Sensation and Perception Lecture
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Transcript of Sensation and Perception Lecture
TRY THIS YOURSELF:
What do you see?
All outside information comes into us through our senses.
Sensation—the process of detecting, receiving, converting and transmitting information resulting from stimulation of sensory receptors.
Perception—the process of selecting, identifying, organizing and interpreting sensory input into a useful and meaningful mental representations of the world in the light of relevant memories from past experiences.
The basic function of sensation is detection of sensory stimuli, whereas perception generally involves interpretation of the same stimuli.
Our senses tell us something is out there. Our perception tell us what that something is.
In practice, sensation and perception are virtually impossible to separate, because they are part of one continuous process.
SENSATION IS THE PROCESS OF DETECTING AND ENCODING STIMULUS IN THE WORLD.
Vision (sense of sight) sensitive to LIGHT ENERGY
Auditory (sense of hearing)
stimulated by SOUND ENERGY
Olfaction (sense of smell) stimulates our nostrils by CHEMICAL ENERGY
Gustation (sense of taste)
Tactile (skin senses for pressure, temperature, pain)
THERMAL ENERGY
Vestibular (sense of balance)
Kinesthesia (sense of posture and movement)
Organic (sensation from internal organs such as hunger, thirst, drowsiness)
When neural impulses reach the particular area in the brain,
they are changed into meaningless bits of information called
sensation which involves the detection of sensory stimuli.
Transduction—after stimuli enter sensory organs, the sense
receptor will change/covert the stimulus into electrical signals
called neural impulses which are sent to the brain.
Information (e.g. light, sound)—activate our sense
receptors in the sensory organs which receive and
process sensory information from environment.
These meaningless bits of information are then changed into
meaningful and complete images called perception—the
interpretation of sensory stimuli.
Our sense organs translate physical energy from the environment into electrical impulses processed by the brain.
For example, light, in the form of electromagnetic radiation, causes receptor cells in our eyes to activate and send signals to the brain.
But we do not understand these signals as pure energy. The process of perception allows us to interpret them as objects, events, people, and situations.
Without the ability to organize and interpret sensations, life would seem like a meaningless jumble of colors, shapes, and sounds. A person without any perceptual ability would not be able to recognize faces, understand language, or avoid threats.
Sensory reduction—the process in which we filter and analyze sensory information before they are sent to the brain.
Why do we need to reduce the amount of sensory information we receive? So that the brain is not
overwhelmed with unnecessary information because it needs to be free to respond to stimuli that have meaning for survival.
All species have evolved selective receptors that suppress or amplify information to allow survival.
Sensory adaptation—
repeated or constant
stimulation decreases
the number of sensory
messages sent to the
brain, which causes
decreased sensation.
Threshold—refers to a
point above which a
stimulus is perceived
and below which it is
not perceived. It
determines when we
first become aware of
a stimulus.
SENSORY
THRESHOLDS
HOW CLOSE DOES AN
APPROACHING BUMBLE
BEE HAVE TO BE,
BEFORE YOU CAN HEAR
IT BUZZING?
HOW FAR DOES A
BREWING COFFEE POT
HAVE TO BE, FOR YOU
TO DETECT THE AROMA
OF THE COFFEE.
Difference threshold—or
just noticeable difference,
is the smallest change in
stimulus that we can detect.
Example: An artist might
detect the difference
between two very similar
shades of color
Absolute threshold—the smallest amount of stimulus that can be detected. When a stimulus has more
energy than the absolute threshold, we can detect its presence.
When a stimulus has less energy than the absolute threshold, we cannot detectits presence.
• Some established absolute thresholds are:
• vision: a candle flame 30 miles away on a clear night.
• hearing: a watch ticking 20 feet away
• taste: 1 teaspoon of sugar dissoved in 2 gallons of water
• smell: a single drop of perfume in a three-room house
• touch: a bee's wing falling a distance of 1 centimeter onto the cheek.
Absolute threshold
• PEOPLE HAVE DIFFERENT THRESHOLDS, BECAUSE SOME PEOPLE HAVE BETTER HEARING THAN OTHERS, AND SOME PEOPLE HAVE BETTER VISIONS THAN OTHERS.
