Transcript Intro to Sensation and Perception

INTRO TO SENSATION AND PERCEPTION
SENSATION

The passive process of bringing information
from the outside world into the body and to the
brain.

The process is passive in the sense that we do
not have to be consciously engaging in a
"sensing" process.
SENSATION OCCURS
a)
Sensory organs absorb energy from a physical
stimulus in the environment.
b) Sensory receptors convert this energy into
neural impulses and send them to the brain.
PERCEPTION

The active process of selecting, organizing, and
interpreting the information brought to the
brain by the senses.
PERCEPTION OCCURS
When the brain organizes the information and
translates it into something meaningful.
BOTTOM-UP PROCESSING
The interpretation of data is determined mostly
by information from the senses, not by
expectations or previous knowledge
TOP-DOWN PROCESSING
Information processing based on previous
knowledge or schemata—allows us to make
inferences: to "perceive" or "know" more than is
contained in the data.
Selective Attention
HOW DO WE KNOW WHAT INFORMATION IS
IMPORTANT AND SHOULD BE FOCUSED ON?
SELECTIVE ATTENTION
The process of discriminating between what is
important & is irrelevant, and is influenced by
motivation.
 For example - students in class should focus on
what the teachers are saying and the
overheads being presented. Students walking
by the classroom may focus on people in the
room, who is the teacher, etc., and not the
same thing the students in the class.
THE COCKTAIL PARTY EFFECT
Our impressive ability to tune our attention to
just one voice from a multitude.
 Example:

At a party people are arrayed all around us and
their conversations come from various different
directions. We seem to be able to use this
information to reject all but the one in which we are
interested.
INATTENTIONAL BLINDNESS
A type of attention which involves focusing on a
specific aspect of a scene while ignoring other
aspects.
 Conscious – When you chooses to attend to an
interesting object, like a tv, instead of a less
interesting one, like a coffee table
 Unconscious- Like a green field with a single red
tulip - the tulip will receive attention initially.
 Often, we think we have taken in an entire scene
when, in reality, we have processed only the area
we are attending to and only have a general "gist"
of the rest of the scene

CHANGE BLINDNESS

A phenomenon in visual perception where
apparently large changes within a visual scene
are undetected by the viewer. Typically for
change blindness to occur, the change in the
scene has to coincide with some visual
disruption such as an eye movement or a brief
obscuration of the observed scene or image.
PERCEPTUAL EXPECTANCY
How we perceive the world is a function of our
past experiences, culture, and biological
makeup.
PSYCHOPHYSICS

The study of psychological reactions to physical
stimuli.

At what point does physical reality becomes
human reality?
 Absolute
Threshold
DIFFERENCE THRESHOLDS

The smallest physical difference between two
stimuli that can be recognized

Preamble
ABSOLUTE THRESHOLD

The smallest, weakest amount of a stimulus
that a person can detect.
 Absolute
threshold is when 50 percent of the time
you can detect the stimulus
 Absolute thresholds change with age
 Example sounds1
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SUBLIMINAL STIMULATION

Two Assumptions of subliminal stimulation
We can unconsciously sense below our threshold
stimuli
2. Without our awareness, these stimuli have
extraordinary suggestive powers.
Can we? Do they?
Front
Back
1.
SENSORY ADAPATION
A phenomenon in which sensory neurons
change their level of sensitivity to a constant
stimulus over time. This adaptation allows
people to adapt to their environments while
balancing the need to receive new sensory
input. Neurons involved with smell, hearing,
taste, touch, and sight can all exhibit sensory
adaptation.
 Glasses

We perceive the world not exactly as it is, but as
it is useful for us to perceive it.