Perception is the mental process by which stimuli are interpreted and formulated in a way that can be understood, and then a concept, judgment, or decision is reached.

Gestalt theory may be the most concerned cognitive theory with the subject of perception, which asserts that the things we deal with in this world do not exist independently and separately from other things.

Shapes, sounds, and other stimuli are usually located within a general context, and without this context they are difficult to distinguish. When we look at a scene, we often choose a specific stimulus (a specific scene) and focus on it rather than other stimuli. Such a stimulus is a (figure) and is like a specific part within the general context (the ground), which appears more distinct than the other parts, so that it attracts the individual's attention and appears to be meaningful and valuable to him.

The question is: Why do we consider a specific part to be the shape and the other parts surrounding it to be the background?!

According to the Gestalt theory, this depends on the characteristics of things, as things are characterized by a set of characteristics that prompt the individual to group them together in a group to represent the shape, according to the following principles:

Proximity principle:

Sensory stimuli that are close in time and space are perceived as belonging to one group. The closer the group of elements is, the more they are perceived as belonging to one group, and thus the process of storing and remembering them later is facilitated.

Similarity principle:

Similar things are easier to perceive than dissimilar things. Things that share certain characteristics such as color, shape, rhythm, or size are often perceived as belonging to one group, so they are acquired and remembered faster.

Continuity principle:

By our perceptual nature, we tend to perceive sensory stimuli that form a continuous pattern as belonging to a single group, that is, we perceive stimuli that appear to be a continuation of other stimuli that preceded them as a single unit.

Closure principle:

In most cases, complete and stable things are perceived more easily than incomplete things. In the case of incomplete sensory stimuli, our perceptual system works to provide some information based on previous experiences to fill in the gaps and complete the deficiency in order to reach a state of completeness or stability.

Common Direction:

Our nature of perception is characterized by taking a certain adaptive pattern, so that things that move in a certain direction are perceived as belonging to one group, while things that differ from it in direction are perceived as belonging to another group.

Simplicity principle: 

Individuals tend to group together the characteristics of stimuli in a way that allows them to achieve a simpler and easier interpretation of them, in an attempt to avoid difficulty and complexity. Therefore, it is important to expand the field of perception so that judgments and decisions are better and more mature.