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Sensation and

Perception

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What is Sensation??There are sense receptors for smell, temperature, vision, hearing, and taste

When the sense receptors detect an appropriate stimulus they convert the energy of the stimulus into electrical impulses that travel through neurons to the brain.

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What is Perception?

It is a set of mental operations that gives organization changes the sensory impulses into meaningful patterns.

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What are the receptor cells for each of the Senses?

• Vision- Rods and cones in the eye• Hearing-The hair cells in the inner

ear.• Smell-The receptor cells in the

nose.• Taste-The taste buds in the tongue.• Touch-Nerve endings in the skin.

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Absolute Thresholds• Defined as the weakest amount of

stimuli that can be sensed.• Vision-A candle flame viewed from 30

miles on a dark night• Hearing-The ticking of a watch 20 feet

away.• Smell-One drop of perfume in a small

house.• Taste-One teaspoon of sugar dissolved

in 2 gallons of water.• Touch-The wing of a fly falling on a

cheek.

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Difference Thresholds?• Defined as The minimum amount

of difference that can be detected between two stimuli.

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The Structure of the EYE

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Eye See You!!Part FunctionA. Lens Inside the Iris that changes in

shape to focus on objectsB. Iris The colored part of the eye that

dilates and constricts according to the available light

C. Cornea The front surface of the eyeball that bends light rays

D. Retina A layer of tissue in the back of the eye that contains the rods and cones. Images are projected onto the retina

E. Optic Nerve Composed of ganglion cells that leave the eye and go to the brain

F. Blind Spot There are no rods and cones where the optic nerve leaves the eye and, thus, no vision

G. Fovea A small area of the retina that has the sharpest and clearest vision because of the largest concentration of rods and cones.

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What are the properties of Rods and

Cones?Rods Cones

Type of Vision

Black & White

Color

Light conditions

Dimly Lit Well lighted

Distribution

Not on fovea

On fovea scattered on retina

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Related Terms• Afterimage

– Is a color’s complimentary color • The Blind Spot

– The point where the optic nerve leaves the eye and where there is no vision .

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The Structure of the Ear

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Structure of the EarPart FunctionA. Ear Drum Tissue that vibrates in response

to sound waves and transmits sound waves to middle the middle ear

B. Malleus (hammer) Vibrations cause the Malleus to vibrate Incus.

C. Incus (anvil) The vibrations cause the Incus to vibrate the Stapes

D. Stapes (stirrup) The Stapes vibrates the oval window

E. Oval Window The oval window connects the middle ear to the cochlea.

F. Cochlea Vibrations from the oval window causes motion to the fluid inside the cochlea

G. Semi-circular Canals Involved in the sensing of movement of the body

H. Auditory Nerve Carries impulses from the ear to the brain

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The Structure of the Tongue

• The sense of taste or gustation is activated by receptors called taste buds. Each bud has approximately 50 receptor cells.

• The basic tastes are sweet, sour, salty, and bitter. In some cultures, umami is considered to be a sixth taste. It is the taste of monosodium glutamate.

• Flavor is an interaction between taste and smell.

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Perception• Influences would include…

– Bottom-Up Processing• Small components are combined until a

complete perception is formed.– Top-Down Processing

• Past experiences and knowledge are used to recognize the and identify the simpler elements of the whole figure.

– Perceptual set• An expectation of what will be perceived.

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Gestalt Organizing Principles

• Figure-ground• Similarity• Proximity• Continuity• Closure

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Perceptual Constancies• Shape Constancy• Size Constancy• Brightness Constancy

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Is it me or is this hallway getting smaller???? What is

that light? We’ll have to bend down to get out!!

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Is Mr. Matiya bigger than Mr. Wooley?

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Right before your eyes!! Mr. Wooley is growing!!

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Mr. Geiger? How small is Mr. Wooley?

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How BIG are we?? In Real-Life?

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Depth Perception• The ability to see the world in

three dimensions• Binocular Depth cues such as

convergence and binocular disparity

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Depth Perception• Monocular Perception

– Interposition– Linear perspective– Relative Size– Texture Gradient– Shadows and shading– Motion parallax

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Hall of Illusions

The Devil’s pitchfork!Here doggie, come here

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Hall of Illusions

Triangles or…a cube?

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Hall of Illusions

Let me count using my fingers, that’s 1, 2,3, 4, 5, 6, 7, 8!!!!

What cube?

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Hall of Illusions

Do not stare at the dot. I warned you!!!!

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Hall of Illusions

Why is it called an impossible triangle???

Jesus?

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Hall of Illusions

Young lady or old lady? Are you, a Man or a

Mouse?

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Hall of Illusions

Tree or wolf?

Question mark or bird?

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Hall of Illusions

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The Impossible Triangle

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An illusion or do we see what we want to see??

A hidden picture in the lettering of Coca-Cola of a man doing cocaine?

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Hall of Illusions…The End