AP Psych Unit 4: Sensation and Perception

Last updated 11/17. All of Ms. Rabadan's slides from Unit 4.

Sensation

The experience of sensory stimulation.

Bottom-Up Processing

When sensory receptors pick up signals for the brain to integrate and process

brains

Beginning with stimulation of our senses, we interpret sensory information with our _______

Transduction

The action or process of converting something and especially energy or a message into another form

Light waves to neural impulses
Sound waves to neural impulses

Physical pressure/temperature to nerve impulses, etc.

Examples of Transduction

Perception

The process of creating meaningful patterns from raw sensory information (brain making sense of impulses)

Top-Down Processing

Perceiving things based on your prior experiences and knowledge

Perception

"I see a cat” or “I hear footsteps” is an example of…

schemas and past experiences

Unlike sensation, perception uses ______________________ to interpret sensory information to construct deeper meaning

The Basic Process

Energy stimulates receptor cell in one of the sense organs. If stimulus is strong enough, a signal is sent by receptor through sensory/afferent nerves (we know what these are) to appropriate area of cerebral cortex (we also know what this is).

Receptor cells

Specialized neurons that respond to specific types of stimuli.

Sense organs

Where do receptor cells exist?

Law of specific nerve energies (Muller)

One-to-one relationship between stimulation of a specific nerve and the resulting sensory experience. (For example, applying pressure with your finger to your eye results in a visual experience – try it!)

Johannes Muller

Who founded the law of specific nerve energies?

How many neurons fire, which neurons are activated or inhibited, the rate at which the neurons fire

Different stimuli affect…

Absolute threshold

The minimum amount of energy that can be detected 50% of the time

50%

If the responders can identify a sound ___ of the time they hear it, that’s absolute threshold

A candle flame 30 miles away

Example of Vision’s absolute threshold

A watch ticking 20 feet away

Example of Hearing’s absolute threshold

A drop of perfume in a six-room house

Example of Smell’s absolute threshold

A teaspoon of sugar in a gallon of water

Example of Taste’s absolute threshold

A wing of a fly on your check, dropped 1 cm

Example of Touch’s absolute threshold

Difference Threshold

The smallest change in stimulation that can be detected 50% of the time

Just Noticeable Difference (JND)

Another name for Difference Threshold

Weber’s Law

JND is a constant proportion of the specific stimulus (Example: Would you feel an additional 2.5 pounds on each side of barbell when you’re benching 200 lbs? Benching 45 lbs?)

Sensory adaptation

An adjustment of the senses to the level of stimulation they are receiving

When you get back in, your ears won’t instantly adjust.

If you are blasting your car radio, then ___________.

Toothpaste/orange juice (ice cream/soda) phenomenon

“sweet” taste buds adapt (become less sensitive)

Perfume, swimming/baths

Sensory adaptation examples

Signal Detection Theory (SDT)

Challenges the notion of the absolute threshold (the threshold can change, detection of a stimulus depends on a person’s experience, expectations, motivations and fatigue.)

How and when we will detect the presence of a faint stimulus or signal

SDT is a mathematical model that predicts…

Subliminal Perception

The notion that we may respond to stimuli that are below our level of awareness (ah!)

The unconscious activation of certain associations may alter perception, memory or response

A “subliminal stimulus falls below our threshold for conscious detection, HOWEVER…

Priming

Occurs when an individual's exposure to a certain stimulus influences their response to a subsequent prompt, without any awareness of the connection.

Individuals flashed a pleasant or unpleasant image before viewing a photo of a person were influenced to judge the person positively if they saw a pleasant picture and negatively if unpleasant.

Priming Example

Subliminal stimulus

Falls below the threshold for conscious detection

390-750 nanometers

We can only see a small part of the electromagnetic spectrum…how much?

