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Sensation and Perception PowerPoint PPT Presentation

Bringing the outside world into the brain

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Sensation and Perception

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Perception

Sensation

and


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Important Terms

  • Sensation: a sensory message; transmission of information about the environment to the brain.

  • Transduction: converting physical energy into neural energy.

  • Perception: the interpretation of a sensory message by the brain.


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The Direction of Sensation

Physical Energy

The Receptor

The Receptor Cell

A Neural Signal

The Brain


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Sensory

Thresholds

Can taste 1

teaspoon of

sugar in 2

gallons of

water.

A candle flame

can be seen from

a distance of 30

miles on a clear night.

Can hear the

ticking of a

wristwatch in

a quiet room at

20 feet.

Can smell a drop

of perfume diffused

throughout a 3-room

apartment.

Can feel a bee's wing

fall on your cheek

from 1 centemeter.


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Subliminal Perception

  • Stimulation below the threshold of conscious awareness.

    There is no evidence to support subliminal perception occurring.

  • Reverse Masking

    There is no evidence to support reverse masking causes subliminal or any other stimulation.


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Subliminal Ads


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More

Subliminals


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Vision

  • The Structure of the Eye

    The Cornea

    The Iris

    The Pupil

    The Lens

    The Retina

    The Fovea

    The Optic Nerve


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At the rear of the eye is the retina containing the receptor cells.

Before light gets to the retina, it passes through blood vessels & connecting cells.

The Back of the Eye


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Rods are absent from the fovea

Rods become more common toward the periphery of the retina

Rods have low sensitivity to detail because many of them funnel into a single postsynaptic neuron

The Rods


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The Cones

  • More common toward the center of the retina

  • Fewer in the periphery of the retina

  • More of them because fewer cones funnel onto a single postsynaptic neuron


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The Retina

  • The Rods

    Specialized for low light

  • The Cones

    Color vision and bright light

    The rods and cones connect to BI-POLAR cells.

    The bi-polar cells connect to GANGLION CELLS.

    The ganglion cells’ axon becomes the OPTIC NERVE.


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Trichromatic Theory

Three types of cones: RED, GREEN, and BLUE.

Opponent Process Theory

Cones are in opposing pairs. When one is activated, the other is suppressed.

White/Black

Blue/Orange

Green/Red

SeeingColor


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The Visible Spectrum

  • We see about 1/1 millionth of a meter of the whole electromagnetic spectrum.

  • The electro-magnetic spectrum includes both invisible long and short waves.


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Perceiving Reality

  • Apparent Motion

  • The Autokinetic Effect

    Apparent motion of a single light in total darkness.

  • The Phi Phenomenon

    A series of blinking lights.

  • The Stroboscopic Effect

    The “jerky” effect of a strobe light blinking in total darkness with movement.


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Figure – Ground

The simplest type of organizational principle

Reversible Figure-Ground

Unclear Figure-Ground

Illusory Figure-Ground

Perceptual Organizational Principles


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Filling in the Gaps

  • Closure

    The tendency to perceive an object or shape even when the form isn’t complete.


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Similarity

Similar objects are perceived as being together.

Proximity

Stimuli close together are perceived as being together.

Perceiving Depth & Distance


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Interposition

Something is placed between the eye and the object.

Texture Gradient

Textured objects further away look smooth.

Perceiving Depth & Distance


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Linear Perspective

Convergence of lines or the vanishing point in art.

Aerial Perspective

Close objects appear clearer than those farther away.

Perceiving Depth & Distance


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Motion Paralax

Closer objects seem to move faster than those farther away when in motion.

Light and Shadow

Gives objects the appearance of three dimensions.

Perceiving Depth & Distance


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Relative Size

The smaller the image of an object is on the retina, the farther away it seems.

Relative Height

Objects higher in the visual field are perceived as farther away.

Perceiving Depth & Distance


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The Optic Chiasm

  • Point in the temporal area of the brain where the optic nerve crosses over from left to right.

    This is where stereo vision is created.


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Stereoscopic Vision

  • Seeing the world in Three-Dimensions

  • Binocular cues:

    Retinal Disparity

    The difference between the two eyes

    Convergence

    The eyes focusing close up

    Stereoscopic Vision

    Seeing depth naturally


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Perceptual Constancies

  • Size Constancy

    Objects continue to remain the same size no matter how distant.

