Learning Activity 17 - Essay: The roles of visual perception principles.
We use Visual Perception Principles everyday, mostly without knowing, because they
occur automatically with vision. Visual perception principles are rules applied to
incoming visual stimuli to assist organisation and interpretation in a important way.
There are three categories of principles. The first is The Gestalt Principles. These set of
principles describe how we organize our sensations into perceptions. The second is Depth
Perception Cues, which he us determine where objects are located. The last category is
perceptual constancies, which helps us to perceive objects as remaining stable and
unchanging despite any changes that may occur to the image cast on the retina. Visual
perception principles may be used intentionally in artwork to give an impression of
distance and depth.
Gestalt is a German word, the closest English translation is ‘form’ or ‘shape’. The Gestalt
principles refer to the numerous ways in which we organize the elements in our visual
field by grouping them into the perception of a whole, complete form, usually in the
simplest possible way. The four principles that make up the Gestalt Principles are
closure, which is the tendency to fill in or ignore gaps in visual stimuli and perceive
incomplete objects as complete. Figure-ground which proposes that whenever we view a
stimulus pattern, part of it, is viewed as a well defined figure and the rest becomes the
ground which surrounds the figure. Similarity, occurs when elements of a stimulus
pattern which have similar features tend to be grouped together to form a meaningful
whole. Proximity is the last Gestalt principle and proposes that elements that are close
together to each other tend to be perceived as belonging together. The Gestalt Belief is
that ‘the whole is greater than the sum of its parts’, which is what all of the principles are
based upon.
The next perception principles are Depth Perception Cues. Depth cues are sources of
information from the environment (external cues) or from within our body (internal cues)
that help us perceive how far away objects are. There are two different types of depth
perception cues. Monocular depth cues and Binocular depth cues. Monocular depth cues
which requires the use of only one eye to provide information to the brain about depth
and distance. The depth cues for monocular vision is accommodation. There is also a
category of monocular depth cues called pictorial depth cues, which are depth and
distance cues for visual perception that can be represented pictorially. These include,
relative size, height in the visual field, interposition, liner perspective, texture gradient.
Binocular depth cues, which requires the use of both eyes working together to provide
information to the brain about depth and distance. The binocular depth cues are retinal
disparity and convergence.
The last type of Visual perception principles is Perceptual constancies. Perceptual
constancies refers to the tendency to perceive a visual stimulus as remaining stable and
unchanging despite any changes that may occur to the image cast on the retina. The four
types of constancies are size constancy, shape constancy, orientation constancy and
brightness constancy. The role size constancy is to make sure we understand that an
object does not change in size when we move towards or away from it, the image size
changes on our retina. Shape constancy is the tendency to perceive an object as not
changing even when the shape of the image in our retina changes. Brightness constancy
is the tendency to know that objects have not changed in their brightness when there is a
change in light intensity and orientation constancy is the tendency to visually perceive the
proper position of an object in the environment even though the retinal image of the
object may be at a different orientation. For instance when you hanging upside down, you
realize the world hasn’t turned upside down.