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Adolescence

Physical Development

Due to earlier maturation and prolonged education, adolescencethe transition yearsbetween biological maturity and social independencehas lengthened in many countries.

Adolescence begins with a growth spurt that heralds the period of sexual maturation wecall puberty and ends with the achievement of adult independence. Depending on how

other people react, early or late maturation can influence adjustment, again illustratinghow our genes and our environment interact in shaping us.

Cognitive Development

Piaget theorized that adolescents develop the capacity for formal operations, whichenables them to reason abstractly. Todays developmentalists find the rudiments of

formal logic appearing earlier than Piaget believed.Following Piagets lead, Lawrence Kohlberg contended that moral thinking likewise

proceeds through a sequence of stages, from a preconventional morality of self-interest,

to a conventional morality concerned with gaining others approval or doing ones duty,to (in some people) a postconventional morality of agreed-upon rights or universal ethicalprinciples. But morality also lies in actions, which are influenced by the social situation

and inner attitudes as well as by moral reasoning. Moreover, say Kohlbergs critics, thepostconventional level represents morality from the perspective of individualist, liberal-

minded males. The social intuitionist perspective on morality suggests that moral feelingsmay precede moral judgments and influence our actions.

Social Development

Erik Erikson theorized that a chief task of adolescence is solidifying ones sense of selfones identity. For many people, this struggle continues into the adult years as new

relationships emerge and new roles are assumed. Although adolescence has traditionallybeen viewed as a time of storm and stress, researchers have found that most teenagers

relate to their parents reasonably well and generally affirm their parents beliefs andattitudes. A correlation has been found between a positive relationship with parents and

positive peer relationships. Adolescence marks a time when parental influence diminishesand peer influence increases.

Emerging AdulthoodThe window of time between adolescence and fully independent adulthood is now termed

emerging adulthood. This refers to people between the ages of 18 and the mid-twenties.With changes in Western society, such as an increase in years of schooling, the marks of

adult independence appear later. Emerging adults may be in college managing their own

time and activities but still look to their parents for financial and emotional support. Onthe other hand, sexual maturity begins earlier, thus creating a larger gap betweenbiological maturity and social independence.

Adulthood

During early life, we sail a narrow channel, constrained by biological maturation. As theyears pass, the channel widens, allowing us to diverge more and more. By adulthood, age

no longer neatly predicts a persons life experience and traits. Yet in some ways our

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bodies, minds, and relationships still undergo predictable changes. As long as we live, weadapt.

Physical DevelopmentThe barely perceptible physical declines of early adulthood begin to accelerate during

middle adulthood. For women, a significant physical change is menopause, whichgenerally seems to be a smooth rather than rough transition. For both men and women

perceptual acuity, strength, and stamina decline after 65, but short-term ailments arefewer. Neural processes slow, and except for those who suffer brain disease, such as the

progressive deterioration of Alzheimers disease, the brain remains healthy.Cognitive Development

As the years pass, recognition memory remains strong, although recall begins to decline,especially for meaningless information. Research on how intelligence changes with age

has progressed through several phases: cross-sectional studies suggesting a steadyintellectual decline after early adulthood; longitudinal studies suggesting intellectual

stability until very late in life; and todays view that fluid intelligence declines in later

life, but crystallized intelligence does not.Social DevelopmentFrom close study of small samples of individuals, some theorists maintain that adults pass

through an orderly sequence of life stages. Some have contended that moving from onestage to the next entails recurring times of crisis, such as the transition to midlife during

the early forties. But people are not so predictable. Adult life is influenced inunanticipated ways, not only by events involving love and work but also by chance

occurrences. Since 1960, marriage has been in decline, as reflected in later marriages,increased cohabitation, and doubled divorce rates.

Although few people grow old gratefully, most age gracefully, retaining a sense of well-being throughout life. Those who live to old age must, however, cope with the deaths of

friends and family members and with the prospect of their own deaths. Our experiencewith death is influenced by our experiences in life.

Reflections on Two Major Developmental Issues

We have touched on two of developmental psychologys pervasive issues: continuity and

discrete stages, and stability and change in personality. Although the stage theories ofPiaget, Kohlberg, and Erikson have been modified in light of later research, each theory

usefully alerts us to differences among people of different ages and helps us keep the life-span perspective in view. Research findings that reveal how peoples traits continue to

change in later life have helped create a new emphasis on lifelong development.

Nevertheless, there is also an underlying consistency to most peoples temperaments andpersonality traits.

CH 5

Sensing the World: Some Basic Principles

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To study sensation is to study an ageless question: How does the world out there getrepresented in here, inside our heads? Put another way, how are the external stimuli that

strike our bodies transformed into messages that our brains comprehend?