  • Shape Constancy

    Objects remain the same shape even if the image on the retina shows a different shape.

  • Color Constancy

    Influenced by lighting (artificial, colored, or natural).


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Visual Illusions


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More Illusions


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More Illusions


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Hearing

  • The Construction of the Ear

    The Pinna

    The External Auditory Canal

    The Ear Drum

    The Hammer, Anvil, & Stirrup

    The Oval Window

    The Cochlea

    The Hair Cells

    The Nerve Cells

    The Auditory Nerve


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Inside the Ear

  • The Middle & Inner Ear

    The Eardrum

    The Hammer, Anvil, & Stirrup

    The Oval Window

    The Cochlea

    The Semicircular Canals


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Medical Science

Is Always Finding

Something New


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The Cochlea

  • The Cochlea is the organ of hearing

  • Contained within the Cochlea are the hair cells

    The hair cells are connected to neurons and the axons of the neurons create the auditory nerve.


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Theories of Hearing

  • The Place Theory of Hearing

    Different areas of the basilar membrane respond to different frequencies. High tones register most strongly at the base of the cochlea (near the oval window), lower tones mostly move the hair cells near the outer tip of the cochlea.

  • The Frequency Theory of Hearing

    The entire basilar membrane acts like a microphone, vibrating as a whole in response to sound. The nerve receptors send out impulses that are tied directly to the frequency of the sounds: Frequency = Impulses


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Deafness

  • Conduction Deafness

    When the eardrums or ossicles are damaged or immobilized by disease or injury reducing the transfer of sound to the inner ear.

  • Nerve Deafness

    When there is damage to the hair cells or auditory nerve.

  • Stimulation Deafness

    Caused by a noisy environment damaging the hair cells in the cochlea.


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The Sense of Smell

  • Olfaction

    A chemical sense

  • The Route

    Nerve Endings toThe Neuronsto The Olfactory Bulbto The Limbic System

  • The Lock & Key Theory

  • 5 Odors Identified

    Floral, Camphoric, Musky, Minty, & Etherish


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Taste

  • Gustation

    A Chemical Sense

  • The Route

    The Tongue to The Papillae to The Taste Buds to The Brain

  • 5 Tastes Identified

    Sweet, Sour, Salty, Bitter, & Umami


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Grace and Balance

  • The Kinesthetic Sense

    Keeps us informed about movement of body parts & their position in relation to each other.

    Muscle Movement, Posture, & Joints

    Information comes from stretch receptors, the tendons, & the internal organs.


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Balance & Equilibrium

  • Vestibular Sense

    The Vestibular Sense keeps us informed about balance & the position of our body in space.

    Hair cells in the inner ear bend in relation to the position & movement of the head giving information that the brain uses to help us maintain our balance and to sense changes in our movement through space.


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The Tactile Senses

  • Touch

    Skin receptors that make us aware of how & where we’re being touched.

  • Pressure

    Receptors beneath the skin that make us aware of deeper touch.

  • Temperature

    Receptors are found just beneath the skin to give the sensation of hot, cold, and warm.


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Pain

Pain is adaptive & lets us know there’s something wrong.

Pain receptors are located not just in the skin, but also in other parts of the body: muscles, joints, ligaments, teeth, & the internal organs.

2 Kinds of Pain

Dull (slow) pain

Long axons

Sharp (fast) pain

Short axons

The Gate Control Theory of Pain

There is a “neurological gate” in the spinal cord controlling the transmission of pain messages to the brain.

Dull, throbbing pain is conducted through the gate by thinner & slower nerve fibers that carry signals for touch & temperature.

Faster, thicker nerve fibers cause a bottleneck at the gate, blocking the passage of other messages.

The Tactile Senses


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What Influences Pain?

  • The Biosocial Theory

    The interaction of biological, psychological, and cultural factors influence the intensity & duration of pain.

  • The Placebo Effect

    Any direct or indirect procedure or object that can cause relief from pain or illness.

    With pain, it appears to come from the release of endorphins.


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What Influences Our Perceptions?

  • We respond selectively

  • Genetics & genetic predispositions

  • Individual characteristics

    Motivation

    Values

    Expectations

    Cognitive Style

    Personality

    Experience & Culture


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