SENSATION AND PERCEPTION (MODULE 3)

is the stimulation of sensory receptors and the transmission of sensory information to the central nervous system (the spinal cord or brain).

SENSATION

is the process by which sensations are organized into an inner representation of the world.

PERCEPTION

is the minimal amount of energy that can produce a sensation.

ABSOLUTE THRESHOLD

is the highness or lowness of a sound, as determined by the frequency of the sound waves

PITCH

sensory stimulation below a person’s absolute threshold for conscious perception

SUBLIMINAL STIMULATION

the minimal difference in intensity required between two sources of energy so that they will be perceived as being different

DIFFERENCE THRESHOLD

Psychophysicist _______ discovered through laboratory research that the threshold for perceiving differences in the intensity of light is about 2% (actually closer to 1/60th) of their intensity

Ernst Weber

Is the minimal amount by which a source of energy must be increased or decreased so that a difference in intensity will be perceived.

Gustav Fechner

Psychophysicists look for the __________ by exposing individuals to progressively stronger stimuli until they find the minimum stimuli that the person can detect 50% of the time.

ABSOLUTE THRESHOLD

_______ are not all that absolute

ABSOLUTE THRESHOLD

“Advertising”

SUBLIMINAL STIMULATION

auto ads frequently associate attractive people with cars

Appealing Stimuli

can be flashed too briefly to enable us to process them.

Visual Stimuli

can be played at a volume too low to consciously hear or can be played backward

Auditory Stimuli

Is the view that the perception of sensory stimuli involves the interaction of physical, biological and psychological factor

Signal Detection Theory

are neurons in the sensory cortex that fire in response to specific features of sensory information such as lines or edges of objects.

FEATURE DETECTORS

he processes by which organisms become more sensitive to stimuli that are low in magnitude and less sensitive to stimuli that are constant or ongoing in magnitude

SENSORY ADAPTATION

the type of sensory adaptation in which we become more sensitive to stimuli that are low in magnitude. Also called positive adaptation

SENSITIZATION

the type of sensory adaptation in which we become less sensitive to constant stimuli. Also called negative adaptation.

Ex. Becoming immune to traffic sounds

DESENSITIZATION

the part of the electromagnetic spectrum that stimulates the eye and produces visual sensations.

Visible Light

the color of the light as determined by its wavelength

Hue

The wavelengths of these rays from outer space are only a few trillionths of an inch long.

Cosmic rays

Some radio signals extend for miles.

Radio waves

Roses are red, and violets are blue.

Visible light

the shortest at about 400 billionths of a meter in length

VIOLET

the longest at 700 billionths of a meter

RED

Protects eye and bends light toward lens.

Cornea

Focuses on objects by changing shape.

Lens

Controls amount of light that gets into eye.

Iris

Widens or dilates to let in more light.

Pupil

Neural tissue lining the back of the eyeball’s interior, which contains the receptors for vision.

Retina

Visual receptors that respond to dim light.

Rods

Visual receptors are involved in color vision.

Most humans have 3 types of this.

Cones

neurons that conduct neural impulses from rods and cones to ganglion cells

Bipolar cells

neurons whose axons form the optic nerve

Ganglion Cells

the nerve transmits sensory information from the eye to the brain

Optic Nerve

an area near the center of the retina that is dense with cones and where vision is consequently most acute

Fovea

the area of the retina where axons from ganglion cells meet to form the optic nerve

Blind Spot

too much curvature of the cornea and/or lens so nearby objects are seen more clearly than distant objects

Near sighted (myopia)

too little curvature of the cornea and/or lens so distant objects are seen more clearly than nearby ones

Far sighted (hyperopia)

an irregularity in the shape of the cornea and/or lens which distorts and blurs the image at the retina

Astigmatism

Beginning in their late 30s to the mid-40s, people’s lenses start to grow brittle, making it more difficult to accommodate to, or focus on, objects. from the Greek words for “old man” and “eyes”

It makes it difficult to perceive nearby visual stimuli.

PRESBYOPIA

Where the optic nerve exits the retina, there are no rods or cones –

this is your ________

Blind Spot

You also have special neurons called ________ that help

you to distinguish contours, orientation, and basic shape

Feature Detectors

_________ are what is fooled by optical illusions

Feature Detectors

occurs when we move from the dark into bright light.

LIGHT ADAPTATION

occurs when going from a well light area to a dark area.

DARK ADAPTATION

the lingering visual impression made by a stimulus that has been removed

After Image

determined by wavelength of light

Hue

degree of brightness or darkness

Value

how intense a color appears to us

Saturation

Young (1802) & von Helmholtz (1852) both proposed that the

eye detects 3 primary colors:

red, blue, & green

All other colors can be derived by combining these three.

