The perception produced by detection of a narrow portion of the electromagnetic spectrum… light energy measured in photons
Visual Acuity
ability to see fine detail (when we can see perfectly from 20 feet away)
Visual Form Agnosia
inability to recognize objects by sight
Visual System
visual energy –> neural signals
Wave Intensity/Amplitude (peaks)
brightness
Wave Length
hue
Weber’s Law
JND of stimulus is constant proportion despite variation in intensity (ability to notice change easier = large JND)