The word perception
comes from the Latin
perception-,
percepio, meaning
"receiving, collecting,
action of taking
possession,
apprehension with
the mind or senses."
To identify a pattern of
sensory input is to
categorize it, in which
various expectations,
motives, experiences are
brought into play.
Example:
– If this is a mouse, it is
afraid of cat.
The first step in
perception is
selection—choosing
where to direct our
attention.
We do not perceive everything at once—we select certain objects to perceive while ignoring others.
Attention—is the
direction of
perception toward
certain selected
objects.
Attention is selective—we focus on
specific and important aspects of
experience while ignoring others.
Attention is
shiftable—we may
focus from one
specific object to
another.
Nature—whether visual or auditory, words or images, animate or inanimate objects
Reality—real, concrete things are more attention-getting than hypothetical, abstract or mental
Familiarity—people pay more attention to things that are familiar
Location/Proximity—we pay attention to things that are near than those that are far
Novelty—we pay attention to things that are new and different in contrast to what is customary
Suspense—people pay attention
to things that build suspense.
Conflict—people pay attention to
a good fight.
Humor—people pay attention to
things that are funny.
The vital—people nearly always
pay attention to matters that affect
their health, reputation, property, or
employment.
Activity—things that move, flash
or blink
Intensity—sounds that are louder
are more attention-getting than soft
music
Having selected
incoming
information, we
organize it into
patterns and
principles that will
help us understand
the world.
After selectively sorting through
incoming sensory information and
organizing it into patterns, the brain
uses this information to explain and
make judgments about the external
world. This is the final stage of
perception—interpretation.
Try to read the following passage:
Can you read this text when it is upside down?
Knowledge and experience are extremely
important for perception, because they
help us make sense of the input to our
sensory systems.
In the example above, you did not stop to
read every single letter carefully. Instead,
you probably perceived whole words and
phrases.
In mentally organizing stimuli, objects
that are physically close to one
another are grouped together or seen
as a unit.
In organizing stimuli,
elements that appear
similar in color,
lightness, texture,
shape, or any other
quality are grouped
together.
The law of continuity leads us to see a line as continuing in a particular direction, rather than making an abrupt turn.
We tend to favor smooth or continuous paths when interpreting a series of points or lines.
In organizing stimuli, we tend to fill in any missing part or incomplete figures and see them as complete figures.
In organizing stimuli, we tend to favor symmetrical objects or relationships.
Perception does not only
involve organization and
grouping, it also involves
distinguishing an object
from its surroundings.
Once an object is
perceived, the area around
that object (figure)
becomes the background.
In organizing a
stimuli, we tend to
automatically
distinguish between a
figure or foreground
(object with more
details) and a
ground (has less
detail).
Gestalt psychologists have devised ambiguous figure-ground relationships—that is, drawings in which the figure and ground can be reversed—to illustrate their point that the whole is different from the sum of its parts.
Reversible figures are
those objects that are so
shaped that both may
be seen as either the
figure or the ground—
the object that the
individual is set to
perceive will probably
be noticed first.
Interests or motives
Set of expectations
Socio-cultural factors
Past experiences
Situational context
ESP
• IT IS A PERCEPTION WITHOUT THE
MEDIATION OF THE SENSES. IT
INCLUDES:
– CLAIRVOYANCE – IS EXTRA SENSORY
AWARENESS OF OBJECTS.
– CONTACT BETWEEN THE MIND OF THE
PERSON AND ON THE OJECT.
– TELEPATHY – IS A THOUGHT
TRANSMISSION FROM ONE MIND TO
ANOTHER.
– PRECOGNITION – IS FOREKNOWLEDGE
OF SPECIFIC EVENTS WITHOUT ANY
RATIONAL MEANS.
– PSYCHOKINESIS – (MIND OVER MATTER)
INCLUDES MENTAL OPERATIONS THAT
INFLUENCES A MATERIAL BODY OR AN
ENERGY SYSTEM.