Chapter 6
Sunday, February 20, 2022 5:42 PM
Sensation and Perception
- Prosopagnosia - face blindness
○ Inability to recognize familiar faces
○ Sellers (has prosopagnosia), when encountering someone who
previously irritated her, she typically feels no ill will, she does not
recognize the person
- Phonagnosia - voice blindness
○ inability to recognize familiar voices
○ One man flirted on the phone with someone he presumed was his
wife, not realizing it was a different woman
- Human ears are most sensitive to sound frequencies that include human
voices, especially a baby's cry
- Frogs, have cells in their eyes that fire only in response to small, dark,
moving objects (because they feed on insects)
○ A frog could starve to death knee-deep in motionless flies
- Male silkworm moths' odor receptors can detect one-billionth of an ounce
of chemical sex attractant per second, released by a female one mile away
Basic Concepts of Sensation and Perception
- How do we construct our representations of the external world?
Processing Sensation and Perception
6-1 What are sensation and perception? What do we mean by bottom-up
processing and top-down processing?
- Heather Seller's curious mix of 'perfect vision' and face blindness
illustrates the distinction between sensation and perception
- Sensation - the process by which our sensory receptors and nervous
system receive and represent stimulus energies from our environment
○ Seller's sensation is normal when she looks at a friend
- Sensory receptors - sensory nerve endings that respond to stimuli
, - Perception - process of organizing and interpreting sensory information,
enabling us to recognize meaningful objects and events
○ Seller's perception is almost normal
§ She may recognize people from their hair, gait, voice,
physique, just not by their face
- Bottom-up processing - analysis that begins with the sensory receptors
and works up to the brain's integration of sensory information
○ Sensation
- Top-down processing - information guided by higher-level mental
processes, as when we construct perceptions drawing on our experience
and expectations
○ Perception
Transduction
6-2 What three steps are basic to all our sensory systems?
- Vision processes light energy
- Hearing processes sound waves
- ALL our senses:
○ Receive sensory stimulation, often using specializing receptor cells
○ Transform that stimulation into neural impulses
○ Deliver the neural information to our brain
• Transduction - conversion of one form of energy into another
○ In sensation, the transforming of stimulus energies (sights, sounds,
smells), into neural impulses that our brain can interpret
• Psychophysics - the study of relationships between the physical
characteristics of stimuli, such as their intensity, and our psychological
experience of them
○ Relationship between the physical energy we can detect and its
effects on our psychological experiences
What is the rough distinction between sensation and perception?
Sensation is the bottom-up process by which your sensory receptors and
nervous system receive and represent stimuli. Perception is the top-down
process by which your brain creates meaning by organizing and
interpreting what your senses detect
,Thresholds
6-3 How do absolute thresholds and difference thresholds differ?
- Migrating birds stay on course aided by an internal magnetic compass
- Bats and dolphins locate prey by using sonar, bouncing echoing sound off
objects
- Bees navigate on cloudy days by detecting invisible (to us) polarized light
Absolute Thresholds
- Absolute thresholds - minimum stimulus energy needed to detect a
particular stimulus 50% of the time
○ EX: hearing specialist would send tones at varying levels into each of
your ears and record whether you could hear each one to test your
absolute threshold for sounds
§ That 50-50 point where for any sound frequency half the time
you can detect the sound and half the time you could not is
your absolute threshold
• Signal detection theory - a theory predicting how and when we detect the
presence of a faint stimulus (signal) amid background stimulation (noise)
○ Assumes there is no single absolute threshold and that detection
depends partly on a person's experience, expectations, motivation,
and alertness
○ Signal detection theorists seek to understand why people respond
differently to the same stimuli, and why the same person's reactions
vary as circumstances change
• Subliminal - below one's absolute threshold for conscious awareness
○ Stimuli you cannot consciously detect 50% of the time are subliminal
• Sexual orientation subliminal stimulus experiment:
○ People gazed at center of the screen, photo of nude person was
flashed on one side, scrambled nude version flashed on the other
side, nude images were immediately masked by a colored
checkerboard
○ Viewers consciously perceived nothing but flashes of color and so
were unable to state on which side the nude had appeared
○ To test whether this unseen image unconsciously attracted their
attention experimenters then flashed a geometric figure to one side
, attention, experimenters then flashed a geometric figure to one side
or the other, quickly followed by a masking stimulus as well
○ When asked to give the figure's angle: straight men guessed more
accurately when it appeared where a nude woman had been a
moment earlier
○ Gay men and straight women guessed more accurately when the
geometric figure replaced a nude man
• Priming - the activation (often unconsciously) of certain associations, thus
predisposing one's perception, memory, or response
• Subliminal has no greater difference of effects compared to placebo
groups
Difference Thresholds
Sunday, February 20, 2022 5:42 PM
Sensation and Perception
- Prosopagnosia - face blindness
○ Inability to recognize familiar faces
○ Sellers (has prosopagnosia), when encountering someone who
previously irritated her, she typically feels no ill will, she does not
recognize the person
- Phonagnosia - voice blindness
○ inability to recognize familiar voices
○ One man flirted on the phone with someone he presumed was his
wife, not realizing it was a different woman
- Human ears are most sensitive to sound frequencies that include human
voices, especially a baby's cry
- Frogs, have cells in their eyes that fire only in response to small, dark,
moving objects (because they feed on insects)
○ A frog could starve to death knee-deep in motionless flies
- Male silkworm moths' odor receptors can detect one-billionth of an ounce
of chemical sex attractant per second, released by a female one mile away
Basic Concepts of Sensation and Perception
- How do we construct our representations of the external world?
