Sensation and Perception
Psychology Chapter 4 Section 1
Sensation and Perception
• We experience the world through our
senses
• Most people know about the five senses.
Can you name them?
• Vision, hearing, smell, taste, and touch
How many senses do we have?
• Depending on how you measure it, there could be
20 or so senses
• Eyes: Rods: how much light there is
• Eyes: Cones: colors– actually there are three, one
for each primary color
• Ears: there are two with the ears: hearing, balance
• Skin: five skin senses: heat, cold, pain, itch, pressure
• Nose: smell
• Tongue: taste
• But wait… there’s more…
More senses
• Muscles/ joints: where our body parts are (thus we can
walk without looking down, or touch our fingers with
our eyes closed
• Bladder: tells us when it’s time to urinate
• Large intestine: tells us when we are full of food
• We have hunger and thirst sensors
• We have many other bodily sensations, like when we
are about to sneeze or when your leg is tingly when it
falls asleep
• There’s another sense that tells us what position our
body is in without us needing to look. (This sense helps
a cat land on its feet.)
• We even have a sense of time
• So that’s 14- 20 more senses, and there’s still more
The number
of senses
could total up
to a pretty
good game of
Bingo
(pain)
This chart organizes seven of the major senses
Truth or Fiction?
• Discuss the six statements at the beginning of
page 78.
• Decide if each one is truth or fiction
Sensation and Perception
• Read Page 77 about Marc
• What was going on with Marc’s senses in the
reading?
• He tuned out background noise because he was
so enamored with Linda’s voice. When Todd
stepped on his toe, he was surprised and
annoyed, and those intense feelings may have
heightened his pain. Then, Linda’s concern
seemed to soothe the pain.
• Psychologists call these two different processes
sensation (the feeling) and perception ( the
interpretation of the feeling).
Sensation and Perception
• Once we take in information through our senses,
our brain then does something with that
information and interprets it
• The brain might decide whether or not the
message is important enough to do something
about it
• What our brain decides depends on many
factors: our mood, the circumstances, our
cultural background, etc.
While sensations depend on physical ability to sense
something, perception relies on the psychological ability to
interpret that sensation
Sensation and Perception: The Basics
• Sensation is the stimulation of sensory
receptors and its transmission to the central
nervous system
• The stimulation of the senses is automatic–
light, sound, and touch (or chemicals that
stimulate smell or taste) are constantly
stimulating the receptors
Sensation and Perception: The Basics
• Perception is the psychological process through
which we interpret sensory stimulation
• Perception reflects learning, expectations, and
attitudes, as our brain interprets stimuli
Because of our
perception skills
and experience, we
know that the
people in the
foreground of this
picture are NOT
that much bigger
than the people in
the background,
despite the
sensation
produced by the
stimulus
Sensation and Perception
A Good Test Question
• Partner up and have the older partner explain the
difference between sensation and perception,
while the younger one listens.
• Then have the younger partner explain as the older
one listens.
• I will then choose some random people to explain
the difference to the class.
Sensation and Perception: The Basics
• Sensation and perception are affected by
several concepts. Three of these are:
• Absolute Threshold
• Difference Threshold
• Signal Detection Theory
Absolute Threshold
• Absolute threshold is the very lowest level where we
can sense something
• Typical Thresholds:
• Vision: A candle flame from about 30 miles away on a
dark night
• Hearing: Ticking of a watch from 20 feet away
• Smell: One drop of perfume diffused in a small house
• Taste: One teaspoon of sugar dissolved in two gallons
of water
• Touch: A fly’s wing falling on a cheek from 0.4 inches
away
Psychologists often define the absolute threshold as the
lowest intensity that a person can detect 50 percent of
the time. Anything less than that is subliminal
Difference Threshold
•Difference
threshold is our
ability to detect
differences
between stimuli
•Can you tell the
difference
between all these
colors?
Signal Detection Theory
• We focus on whatever we consider important
• If our best friend were playing piano, we might
hear it more than if it were somebody we didn’t
know
• If our nose is stuffy, we don’t taste things as well
• If there’s noise in the room, we don’t hear as well
• Signal Detection Theory takes all these outside
influences into account when describing how
much we sense a stimulus
Sensory Adaptation
• Sensory Adaptation is the process by which
we become more sensitive to weak stimuli and
less sensitive to unchanging stimuli
• If you are in a dark room, your eyes adapt to
the amount of light available and pretty soon
you can see better
• If you are on a long car ride, you start to tune
out the humming motor after a while
• If you jump into a pool of hot or cold water,
after a while you adapt to it
Sensory Adaptation is sometimes
confused with Habituation
Sensory Adaptation
Experiment
Stare at his nose for 30
seconds and then look
at the white space
Assessment
• Complete Questions 1-3 on page 80