Sensation and Perception

Article

Sensation vs. Perception

Sensation= the experience of stimulation of the body’s senses

5 Senses:1. vision2. hearing3. smell4. touch5. taste

Perception= the process by which the brain organizes and interprets sensory information

Sensory Thresholds• Absolute Threshold• -minimum intensity of a stimuli required to produce any

sensation at all

-i.e.: barely enough volume or light to be noticed

• Vision: A single candle flame from 30 miles on a dark, clear night• Hearing: The tick of a watch from 20 feet in total quiet• Smell: 1 drop of perfume in a 3-room apartment• Touch: The wing of a bee on your cheek, dropped from 1 cm• Taste: 1 tsp. Sugar in 2 gal. water

• Adaptation• -senses adjust to level of stimulation in the environment,

applies to all senses

-i.e.: loud noise = ears less sensitive bright light = eyes squint

Subliminal Perception• 2/3 of Americans believe in subliminal advertising

Do You?

Do Subliminal Messages really work?

Yes & No

• Yes- in a controlled lab setting (to process information)

• No- evidence in advertising (they can not control behavior)

Sensory Adaptation

• diminished sensitivity as a consequence of constant stimulation

GEE, this water is cold!

COMON’ IN. THE WATER IS FINE!

Can you think of any others?

Structure of the Eye Structure of the Eye

Part Function

Cornea Transparent protective coating over the front of the eye, light enters the eye here

Pupil Small opening in the eye in which light passes through

Iris Colored part of eye, bright light = pupil gets smaller, dim light = pupil gets larger

Lens Transparent part of eye inside the pupil that focuses light onto the retina, lens changes shape to focus on objects that are closer or farther away

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

Fovea Area of the retina that is the center of the visual field, images are sharpest here = VISUAL ACUITY ( ability to distinguish fine details)

Receptor Cells Specialized cell that responds to a particular type of energy, sensitive to only a small part of the electromagnetic spectrum; 2 types

Rods Receptor cells responsible for night vision and perception of brightness, more sensitive

Cones Receptor cells responsible for color vision, used during the daytime, work best with bright light

Parts of the Eye

How Do We See Color?

• We do not have to learn to see color, we are born with this capability

• We see color because our eyes have different receptors for different wavelengths of light

Hue: or name of a color, such as red, corresponds to a particular wavelength

Saturation: refers to the purity, richness, or intensity of a color.

Colors produced by a very narrow band of wavelengths such as red, are highly saturated, as compared to pink, which is a mixture of red and white

Brightness: refers to the amplitude, or height, of a light wave and to the amount of light energy reaching the retina

Theories of Color Vision1.Trichromatic Theory of Color Vision

T. Young (1802) & H. 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

Trichromats = normal color vision

Dichromats = blind to either red-green or yellow-blue

=> Monochromats = totally colorblind

Thomas Young Hermann von Helmholtz

Color BlindnessGenetic disorder in which people are blind to

green or red colors. This supports the Trichromatic theory.

Ishihara Test

People who suffer red-green blindness have trouble perceiving the number within the design

2. Opponent-Process Theory• There are 3 types of receptors, each capable of responding to either red-green,

yellow-blue, or black-white, but not to all

• The colors of each pair oppose each other; they can not be blended

• But the four primary colors can be mixed with colors from the other pairs, thereby creating all the colors of the visible spectrum

Opponent Colors

Gaze at the middle of the flag for about 30Seconds. When it disappears, stare at the dot and reportwhether or not you see Britain's flag.

Opponent Colors

Gaze at the middle of the flag for about 30Seconds. When it disappears, stare at the dot and reportwhether or not you see Britain's flag.