Processing Sensation and Perception
6-1 What are sensation and perception? What do we mean by bottom-up
processing and top-down processing?
- Heather Seller's curious mix of 'perfect vision' and face blindness
illustrates the distinction between sensation and perception
- Sensation - the process by which our sensory receptors and nervous
system receive and represent stimulus energies from our environment
○ Seller's sensation is normal when she looks at a friend
- Sensory receptors - sensory nerve endings that respond to stimuli
, - Perception - process of organizing and interpreting sensory information,
enabling us to recognize meaningful objects and events
○ Seller's perception is almost normal
§ She may recognize people from their hair, gait, voice,
physique, just not by their face
- Bottom-up processing - analysis that begins with the sensory receptors
and works up to the brain's integration of sensory information
○ Sensation
- Top-down processing - information guided by higher-level mental
processes, as when we construct perceptions drawing on our experience
and expectations
○ Perception
Transduction
6-2 What three steps are basic to all our sensory systems?
- Vision processes light energy
- Hearing processes sound waves
- ALL our senses:
○ Receive sensory stimulation, often using specializing receptor cells
○ Transform that stimulation into neural impulses
○ Deliver the neural information to our brain
• Transduction - conversion of one form of energy into another
○ In sensation, the transforming of stimulus energies (sights, sounds,
smells), into neural impulses that our brain can interpret
• Psychophysics - the study of relationships between the physical
characteristics of stimuli, such as their intensity, and our psychological
experience of them
○ Relationship between the physical energy we can detect and its
effects on our psychological experiences
What is the rough distinction between sensation and perception?
Sensation is the bottom-up process by which your sensory receptors and
nervous system receive and represent stimuli. Perception is the top-down
process by which your brain creates meaning by organizing and
interpreting what your senses detect
,Thresholds
6-3 How do absolute thresholds and difference thresholds differ?
- Migrating birds stay on course aided by an internal magnetic compass
- Bats and dolphins locate prey by using sonar, bouncing echoing sound off
objects
- Bees navigate on cloudy days by detecting invisible (to us) polarized light
Absolute Thresholds
- Absolute thresholds - minimum stimulus energy needed to detect a
particular stimulus 50% of the time
○ EX: hearing specialist would send tones at varying levels into each of
your ears and record whether you could hear each one to test your
absolute threshold for sounds
§ That 50-50 point where for any sound frequency half the time
you can detect the sound and half the time you could not is
your absolute threshold
• Signal detection theory - a theory predicting how and when we detect the
presence of a faint stimulus (signal) amid background stimulation (noise)
○ Assumes there is no single absolute threshold and that detection
depends partly on a person's experience, expectations, motivation,
and alertness
○ Signal detection theorists seek to understand why people respond
differently to the same stimuli, and why the same person's reactions
vary as circumstances change
• Subliminal - below one's absolute threshold for conscious awareness
○ Stimuli you cannot consciously detect 50% of the time are subliminal
• Sexual orientation subliminal stimulus experiment:
○ People gazed at center of the screen, photo of nude person was
flashed on one side, scrambled nude version flashed on the other
side, nude images were immediately masked by a colored
checkerboard
○ Viewers consciously perceived nothing but flashes of color and so
were unable to state on which side the nude had appeared
○ To test whether this unseen image unconsciously attracted their
attention experimenters then flashed a geometric figure to one side
, attention, experimenters then flashed a geometric figure to one side
or the other, quickly followed by a masking stimulus as well
○ When asked to give the figure's angle: straight men guessed more
accurately when it appeared where a nude woman had been a
moment earlier
○ Gay men and straight women guessed more accurately when the
geometric figure replaced a nude man
• Priming - the activation (often unconsciously) of certain associations, thus
predisposing one's perception, memory, or response
• Subliminal has no greater difference of effects compared to placebo
groups
Difference Thresholds
