What are sensation and perception?
Although the distinction between sensation and perception is not always clear, psychologists attempt to distinguish between the two concepts. Sensation is generally viewed as the initial contact between organisms and their physical environment. It focuses on the interaction between various forms of sensory stimulation and how these sensations are registered by the sense organs (nose, skin, eyes, ears, and tongue). The process by which an individual then interprets and organizes this information to produce conscious experiences is known as perception.
The warmth of the sun, the distinctive sound of a jet airplane rumbling down a runway, the smell of freshly baked bread, and the taste of an ice cream sundae all have an impact on the body’s sensory receptors. The signals received are transmitted via the nervous system to the brain, where the information is interpreted. The body’s sensory receptors are capable of detecting very low levels of stimulation. Eugene Galanter’s studies indicated that on a clear night, the human eye is capable of viewing a candle at a distance of thirty miles (forty-eight kilometers), while the ears can detect the ticking of a watch twenty feet (six meters) away in a quiet room. He also demonstrated that the tongue can taste a teaspoon of sugar dissolved in 2 gallons (about 7.5 liters) of water. People can feel a bee wing falling on the cheek and can smell a single drop of perfume in a three-bedroom apartment. Awareness of these faint stimuli demonstrates the absolute thresholds, defined as the minimum amount of stimulus that can be detected 50 percent of the time.
A person’s ability to detect a weak stimulus, often called a signal, depends not only on the strength of the signal or stimulus but also on the person’s psychological state. For example, a child remaining at home alone for the first time may be startled by an almost imperceptible noise. In a normal setting, with his or her parents at home, the same noise or signal would probably go unnoticed. Scientists who study signal detection seek to explain why people respond differently to a similar signal and why the same person’s reactions vary as circumstances change. Studies have shown that people’s reactions to signals depend on many factors, including the time of day and the type of signal.
Much controversy has arisen over the subject of subliminal signals—signals that one’s body receives without one’s conscious awareness. It has long been thought that these subliminal signals could influence a person’s behaviors through persuasion. Many researchers believe that individuals do sense subliminal sensations; however, it is highly unlikely that this information will somehow change an individual’s behaviors. Researchers Anthony Pratkanis and Anthony Greenwald suggest that in the area of advertising, subliminal procedures offer little or nothing of value to the marketing practitioner.
An individual’s response to a stimulus may change over time. For example, when a swimmer first enters the cold ocean, the initial response may be to complain about the water’s frigidity; however, after a few minutes, the water feels comfortable. This is an example of sensory adaptation —the body’s ability to diminish sensitivity to unchanging stimuli. Sensory receptors are initially alert to the coldness of the water, but prolonged exposure reduces sensitivity. This is an important benefit to humans in that it allows an individual to not be distracted by constant stimuli that are uninformative. It would be very difficult to function daily if one’s body were constantly aware of the fit of shoes and garments, the rumble of a heating system, or constant street noises.
The reception of sensory information by the senses, and the transmission of this information to the brain, is included under the term “sensation.” Of equal importance is the process of perception: the way an individual selects information, organizes it, and makes an interpretation, thus achieving a grasp of one’s surroundings. People cannot absorb and understand all the available sensory information received from the environment. Thus, they must selectively attend to certain information and disregard other material. Through the process of selective attention, people are able to maximize information gained from the object of focus, while at the same time ignoring irrelevant material. People are capable of controlling the focus of their attention to some degree; in many instances, however, focus can be shifted undesirably. For example, while one is watching a television show, extraneous stimuli such as a car horn blaring may change one’s focus.
The fundamental focus of the study of perception is how people come to comprehend the world around them through its objects and events. People are constantly giving meaning to a host of stimuli being received from all their senses. While research suggests that people prize visual stimuli above other forms, information from all other senses must also be processed. More difficult to understand is the concept of extrasensory perception (ESP). More researchers are becoming interested in the possible existence of extrasensory perception—perceptions that are not based on information from the sensory receptors. Often included under the heading of ESP are such questionable abilities as clairvoyance and telepathy. While psychologists generally remain skeptical as to the existence of ESP, some do not deny that evidence may someday be available supporting its existence.
Knowledge of the fields of sensation and perception assists people in understanding their environment. By understanding how and why people respond to various stimuli, scientists have been able to identify important factors that have proved useful in such fields as advertising, industry, and education.
Max Wertheimer discussed five laws of grouping that describe why certain elements seem to go together rather than remain independent. These laws include the law of similarity, which states that similar objects tend to be seen as a unit; the law of nearness, which states that objects near one another tend to be seen as a unit; the law of closure, which states that when a figure has a gap, the figure still tends to be seen as closed; the law of common fate, which states that when objects move in the same direction, they tend to be seen as a unit; and the law of good continuation, which states that objects organized in a straight line or a smooth curve tend to be seen as a unit. These laws are illustrated in the figure.