Wavelength vs. Frequency

The frequency of a wave is inversely proportional to its wavelength

Hue

Colors we see such as red and green. Determined by wavelength 

purple, red

Hue: Shorter wavelength results in ________________; longer results in ___

Brightness

“Loudness” or intensity of a color. Determined by amplitude. (In other words, closeness to white or black)

Saturation

Vividness of a hue

Cornea

Transparent protective coating over the front of the eye

Pupil

Small opening in the iris through which light enters the eye (“Constricts/dilates” bc of iris)

Iris

Colored part of the eye, filters some light. Muscle that widens/contracts to make pupil bigger or smaller

Separating wavelengths of light

Red contacts claim to reduce glare and make ball “pop” by…

Lens

Focuses light onto the retina

Retina

Lining of the eye containing receptor cells that are sensitive to light

Fovea

Center of the visual field

blurry, clear

Baby in the video is farsighted, meaning nearby objects are ______ and far objects are _____.

rods and cones

Visual receptors are called… (Located in Retina)

Rods

About 120 million. Respond to light and dark. Very sensitive to light. Provide our night vision. DO NOT Detect color.

Cones

About 8 million. Respond to color as well as light and dark. Work best in bright light

Psychophysics

The branch of psychology that deals with the relationships between physical stimuli and mental phenomena.

in the fovea

Cones are found mainly…

Blind Spot

Area where axons of ganglion cells leave the eye

Bipolar Cells

Receive input from receptor cells. One-to-one in fovea

Ganglion cells

Receive input from bipolar cells. Axons of these cells form optic nerve.

Optic Nerve

Carries neural messages from each eye to brain

rod

Which is more sensitive: A rod or a cone?

Axons of ganglion cells

What is the optic nerve made up of?

Optic chiasm

Point where part of each optic nerve crosses to the other side of the brain

Thalamus

Relays sensory info to visual cortex in occipital lobes

Feature Detectors

Neurons in the brain that respond to specific aspects of a stimulus: edges, lines, movements, angles

send signals to other areas of the cortex for higher-level processing

Feature detectors in the visual cortex…

Supercell clusters

teams of cells that respond to complex patterns, such as faces

Hubel and Weisel

Theory: The properties of complex cells could more logically result from combining input from similarly oriented simple cells than from cells with circular receptive fields.

Additive color mixing

Mixing of lights of different hues. E.G. Lights, T.V., computer monitors (RGB)

add

Lights _____ wavelengths

Subtractive color mixing

Mixing pigments, e.g., paints.

absorb or subtract

Pigments ______________ wavelengths

Trichromatic theory

Three different types of cones

red

CONE 1) Respond to ______ (long wavelength)

green

CONE 2) Respond to _______ (medium wavelength)

blue-violet

CONE 3) Respond to _______________ (short wavelength)

Mixing of the signals from cone receptors

Experience of color is the result of…

Dichromats

People who are blind to either red-green (most common) or blue-yellow

Monochromats

People who see no color at all, only shades of light and dark

Colorblindness

Deficiency in red, green, or blue cone

Optic Chasm

Contributes in conveying visual information from the eye to the cortex, overlaps the optic nerves

True

True or False: Trichromatic theory cannot explain all aspects of color vision

Opponent-Process Theory

Expands upon the Trichromatic Theory. Color receptors work in pairs working in opposition from one another. Can explain color afterimages.

yellow-blue, red-green, black-white

In the Opponent-Process Theory, all color receptors work in pairs. What are those pairs?

Color Afterimages

Firing levels decrease (sensory adaptation) due to overstimulation; next color which is relatively “less” of the original color will be interpreted as opposing color pair

Isihara Colorblindness Test

Describe this image

Dark Adaptation

Increased sensitivity of rods and cones in darkness

Light Adaptation

Decreased sensitivity of rods and cones in bright light

di

Most animals are ___chromats

mono

Rodents tend to be ____chromats

Bees

____ can see ultraviolet light

Stomatopods

______________ have the most complex color hyperspectral vision in the animal kingdom, allowing them to differentiate between colors that may appear the same to other human and non-human animals.

Sound

A psychological experience caused by sound waves hitting the ear.

Soundwaves

Changes in pressure caused by molecules of air moving

Frequency

Number of cycles per second in a wave. Measured in Hertz (Hz). Determines pitch

Hertz

Frequency is measured in…

Amplitude

Magnitude (height) of sound wave. Measured in decibels (dB). Determines loudness

decibles

Amplitude is measured in…

Overtones

Multiples of the basic tone

Timbre

Quality of texture of sound, created by overtones. We know the difference between Cartman singing and Kyle singing because of the differences in….