Perception in psychology

The process by which we recognize, interpret, or give meaning to the information provided by the sense organs is called the perception/ perceptual process. In interpreting stimuli/events, individuals often construct them in their own way. It is not simply an interpretation of objects and events of the external/internal world as they exist; it is a construction of those objects and events from the perspective of the individual. 

The process of making meaning involves the certain sub-process


The notion that recognition begins with the overall recognition of something is called bottom-up processing. The top-down processing concept is based on the notion that the recognition process begins with the whole and ultimately identifies its various components. The bottom-up approach puts emphasis on the perceiver and considers perception as the recognition/ identification of stimuli. It has been shown in studies that perception relies upon both processes to give us an understanding of reality. 

The perceiver: The human race is creative, and tries to understand the external world in its unique ways. A person's motivation and expectations, cultural knowledge, past experiences, and memories, as well as values, beliefs, and attitudes all, play a significant role in determining how the external world is perceived. 


  • Motivation: A perceiver’s needs and desires greatly influence their perceptions. Various means are employed by humans to satisfy their needs and desires. An effective way to accomplish this is to see objects in the picture as something that will meet their needs. Researchers examined how hunger influences perceptions. Hunger-induced person perceives ambiguous pictures more like food objects than satiated (non-hungry) persons.
  • Expectations/  perceptual sets: Perception can also be affected by our expectations about what we might see in a particular situation. This phenomenon of perceived familiarity or perceived generalization is caused by our tendency to perceive what we expect to see regardless of whether that is what is actually occurring. For instance: If our milkman arrives every morning to deliver milk at 6:00 am, any knock at the door during this time will probably be interpreted as a milkman.
  • Cognitive sets: It is basically a consistent way of dealing with the environment. It plays a huge part in how we perceive the world around us. People perceive the environment in several different ways depending on their cognitive styles. In the studies, the one most widely used is the “field-dependent & field-independent” cognitive style. Field-dependent people perceive the external world holistically, on a global scale. Field independent people perceive the external environment through the division of it into smaller components. CEFT ( how many triangles).
  • Cultural background and experiences: Different cultural settings influence a person’s knowledge and perception in different ways. Those who grow up in an environment without pictures fail to recognize images. The study by Hudson revealed several difficulties that African subjects had in identifying objects in pictures. There are various types of snow that Eskimos can discern in ways we may not. In the Siberian region, indigenous peoples have been found to distinguish between dozens of different skin colors, which is something we would not be able to do. These studies conclude that the perceiver is crucial to perception. Every individual processes and interprets stimuli differently based on his or her personal, social, and cultural circumstances. These factors affect not only our perceptions but also how we perceive them.

Several scholars have tried to answer questions like how different parts of objects are organized into a meaningful whole or are there any certain factors that facilitate or inhibit the process of organization, but the most widely accepted answer has been given by a group of researchers, called Gestalt psychologists. Prominent amongst them were Wolf Quang Kohler, Kurt Koffka, and Max Wertheimer.

Gestalt psychologists believe that we perceive stimuli not as discrete elements, but rather as organized wholes with a definite form. Gestalt psychologists also indicate that our cerebral processes are always oriented towards the perception of a good figure / Pragnanz. This is the reason why we perceive everything in an organized form. The most primitive organization involves figure-ground segregation. For example: When we see birds flying in the sky stay behind as a background as birds are perceived as figures. 


Sociocultural factors play an important role in our perception by causing differences in familiarity with and salience of stimuli, which in turn create certain habits of perceptual inferences between people. Several studies suggest that individuals’ interpretations of pictures are strongly influenced by their cultural background. Usually, recognizing familiar objects in pictures does not pose a problem to people, but those who are less familiar with them have difficulty interpreting what is being depicted. 


The stability of perception of an environment is called perceptual constancy. Consistences: Our tendency to perceive physical objects as unchanging, even when the sensations they create change. We commonly experience three types of perceptual constancies in our visual domain:  

  1. Size constancy: The size of the image on the retina changes as the object’s distance from the eye changes. As the distance increases, the image becomes smaller. The size constancy refers to the fact that we tend to perceive an object as about the same size regardless of the size of its representation on the retina when it is near or far. According to several studies, perceptual size constancy results when an object and its background do not change together, thus maintaining their relationships. Size constancy is the basis for many visual illusions.
  2. Shape constancy: When we perceive familiar objects, these shapes remain unchanged regardless of the retinal images that change as a result of their orientation.
  3. Consistency of brightness: Visual objects appear constant not only in their form and size, but also in their degree of whiteness, grayness, or blackness, even if the amount of physical energy reflected from them varies greatly. So despite the changes in the amount of light reflected into our eyes, our experience of brightness does not change. The property of maintaining apparent brightness under changing amounts of illumination is called brightness constancy.


