How did the Italian Renaissance end?

The Renaissance (the word means “rebirth”) is generally understood to have started during the 14th century and lasted until the mid-16th century.  This marked the transition between the Medieval or Dark Ages to Early Modern Europe.  It was exemplified by a renewed interest in the arts, science, and philosophy. 

During the flowering of the Italian Renaissance, however, there were a number of catastrophes that contributed to its demise.

A change in climate resulted in harsh winters and the decline of agriculture; this led to repeated famines and shortages. On the heels of a previous swell in the population, these shortages exacerbated the food problem.

Trade throughout northwest Europe was disrupted by the Hundred Years’ War between England and France, and the expansion of the Ottoman Empire.  When King Edward III of England refused to pay his debts, this had a ripple effect that caused the two largest Florentine banks (Bardi and Peruzzi) to collapse.  

The Black Death was wiping out inhabitants in densely populated Northern Italian cities and it kept returning. As with any major health crises in a city, disorder and pandemonium resulted.  It is believed that the Black Death reduced Europe’s population by one third.

As the population saw that the Church was at a loss to provide relief or succor during the Black Death, this had a hand in the decline of church influence.

There is a school of thought that espouses that the rise to power in Florence of Girolamo Savonarola marked the end of the city’s flourishing. For others, it is the return of the Medici.  Some say the end of the Renaissance was hastened by French invasions of the early 16th century, and then the battle between France's and Spain's rulers for control of Italian territory.

It is notable that during the time of Savonarola’s rise to power a backlash towards the permissive atmosphere of the Renaissance caused many works of art to be destroyed; an Inquisition was formed, and there was a prohibition and ban on many Renaissance works of literature. This prohibition saw the end of the illuminated manuscript.

The Italian Wars, when the northern states were invaded by France (1494), ended independence for many of the city-states.  With the sacking of Rome (1527) by the Spanish and German, the role of the Papacy (as the largest patron of Renaissance art and architecture) all but ended.  Then there was war between Florence and Milan; at sea, there were battles between Pisa, Genoa and Venice.

There was the matter of trade. The way to India had been opened by Vasco da Gama (1498), and the discovery of the New World shifted trade routes away from Italy and the Mediterranean and toward Portugal and Europe’s west coast; this decreased Italian income.

Equally important was that the resurgence of art, science and literacy engendered an educated class, and this class questioned the teachings of the Church. As much of the Renaissance was powered by the Church’s wealth, when the educated class (the wealthy and the nobles) began to turn a deaf ear, the Church contributed less to fund art.

Would it be accurate to call The Brothers Ashkenazi by Irael Joshua Singer a portrayal of politics in a state of futility for Jewish solidarity?

Jewish solidarity is essentially described by scholars as the impulse that is acted upon by Jews to come to the aid of or to reach out with help to other Jews who are suffering hardships in other communities (Rabbi Berel Wein). I.J. Singer's book The Brothers Ashkenazi portrays the story of two rival brothers, twins, during a political era that ends in random violent turbulence aimed as a pogrom at the Jews of Lodz. Political futility reigns as Simcha Meir ("Max") learns that wealth and power cannot protect him against anti-Semitic violence.

Whether Singer means to point to a state of political futility for Jewish solidarity is a question worth debate, since he ends the story with Jacob rescuing his brother; the brothers then reconcile and overcome their past enmity. Yet, when they attempt to reenter Poland together, Jacob refuses to repudiate his Jewish religion and is killed for it, while Max, encouraged by the Polish guards, does reject his religion.