Thresholds

Each species comes equipped with sensitivities that enable it to survive and thrive. Wesense only a portion of the sea of energy that surrounds us, but to this portion we are

exquisitely sensitive. Our absolute threshold for any stimulus is the minimum stimulationnecessary for us to detect it 50 percent of the time. Signal detection researchers report

that our individual absolute thresholds vary with our psychological state.Experiments reveal that we can process some information from stimuli too weak to

recognize. But the restricted conditions under which this occurs would not enableunscrupulous opportunists to exploit us with subliminal messages.

To survive and thrive, an organism must have difference thresholds low enough to detect

minute changes in important stimuli. In humans, a difference threshold (also called a just

noticeable difference, or jnd) increases in proportion to the size of the stimulusaprinciple known as Webers law.

Sensory AdaptationSensory adaptation refers to our ability to adapt to unchanging stimuli. For example,

when we smell an odor in a room weve just entered and remain in that room for a periodof time, the odor will no longer be easily detected. The phenomenon of sensory

adaptation focuses our attention on informative changes in stimulation by diminishingour sensitivity to constant or routine odors, sounds, and touches.

Vision

Each sense receives stimulation, transduces it into neural signals, and sends these neuralmessages to the brain. We have glimpsed how this happens with vision.

The Stimulus Input: Light EnergyThe energies we experience as visible light are a thin slice from the broad spectrum of

electromagnetic radiation. The hue and brightness we perceive in a light depend on thewavelength and intensity.

The Eye

After entering the eye and being focused by a camera-like lens, light waves strike theretina. The retinas light-sensitive rods and color-sensitive cones convert the light energy

into neural impulses, which are coded by the retina before traveling along the optic nerveto the brain.

Visual Information Processing

In the cortex, individual neurons called feature detectors, respond to specific features of avisual stimulus, and their information is pooled for interpretation by higher-level brain

cells. Sub-dimensions of vision (color, movement, depth, and form) are processedseparately and simultaneously, illustrating the brains capacity for parallel processing.

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The visual pathway faithfully represents retinal stimulation, but the brains representationincorporates our assumptions, interests, and expectations.

Color Vision

Research on how we see color supports two nineteenth-century theories. First, as the

Young-Helmholtz trichromatic (three-color) theory suggests, the retina contains threetypes of cones. Each is most sensitive to the wavelengths of one of the three primarycolors of light (red, green, or blue). Second, as opponent-process theory maintains, the

nervous system codes the color-related information from the cones into pairs of opponentcolors, as demonstrated by the phenomenon of afterimages and as confirmed by

measuring opponent processes within visual neurons of the thalamus. The phenomenonof color constancy under varying illumination shows that our brains construct our

experience of color.

Hearing

The Stimulus Input: Sound Waves

The pressure waves we experience as sound vary in frequency and amplitude, andcorrespondingly in perceived pitch and loudness.

The EarThrough a mechanical chain of events, sound waves traveling through the auditory canal

cause minuscule vibrations in the eardrum. Transmitted via the bones of the middle ear tothe fluid-filled cochlea, these vibrations create movement in tiny hair cells, triggering

neural messages to the brain.Research on how we hear pitch supports both the place theory, which best explains the

sensation of high-pitched sounds, and frequency theory, which best explains the sensationof low-pitched sounds. We localize sound by detecting minute differences in the intensity

and timing of the sounds received by each ear.

Hearing Loss and Deaf CultureHearing losses linked to conduction and nerve disorders can be caused by prolonged

exposure to loud noise and by diseases and age-related disorders. Those who live withhearing loss face social challenges. Cochlear implants can enable some hearing for deaf

children and most adults. But Deaf Culture advocates, noting that Sign is a completelanguage, question the enhancement. Additionally, deafness can lead to sensory

compensation where other senses are enhanced. Advocates feel that this furthers theirview that deafness is not a disability.

Other Important Senses

TouchOur sense of touch is actually four sensespressure, warmth, cold, and painthat

combine to produce other sensations, such as "hot." One theory of pain is that a "gate" inthe spinal cord either opens to permit pain signals traveling up small nerve fibers to reach

the brain, or closes to prevent their passage. Because pain is both a physiological and apsychological phenomenon, it often can be controlled through a combination of physical

and psychological treatments.

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Taste

Taste, a chemical sense, is likewise a composite of five basic sensationssweet, sour,salty, bitter, and umamiand of the aromas that interact with information from the taste

buds. The influence of smell on our sense of taste is an example of sensory interaction.

