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Bringing the outside world into the brain

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important terms
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.
the direction of sensation
The Direction of Sensation

Physical Energy

The Receptor

The Receptor Cell

A Neural Signal

The Brain




Can taste 1

teaspoon of

sugar in 2

gallons of


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


Can feel a bee's wing

fall on your cheek

from 1 centemeter.

subliminal perception
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.




v i s i o n
  • The Structure of the Eye

The Cornea

The Iris

The Pupil

The Lens

The Retina

The Fovea

The Optic Nerve

the back of the eye
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
the rods
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
t h e c o n e s
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
the retina
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.

s e e i n g c o l o r
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.




the visible spectrum
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.
perceiving reality
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.

perceptual organizational principles
Figure – Ground

The simplest type of organizational principle

Reversible Figure-Ground

Unclear Figure-Ground

Illusory Figure-Ground

Perceptual Organizational Principles
filling in the gaps
Filling in the Gaps
  • Closure

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

perceiving depth distance

Similar objects are perceived as being together.


Stimuli close together are perceived as being together.

Perceiving Depth & Distance
perceiving depth distance20

Something is placed between the eye and the object.

Texture Gradient

Textured objects further away look smooth.

Perceiving Depth & Distance
perceiving depth distance21
Linear Perspective

Convergence of lines or the vanishing point in art.

Aerial Perspective

Close objects appear clearer than those farther away.

Perceiving Depth & Distance
perceiving depth distance22
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
perceiving depth distance23
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
the optic chiasm
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.

stereoscopic vision
Stereoscopic Vision
  • Seeing the world in Three-Dimensions
  • Binocular cues:

Retinal Disparity

The difference between the two eyes


The eyes focusing close up

Stereoscopic Vision

Seeing depth naturally

perceptual constancies
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).

  • 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

inside the ear
Inside the Ear
  • The Middle & Inner Ear

The Eardrum

The Hammer, Anvil, & Stirrup

The Oval Window

The Cochlea

The Semicircular Canals


Medical Science

Is Always Finding

Something New

the cochlea
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.

theories of hearing
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

  • 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.

the sense of smell
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

  • 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

grace and balance
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.

balance equilibrium
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.

the tactile senses
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.

the tactile senses41

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
what influences pain
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.

what influences our perceptions
What Influences Our Perceptions?
  • We respond selectively
  • Genetics & genetic predispositions
  • Individual characteristics




Cognitive Style


Experience & Culture