Unit 6 Sensation and Perception

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, enabling us to recognize meaningful objects and events

Bottom-Up Processing

processing sensory information as it is coming in; like notes into a song.

Top-Down Processing

Forming our perceptions starting with a larger object, concept, or idea before working our way toward more detailed information.

Schema

System of knowledge you have about a given concept, and the related expectations and beliefs you have about the concept.

Transduction

A physical stimulus present in the environment emits energy that is absorbed by a sensory organ, which is then transformed into an electro-chemical message that can be carried by our nervous system to our brain for processing, causing sensation.

Absolute Threshold

The minimum stimulation (of a sense) needed to detect a particular stimulus 50 percent of the time

Subliminal Message

a message that is presented below one's absolute threshold for awareness

Difference Threshold

The minimum amount of difference that can be detected between two stimuli

Weber's Law

the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount)

Just Noticeable Difference

The smallest change in the intensity of a stimulus that we can detect

Signal Detection Theory

Ability to identify a stimulus when it's embedded in a distracting background

What factors increase successful signal detection?

Motivation and experience increase the ability to identify a stimulus even when it is embedded in a distracting background

What factors decrease successful signal detection?

Distractions, lack of motivation to find the signal, inexperienced at finding the signal, and too much noise which drowns out the signal are examples of factors that decrease the ability to identify a stimulus

Priming

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

Sensory Adaptation

Diminished sensory sensitivity as a consequence of constant stimulation over a prolonged period of time

Perceptual Set

a mental predisposition toward viewing objects in a certain way based on our experiences, beliefs, and expectations

Habituation

The diminishing of an innate (natural) physiological or emotional RESPONSE to a frequently repeated stimulus.

Context Effect

Uses context information to make sense of, interpret, and perceive anything you're trying to process

wavelength

color is determined by this
-distance affects the color (hue) we see and the sound
-distance between the peak of one light or sound wave to the peak of the next

amplitude

HEIGHT of wave- determines intensity (bright or dull)
-influences brightness or sound

cornea

PROTECTS the eye
-protective covering
function: slight ability on focusing

pupil

adjustable opening in the center of the eye through which light enters, controlled by iris

iris

muscle around pupil - colored portion of the eye
function: controls SIZE of pupil opening

lens

behind the pupil - FOCUSES images on the retina (back of the eye)-changes shape to help focus images on the retina, BENDS AND SENDS

retina

holds visual receptors (rods and cones), CONVERTS light into neural signals and sends to brain
-light sensitive inner surface of the eye
-processes visual information

rods

retinal receptors detect BLACK, white, gray , dim light
-necessary for PERIPHERAL and twilight vision (night)
-in the back of the eye

cones

retinal receptors used for COLORS, detail vision, daytime, bright light
-fine detail
-give rise to color sensations, most are in fovea

fovea

CENTER of the retina
*contains mostly cones cluster, sharpest vision

bipolar cells

receive information from rods and cones and the process of TRANSDUCTION takes place

ganglion cells

receive information from bipolar cells and TWIST to form optic nerve, which carries messages to the brain

optic nerve

carries visual information from RETINA to visual centers of BRAIN

blind spot

spot on retina where there are no visual RECEPTOR cells

feature detectors

nerve cells in brain that respond to specific FEATURES of stimulus - shape, angle, movement
- in occipital lobe (visual cortex)

parallel processing

idea that we can process all aspects of what we are viewing because we have feature detectors
-simultaneously
- process many aspects

Young Helmholtz Trichromatic Theory
(three color)

inside the retina we have cones that receive red, blue and green
-when stimulated in combo, we can produce perception of any color

Opponent Process Theory

happens in the brain
-red/green
-yellow/blue
-white/black

*see red, green is blocked (vice versa)

After image

proves opponent process theory

Wavelength

Determines pitch or frequency of a sound

Amplitude

Determines loudness or volume

Bones of the Middle Ear

Amplify and send eardrums vibrations

Semicircular Canals

Provides information about orientation to the brain and helps maintain balance

Auditory Nerve

the cranial nerve that carries sound from the cochlea of the inner ear to the brain

Cochlea

a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses

Ear drum

The part of the ear that vibrates to allow us to hear sound.

Hammer

A tiny bone that passes vibrations from the eardrum to the anvil

Anvil

A tiny bone that passes vibrations from the hammer to the stirrup

Hair Cells

The hairlike sensory receptors for sound, which are embedded in the basilar membrane of the cochlea.