SmellLike taste, smell is a chemical sense, but there are no basic sensations for smell, as there

are for touch and taste. Unlike the retinas receptor cells that sense color by breaking itinto component parts, the 5 million olfactory receptor cells with their 1000 different

receptor proteins recognize individual odor molecules. Some odors trigger a combinationof receptors. Like other stimuli, odors can spontaneously evoke memories and feelings.

Body Position and Movement

Finally, our effective functioning requires a kinesthetic sense, which notifies the brain ofthe position and movement of body parts, and a sense of equilibrium, which monitors the

position and movement of the whole body.

Chapter 6: Perception

Selective Attention

At any moment we are conscious of a very limited amount of all that we are capable of

experiencing. One example of this selective attention is the cocktail party effectattending to only one voice among many. Another example is inattentional blindness,

which refers to our blocking of a brief visual interruption when focusing on other sights.

Perceptual Illusions

Visual and auditory illusions were fascinating scientists even as psychology emerged.

Explaining illusions required an understanding of how we transform sensations intomeaningful perceptions, so the study of perception became one of psychologys first

concerns. Conflict between visual and other sensory information is usually resolved withthe minds accepting the visual data, a tendency known as visual capture.

Perceptual Organization

From a top-down perspective, we see how we transform sensory information into

meaningful perceptions when we are aided by knowledge and expectations.

The early Gestalt psychologists were impressed with the seemingly innate way we

organize fragmentary sensory data into whole perceptions. Our minds structure theinformation that comes to us in several demonstrable ways:

Form Perception

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To recognize an object, we must first perceive it (see it as a figure) as distinct from itssurroundings (the ground). We must also organize the figure into a meaningful form.

Several Gestalt principlesproximity, similarity, continuity, connectedness, andclosuredescribe this process.

Depth PerceptionResearch on the visual cliff revealed that many species perceive the world in threedimensions at, or very soon after, birth. We transform two-dimensional retinal images

into three-dimensional perceptions by using binocular cues, such as retinal disparity, andmonocular cues, such as the relative sizes of objects.

Motion Perception

Our brain computes motion as objects move across or toward the retina. Large objectsappear to move more slowly than smaller objects. A quick succession of images, as in a

motion picture or on a lighted sign, can also create an illusion of movement.

Perceptual ConstancyHaving perceived an object as a coherent figure and having located it in space, how then

do we recognize itdespite the varying images that it may cast on our retinas? Size,shape, and lightness constancies describe how objects appear to have unchanging

characteristics regardless of their distance, shape, or motion. These constancies explainseveral of the well-known visual illusions. For example, familiarity with the size-distance

relationships in a carpentered world of rectangular shapes makes people more susceptibleto the Mller-Lyer illusion.

Perceptual Interpretation

The most direct tests of the nature-nurture issue come from experiments that modify

human perceptions.

Sensory Deprivation and Restored VisionFor many species, infancy is a critical period during which experience must activate the

brains innate visual mechanisms. If cataract removal restores eyesight to adults whowere blind from birth, they remain unable to perceive the world normally. Generally, they

can distinguish figure from ground and can perceive colors, but they are unable torecognize shapes and forms. In controlled experiments, animals have been reared with

severely restricted visual input. When their visual exposure is returned to normal, they,too, suffer enduring visual handicaps.

Perceptual AdaptationHuman vision is remarkably adaptable. Given glasses that shift the world slightly to theleft or right, or even turn it upside down, people manage to adapt their movements and,

with practice, to move about with ease.

Perceptual SetClear evidence that perception is influenced by our experienceour learned assumptions

and beliefsas well as by sensory input comes from the many demonstrations of

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perceptual set and context effects. The schemas we have learned help us to interpretotherwise ambiguous stimuli, a fact that helps explain why some of us "see" monsters,

faces, and UFOs that others do not.

Perception and the Human Factor

Perceptions vary, and may not be what a designer assumes. Human factors psychologiststherefore study how people perceive and use machines, and how machines and physicalenvironments can be better suited to that use. Such studies have improved aircraft safety

and spawned user-friendly technology.Is There Extrasensory Perception?

Many believe in or claim to experience extrasensory perception (ESP). To believe in ESPis to believe that the brain can perceive without sensory input. Most US scientists are

skeptical, yet five British universities have parapsychology departments.

Examples of ESP include astrological predictions and communication with the dead.

Three forms of ESP, telepathy, clairvoyance, and precognition, are deemed the mosttestable. However, parapsychologists have tried to documents several forms of ESP butfor several reasons, especially the lack of a reproducible ESP effect, most research

psychologists remain skeptical.