  • Space: Visual field/surface in which things exist, move/can be positioned. The environment in which we live is 3D. We perceive both the spatial attributes of objects (such as their size, shape, direction) and the distance between them. Despite our retina projecting images with two dimensions (left, right, up, down), we still perceive space as three-dimensional. This occurs when we convert a 2D retinal image into a 3D image.
  • Distance / Depth Perception: The process of seeing words in 3D. Deep perception is essential for every aspect of our lives. For example, We use depth when driving to gauge the distance of an approaching car. Perceiving depth depends on two sources of information, namely cues.  
    • Binocular cues: Some important cue to depth perception in 3D space are provided by both the eyes. Three of them have particularly been found to be interesting:
      1. Retinal/ Binocular disparity: It occurs because the two eyes are in different positions in our heads. There is a horizontal distance of about 6.5 cm between them. It is due to this distance that the retina of each eye forms a slightly different image of the same object. This is called retinal disparity. The brain interprets a large retinal disparity to be a distant object because there is less disparity for far off objects and more for close up objects.
      2. Convergence: Whenever we see a nearby object, our eyes converge inward, bringing the image onto the fovea of each eye. Muscles transmit information to the brain regarding how far inward the eyes are turning, and the brain interprets the signals as clues to depth perception. When the observer moves away from the objects, the degree of convergence decreases. If you hold your finger in front of your nose and slowly bring it closer to your nose, you will experience convergence. You perceive the object in space as nearer with your eyes converged or turning inward.
      3. Accommodation: It refers to a process by which the ciliary muscle focuses the image onto the retina. It changes the thickness of the lens of the eye. A muscle is relaxed if the object gets away (more than 2 meters). Increased proximity causes muscles to contract and lens thickness to increase. Signals sent by the muscles are transmitted to the brain, which uses this information to calculate distances.
    • Monocular cues (Psychological Cues/ Pictorial Cues ) : Allow us to perceive depth with only one eye .A no. of cues are used to change a 2 dimensional image into 3Dperception. These are effective when the objects are viewed with only one eye . These cues are often used by artists to induce depth in 2D painting by artists (pictoral cues). Some monocular cues :
      1. Relative size constancy: The tendency to perceive physical objects as having a constant size even when the size of the image it casts on the retina changes. The size of retinal image allows us to judge distance based on our past and present experiences with similar objects . As the objects get away , the retinal image becomes smaller and smaller . When we tend to perceive an object farther away when it appears small, and closer when it appears bigger.
      2. Interposition / Overlapping: It occurs when one object obstructs our view of another . When one object is completely visible while another is partially covered by it, the first object is perceived as nearer. These cues occur when some portion of the object is covered by another object. The overlapped object is considered farther away, whereas the object that covers it appears nearer.
      3. Liner perspective: The distances separating the images of far objects appear to be smaller. This reflects a phenomena by which distant objects appear to be closer together  than the nearer objects. Foe ex: parallel lines such as rail tracks appear to converge with increasing distance with a vanishing point at the horizon . The more the lines converge , the farther away they appear.
      4. Aerial perspective: The air contains microscopic particles of dust and moisture that make distant objects look hazy or blurry . This effect is called aerial perspective . For ex: distant mountains appear blue due to scattering of blue light in the atmosphere, whereas the same mountain are perceived to be closer when the atmosphere is clear.
      5. Light  and  shade: In the light some parts of the object get highlighted, whereas some parts become darker. Highlights and shadows provide us with the information about an object’s distance.
      6. Relative height: Larger objects are perceived as being closer to the viewer and smaller objects as being farther away. When we expect two objects to be same size and they are not, the larger of two will appear closer and the smaller will appear farther.
      7. Texture gradient: A gradient is a continuous change in something – a change without abrupt transitions. In some situations, we can use the continuous gradation of   texture in the visual field as a clue for depth . The regions closer to the observer have a coarse texture and many details; as the distance increases , the texture becomes finer and finer. This continuous gradation of texture gives the eye and brain info that can be use to produce an experience, or perception, of depth.
      8. Motion parallax/movement: It is a kinetic monocular cue, and hence not considered as a pictorial cue. It occurs when objects at different distances move at a diff relative speed. The distant object appear to move slowly than the objects that are close . The rate of an object’s movement provides a cu to its distance. For ex : when we travel in a bus , closer objects move “against” the direction of the bus , whereas the farther objects move “with” the direction of the bus.


Perceptions are not always accurate. We sometimes fail to interpret sensory information correctly. It causes a mismatch between the physical stimuli and its perception. Misperceptions resulting from misinterpretation of information from our sensory organs are referred to as illusions. Individuals experience them as a result of external stimuli, resulting in the same kinds of experiences. Thus, the illusion is also called “primitive organization”. Even though illusions can be experienced in any sense mode, psychologists have studied them more frequently in the visual than in other sense modalities.  

Some perceptual illusions are universal and found in all individuals (rail tracks). These illusions are called universal illusions /permanent illusions as they do not change with experience or practice. Some other illusions seem to vary from individual to individual hence are called personal illusions.

  • Geometrical Illusion: In muller Lyer illusion all of us perceive line A as shorter than B , although both the lines are equal .

                          _______________     A       

                     B   _______________

This illusion is experienced even by children. There are some studies that suggest that even animals experience this illusion more or less like us. Vertical and horizontal lines illusions. Although both the lines are equal we, perceive the vertical line as longer than the horizontal line.

  • Apparent Movement Illusion: The illusion occurs when motionless pictures are projected at an appropriate rate one after another. This illusion is known as “phi-phenomena”. In cinema shows, we are affected by this kind of illusion when we see moving images. People aren’t always aware of the world as it really is; rather, they construct it based on the experiences they have in a particular environment.
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