It is true, therefore, that the novel seems to depict a state of futility for Jewish solidarity: Jewish sons turn against fathers; Jewish sons turn against other Jewish sons (i.e., Nissan and Simha Meir); Jewish communities turn against other Jewish communities (e.g., Lodz Jews and Litvaks). It may be that Singer intends to present a portrayal of politics in a state of futility for human solidarity, as Rebecca Newberger Goldstein explains in "Love, Tough and Not Tough": 

It is not religious backwardness or economic conditions or political theories that are ultimately to blame. It is human nature itself that damns us, in I. J. Singer’s eyes. The possibility that Nissan can only glance at in his utter despair—the corruption mixed with human nature—is Israel Joshua’s conclusion. (Goldstein)

[Nissan]: "Maybe man was essentially evil. Maybe it wasn't the fault of economic circumstances, as he had been taught, but the deficiencies of human character." (The Brothers Ashkenazi)

Simha Meir, in particular, drawing from inexhaustible reserves of ingenuity and drive, serves only to demonstrate, by the very indefatigability of his exertions, the awful fatality and futility of human efforts in a world so thoroughly deformed by injustice... (Goldstein)

In Animal Farm, what does Napoleon mean when he says "but any animal that absented himself would have his rations reduced by half"?

This quote can be found at the beginning of Chapter Six. This chapter picks up at a point when the experiment on the farm is beginning to go a bit sour. Snowball has just been driven from the farm, leaving Napoleon basically unchallenged in his rule. The animals are exerting themselves more and more in the construction of the windmill (which was Snowball's idea, though Napoleon has now taken credit for it). The animals, we learn, are working "like slaves," and Napoleon adds to their sixty-hour a week workload by announcing that there will be a workday on Sunday as well. While work is "voluntary," the animals will have their "rations reduced by half." This refers to their food rations, and therefore means that the work is not really "voluntary": if they refuse to work on Sundays, they will starve. Aside from showing how Napoleon, like other dictators, consolidates his power by perverting the ideals of the society, this passage demonstrates an important theme in Animal Farm--the manipulation of language in service of power. By saying that extra work on Sundays is "voluntary," Napoleon keeps the facade of democracy on the farm. But in reality, as we have seen, it is hardly voluntary. It is an exercise in arbitrary power by a pig who is becoming increasingly despotic and abusive of his authority.

What are skin disorders?

Anatomy of the Skin

The skin is the largest organ of the body. It provides a barrier between the external world and the internal world: It protects against external contamination and helps to maintain the sterility of the internal body. The skin also assists in temperature regulation; humans can survive only within a narrow temperature range. The skin has nerve receptors that supply the brain with information, providing an interface with the world. There are specialized receptors for touch, temperature, vibration, and position in space (proprioception).

Appendages to the skin are fingernails, toenails, and hair. They are mainly of psychological importance. Nails protect the tips of fingers and toes in humans but are not needed for protection as claws are in lower animals. Hair is analogous to feathers. In birds, tiny muscles attached to the base of each feather cause them to be ruffled; this creates air pockets and allows birds to conserve heat and keep warm. The same muscles persist in humans, causing “goose flesh,” but they do not serve any other function. The main importance of these appendages is cosmetic. For example, people spend billions of dollars on hair care products each year. The motivation for this activity is psychological.

The two main layers in skin are the epidermis and the dermis. The epidermis is the upper or outermost layer, and cells are continually formed at its base. As new cells are formed, existing cells are pushed toward the surface of the skin. These cells gradually lose their watery central contents, causing them to dry out (desiccate) and become flattened. This process normally spans approximately a month. Thus, the surface of the body is largely composed of dead cells that have become flattened. These cells are normally lost on a continual basis and create dandruff when shed from the scalp. On other parts of the body, sloughed cells provide excellent conditions for bacterial growth, accounting for the unpleasant odors that accompany poor hygiene habits.

Two other important types of cells are found in the epidermis: melanocytes and Langerhans cells. Melanocytes contain melanin and provide all the variations of pigmentation found in the human species. They multiply when stimulated by the ultraviolet radiation in sunlight. This causes the skin to become darker, a protective mechanism against damage from ultraviolet radiation. Langerhans cells contain surface receptors for immunoglobulins. They play a central role in allergic reactions of the skin, such as contact dermatitis or delayed hypersensitivity reaction.

