Matakuliah : L0014/Psikologi
Tahun
: 2007
Perception
Pertemuan 5
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PERCEPTION(1)
http://en.wikipedia.org/wiki/Perception
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Definition :
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is the process of acquiring, interpreting, selecting, and organizing sensory information
The process of organizing and intepreting information received from the outside world
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Perception is one of the oldest fields within scientific psychology, and there are
correspondingly many theories about its underlying processes. The oldest quantitative law
in psychology is the Weber-Fechner law, which quantifies the relationship between the
intensity of physical stimuli and their perceptual effects. It was the study of perception
that gave rise to the Gestalt school of psychology, with its emphasis on holistic approach. .
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Sensory is a system that consists of a sensory cell type (or group of cell types) that
responds to a specific kind of physical phenomenon, and that correspond to a defined
region (or group of regions) within the brain where the signals are received and
interpreted
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Stimulus : any aspect of the outside world that directly influences our behavior or
conscious experience
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1. Visual Perception
2. Multisensory Integration
3. Motivation, Emotion and Perception
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VISUAL PERCEPTION
Perceptual Organization
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VISUAL PERCEPTION
• What We perceive is often based on how sensory information is
processes in our brains than what is in front of our eyes (Long &
Toppino, 2004)
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VISUAL PERCEPTION
Perceptual Organization
1.
Figure Ground
Part of visual stimulus will be the center of our attention (figure) and the rest will be the
indistinct ground. Sometimes the figure and the ground can be reversed in our
perception of the same stimulus
2.
Continuity
The lines or patterns that follow the smooth contour will be perceived as part of a single
unit
3.
Proximity
Parts of a visual stimulus that are close together will be perceived as belonging together
4.
Similarity
Parts of visual stimulus that are similar will be perceived as belonging together
5.
Closure
The Incomplete figures of familiar objects will tend to be perceived as wholes
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FIGURE GROUND
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CONTINUITY
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PROXIMITY
• This that are close together are usually perceived as belonging
together
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SIMILARITY (1)
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SIMILARITY (2)
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CLOSURE
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VISUAL PERCEPTION
Depth Perception
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VISUAL PERCEPTION
Depth Perception (1)
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Retina has 2 – dimensional surface : up – down, left – right
Monocular cues to depth perception can be perceived by one eye
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8 monocular cues :
Texture gradient
Linear perspective
Superposition
Shadowing
Speed of movement
Aerial perspective
Accommodation
Vertical position
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TEXTURE GRADIENT (1)
• The texture of object is larger and
more visible up close and smaller the
far away
• On curve surfaces, the elements of
texture are more slanted when the
surface does not squarely face us
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TEXTURE GRADIENT (2)
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TEXTURE GRADIENT (3)
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LINEAR PERSPECTIVE
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Objects cast smaller images on the retina when they are more distant
The parallel line appear to grow closer together the farther away they are from
us
Objects with larger relative size appear to be closer than objects with smaller
relative size
SUPERPOSITION
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Closer objects tend to be partially in from of, or partially cover up, more distant
objects
SHADOWING
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The shadows cast by objects and highlights of reflected light suggest their depth
SPEED OF MOVEMENT
Object farther away appear to move across
the field of vision more slowly than do the
closer objects
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AERIAL PERSPECTIVE
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Aerial perspective or atmospheric perspective is
the effect on the appearance of an object by the
atmosphere between it and a viewer (or the
technique of depicting this effect in a work of art,
such as a landscape painting). As the distance
between an object and a viewer increases, the
contrast between the object and its background
decreases. The contrast of any markings or details
on the object also decreases. The colors of the
object also become less saturated and shift
towards blue.
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Aerial perspective was discovered and named by
Leonardo Da Vinci, who used it in many of his
works, such as the Mona Lisa, in order to suggest
distance. In such early paintings the distant objects
tend to be represented as gray-green.
http://en.wikipedia.org/wiki/Aerial_perspective
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ACCOMODATION
• The shape of the lens of the eye must change to focus the visual
image on the retina from stimuli that are different distances from
the eye.
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VERTICAL POSITION
• When objects are on the ground, the farther they appear to be
below the horizon, the closer they appear to be to us
• For the objects in the air, the farther they appear to be above the
horizon, the closer they appear to be to us
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VISUAL PERCEPTION
Depth Perception (2)
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Binocular Cues in depth perception can only perceived using two
eyes
1. Convergence
When both eyes are looking at an object in the center of the visual field, they
must angle inward more sharply for a near object than for a distant object
2. Retinal Disparity
The principle behind the old fashion stereopticon
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CONVERGENCE
• When both eyes are looking at an object in the center of the visual
field, they must angle inward more sharply for a near object than a
distant object.
