Unit 4 - Sensation and perception

prosopagnosia

prosopagnosia

face blindness

sensation

the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

perception

the process of organizing and interpreting sensory information, establishing us to recognize meaningful objects and events

bottom-up processing

analysis that begins with sensory receptors and works up to the brain´s integration of sensory info

(ex: looking at a dress/shoe, listening to a recording)

top-down processing

info processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

(ex: deciding the color of the dress/shoe, determining what the recording is saying)

selective attention

the focusing of conscious awareness on a particular stimulus

cocktail party affect

one´s ability to attend to one voice among a sea of other voices

stroop effect

the delay in reaction time between congruent and incongruent stimuli

(color vs word test that I was good at)

inattentional blindness

failing to see visible objects when attention directed elsewhere

(ex: basketball pass gorilla)

change blindness

failing to notice changes in the environment; form of inattentional blindness

(ex: painting men map direction switch)

Change deafness

failing to detect a change in voice; form of inattentional blindness

(when too different → pop-out)

choice blindness

failure to recall a choice immediately after we have made that choice

(ex: pic attraction switch test)

transduction

conversion of one energy to another. in sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brain can interpret

(basically known as translation;

1. RECEIVE sensory stimulation

2. TRANSFORM that stimulation into neural impulses

3. DELIVER the neural info to our brain)

psychophysics

the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them (top-down, bottom-up)

absolute threshold

the minimum stimulus energy needed to detect a particular stimulus 50% of the time

signal detection theory

a theory predicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). assumes there is no single absolute threshold and that detection depends partially on a person’s experience, expectations, motivation, and alertness

subliminal

bellow one’s absolute threshold for conscious awareness (still effects)

(ex: study on famous movies)

difference threshold (aka just noticeable difference (JND))

the minimum difference between 2 stimuli required for detection 50% of the time

(ex: 40 decibels ± 5 more noticeable than 110 decibels ± 5)

weber’s law (WEBBER)

for an average person to perceive a difference, two stimuli must differ by a constant minimum percentage (not a constant amount) →exact percentage varies depending on the stimulus (light intensity: 8%, weight: 2%, tones: 0.3%)

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

(ex: strong perfume)

habituation

the decreased response that occurs as a result of repeated exposure to a stimulus

(ex: moving to a city and overtime getting used to the loudness)

perceptual set

a mental predisposition to perceive one thing and not another

a set of mental tendencies and assumptions that affects, top-down, what we hear, taste, feel, and see

Muller-Lyer illusion

arrows with ends opened/closed, even though line are the same they seem to be different lengths

wavelength

distance from one peak to another (light/sound)

hue

the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth

wavelength: short = blueish , long = reddish

intensity

amount of energy in a light/sound wave; influences what we perceive as brightness/intensity is determined by the wave’s amplitude (height)

amplitude: great = bright , small = dull

saturation

the intensity of the hue experienced, raging from hueless to deeply saturated

accommodation

the process by which the eye’s lens change shape to focus near or far objects on the retina

blind spot

the point at which the optic nerve leaves the eye, creating a “blind spot” because no receptor cells are there

acuity

sharpness/keenness of thought/vision/hearing

(ex. fatigue affects ability)

nearsightedness (myopia)

a refractive error that makes far away objects look blurry (focal point too close)

parallel processing

processing many aspects of a problem simultaneously; the brain’s natural mode of info processing for many functions, including vision

phi phenomenon

an illusion of movement created when two or more adjacent lights blink on and off in quick succession

gustation

our sense of taste

olfaction

sense of smell

olfactory bulb

structure located in the forebrain of vertebrates that receives neural input about odors detected by cells

kinesthesia

our movement senses → our system for sensing the position and movement of individual bady parts

vestibular sense

our sense of body movement and position that embodies our sense of balance

opponent-process theory of color

theory that opposing retinal processes (red-green, blue-yellow, white-black) enable color vision

(ex. some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green)

McGurk effect

illustrates how perceivers merge info for speech sounds across the senses

(ex. when mouth says something different from the movement it changes sound)

priming

the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response

context effect

our context and info influence our interpretation

ex: pedestrian hates driver/driver hates pedestrian, cultural views

cornea

the eye’s clear, protective outer layer, covering the pupil and iris

• astigmatism is an irregularly shaped ____ that interferes with focusing

pupil

the adjustable opening in the center of the eye through which light enters

• dilated: open

• constricted: closed

iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

• accommodation: the process of curving the ____ to protect images of near or far objects on the retina

• cataracts: clouding of the ____ , limits the amount of light, disrupts vision

retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual info

contains photoreceptors - transduction begins here

rods

retinal receptors that detect black, white, and grey, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don’t respond

you have around 120 million (a lot)

• sensitivity in dim light - high

• color sensitivity - low

• detail sensitivity - low

cones

retinal receptors that are concentrated near the center of the retina and function in daylight or in well-lit conditions

detect fine detail and give rise to color sensations

around 6 million (a lot less than rods)

• sensitivity in dim light - low

• color sensitivity - high

• detail sensitivity - high

optic nerve

the nerve that carries neural impulses from the eye to the brain

middle of cranial fossa

(glaucoma: loss of vision due to ____ damage. can be associated with eye pressure)

fovea

the central focal point in the retina, around which the eye’s cones cluster

trichromatic color theory (YOUNG & HELMHOLTZ)

the theory that the retina contains three different types of color receptors - one most sensitive to red, one to green, one to blue - which, when stimulated in combination, can produce the perception of any color

feature detectors (HUBEL & WISEL)

nerve cells in the brain’s visual cortex that respond to specific features of the stimulus, such as shape, angle, or movement