The laws of grouping are frequently utilized in the field of advertising. Advertisers attempt to associate their products with various stimuli. For example, David L. Loudon and Albert J. Della Bitta, after studying advertisements for menthol cigarettes, noted that the advertisers often show mentholated cigarettes in green, springlike settings to suggest freshness and taste. Similarly, summertime soft-drink advertisements include refreshing outdoor scenes depicting cool, fresh, clean running water, which is meant to be associated with the beverage; and advertisements for rugged four-wheel-drive vehicles use the laws of grouping by placing their vehicles in harsh, rugged climates, causing the viewer to develop a perception of toughness and ruggedness.
The overall goal of advertisers is to provide consumers with appropriate sensations that will cause them to perceive the products in a manner that the advertisers desire. By structuring the stimuli that reach the senses, advertisers can build a foundation for perceptions of products, making them seem durable, sensuous, refreshing, or otherwise desirable. By using the results of numerous research studies pertaining to perception, subtle yet effective manipulation of the consumer is achieved.
Another area that has been researched extensively by industry deals with color. If one ordered dinner in a restaurant and received an orange steak with purple french fries and a blue salad, the meal would be difficult to consume. People’s individual perceptions of color are extremely important. Variations from these expectations can be very difficult to overcome. Researchers have found that people’s perceptions of color also influence their beliefs about products. When reactions to laundry detergents were examined, detergent in a blue box was found to be too weak, while detergent in a yellow box was thought to be too strong. Consumers believed, based on coloration, that the ideal detergent came in a blue box with yellow accentuation. Similarly, when individuals were asked to judge the capsule color of drugs, findings suggested that orange capsules were frequently seen as stimulants, white capsules as having an analgesic action, and lavender capsules as having a hallucinogenic effect.
Studies have shown that various colors have proved more satisfactory than others for industrial application. Red has been shown to be typically perceived as a sign of danger and is used to warn individuals of hazardous situations. Yellow is also a sign of warning. It is frequently used on highway signs as a warning indicator because of its high degree of visibility in adverse weather conditions. Instrument panels in both automobiles and airplanes are frequently equipped with orange- and yellow-tipped instrument indicators, because research has demonstrated that these colors are easily distinguished from the dark background of the gauges. Finally, industry has not overlooked the fact that many colors have a calming and relaxing effect on people. Thus, soft pastels are often used in the workplace.
The field of education has also benefited from research in the areas of sensation and perception. Knowing how young children perceive educational materials is important in developing ways to increase their skills and motivation. Textbook publishers have found that materials need to be visually attractive to children to help them focus on activities. Graphics and illustrations help the young learner to understand written materials. It is also important that the size of the printed text accommodate the developmental level of the student. For example, primers and primary-level reading series typically have larger print to assist the student in focusing on the text. As the child’s ability to discriminate letters and numbers becomes more efficient with age, the print size diminishes to that of the size of characters in adult books. Similar techniques continue into high school and college; especially in introductory courses, texts are designed using a great deal of color and variation in page design. The reader’s eyes are attracted by numerous stimuli to pictures, figures, definitions, and charts strategically placed on each page. This technique allows the author to highlight and accent essential points of information.
The study of sensation and perception began more than two thousand years ago with the Greek philosophers and is one of the oldest fields in psychology. There are numerous theories, hypotheses, and facts dealing with how people obtain information about their world, what type of information they obtain, and what they do with this information once they obtain it. None of this information has been sufficient to account for human perceptual experiences and perceptual behavior, so research in the area of sensation and perception continues.
The philosopher Thomas Reid made the original distinction between sensations and perceptions. He proposed that the crucial difference between them is that perceptions always refer to external objects, whereas sensations refer to the experiences within a person that are not linked to external objects. Many psychologists of the nineteenth century proposed that sensations are elementary building blocks of perceptions. According to their ideas, perceptions arise from the addition of numerous sensations. The sum of these sensations thus creates a perception. Other psychologists believed that making a distinction between sensations and perceptions was not useful.
The first psychologists saw the importance of perception when they realized that information from the senses was necessary to learn, think, and memorize. Thus, research pertaining to the senses was a central research component of all the psychological laboratories established in Europe and the United States during the late nineteenth and early twentieth centuries.
By studying perceptions, researchers can identify potential environmental hazards that threaten the senses. Studying perception has also enabled people to develop devices that ensure optimal performance of the senses. For example, on a daily basis, one’s senses rely on such manufactured objects as telephones, clocks, televisions, and computers. To be effective, these devices must be tailored to the human sensory systems.
The study of sensations and perceptions has also made it possible to build and develop prosthetic devices to aid individuals with impaired sensory function. For example, hearing aids amplify sound for hard-of-hearing individuals; however, when all sounds are amplified to the same degree, it is often difficult for people to discriminate between sounds. From the work of British psychologist Richard Gregory, an instrument was developed that would amplify only speech sounds, thus allowing a person to attend more adequately to conversations and tune out background noise.
Finally, understanding perception is important for comprehending and appreciating the perceptual experience called art. When knowledge of perception is combined with the process of perceiving artistic works, this understanding adds an additional dimension to one’s ability to view a work of art.
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