The
dermis is an inner layer of skin located beneath the epidermis. Its main function is protection. Within the dermis are highly specialized cells containing microscopic filaments. These cells impart tensile strength to the skin in much the same way that fibers strengthen fiberglass or reinforcing steel mesh strengthens concrete. Because they are so dense, they also serve as a barrier to the entry of most pathogens and many chemicals. Eccrine sweat glands are found in the dermis throughout the entire body. These produce a salty secretion (essentially salt water) that assists in
thermoregulation through evaporative cooling. They are also sensitive to emotional stress. Apocrine sweat glands are primarily in the armpits (axilla) and the groin, and they produce a milky secretion. When these secretions are broken down by bacteria on the surface of the skin, a characteristic odor is produced. The bases of hair follicles are also found in the dermis. The small sebaceous, or oil-secreting, gland associated with most hair follicles has the function of softening and moisturizing the hair.

Hair is found on most surfaces of the body; exceptions are the palms of the hands, the soles of the feet, and the glans penis in men. The texture and length of the hair vary with location on the body, gender, genetic heritage, and age. Dramatic increases in the growth and distribution of hair occur at puberty. With increasing age, hair is typically lost from the scalp and other body parts. It also changes color, assuming a gray or white color because of the loss of melanin at the base of the hair follicle.

Complications and Disorders

When normal skin anatomy and physiology are upset, several common diseases or disorders result. When the barrier provided by the skin is broken, bacteria, viruses, fungi, and other pathogens can invade the body, leading to infections. Locally, these infections can cause inflammation (redness and pain) of the skin; if widespread, they can lead to systemic infections. When the cells and other substances found in the skin become irregular or are abnormal, skin disorders or conditions result.

Skin disorders and conditions.

Pigmentation of the skin results from the presence of melanocytes, cells that manufacture and contain melanin. Most humans have pigmentation over their entire bodies; the degree of pigmentation varies with different racial and ethnic groups. Local areas of increased color have a range of names depending on the size of the pigmented area. A freckle is small and discrete. A nevus (mole) is a larger area of hyperpigmentation. These conditions are attributable to underlying variations in the distribution of melanocytes. They are genetic in origin and permanent; they are also accentuated by exposure to sunlight. Melasmas are irregular, flat, light brown areas on the neck, cheeks, or forehead. They are caused by hormonal changes associated with pregnancy or contraceptive pills and by exposure to sunlight. Melasmas fade with the reduction of excess hormones. There are also color changes in the labia of females during pregnancy; these changes are both harmless and permanent.

Generalized increases in skin coloration can occur with some metabolic diseases. Addison disease
involves an increase in melanocyte-stimulating hormone. This leads to an overall bronzing of the body, with accentuation in creases of the palms and soles. The condition subsides with treatment of the underlying cause of the disease. Similar pigment increases are associated with some forms of lung cancer, hemochromatosis, and chronic arsenic exposure. The latter two conditions are caused by the deposition of iron (hemochromatosis) and arsenic in the skin.

Generalized decreases in skin coloration can also occur. If melanocytes fail to migrate to the skin during embryologic development, hair follicles will lack color, resulting in a condition called piebaldism. Characteristically, this is a white patch in the hair of the forehead.
Vitiligo is caused by an immunologically mediated loss of melanocytes. Individuals with Phenylketonuria (PKU)
experience a generalized depigmentation of hair and eye color, in addition to intellectual disabilities, if the condition is not adequately and promptly treated. An individual totally lacking melanocytes is called an albino. The loss of hair is called alopecia. It can occur because of aging, sustained pulling on the hair with some hairstyles, and genetics. Women do not usually experience much
alopecia until after the menopause. Conversely, some men start to lose their hair during their twenties.

Skin diseases.
Eczema
or
dermatitis is a general term that describes a skin disease involving vesicles that ooze fluid. These conditions are usually characterized by a rash; they are inflammatory reactions, commonly caused by contact with a chemical or plant material. They can be caused by an adverse reaction to a drug or by sunlight. Bacteria, yeasts, or other fungi on the skin can cause infections; one common example, often mistaken for eczema, is althete's foot. Most rashes itch or burn; they can be spread by scratching.

Maculopapular diseases encompass several common skin conditions, such as red measles (rubeola), German measles (rubella), and scarlet fever. Viruses that land on the skin cause these diseases. They are characterized by relatively large, localized areas of changed skin color (macules) that are also raised (papules) but not fluid-filled. After their clinical course is run, they disappear without leaving a scar. The more dangerous toxic shock syndrome also belongs to this group of diseases; it is caused by toxin from the bacteria Staphylococcus aureus.

