Ralph Ellison’s Invisible Man: Characters, Symbols & Themes

Bottom-up Processing

Sensory receptors relay information to the brain

The brain interprets this information

Top-down Processing

Previous experience and expectations affect the detection and analysis of information from the senses

Explains visual illusions

Selective Attention

The focusing of conscious awareness on a particular stimulus while tuning out the rest

*cocktail party effect

Selective Inattention

Change blindness: failure to notice changes in the environment

Inattentional blindness

failure to see visible objects when attention is directed elsewhere

Perceptual Set or Schema

Perception influenced by:

expectations, preconceptions, culture, experiences

*top down processing

We create a "set" for interpreting stimuli that conforms to expectations

Figure Ground (Gestalt grouping )

Perceiving figures that stand out from the surrounding background

Proximity (Gestalt grouping )

Perceive objects as belonging together when they are close to one another

Similarity (Gestalt grouping )

Tendency to group objects that have similar characteristics

Closure (Gestalt grouping )

Grouping disconnected pieces into a meaningful whole

Gestalt grouping

Tendency to organize stimuli into coherent groups.

Depth Perception

Ability to see the world in three dimensions and know how far away an object is - judging distance

Develops with experience

Retinal Disparity

eyes are 3ish inches apart, retinas get different images, brain puts them together

more different the closer it is to you

Convergence

muscular tension when turn eyes inward, the brain uses as a cue

Closer objects cause more convergence

Relative Size

An object that appears larger than another object believed to be of the same size is judged to be closer

Interpostion

Objects that are obscured by other objects are perceived as being farther away

Relative Clarity

Nearby objects are clearer than more distant objects

Linear Perspective

Objects and the spaces between them look smaller as they become more distant. Parallel lines appear to converge as they recede into the distance

Frequency

Length of the sound wave; perceived as high and low sounds (pitch) (corresponds to our perception of pitch)

Amplitude

Height or intensity of sound wave; perceived as loud and soft (volume) (Corresponds to our perception of loudness)

Ossicles bones (Middle Ear)

Three tiny bones amplify vibration, and pass them inner ear

Semicircular Canals (Inner Ear)

Fluid filled channels help maintain balance *vestibular sense

Eardrum (Middle Ear)

Membrane that vibrates when hit by sound waves

Auditory Nerve (Inner Ear)

Nerve cells; sends neural messages to the brain's thalamus and auditory cortex

Cochlea (Inner Ear)

A coiled tube - sound waves are transduced by hair cells on basilar membrane

Place Theory

sound frequencies stimulate basilar membrane on specific hair cells (places) resulting in perceived pitch - works to explain high pitch, low were hard to locate

Frequency Theory

nerve impulses match the frequency of a tone, thus enabling us to sense its pitch - best for low pitch

Volley Theory

Groups of neurons work together to perceive sounds at frequencies beyond the individual firing (by firing rapidly, create a "volley" of signals)

Localizing Sound Sources

Ears on either side of the head gives us stereophonic hearing.

Timing method

noting direction of sound by which ear is stimulated first (best with low frequency sounds)

Volume method

noting direction of sound by which ear is stimulated most vigorously (best with high frequency sounds)

Conductive Hearing Loss

Problem transferring sound waves anywhere along the route through the outer or middle ear. Help- Hearing aids.

Sensorineural Hearing Loss:

Damage to inner ear (cochlea, hair cells)

Can be from excessive loud sounds, earbuds, concerts Help- Cochlear implant

Sensation

detection of environmental stimuli, such as sounds, objects and smells

Perception

experience of detecting those stimuli - how our brains organize and interpret sensory info

Vision

Transform light energy into neural signals

TRANSDUCTION

Wavelength

—distance from one peak to the other

Hue—the color experienced

Amplitude

—height of the wave

Intensity—determined by the wave's amplitude

Lens

focuses light onto the retina

Accommodation

lens changes shape to focus near or far objects on the retina.

Nearsighted

faraway objects are focused in front of the retina

Farsighted

nearby objects are focused beyond the retina

Retina

back of the eye - rods/cones

Macula

light sensitive tissue, back of the eye

Fovea

center macula, acuity is the highest

Ganglion cells

nerves that transmit visual messages *transduction

Rods

Function in dim light

Detect black and white vision, but not colors

Necessary for peripheral and twilight vision

Cones

Enable color perception

Most in fovea, center of retina

bright or daylight *detail

Trichromatic Theory

Three types of cones sensitive to different wavelengths

Red light - long

Green light - medium

Blue light - short

Colors other than red, green and blue stimulate a combination of cones

Opponent Process

Color sensitive ganglion cells, 3 sets: red-green, blue-yellow, and black-white

Each color opposes the other

Light waves excite one color pair - inhibit the opposing color

Vestibular

how the body is oriented in space; balance Transduction: occurs in the vestibular sacs where the fluid moves the hair cells, activating neural messages

Kinesthetic Sense

feedback about position and orientation of body parts in relation to each other *transduction

Message sent to thalamus and then sensory cortex in parietal lobe

Sensory Interaction

Multiple sensory modalities combine to a single perception

Transduction

Olfactory bulb neural signals go directly to amygdala and hippocampus

strong impact on memory and emotion

Pheromones

Chemicals used to draw attention to or warn others

Smell (Olfaction)

Molecules absorbed by olfactory receptors in nasal cavity

receptor corresponds to one molecule - "lock and key"

Taste (Gustation)

Papillae on the tongue - taste buds detect flavors

transduction, taste buds turn the flavors of food into neural signals to the thalamus

Sweet

gives us energy

Bitter

alerts us to a potential poison

Salty

maintain the sodium

Sour

perceive a potentially toxic acid

Umami

helps us identify foods with protein for growth and tissue repair

Oleogustus (oil)

helped realize food could be spoiled

nociceptors

free nerve endings on the skin and organs that transduce into neural firing

goes to thalamus and sensory cortex

phantom limb

amputees can sometimes still perceive pain from that limb (Pain is cognitive)

gate control theory

ome pain messages have higher priority; non-painful sensations can override in spinal cord/reduce painful sensations

Synesthesia

one sense is simultaneously perceived as if by one or more additional senses

Sensory adaptation

Diminishing sensitivity to an unchanging stimulus

Psychometrics

Methods that measure the strength of a stimulus and the observer's sensitivity to the stimulus

Threshold

the point at which a stimulus is strong enough to be detected by activating a sensory receptor

Absolute Threshold

Minimum stimulus necessary to detect a stimulus correctly half of the time

(going from nothing to something)

Difference Threshold (Just Noticeable Difference or JND)

Minimum change in a stimulus that can just barely be detected

(going from something to something)

Weber's Law

For a difference to be perceptible, two stimuli must differ by a constant proportion, rather than amount, AS STIMULI INCREASES, THE JND BECOMES PROPORTIONALLY LARGER