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RETINAL DISPARITY
• Our eyes are couples of inches apart, they
do not see the same view of 3-dimentional
objects, especially when the object is
close.
• The difference between the images on the
2 retinas is a key factor in depth
perception
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VISUAL PERCEPTION
Visual Illusion
• Visual stimuli in which the cues used in visual perception create
false perception
• An optical illusion is always characterized by visually perceived
images that, at least in common sense terms, are deceptive or
misleading. Therefore, the information gathered by the eye is
processed by the brain to give, on the face of it, a percept that does
not tally with a physical measurement of the stimulus source.
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VISUAL ILLUSIONS (1)
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VISUAL ILLUSIONS (2)
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VISUAL ILLUSIONS (3)
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PONZO ILLUSION
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The Ponzo illusion is an optical illusion that was
first demonstrated by the Italian psychologist
Mario Ponzo (1882-1960) in 1913.
He suggested that the human mind judges an
object's size based on its background.
He showed this by drawing two identical lines
across a pair of converging lines, similar to
railway tracks. The upper line looks longer
because we interpret the converging sides
according to linear perspective as parallel lines
receding into the distance.
In this context, we interpret the upper line as
though it were farther away, so we see it as
longer – a farther object would have to be longer
than a nearer one for both to produce retinal
images of the same size.
THE ZOLLNER ILLUSION
• a classic optical illusion named after
its discoverer, German astrophysicist
Johann Karl Friedrich Zöllner.
• In this figure the black lines seem to
be unparallel, but in reality they are
parallel. The shorter lines are on an
angle to the longer lines. This angle
helps to create the impression that
one end of the longer lines is nearer
to us than the other end.
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THE MϋLLER-LYER ILLUSION
• an optical illusion consisting of nothing
more than an arrow.
• occurs because the visual system
processes that judge depth and distance
assume in general that the “angles in”
configuration corresponds to an object
which is closer, and the “angles out”
configuration corresponds to an object
which is far away.
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THE AMES ROOM (1)
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The distorted room seen above is named
after the American ophthalmologist
Adelbert Ames, Jr., who first constructed
such a room in 1946. He based his design
on a concept originally conceived by
Hermann Helmholtz in the late 19th
century.
There are two illusions associated with
the Ames Room. First the room appears
cubic when viewed monocularly from a
special viewing point (the true shape of
the room is trapezoidal). Secondly,
within an Ames Room people or objects
can appear to grow or shrink when
moving from one corner to the other.
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THE AMES ROOM (2)
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This diagram shows how the Ames Room forms an identical
image of a normal cubic room on your retina. If a straight
line (representing a ray of light) is drawn from one corner of
an imaginary cubic room to your eye, the corner can meet
this ray at any point along its length and still appear cubic
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When you look (through a peephole -- to
remove any cues from stereopsis) into an
Ames Room, the room looks normal and
cubic, but its true shape is cleverly
distorted. The floor, ceiling, some walls,
and the far windows are actually
trapezoidal surfaces. Although the floor
appears level, it is actually at an incline
(the far left corner is much lower than
the near right corner). The walls appear
perpendicular to the floor, although they
are actually slanted outwards.
POGGENDORF ILLUSION
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The Poggendorf illusion is one of the most famous
distortion illusions known. Although much has been
written about it since its discovery in 1860, the
underlying mechanism that gives rise to this effect is
still not well understood.
An adequate explanation of the Poggendorf illusion
must take all the above factors into account, as well as
several others. For example, the Poggendorf illusion is
not confined to two-dimensional representations: It also
occurs with three-dimensional objects. Secondly,
perspective cues can have a drastic effect on
diminishing the effect of this illusion.
While the Poggendorf illusion is over 100 years old (it
was discovered in 1860), there have been no end of
theories to try to account for it. Recently, interactive
versions have revealed new characteristics and
variations of this illusion. There is, unfortunately, no
theory to date that will adequately account for all the
variations perceived.
VISUAL PERCEPTION
Color Perception
• The perception of color is based on more than the information that
reaches the brain about the wavelengths of light that reach the
cones
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COLOR PERCEPTION (1)
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COLOR BLIND
Color blindness, (also known as Dyschromatopsia) or color vision deficiency, in
humans is the inability to perceive differences between some or all colors that
other people can distinguish. It is most often of genetic nature, but may also
occur because of eye, nerve, or brain damage, or due to exposure to certain
chemicals.
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MULTISENSORY INTEGRATION
• Integrate and interpret information from multiple senses at the
same time (Ernst & Bulthoff, 2004)
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MOTIVATION, EMOTION AND PERCEPTION
• Motivation influence perception
– Hungry  taste the food more delicious
• Emotion influence perception
– Anxious  hear the ambiguous statement more threatening
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