Trichomatic Theory

Ewald Herring suggests that the ability to perceive color is controlled by three receptor complexes with opposing actions.

These three receptor complexes are the red-green complex, the blue-yellow complex, and the black-white complex.

OPPONENT PROCESS THEORY

a person with normal color vision

trichromat

a person who is sensitive to black and white only and hence color–blind

monochromat

a person who is sensitive to black–white and either red–green or blue– yellow and hence is partially color–blind

dichromat

the tendency to integrate perceptual elements into meaningful patterns

PERCEPTUAL ORGANIZATION

when first looking at a stimuli, we must first perceive a figure from its surrounding in order to make it meaningful

FIGURE GROUND

this is an automatic technique that forms stimuli into groups

Grouping

the tendency to perceive a broken figure as being complete or whole

Closure

nearness; the perceptual tendency to group together objects that are near one another

Proximity

the perceptual tendency to group together objects that are similar in appearance

Similarity

the tendency to perceive a series of points or lines as having unity

Continuity

the tendency to perceive elements that move together as belonging together

Common Fate

is the processing of sensory information as it enters the sensory structures and travels to the brain

Example: Send raw experience to brain for analysis.

Bottom-up processing

is the brain’s use of existing knowledge, beliefs, and expectations to interpret the sensory stimulation

Example: "big chunk“ – make sense of situation based on what you already know

Top-down processing

since we have two eyes, we have different ocular cues that allow us to see the world in three dimensions

One way our ______ is tested is with a visual cliff experiment

DEPTH PERCEPTION

these are depth cues, like retinal disparity, that depend on the use of two eyes

BINOCULAR CUES

using both retinas to compare an image we know the distance, the greater the disparity between two images, the closer the object

RETINAL DISPARITY

a binocular cue for depth based on the inward movement of the eyes as they attempt to focus on an object that is drawing nearer size constancy the tendency to perceive an object as being thesame size even as the size of its retinal image changes according to the object’s distance

CONVERGENCE

only need one eye to perceive these.

Relative height

Relative size

Light & shadow

MONOCULAR CUES

a monocular cue for depth based on the convergence (coming together) of parallel lines as they recede into the distance texture

perspective

a monocular cue for depth based on the perception that closer objects appear to have rougher (more detailed) surfaces

gradient

a monocular cue for depth based on the perception that nearby objects appear to move more rapidly in relation to our own motion

motion parallax

we perceive motion through two basic principles: something leaving is shrinking in size, something approaching gains in size.

Motion Perception

sensations that give rise to misperceptions

Illusions

a visual illusion in which the perception of motion is generated by a series of stationary images that are presented in rapid succession

stroboscopic motion

This function allows to see stimuli as unchanging, which part of Top-down processing

Perceptual Constancy

With our vision, we have the ability to adjust to an artificially displaced vision field

Perceptual Adaptation

this is a mental pre-disposition that greatly influences how we perceive something

Perceptual Sets

Our perception can be greatly influenced on context

Context Effects

Influenced top-down by our emotions and motivations

Emotions/Motivations

Sight will always be our most used sense, though _______ is a close second

________ is most helpful for language transmission

Hearing

result from the mechanical vibration of molecules from your vocal chords or from a musical instrument / other source.

Sound Waves

Short wavelength = ___________

High Frequency

___________= Low frequency

Long wavelength

distance in one cycle of a wave, from one crest to the next

Wavelength

is the amount of energy in a wave, its intensity, which is the height of the wave at its crest (dB)

Amplitude

is the number of times a sound wave cycles in one second

Frequency

The highness or lowness of the sound (Hz)

Pitch

The distinguishing quality of sound

Can you tell the difference between a trumpet playing a C# and a guitar playing a C#?

Timbre

The transformation of stimulus energy to the electrochemical energy of neural impulses.

Transduction

the process by which you determine the location of a sound.

Sound Localization

The position on the basilar membrane at which waves reach their peak depends on the frequency of a tone. (structure)

Place Theory

The rate of the neural impulse traveling up the auditory nerve matches the frequency of a tone, enabling you to sense it’s pitch. (neural)

Frequency Theory

you damage your ear (physically) and you have trouble hearing because your ossicles have trouble vibrating.

A conventional hearing aid can help

Conduction deafness

can occur from aging, disease, or continued exposure to loud noise – these all damage the hair cells in the basilar membrane

cochlear implant can help

Nerve / Sensorineural deafness

has an important role in human behavior. It contributes to the flavor of foods

SMELL

the nerve that transmits information concerning odors from olfactory receptors to the brain

OLFACTORY NERVE

include touch, pressure, warmth, cold,

and pain.

There is a distinct sensory receptors for pressure, temperature, and pain, but some nerve endings may receive more than one type of sensory input

Skin Senses