CS228 HumanComputer Interaction

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CS228 Human-Computer Interaction
Memory, attention and perception
Different types of perception, related to our
sensory channels visual perception, auditory
perception, tactile perception, etc. As humans
are visual creatures, most study has been
carried out on visual perception. Most visual
perception is not only active, but, more
specifically, is constructive Construct our
perceptions of the world from some visual stimuli.
Gestalt law of perception Reification Gestalt
Whole is more than the sum of its parts.
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CS228 Human-Computer Interaction
Memory, attention and perception
Different types of perception, related to our
sensory channels visual perception, auditory
perception, tactile perception, etc. As humans
are visual creatures, most study has been
carried out on visual perception. Most visual
perception is not only active, but, more
specifically, is constructive Construct our
perceptions of the world from some visual
stimuli. Context of perception is very
important Richard Gregory (1973) focuses on
the constancies in our constructed world
views. J. J. Gibson (1950s onward) claims that
we focus on the changes in our constructed world
views. Constancy (or change) is determined by
context the visual relationship of objects in
the scene to one another.
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views.
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views.
External context (the cylinder and its
shadow) alters our perception of color. Another
external context (the grey bars) alters it back
again.
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views. What type of constancies exist in
our world? Color of an object does not change
in response to ambient light levels. (A red
ball is still red, by day or night perceptual
constancy). Objects near to one another tend to
be physically connected to one another
(We tend to see one object here, not five.)
Gestalt law of perception continuity
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views. What type of constancies exist in
our world? Color of an object does not change
in response to ambient light levels. (A red
ball is still red, by day or night perceptual
constancy). Objects near to one another tend to
be physically connected to one another
15 visual objects
151429 visual objects
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views. What type of constancies exist in
our world? Color of an object does not change
in response to ambient light levels. (A red
ball is still red, by day or night perceptual
constancy). Similar objects tend to be grouped
together
(We tend to three rows here, rather than 6
columns.)
Gestalt law of perception similarity
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views. What type of constancies exist in
our world? Color of an object does not change
in response to ambient light levels. (A red
ball is still red, by day or night perceptual
constancy). It is easier to perceive closed
objects than incomplete or open ones
(We tend to one vase here, rather than two faces.)
Gestalt law of perception closure
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views. What type of constancies exist in
our world? Color of an object does not change
in response to ambient light levels. (A red
ball is still red, by day or night perceptual
constancy). Shapes remain the same, regardless
of the actual shape they form on our retina
(shape constancy)
What shape is this object?
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views. What type of constancies exist in
our world? Color of an object does not change
in response to ambient light levels. (A red
ball is still red, by day or night perceptual
constancy). Shapes remain the same, regardless
of the actual shape they form on our retina
(shape constancy)
What shape is this object?
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception Richard Gregory (1973)
focuses on the constancies in our constructed
world views. What type of constancies exist in
our world? Color of an object does not change
in response to ambient light levels. (A red
ball is still red, by day or night perceptual
constancy). Shapes remain the same, regardless
of the actual shape they form on our retina
(shape constancy)
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception J. J. Gibson (1950s onward)
claims that we focus on the changes in our
constructed world views. What does change tell
us about our world? Objects moving faster than
others are closer to us. (Motion parallax)
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CS228 Human-Computer Interaction
Memory, attention and perception
Visual perception J. J. Gibson (1950s onward)
claims that we focus on the changes in our
constructed world views. What does change tell
us about our world? Objects getting smaller or
objects approaching the center of the screen
are moving further away / becoming less
significant or accessible (optic flow /
perspective)
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CS228 Human-Computer Interaction
Memory, attention and perception
Weve been discussing how technologies can
exploit users perceptions but how can we
enable interactive technologies to perceive? Q
How could a robot detect any object that will
collide with it, using only an ultrasonic sensor
(detects distance)?
Stay still
Stay still
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CS228 Human-Computer Interaction
Memory, attention and perception
Weve been discussing how technologies can
exploit users perceptions but how can we
enable interactive technologies to
perceive? Difficult, because it is hard to see
the world through the robots eyes
but the robot sees this
We see this
0.00sec 30mm 0.25sec 30mm 0.50sec 08mm 0.75sec 30m
m 1.00sec 30mm 1.25sec 30mm 1.50sec 06mm
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CS228 Human-Computer Interaction
Memory, attention and perception
Weve been discussing how technologies can
exploit users perceptions but how can we
enable interactive technologies to
perceive? Known as the frame-of-reference
problem Must imagine what the user/technology
sees, and how it can react, not what we can see,
and how we can react. Difficult to do with
people as well Q What can the instructor at the
front of the room see? From where youre
sitting, try to draw what the instructor
sees draw an oval for each students
head. Which students are occluding which others,
from the instructors perspective? Now, come up
to the front (by rows), and see how you did.