Basilar Membrane

A structure that runs the length of the cochlea in the inner ear and holds the auditory receptors, called hair cells.

Oval Window

Allows fluid to move within cochlea, which moves the hairs that allow us to hear.

Stirrup

Vibrates to transfer sound waves to the cochlea

Frequency Theory

the brain reads pitch by monitoring the frequency of neural impulses traveling up the auditory nerve

Place Theory

we hear different pitches because different sound waves trigger activity at different places along the cochlea's basilar membrane

Volley Principle

Like soldiers who alternate firing so that some can shoot while others reload, neural cells can alternate firing. By firing in rapid succession, they can achieve a combined frequency above 1000 waves per second.

Conduction

Caused by damage to the mechanical system that conducts sound

Sensorineural

Damage to the cochlea's hair cell receptors of their associates nerves

Cochlear Implant

Electronic device translates sounds into electrical signals that, wired into the cochlea's nerves

Nociceptors

receptors that fire specifically to potentially tissue-damaging stimuli

Gate-Control Theory

the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain

Sweet

energy source

Salty

sodium essential to physiological processes

Sour

potentially toxic acid

Bitter

potential poisons

Umami

a category of taste in food corresponding to the flavor of glutamates (especially MSG). The purpose is for proteins to grow and repair tissue.

Sensory interaction

the principle that one sense may influence another, as when the smell of food influences its taste

Olfaction

We smell something when the molecules of a substance carried in the air reach a tiny cluster of 20 million receptor cells at the top of each nasal cavity. These receptor cells alert the brain through their axon fibers.

All senses pass through the thalamus except:

Olfaction

Kinesthesis

your sense of the position and movement of your body parts

Semicircular Canals

contain fluid that moves when your head rotates or tilts. The movement stimulates hairlike receptors, which sends messages to the cerebellum at the back of the brain, thus enabling you to sense your body's position and maintain balance.

Vestibular Sense

Monitors your head's (and body's) position and movement. The biological gyroscopes for this sense of equilibrium are in your inner ear canal

concept of gestalt

the whole of anything is greater than its parts

figure ground

the organization of the visual field into objects that stand out from the surroundings.

(vase vs face)

proximity

We group nearby figures together 

(we dont see 6 separate lines but 3 sets of 2 lines)

Continuity

We perceive smooth, continuous patterns rather than discontinuous ones

(could be series of alternating semi circles but we see one wavy and one straight line)

Similarity

We tend to group objects together that look similar

Closure

We fill in gaps to create a complete, whole object

We assume its a triangle 

visual cliff

Experiment with a “canyon like” structure created to investigate the depth perception in humans

depth perception

Ability to judge distance between objects

Retinal Disparity

Difference between the two images our retinas receive

The greater the retinal disparity, the closer the object

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Relative Height

We perceive objects higher in our field of view as farther away

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Relative Motion (Parallax)

If we assume two objects are the same size, most people perceive the one that smaller retinal image as farther away

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Interposition

if one objects partially blocs our view of another, we perceive it as closer

Light/Shadow

 shading produces a sense of depth consistent with our assumption that light comes from above.

Linear Perspective

parallel lines appear to meet in the distance. The sharper the angle of convergence, the greater the perceived distance

Stroboscopic movement phenomenon

Continuous movement in a rapid series of slightly varying images

Ex. film animation

Phi phenomenon

* When two adjacent stationary lights blink on and off in quick succession, we perceive a single light moving back and forth between them
* Ex a moving arrow

Perceptual constancy

* Recognize objects without being deceived by changes in their color, brightness, shape, or size
* Ex. recognizing people

Color constancy

 our ability to perceive colors as relatively constant over varying illuminations

Brightness constancy

Ability to perceive a familiar object having the same brightness under different conditions of illumination

Shape constancy

we perceive objects as staying the same shape, even when they're rotated or viewed from different angle

Size constancy

we perceive objects as staying the same size, even when they're far away or close up

Critical period

Time span where normal sensory and perceptual development must occur

Perceptual adaptation

* ability to adjust to changes in our visual input/sensation
* New glasses

Interaural level differences

A sound coming from your right side of the body is more intense at you right ear than your left ear because of the attenuation of the sound wave as it passes through your head

Interaural timing difference

Small difference in the time at which a given sound wave arrives at each ear (Constructs where a sound originates from)