Perception
While our sensory receptors are constantly collecting information from the environment, it is
ultimately how we interpret that information that affects how we interact with the world.
Perception refers to the way sensory information is organized, interpreted, and consciously experienced.
Relationship of sensation and perception
“Although perceptions are built from sensations, not all sensations result in perception.”
Perception involves both bottom-up and top-down processing.
Bottom-up processing refers to the fact that perceptions are built from sensory input, stimuli from the
environment.
On the other hand, how we interpret those sensations is influenced by our available knowledge, our
experiences, and our thoughts related to the stimuli we are experiencing. This is called top-down
processing.
One way to think of this concept is that sensation is a physical process, whereas perception is
psychological.
For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls,
the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be “Mmm,
this smells like the bread Grandma used to bake when the family gathered for holidays.”
Sensation is a signal from any of our senses. Perception is the brain’s response to these signals.
When we see our professor speaking in the front of the room, we sense the visual and auditory signals
coming from them and we perceive that they are giving a lecture about our psychology class.
The sensation can be viewed as something more objective. This is the response to the situation that comes
after the analysis and perception of it.
Perception is subjective, and it reflects human’s attitudes to the different phenomena or accidents based
on experience or the system of beliefs.
Sensory Adaptation
Although our perceptions are built from sensations, not all sensations result in perception. In fact, we
often don’t perceive stimuli that remain relatively constant over prolonged periods of time. This is known
as sensory adaptation.
Imagine entering a classroom with an old analog clock. Upon first entering the room, you can hear the
ticking of the clock; as you begin to engage in conversation with classmates or listen to your teacher greet
the class, you are no longer aware of the ticking. The clock is still ticking, and that information is still
affecting sensory receptors of the auditory system. The fact that you no longer perceive the sound
demonstrates sensory adaptation and shows that while closely associated, sensation and perception are
different.
There is another factor that affects sensation and perception: attention. Attention plays a significant role
in determining what is sensed versus what is perceived.
Imagine you are at a party full of music, chatter, and laughter. You get involved in an interesting
conversation with a friend, and you tune out all the background noise. If someone interrupted you to ask
what song had just finished playing, you would probably be unable to answer that question.
Gestalt laws
Developed by German psychologists, the Gestalt principles, also known as the Gestalt laws of perceptual
organization, describe how we interpret the complex world around us.
They explain why a series of flashing lights appear to be moving and why we can read a sentence like
this: notli ket his ort hat.
History of the Gestalt Principles
Discovered by German psychologist Max Wertheimer, this illusion of movement became a basis for
Gestalt psychology.
According to Gestalt psychology, this apparent movement happens because our minds fill in missing
information. Motion pictures are based on this principle, with a series of still images appearing in rapid
succession to form a seamless visual experience.
Gestalt psychology focuses on how our minds organize and interpret visual data. It emphasizes that the
whole of anything is greater than its parts.
Based upon this belief, Wertheimer along with Gestalt psychologists Wolfgang Köhler and Kurt Koffka,
developed a set of rules to explain how we group smaller objects to form larger ones (perceptual
organization). They called these rules the Gestalt laws of perceptual organization.
These are following laws:
1. Law of similarity
2. Law of prägnanz
3. Law of proximity
4. Law of continuity
5. Law of closure
6. Law of common region
Law of Similarity
The law of similarity states that similar things tend to appear grouped together. Grouping can occur in
both visual and auditory stimuli.
In the image at the top of this page, for example, you probably see two separate groupings of colored
circles as rows rather than just a collection of dots.
Law of Pragnanz
The law of prägnanz is sometimes referred to as the law of good figure or the law of simplicity. This law
holds that when you're presented with a set of ambiguous or complex objects, your brain will make them
appear as simple as possible. For example, when presented with the Olympic logo, you see overlapping
circles rather than an assortment of curved, connected lines.
The word prägnanz is a German term meaning "good figure."
Law of Proximity
According to the law of proximity, things that are close together seem more related than things that are
spaced farther apart.
In the image at the top of the page, the circles on the left appear to be part of one grouping while those on
the right appear to be part of another. Because the objects are close to each other, we group them together.
Law of Continuity
The law of continuity holds that points that are connected by straight or curving lines are perceived as
continuous line. In other words, elements in a line or curve seem more related to one another than those
positioned randomly.
Law of Closure
According to the law of closure, we perceive elements as belonging to the same group if they
seem to complete some entity. Our brains often ignore contradictory information and fill in gaps in
information.
In the image at the top of the page, you probably see the shape of a diamond because your brain fills in
the missing gaps in order to create a meaningful image.
Law of Common Region
The principle of common region says that items within a boundary are perceived as a group and
assumed to share some common characteristic or functionality.
Figure and ground effect
It refers to the relationship between a subject or figure and the background against which it is set.
DEPTH PERCEPTION
Depth perception is the ability to see the environment in three dimensions and to estimate the
spatial distances of objects from ourself and from each other.
Example: Seeing a dog running away and knowing how far away it is.
Perception of movement
To detect motion in an object is called motion perception or perception of movement.
Motion in the world is created by the continual change in position of an object relative to some
frame of reference. That is, we watch the cat run across the kitchen tiles. We watch the leaves of the trees
bend back and forth in the wind. We watch the ducks swim across the pond. This is real motion.
However, human beings also perceive a number of forms of illusory motion, that is, situations in which
we perceive motion when none actually occurs.
One form of this illusory motion is apparent motion. Apparent motion is the appearance of real
motion from a sequence of still images. Apparent motion occurs whenever stimuli separated by time and
location are actually perceived as a single stimulus moving from one location to another. Apparent
motion is the basis of our sense of motion in watching videography and animation.
Perceptual Illusions
Illusions are special perceptual experiences in which information arising from “real” external
stimuli leads to an incorrect perception, or false impression, of the object or event from which the
stimulation comes.
An illusion is distinguished from a hallucination, an experience that seems to originate without an
external source of stimulation.
Time perception
Time perception refers to a person’s subjective experience of the passage of time, or the
perceived duration of events, which can differ significantly between different individuals and/or in
different circumstances.
As a field of study within psychology and neuroscience, time perception came of age in the late
th
19 Century with the studies of the relationship between perceived and measured time by one of the
founders of modern experimental psychology, Gustav Theodor Fechner.
We do not so much perceive time itself, but changes in or the passage of time, or what might be
described as “events in time”.
