Sensation and
Perception
Gateway to the outside
world
Definitions

Sensation


The stimulation of
sensory receptors and
the transmission of
sensory information to
the Central Nervous
System
Perception

The psychological
process through which
we interpret sensory
information
Definitions
 Absolute threshold
 The weakest amount of
stimulus that can be
sensed
 Difference threshold
 The minimum amount of
difference that can be
detected between two
stimuli
Absolute Threshold
Definitions
 Sensory adaptation
 The process by which
we become more
sensitive to weak stimuli
and less sensitive to
unchanging stimuli
Definitions
 Signal-Detection Theory
 The method of distinguishing
sensory stimuli that takes into
account not only the stimuli’s
strengths but also such
variable elements as the
setting, your physical state,
your mood, and your
attitudes
Vision
 How
does sight work?
 What are the main parts of the eye?
 How does color vision work?
 What is color blindness and what causes
it?
Vision
 Vision
accounts for 80%
of the sensory
information processed
by the brain
 The key component of
vision is light
Vision



Light is comprised of
electromagnetic
waves
The human eye sees
a small portion of the
spectrum of
wavelengths
Visible light can be
broken down into its
key components
Vision
 In
order from
shortest to longest:
red, orange,
yellow, green, blue,
indigo, violet
 The nonvisible
ranges include
ultraviolet and
infrared
Parts of the Eye
 Pupil

Controls the amount of
light that enters the eye
 Lens

The lens controls the
clarity of the image
 Retina

The surface upon which
the image is projected
Parts of the Eye
 Photoreceptors
 Neurons which are sensitive
to light
 Information is transmitted via
the photoreceptors to the
brain
 Rods
 Sensitive to the brightness of
light
 Cones
 Cones provide color vision
Vision
Definition
 Visual


acuity
The sharpness of an
image which is
determined by the
ability to see visual
details in normal light
Measured by a
Snellen Chart
Vision
 Measured
against
a distance of 20
feet
 Numbers show
what a person
would see against
a normal person’s
vision
 Farsighted vs.
nearsighted
Vision
 Afterimages

Visual impression
that remains after
the original image
is removed
 Blind

spot
Area vision which is
blocked by lack of
photoreceptors
How vision works
Color Blindness




Some people are
unable to see normal
color vision
Due to the absence or
malfunction of the
cones
Most common (99%) is
red-green in which
person has difficulty
seeing shades of red or
green
8% of males and 1% of
females
Hearing
 What
two characteristics do every sound
have?
 What are the main parts of the ear and
how do they work?
 What are some causes of deafness?
Sound
 Pitch



How high or low a
sound is
(frequency)
The frequency
depends on the
number of cycles
per second
The more cycles,
the higher the pitch
Sound
 Pitch
is measured in Hertz (Hz)
 Over the course of time, we lose the
ability to hear different frequency.
 At age 25, you begin to lose your ability
to hear over 15,000 Hz
 Take the test

http://www.noiseaddicts.com/2009/03/c
an-you-hear-this-hearing-test/
Sound
 Loudness



The loudness of a
sound is determined
by the height of the
sound wave
This is known as the
amplitude
Loudness is measure
in decibels (dB)
Sound
 Loudness
can be
subjective
 A person’s
sensitivity to sound
and the duration
can influence
perceived
loudness
The Ear
The Ear

Pinea


Eardrum


Outer flap of tissue that is
use to help funnel the
sound to the eardrum
A thin membrane that
vibrates when sound hits
it
Hammer, Anvil, & Stirrup


Small bones in the middle
ear which transmit the
sound to the inner ear
Stirrup is smallest bone in
the body
The Ear

Cochlea


Bony tube in the ear
that contains the
fluids and neurons
needed to transmit
sounds to the brain
Auditory nerve

Nerve that transmits
neural impulses from
the inner ear to the
brain
Locating Sound
 Determining
locations of sounds
is based upon the
principles of stereo
sound
 The level measured
in each ear helps
to determine
where the sound
originated
Deafness
 May
be inherited
or caused by injury,
disease or old age
 Two primary types
of deafness


Conductive
Sensorineural
Conductive Deafness
 Occurs
due to
damage to the
middle ear
 Usually aided by
devices that
amplify sound
 Happens when the
eardrum is ruptured
or through aging
Sensorineural Deafness




Caused due to
damage in the inner
ear
May be mild, moderate
or severe
Can be born this way or
due to prolonged
exposure to loud sounds
Can be aided by
cochlear implants