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Structure of the Ear Structure of the Ear

anvil - a tiny bone that passes vibrations from the hammer to the stirrup.cochlea - a spiral-shaped, fluid-filled inner ear structure; it is lined with cilia (tiny hairs) that move when vibrated and cause a nerve impulse to form.eardrum - (also called the tympanic membrane) a thin membrane that vibrates when sound waves reach it.Eustachian tube - a tube that connects the middle ear to the back of the nose; it equalizes the pressure between the middle ear and the air outside. When you "pop" your ears as you change altitude (going up a mountain or in an airplane), you are equalizing the air pressure in your middle ear.

hammer - a tiny bone that passes vibrations from the eardrum to the anvil.nerves - these carry electro-chemical signals from the inner ear (the cochlea) to the brain.outer ear canal - the tube through which sound travels to the eardrum.pinna - the visible part of the outer ear. It collects sound and directs it into the outer ear canalsemicircular canals - three loops of fluid-filled tubes that are attached to the cochlea in the inner ear. They help us maintain our sense of balance.stirrup - a tiny, U-shaped bone that passes vibrations from the stirrup to the cochlea. This is the smallest bone in the human body.

Parts of the Ear

Hearing

• Sound: Psychological experience created by your brain in response to stimulation

The Most Annoying Sound in the World

5 Most Annoying Sounds Ever

Frequency (Pitch)

Frequency (pitch): The dimension of

frequency determined by the

wavelength of sound.

Wavelength: The distance from the

peak of one wave to the peak of the next.

Intensity (Loudness)

Intensity (Loudness): Amount of energy in a wave, determined by the amplitude,

relates to the perceived loudness.

Smell

• Also known as olfaction• Smell is a chemical

sense• Sense of smell peaks in

adulthood• Women and young

adults have the best sense of smell

Smell

• Humans can identify over 10,000 odors

• Pheromones- odor molecules that animals of the same species interpret as a sexual message

• Some believe that humans also use pheromones to communicate sexual interests

Pheromones

Even if humans use pheromones to communicate sexual interests, they are just one of many factors involved in the complex nature of human sexual attraction

Odors can have the power to evoke powerful memories and feelings.

Taste

Our emotional response to taste is innate (everyone makes the same face after eating something sour)

4 Primary Taste Qualities:

1. Bitter

2. Sour

3. Salty

4. Sweet

Taste buds= taste receptors-

Most are located on the tongue, but they are also in other parts of the mouth, such as the palate (roof of the mouth)

Young children like salty food

As people age, their taste buds become less sensitive, and many therefore develop a taste for spicy food

The sense of smell is also involved in our experience of taste and allows us to experience complex taste.

When you nasal passages are blocked, you can not smell the food, and this restricts your ability to taste the food

Touch • 4 Distinct Skin Senses: Somatic Receptors 1. Touch2. Pressure3. Temperature (heat and cold)4. Pain

These are essential for development from start of life

The tongue, lips, face, hands, and genitals have much greater numbers of receptors and are therefore more sensitive to stimuli.

Pain “No brain, no pain”

• Pain serves as a warning signal, providing us with vital information about illness or possible tissue damage

• Pain Thresholds: vary with each individual

Some people have a very low tolerance for pain, while others can withstand a great deal of pain

PainPeople born without the ability to feel pain usually die at a young age

Chronic Pain: constant or reoccurring pain

Pain control: distracting thoughts is an effective way to increase pain tolerance

Drugs

Surgery

Massage

Exercise

Hypnosis

Thought Distraction

Perception

• Perception occurs when the brain organizes information to make it meaningful

• It is an experience caused by stimulation of the senses

Perceptual Constancies

=> Size Constancy-perception of object as same size regardless of the distance from which it is viewed

- depends partly on experience =>stored in memory

=> Shape Constancy -tendency to see an object as the same shape no matter what angle it is viewed from(i.e. door at an angle => rectangle / trapezoid)

=> Brightness & Color Constancy -perception of original brightness & color of an object despite changes in sensory info. (i.e. amount of light)

Our memories play an important role in helping us interpret all new incoming stimuli and allowing us to perceive certain aspects of our world as constant or unchanging

Top-Down Processing Involves a person’s knowledge of the world

It starts with an analysis of higher-level information, such as the context in which a stimulus is seen, for example…

When you encounter something new, do you start by studying the details? Or do you look at the big picture?

Cambridge Study

Observer Characteristics

Depends on past experiences and prior learning

Expectations influence what we observe = “mind set”

Your culture (religion, government, customs etc. can influence an observer’s perception.

Motivations and values shape our observations; we desire and we need (wants and needs)

Perceptual FamiliarizationYou perceive what you are familiar with

Library Activity

Perception Perception