(individual neurons - or groups of neurons - in the brain which code for personally significant stimuli)

sclera

outer layer that extends from cornea (front) to optic nerve

gives eyeball white color

helps maintain the eyeball’s shape and protects from injury

vitreous humor

the transparent gelatinous tissue filling the eyeball between the lens and the retina

provides nutrients to your eye and helps your eye keep its shape

(related: floaters)

ganglion cells

along the inner margin of the retina

major output cells of the retina

projection neurons of the vertebrate retina

optic disc

the location where ganglion cell axons exit the eye to form the optic nerve

nasal side of the retina

transfers signals from the photoreceptors

(related: blind spot)

bipolar cells

one of the main retinal interneurons (vertebrate retina)

provide main pathways from photoreceptors to ganglion cells

(conveying light-driven signals from rods and cones to the retinal output)

(middle men)

optic chiasm

a visual pathway at the base of the brain interior (inferior to the hypothalamus)

where the optic nerves cross

aims to combine visual input info from the two halves of each retina that receive light from the same portion of the visual field

farsightedness (hyperopia)

a refractive error that makes close objects look blurry

focal point too far (behind retina)

dark adaptation

the ability to adjust to conditions of low illumination by an increase of sensitivity to light

light adaptation

the adjustment of the eyes when we move from darkness into a location with light (illuminated)

color blindness

the decreased ability to see color/differences in color

afterimage

a visual illusion in which retinal impressions persist after the removal of the stimulus

ex: sun, flag

gestalt

an organized whole. _____ psychologists emphasized our tendency to integrate pieces of information into meaningful wholes (grouping)

figure-ground

(gestalt grouping principle) the organization of the visual field into objects that stand out from their surroundings

grouping

(gestalt grouping principle) the perceptual tendency to organize stimuli into coherent groups

proximity, continuity, closure

proximity

(gestalt grouping principle) the tendency to group stimuli close to one another

similarity

(gestalt grouping principle) the tendency to group stimuli that are alike

continuity

(gestalt grouping principle) the ability to continue stimuli that we can’t see based on patterns that we can

ex: we continue a cube even when it is behind something

connectedness

(gestalt grouping principle) grouping stimuli together because of a line/connector more so than without the line

closure

(gestalt grouping principle) the tendency to fill in gaps; to create a complete whole object; illusion of seeing an incomplete stimulus as though it were whole

depth perception

the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance

visual cliff (GIBSON & WALK)

a laboratory device for testing depth perception in infants and young animals (a model of a cliff with a “drop-off” area that was actually covered with sturdy glass)

binocular cue

a depth cue, such as a retinal disparity, that depends on the use of two eyes

retinal disparity

a binocular cue for perceiving depth. by comparing retinal images from the two eyes, the brain computes distance - the greater the disparity (difference) between the two images, the closer the object

monocular cue

a depth cue, such as interposition or linear perspective, available to either eye alone

convergence

(binocular depth cue) the inward angle of the eyes focusing on a near object

a depth cue only effective within 10 meters that takes into account the difference in the direction of our eyes

relative size

(monocular depth cue) the ability to measure how far away smth is based on its size (assumes size constancy)

closer objects will look bigger while objects further away will look smaller

interposition (overlap)

(monocular depth cue) when one object partially covers another. it creates the appearance that the object being covered, or overlapped, is the one that is further away

relative clarity

(monocular depth cue) when nearer objects are clearer in detail, whereas more distant objects are less distinct

(note: atmospheric changes can be fog, dust, snow, rain, clouds, etc.)

texture gradient

(monocular depth cue) the distortion in size which closer objects have compared to objects further away; also involves groups of objects becoming denser as they move farther away

motion parallax (relative motion)

(monocular depth cue) when an individual is in motion, the objects closest to them seem to be moving by the quickest while farther away objects seem to move more slowly

ex: when in a car the fence on the side of the road is speeding by while the mountains in the background seem to be hardly moving at all

linear perspective

(monocular depth cue) causes parallel lines to appear to meet at some point in the distance; the vanishing point is where the lines seem to merge

as you look at parallel lines further and further away, they seem to get closer and closer together

ex: rail road tracks

relative brightness

(monocular depth cue) objects up close appear brighter than objects farther away

relative height

(monocular depth cue) things at a distance look like their base is higher

* not the height of the object, but the location within the visual field

stroboscopic movement

the visual phenomenon in which viewing a series of slightly varying pictures in rapid succession produces the effect of continuous motion

perceptual constancy

perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change

brightness constancy

perceiving an object as having a constant brightness even as illumination varies

color constancy

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

shape constancy

perceiving the form of familiar objects as constant even while our retina’s receive changing images of them

size constancy

perceiving an object as having an unchanging size, even while our distance from it varies

perceptual adaption

the ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field

ex: inverted glasses experiment

audition

the sense or act of hearing

frequency

the number of complete wavelengths that pass a point in a given time (for example, per second)

pitch

a tone’s experienced highness or lowness; depends on frequency

short wavelengths - high

long wavelengths - low

decibels

(audition) unit of intensity

great amplitude - loud

small amplitude - soft (quiet)

hertz

(audition) unit of frequency

short wavelengths - high pitch

long wavelengths - low pitch

middle ear

the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window

cochlea

(inner ear) a coiled, bony, fluid-filled tube; sound waves travelling through the fluid (vibrating the fluid) trigger nerve impulses