Thickening of the skin and the formation of red to purple areas having sharply defined borders characterize papulosquamous skin diseases. The most common example is
psoriasis. Other examples are pityriasis and ichthyosis. The pathology responsible for psoriasis is an alteration in the normal development of skin cells. In individuals with psoriasis, new skin cells develop and migrate to the surface in only five days instead of the usual thirty. This fact alone explains the flaking (rapid cell turnover), redness (thinner skin and a rich blood supply for new skin), and pain and itching (less protection for sensory nerve endings) experienced. Pityriasis includes a group of different conditions caused by different viruses. Patches or large spots develop on the skin. They usually resolve within a few weeks. Aside from being locally photosensitive, they usually are not serious. Ichthyosis describes a group of genetic
conditions characterized by extreme scaling of the skin.

Vesiculobullous diseases have fluid-filled blisters that can vary in size from relatively small (vesicles) to relatively large (bullae). Insect bites, herpes, and some bacterial infections lead to the formation of vesicles or bullae. Such conditions are attributable to an immune reaction that leads to the formation of blisters at the junction between epidermis and dermis. They can be accompanied by intense pruritus (itching); scratching often leads to scarring.

Pustular diseases of the skin include
acne, folliculitis, and candidiasis. They are characterized by the inflammation of hair follicles caused by surface bacteria or yeasts. Adequate personal hygiene is the most effective method of prevention. These diseases are usually not serious, but prolonged or repeated attacks can result in scarring and disfigurement. The sebaceous glands, which secrete oil at the base of hair follicles, can increase in size. The subsequent increase in oil output worsens the condition.

Clogged sweat glands can lead to acne. While this is primarily a problem for teenagers, it can affect individuals of any age. Exposure to cutting oils and other hydrocarbons such as gasoline and paint thinners can cause a similar condition called chloracne, which is inflammation in the base of hair follicles found on exposed skin in areas such as the nape of the neck, forearms, and face. The inability to sense temperature and regulate body heat through sweating is called anhidrosis, a condition that can cause shock and potentially death.

Other diseases that can affect the skin. Five such diseases are worthy of mention: leprosy, scleroderma, lupus, atherosclerosis, and diabetes mellitus. Leprosy, or Hansen’s disease, is caused by infection by Mycobacterium leprae, a relative of the bacteria that cause tuberculosis. In leprosy, the causative organism accumulates in the skin and peripheral nerves. This causes disfigurement and loss of sensation, the latter being similar to that experienced by an uncontrolled diabetic. Disfigurement is responsible for the stigma associated with leprosy since ancient times: loss of fingers and toes, as well as mutilation of the nose and ears. Leprosy is caused by long-term association with the organism and can be adequately treated with appropriate antibiotics.

Scleroderma (literally, “hard skin”) is an uncommon disease characterized by fibrosis of the skin and involvement of visceral organs. The skin involvement can range from an isolated, hardened patch to a life-threatening, generalized condition described as an ever-tightening case of steel. The skin becomes stretched tightly over the underlying skeleton. Skin tone is lost with restriction of movement.

Systemic lupus erythematosus is a disease of unknown etiology that is characterized by inflammation in many different organ systems. The skin is usually involved, as nearly all individuals with lupus develop a characteristic butterfly-shaped rash on their faces. This red coloration covers the cheeks and nose. Persons with lupus are also sensitive to sunlight, and many develop alopecia. Most of those affected are female. The disease waxes and wanes; treatment depends on the particular organs involved.

Atherosclerosis and diabetes can block the arteries supplying the nerves of the skin, leading to a loss of sensory input. When the patient is unable to experience pain, cuts and other abrasions on the skin are not noticed. Untreated, these lesions can lead to
gangrene, sometimes requiring
amputation of a body part.

