Unit 5
Perception 2
Sleep and Dreams
Depth Perception
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Depth Perception
• How do we see different depths？
– Binocular cues
– Monocular cues
Depth Perception
• Binocular cues
– Retinal disparity
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Two objects at different distances cause displacements on two retinas
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Depth Perception
• How to see 3D images on a 2D surface?
– When the image to the right eye is slightly
different from the image to the left eye.
Depth Perception
• Binocular cues
– Convergence
• When focusing on one object, we need to converge our
eye gaze so the object image can be projected to the
centers of the two eyes
The closer the object is, the tenser the eye muscles are. 國立交通大學通識教育中心 羅仕宇老師
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Depth Perception
• Monocular cues
– interposition
Depth Perception
• Monocular cues
– Relative size
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Depth Perception
• Monocular cues
– Linear perspective
Depth Perception
• Monocular cues
– Texture gradients
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Is there any other thing that can affect our perception?
Knowledge
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Attention
• https://www.youtube.com/watch?v=vJG698U
2Mvo
Hearing
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Hearing
• Imagine a big lake, and you put your
handkerchief on one side of this lake
– Can you use the vibration of this handkerchief to
know what’s happening deep in the lake?
• Do you think it’s hard?
– But this is what your auditory system does.
Hearing
• Physics of Sound
– Frequency
– Amplitude
Frequency＝speed / wave length
W L.
A
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Hearing
• Psychological dimensions of sound
– Pitch
– Loudness
– Timbre
Hearing
• Psychological dimensions of sound
– Pitch
• Frequency: 20~20000 Hz (audible range)
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Hearing
• Psychological dimensions of sound
– Loudness
• Amplitude
Hearing
• Psychological
dimensions of
sound
– Timbre
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Hearing
• Bear in mind, neural signals are the only code
that your brain understands.
• Why we see?
– retina converts lights to neural signals
• Why we hear?
– Someone needs to convert the air vibrations into
neural signals
– https://www.youtube.com/watch?v=PeTriGTENoc
Hearing
• The auditory system
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Hearing
• How we hear different pitches?
– Place theory
– Frequency theory
Hearing
• How we hear different pitches?
– Place theory
– Frequency theory
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Hearing
• How we hear different
pitches?
– Place theory
• Different frequencies
produce their most
movement at particular
locations along the
basilar membrane
– High frequency: base of
cochlea
– Low frequency: opposite
end
Hearing
• How we hear different pitches?
– Place theory
– Frequency theory
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Hearing
• How we hear different pitches?
– Frequency theory
• A sounds of 100 Hz will set the basilar membrane
vibrating 100 times per second
– But neurons cannot fire 1000 times per second
– Volley principle
» Several neurons can fire together
Are they really contradictory?
• How we hear different pitches?
– Place theory
• Accounts well for frequency above 1000 Hz
– Frequency theory
• Accounts well for frequency below 5000 Hz
• Between 1000~5000
– Both systems
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Hearing
• How we know where
the sound comes
from?
– Comparing the
relative times
– Comparing the
relative intensities
Hearing
• What if they are
all the same
– You have to move
your head
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Other senses
Other senses
• Smell (Olfaction)
嗅球
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Smell
• Pheromones
– Chemical substance to signal
•
•
•
•
sexual receptivity
danger
territorial boundaries
food resources
– odorless
Other senses
• Taste（Gustation）
– Sweet, sour, bitter, saline
– Umami 鮮 （MSG）
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Other senses
• Touch (cutaneous sense)
Other senses
• Vestibular sense
– how your body is oriented in the world with
respect to gravity
– https://www.youtube.com/watch?v=UKaBZprL3t4
(1:30)
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Other senses
• Kinesthetic sense
– Information about the positions and the
movements of the body parts
– Receptors
• joints
• Muscles and tendons
Other senses
• Pain
– Receptors for
• Temperature signals
• chemical signals
• Mechanical signals
– Endorphins
• Endo + Morphine
– Gate‐control theory
• Cells in the spinal cord act as “gates” for pain signals
• Message from the brain can close the gates
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Pain
• Cognition and pain：shifting attention
• https://www.youtube.com/watch?v=CH4wEs2
HLjk
• So, that was how we “perceive” the world
• But, in some cases, we are not perceiving the
“world” outside, but something else…
– Can you think of any example, where there’s
nothing, but we still “perceive” something…?
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Sleep and Dreams
How do psychologists see “dreams”?
• Psychoanalysis
– The contents in your sub‐consciousness can be
manifested in dreams
• Might be in different forms
• For example, the urge to leave might be manifested in a
dream with a bridge.
• Do you remember that psychology nowadays is a
science.
– So, what kind of difficulty do you think that
psychoanalysis is confronted with.
– Can dreams be scientifically studied?
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Sleep and dreams
• EEG recording
Dream: The necessary angel of learning and memory
• https://www.youtube.com/watch?v=VMZ5zrD
pf1M
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Facts about sleep and dreams
• The stages of sleep
Facts about sleep and dreams
• Sleep over a life time
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Facts about sleep and dreams
• Sleep paralysis
• One possibility
– Muscles are inhibited during REM sleep
– What happens if muscles are still inhibited after
awakening?
Facts about sleep and dreams
• Sleepwalking
– During non‐REM sleep
– More common on children
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Facts about sleep and dreams
• I didn’t dream？
– You just don’t remember
• We’ve talked about one of the conditions
where there’s nothing out there, but you still
perceive something
– Is there any other condition like that?
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Hypnosis Hypnosis • A state of human consciousness
– enhanced capacity for response to suggestion.
• When someone gets a suggestion that “your
arm is turned into an iron rod”
– This person might not be able to bend his arm.
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Hypnosis • It’s easy to imagine what the difference is
between sleeping and waking
– But, what’s going on when someone is being
“hypnotized?”
– Is it something between sleeping and waking, or
something totally unique?
– There’s no way you can know about it, unless you
are being “hypnotized”
– But, it’s not everyone can be.
Altered states of consciousness
• Hypnotizability
– Low correlation with how gullible this person is.
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