Hockenbury Discovering Psychology 5th txtbk

The Chemical and Body Senses109buds are also located on the insides of your cheeks, on the roofof your mouth, and in your throat. Each taste bud shows maximumsensitivity to one particular taste and lesser sensitivity toother tastes (Chandrashekar & others, 2006). When activated,special receptor cells in the taste buds send neural messagesalong pathways to the thalamus in the brain. In turn, the thalamusdirects the information to several regions in the cortex(Shepherd, 2006).There were long thought to be four basic taste categories:sweet, salty, sour, and bitter. However, scientists identified the receptorcells for a fifth basic taste, umami (Chaudhari & others,2000). Loosely translated, umami means “yummy” or “delicious”in Japanese. Umami is the distinctive taste of monosodiumglutamate and is associated with meat and other protein-richfoods. It’s also responsible for the savory flavor of Parmesan andother aged cheeses, mushrooms, and seaweed.From an evolutionary view, these five basic tastes supply the information weneed to seek out nutrient-rich foods and avoid potentially hazardous substances(Chandrashekar & others, 2006). Sweet tastes attract us to energy-rich foods,umami to protein-rich nutrients. Bitter or sour tastes warn us to avoid many toxicor poisonous substances. Sensitivity to salty-tasting substances helps us regulate thebalance of electrolytes in our diets.Most tastes are complex and result from the activation of different combinationsof basic taste receptors. Taste is just one aspect of flavor, which involves severalsensations, including the aroma, temperature, texture, and appearance of food(Shepherd, 2006).The Skin and Body SensesWhile vision, hearing, smell, and taste provide you with important informationabout your environment, another group of senses provides you with informationthat comes from a source much closer to home: your own body. In this section,we’ll first consider the skin senses, which provide essential information about yourphysical status and your physical interaction with objects in your environment. We’llnext consider the body senses, which keep you informed as to your position and orientationin space.TouchWe usually don’t think of our skin as a sense organ. But the skin is in fact the largestand heaviest sense organ. The skin of an average adult covers about 20 square feetof surface area and weighs about six pounds.There are many different kinds of sensory receptors in the skin. Some of thesesensory receptors are specialized to respond to just one kind of stimulus, such aspressure, warmth, or cold. Other skin receptors respond to more than one type ofstimulus (Patapoutian & others, 2003).One important receptor involved with the sense of touch, called the Paciniancorpuscle, is located beneath the skin. When stimulated by pressure, the Paciniancorpuscle converts the stimulation into a neural message that is relayed to the brain.If a pressure is constant, sensory adaptation takes place. The Pacinian corpuscleeither reduces the number of signals sent or quits responding altogether (which isfortunate, or you’d be unable to forget the fact that you’re wearing underwear).Sensory receptors are distributed unevenly among different areas of the body,which is why sensitivity to touch and temperature varies from one area of the bodyto another. Your hands, face, and lips, for example, are much more sensitive to touchthan are your back, arms, and legs. That’s because your hands, face, and lips are muchmore densely packed with sensory receptors.Expensive Taste Nominated for severalOscars, Sideways told the story of a wineconnoisseur and his friend on a road tripthrough California wine country, tastingdifferent vintages as they traveled fromone vineyard to another. Although wineexperts may be able to discern subtle differencesamong wines, amateurs may notbe as objective. To determine the effect ofprice on perceived quality, Hilke Plassmannand her colleagues (2008) asked participantsto decide which tasted better: winepoured from a bottle labeled as costing$90 or from a bottle that cost $10. Althoughthe wine in the two bottles wasidentical, participants overwhelminglythought the $90 bottle tasted better. Theirsubjective, verbal rating was confirmed bybrain scans: Activity in a brain region associatedwith pleasant sensations was muchhigher when they sipped the wine thatthey thought cost $90 a bottle than whenthey sipped the same wine from a bottlethat supposedly cost $10. The moral: Manydifferent factors affect taste, not the leastof which is your expectation of just howgood something is likely to taste.taste budsThe specialized sensory receptors for tastethat are located on the tongue and insidethe mouth and throat.