Skin cancer. The most commonly diagnosed form of cancer is that involving the skin. It is not the most fatal form, but millions of cases are discovered annually. The origin of most skin cancers can be traced to excessive exposure to radiation from the sun. They can occur on any surface of the body, although they are more common on areas that are usually exposed to the sun, such as the face, the backs of the hands, and the neck. Skin cancers can arise in the epidermis or dermis. The majority are noncancerous, or benign. Epidermal nodules are characterized by local thickening of the epidermis, often accompanied by scaling of the skin in the affected area. Nodules in the dermis may appear as lumps with no alteration of the epidermis above them.

There are three malignant forms of skin cancer. Basal cell carcinoma
arises from cells deep in the epidermis. This form of tumor rarely spreads (metastasizes), but it can be extensive and destructive locally. Squamous cell carcinoma is less common but can be invasive (involving adjacent tissues) and can metastasize. Melanoma
is relatively uncommon but can grow extremely rapidly; it has the potential to be fatal in a matter of months. It involves the uncontrolled growth of melanocytes. Melanomas have irregular borders and color or pigmentation. Any pigmented lesion or suspicious change in the skin should be evaluated by a medical professional in a timely manner.

Prevention is the preferred method of dealing with skin cancer. When outside, loose-fitting clothing can provide protection from the sun, and a hat can protect the head. When exposure is unavoidable, a product with a sun-blocking agent will reduce exposure. Limiting the time of exposure to the sun until the body has reacted by producing additional melanocytes (tanned) is recommended.

Prolonged exposure to the sun also accelerates changes in the skin associated with aging. Collagen fibers provide the characteristic firm feel to the skin of a young person. With aging the skin becomes less firm, losing some of its tone, and begins to sag. Inadequate moisture also contributes to the loss of skin tone. Excessive exposure to the sun hastens both of these processes.

Bibliography

Burns, Tony, et al., eds. Rook’s Textbook of Dermatology. 8th ed. Malden, Mass.: Blackwell Science, 2010.

"Diseases and Treatments." American Academy of Dermatology, 2013.

Frankel, David H., ed. Field Guide to Clinical Dermatology. 2d ed. Philadelphia: Lippincott Williams & Wilkins, 2006.

Freinkel, Ruth K., and David T. Woodley, eds. Biology of the Skin. New York: Parthenon, 2001.

Goldsmith, Lowell A., Gerald S. Lazarus, and Michael D. Tharp. Adult and Pediatric Dermatology: A Color Guide to Diagnosis and Treatment. Philadelphia: F. A. Davis, 1997.

Grob, J. J., et al., eds. Epidemiology, Causes, and Prevention of Skin Diseases. Cambridge, Mass.: Blackwell Science, 1997.

Kenet, Barney, and Patricia Lawler. Saving Your Skin: Prevention, Early Detection, and Treatment of Melanoma and Other Skin Cancers. 2d ed. Chicago: Four Walls Eight Windows, 1998.

Owen, Cindy. "Skin Can Show First Signs of Some Internal Diseases." American Academy of Dermatology, Mar. 1, 2013.

Sams, W. Mitchell, Jr., and Peter J. Lynch, eds. Principles and Practice of Dermatology. 2d ed. London: Churchill Livingstone, 1996.

"Skin Conditions." MedlinePlus, May 7, 2013.

Weedon, David. Skin Pathology. 3d ed. New York: Churchill Livingstone/Elsevier, 2010.

What would be 5-7 good points to elaborate on if asked to justify why Claudius' actions were not justified in Shakespeare's Hamlet?

Claudius, the antagonist in Shakespeare's tragedy Hamlet, makes many decisions that lead to conflict between himself and other characters. If you are looking to identify specific actions that can contribute to an argument against any justifications for Claudius, you can easily find 6-7 options. 

First is Claudius' fratricide. While some might argue that specific circumstances can justify murder, the poisoning of King Hamlet was conducted solely from a space of a jealousy and power-seeking. 

Second is Claudius' request for Rosencrantz and Guildenstern to spy on Hamlet. His manipulation of two such loyal friends deconstructs Hamlet's ability to trust anyone around him, further contributing to his downward spiral into madness.

