Perception

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Perception is the mental process of interpreting the information received by the sense organs from the environment. Sensation is a physical process, whereas, perception is a psychological process. For example, upon smelling the scent of roses, a sensation is the scent receptors in the body detecting the odor of roses, but the perception may be "Mmm, this smells like roses."

Introduction

Perception is a set of psychological processes that help us understand the world around us. We encounter numerous stimuli every second through our sensory organs. It brings about awareness and interpretation of our environment. It involves selection, organization, and interpretation of the sensory information based on one's previous experiences, needs, aspirations and even considering other's experiences.

Sensation

Sense organs are the primary sources for gathering information from the world around us and providing it to the mind for further processing. Sense organs receive the reflection emanating from the objects which are then reflected in the inner mind.

Sensory receptors are specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred. For example, light that enters the eye causes chemical changes in cells that line the back of the eye. These cells relay messages, in the form of action potentials to the central nervous system. The conversion from sensory stimulus energy to action potential is known as transduction.

Definition of Perception

An awareness about the external stimuli gathered by the sense-organs is the result of a higher mental process called 'perception'. It helps us interpret the world around us and in making an appropriate decision in simple and complex situations and stimuli. Perception is a process of selecting, organizing, and interpreting the sensory information based on previous experiences, other's experiences, needs or expectations.

Stages of Perception

Broadly, the process of perception involves three steps, when a stimulus is encountered.

1. Selection

Selection is the first stage of perception. At a given time, due to various factors, the human brain consciously or unconsciously, processes only some stimuli ignoring the others. For example, when engaged in deep conversation we tune out of many sounds in the background and do not register them. The selected stimulus becomes the "attended stimulus." It is well known that the five major senses are vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). We also have sensory systems that provide information about

• balance (the vestibular sense)
• body position and movement (proprioception and kinesthesia)
• pain (nociception)
• temperature (thermoception)

Subsequent to selecting the stimulus the interpretation depends on how the information is organized for processing. Selection is influenced by some factors like attention.

2. Organization

It is the second stage of perception. It refers to the way sensory information is organized, interpreted, and consciously experienced. In this stage, stimuli are arranged mentally in a meaningful pattern, thus, organizing the information received. This process occurs unconsciously explained by certain principles such as those of Gestalt. Perception involves both bottom-up and top-down processing. Bottom-up processing refers to the fact that perceptions are built from sensory input. On the other hand, how we interpret those sensations is influenced by our available knowledge, our experiences, and our thoughts. This is called top-down processing.

3. Interpretation

In this last stage of perceptive process, meaning is assigned to the organized stimulus. Interpretation and assigning meaning to the stimuli is based on one's own experiences, expectations, needs, beliefs, other's experiences and other factors. This stage is subjective in nature and the same stimuli can be interpreted differently by different individuals.

Factors affecting sensation and perception

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 professor 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.

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.

Failure to notice something that is completely visible because of a lack of attention is called inattentional blindness.

Motivation

Motivation can also affect perception. Have you ever been expecting a really important phone call and, while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate between a true sensory stimulus and background noise.

Cultural influence

The shared experiences of people within a given cultural context can have pronounced effects on perception. For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a multinational study in which they demonstrated that individuals from Western cultures were more prone to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa.

One such illusion that Westerners were more likely to experience was the Müller-Lyer illusion (Figure 5.3): The lines appear to be different lengths, but they are actually the same length. These perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context. People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999).

Personality

Children described as thrill seekers are more likely to show taste preferences for intense sour flavors (Liem, Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more likely to rate foods labeled as reduced fat as tasting better than people who have less positive attitudes about these products (Aaron, Mela, & Evans, 1994).

Gestalt Principles of Perception

How is perception produced?

Perception Vs Pratyaksha Pramana