Unit 4:
Sensation and
Perception
Mr. McCormick
A.P. Psychology
Essential Question
How do people use the
7 known senses
to understand the
world around them?
Unit 4(A):
Sensation, Perception,
and Attention
Mr. McCormick
A.P. Psychology
Do-Now
(Discussion)
 Open your textbooks to Pg. 229:
“Sensation and Perception”
 What is Prosopagnosia?
 How does this condition illustrate the
difference between sensation and
perception?
Sensation and Perception
 Sensation:
 The process by which our sensory receptors and
nervous system receive and represent stimulus
energies from our environment
 “Bottom-Up”
 Perception:
 The process or organizing and interpreting
sensory information, enabling us to recognize
meaningful objects and events
 “Bottom-Up” and “Top-Down”
Sensation and Perception:
“Bottom-Up” Vs. “Top-Down”
 “Bottom-Up” Processing:
 “Top-Down” Processing:
T E C T
“The Forest Has Eyes”
Bev Doolittle
Sensation and Perception:
“Bottom-Up” Vs. “Top-Down”
 Look at the images on Hand-Out 6-12:
 What does each image represent
 Which process is “Bottom-Up?”
 Why?
 Which process is “Top-Down?”
 Why?
Sensation and Perception
 Organisms are equipped with sensory and perceptual
abilities based upon their individual needs:
 A frog, which feeds on flying insects, has eyes with receptor cells that
fire only in response to small, dark, moving objects. A frog could starve
to death knee-deep in motionless flies. But let one zoom by and the
frog’s “bug detector” cells snap awake.
 A male silkworm moth has receptors so sensitive to the female sexattractant odor that a single female need release only a billionth of an
ounce per second to attract every male silkworm moth within a mile.
That is why there continue to be silkworms.
 Humans are similarly equipped to detect the important features of our
environment. Our ears are more sensitive to sound frequencies that
include human voice consonants and a baby’s cry.
Perception and
Selective Attention
 Selective Attention:
 The focusing of conscious awareness on a
particular stimulus
 The five senses take in 11,000,000 bits of
information per second; however, people
consciously process 40 bits.
Perception and
Selective Attention
 Inattentional Blindness:
 Failing to see visible objects when our attention is
directed elsewhere
 Simons and Chabris:
 “Gorilla Study” (1999)
 50% of participants failed to consciously perceive gorilla
 Change Blindness:
 Failure to notice changes in the environment
 Simons and Levin:
 “Door Study” (1998)
 50% of participants failed to consciously perceive change of actor
Review
 What is the difference between sensation
and perception?
 How do sensation and perception help us
understand the world around us?
 What is selective attention?
 Differentiate between inattentional
blindness and change blindness.
Homework
 Chapter 6 Outline: “Sensation and Perception”
 Unit 4 Key People
 Research Study Response #5: “Take a Long
Look” (Pgs. 36-42)
 Unit 4 Quiz: “Sensation and Perception