Next is Claudius' decision to spy on Ophelia and Hamlet. This decision reinforces the deceit that Claudius relies on to maintain his powerful position. 

After that comes Claudius' soliloquy, in which he confesses to the audience that he regrets his actions. However, he is unwilling to give up the spoils that have been awarded to him from these sins: Gertrude and the throne. As such, the audience can conclude that he is not truly contrite. 

Then, Claudius write orders to have Hamlet assassinated upon his arrival to England. This is a decision he makes out of fear for his own well-being, not for the protection of anyone or anything else. 

Finally, you can use Claudius' manipulation of Laertes' grief for his own purposes. He takes a mourning son and turns him into a weapon, again using others to his own advantage regardless of their state of being. 

In Speak, what is symbolic about "Hairwoman" and the narrator's description of her?

Melinda, the narrator of the young adult novel Speak, describes her English teacher as follows:

My English teacher has no face. She has uncombed stringy hair that droops on her shoulders. The hair is black from her part to her ears and then neon orange to the frizzy ends. I can't decide if she had pissed off her hairdresser or is morphing into a monarch butterfly. I call her Hairwoman.

Melinda initially finds Hairwoman to be a bit too freaky, but gradually grows to appreciate her "warped sense of humor" and the super quirky homework assignments she gives to the class in order to engage them in the act of writing. 

When Hairwoman gives them an assignment to identify the symbolism in Nathaniel Hawthorne's The Scarlet Letter, Melinda comments that looking for this information is fun, "like a code, breaking into his head and finding the key to his secrets. Like the whole guilt thing."

All of Melinda's assessments of Hairwoman and the classwork that she doles out actually seem to be reflections of Melinda herself. Melinda hides herself much the same way that Hairwoman hides her face; both are deeply self-conscious and struggle with expression. Melinda's judgmental attitude of Hairwoman's appearance and Melinda's own attitude toward her body suggest that Melinda projects her negative feelings about herself onto others.

Melinda's commentary on the Hawthorne assignment also seem to be a commentary on her own desires--the wish that someone would break into her own head and unlock her guilt and her secret about the tragic assault she suffered through in silence during the previous summer. 

When Hairwoman gets a buzzcut, Melinda wonders:

I don't know what caused this. Has she fallen in love? Did she get a divorce? Move out of her parents' basement? ...I'm thinking she found a good shrink, or maybe she published that novel she's been writing since the earth cooled.

This interest in Hairwoman's shifting appearance (and the possible life changes behind it) also represents how Melinda has altered in the past few months. Despite her acerbic attitude, Melinda seems to want good things to happen to Hairwoman. This comes at a time when Melinda is gradually becoming more open to the world around her, even developing a budding friendship with Ivy. Although we cannot see how our narrator has been physically altered, her observations of the new "look" of her teacher might also reflect some new beginnings for Melinda herself.

What are sensation and perception?

Introduction

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.

Signal Recognition

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.

Adaptation and Selective Attention

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.

Five Laws of Grouping

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.

Use in Advertising and Marketing

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.

Color Studies

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.

Use in Education

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.

Early Research

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.

Applications in Contemporary Society

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.

Bibliography

Barth, Friedrich G., Patrizia Giampieri-Deutsch, and Hans-Dieter Klein, eds. Sensory Perception: Mind and Matter. New York: Springer, 2012. Print.

Blake, Randolph, and Robert Sekuler. Perception. 5th ed. New York: McGraw, 2006. Print.

Foley, Hugh J., and Margaret W. Matlin. Sensation and Perception. 5th ed. Boston: Allyn, 2009. Print.

Goldstein, E. Bruce. Sensation and Perception. 9th ed. Belmont: Wadsworth, 2014. Print.

Gregory, Richard L. Eye and Brain: The Psychology of Seeing. 5th ed. Princeton: Princeton UP, 1997. Print.

Harris, John. Sensation and Perception. Thousand Oaks: Sage, 2014. Print.

Schiff, William. Perception: An Applied Approach. Boston: Houghton, 1980. Print.

Wolfe, Jeremy M., et al. Sensation & Perception. 3rd ed. Sunderland: Sinauer, 2012. Print.