Visual Perception and Gestalt Laws
Perception is a set of processes by which we recognize, organize, and make sense of stimuli in our environment. It is clear that what we sense with our sensory organs is not necessarily what we perceive in our minds. Remember the experiments. In visual perception we sometimes cannot perceive what does exist and sometimes we perceive things that do not exist. The mind must create mental representations of objects, properties, or spatial relationships on the base of the sensory information.
The way we represent these objects depends on our viewpoint in perceiving these objects. To explain visual perception two approaches exist:
Direct perception (=bottom-up) states that all the information we need to perceive is in the sensory input we receive in the retina. Three main bottom-up approaches are differentiated: (1) The Template theory states that in our minds we have stored highly detailed templates for patterns we might recognize. To recognize a pattern we compare it with our stored templates and finally choose the template that matches to what we observe. Critics state that for everyday situations, the perceptual system would barely work if it required exact matches for every stimulus. (2) The Prototype-Matching Theory is a best-guess class of related objects or patterns, which integrates the most typical features of a pattern. (3) The Feature-Matching Theory suggests that we match the features of a pattern to features stored in memory, rather than to match a whole pattern to a template or a prototype. An example is the findings of Hubel and Wiesel (1979), who discovered that specific cells in our visual cortex become activated when line segments have particular orientations.
Constructive perception in contrast, states that an individual's perception is based on the combination of sensory information with prior knowledge and previous experience. Hence, successful perception requires the combination of sensory information with previous experiences. During perception, we quickly form and test various hypotheses based on what we sense, what we know, and what we can infer.Understanding these very challenging topics needs a lot of knowledge about the brain and cognition. But luckily there exist a set of very easy to understand phenomena : The Gestalt Principles.
The Gestalt School of Psychology was founded in 1912 when the group of Kurt Koffka, Max Westheimer, and Wolfgang Kohler wanted to investigate the way we perceive form (Ellis, 1938, Koffka, 1935). The findings have been useful for understanding how we perceive groups of objects or parts of objects.
Gestalt theory applies to all aspects of human learning, although it applies most directly to perception and problem-solving. The Gestalt laws provide descriptive insights into form and pattern perception, but they offer few or no explanations for these phenomena. To understand how or why we perceive forms and patterns, we need to consider explanatory theories of perception.
The work of the Gestalt psychologists is still important, because it provides a clear description of many basic perceptual phenomena that are called Gestalt laws.
Proximity. Elements tend to be grouped together according to their nearness.
Similarity. Similar items tend to be grouped together.
Figure-ground. Some objects (figure) seem prominent, and other aspects recede into the background (ground).
Continuity. We tend to construct visual elements that are smooth and continuous, rather than abrupt changes in direction.
Closure. Items are grouped together if they tend to complete some entity.
Connectedness. Items will be organized into simple figures according to symmetry, regularity, smoothness, and connectedness.