5 Steps to a 5 AP Psychology, 2010-2011 Edition (48 page)

Neonates’ adaptive behavior is not limited to reflexes; they also show behaviors that facilitate social interactions. Shortly after birth, infants respond to the human face, voice, and touch. They show a preference for the voice and odor of their mothers. Their vision is best for objects normally about the distance from the infant’s eyes to the caretaker’s face. They can track objects with their eyes when they are only a few days old. Infants can distinguish among different colors, and they prefer certain complex patterns, such as the human face. Newborns also prefer sweet and salty tastes. Their sense of hearing is well developed at birth and typically the dominant sense during the baby’s first months. As structures in the eye and brain develop during infancy, visual acuity (clarity of vision) and depth perception improve, so that sight normally becomes a more dominant sense sometime during the second half of the baby’s first year.

How do psychologists know this information if babies can’t talk? Psychologists depend on gazes, sucking, and head turning measured by sophisticated computerized equipment in response to changes in stimuli to reveal abilities of infants. For example, when infants are shown a stimulus for the first time, they gaze at it for a length of time. With repeated presentations of that stimulus, they look away sooner. If a new stimulus is presented, and the infant can remember and discriminate between the two stimuli, the infant will look at the new stimulus longer than if it perceives no difference between the first and second stimulus. These are called habituation studies.
Habituation
is decreasing responsiveness with repeated presentation of the same stimulus.

An infant’s physical development during the first 2 years is amazing. Brain development proceeds rapidly from the prenatal period, during which about 20 billion brain cells are produced, through the baby’s first 2 years, during which dendrites proliferate in neural networks, especially in the cerebellum, then in occipital and temporal lobes as cognitive abilities grow. Body proportions change as the torso and limbs grow more quickly, so that the head is less out of proportion to body size. Physical development of the musculoskeletal system from head to tail, and from the center of the body outward, accompanies nervous system maturation to enable the baby to lift its head, roll over, sit, creep, stand, and walk, normally in that order. Maturation, motor and perceptual skills, motivation, and environmental support all contribute to development of new behaviors. During childhood, proliferation of dendrites proceeds at a rapid rate, especially in the frontal cortex.

The next growth spurt comes in adolescence, following a dramatic increase in production of sex hormones. The defining feature of
puberty
is sexual maturation, marked by the onset of the ability to reproduce.
Primary sex characteristics
, reproductive organs (ovaries and testes) start producing mature sex cells, and external genitals (vulva and penis) grow. So do
secondary sex characteristics
—nonreproductive features associated with sexual maturity—such as widening of hips and breast development in females, growth of facial hair, muscular growth, development of the “Adam’s apple,” and deepening of the
voice in males, and growth of pubic hair and underarm hair in both. Girls begin their growth spurt about 2 years before their first menstrual period (
menarche
), typically at age 12½. Early maturation of females can put them at a social disadvantage, whereas early maturation of males can put them at a social advantage. Boys start their growth spurt about 2 years later than girls, but about 2 years before ejaculation of semen with viable sperm. During adolescence, changes in the brain include selective pruning of unused dendrites with further development of the emotional limbic system, followed by frontal lobe maturation.

By our mid-20s, our physical capabilities peak, followed by first almost imperceptible, then accelerating, decline. According to evolutionary psychologists, peaking at a time when both males and females can provide for their children maximizes chances of survival for our species. Decreased vigor, changes in fat distribution, loss of hair pigmentation, and wrinkling of the skin are changes associated with advances in age. In females at about age 50,
menopause
—cessation of the ability to reproduce—is accompanied by a decrease in production of female sex hormones. Men experience a more gradual decline in reproductive function as they age. Typically, as adults age the lenses of their eyes thicken, letting less light reach the retina and worsening vision for near objects; ability to detect high-pitched sounds decreases; and sensitivity to tastes, odors, and temperature may decrease. Neural processes slow and parts of the brain begin to atrophy. Physical signs of aging can be slowed, and to some extent reversed, if we stay physically and mentally active and have a healthy diet. Heart disease, stroke, cancer, Alzheimer’s, and other degenerative diseases are often terminal diseases of old age. Since they do not interfere with reproductive success, genes involved in these diseases do not incur any selective pressures. On average, men die about 4 years earlier than women.

Theories of cognitive development look at how our patterns of thinking, reasoning, remembering, and problem solving change as we grow. Most developmental theories focus on infancy, childhood, and adolescence.

Swiss psychologist Jean Piaget developed a stage theory of cognitive development based on decades of careful observation and testing of children. His theory has been very influential because Piaget recognized that children think differently from adults. He thought that certain cognitive structures were innate, but only through a child’s interaction with the environment could they grow and develop over time.

Piaget believed that all knowledge begins with building blocks called
schemas
, mental representations that organize and categorize information processed by our brain. Through the process of
assimilation
, we fit new information into our existing schemas. Through the process of
accommodation
we modify our schemas to fit new information. As babies, we learn through accommodation that not all people fit our schema of mommy.

Piaget called the first stage of cognitive development, from birth to approximately 2 years, the
sensorimotor stage
, during which the baby explores the world using his/her senses and motor interactions with objects in the environment. The concept of
object
permanence
—that objects continue to exist even when out of sight—to Piaget seemed to develop suddenly between 8 and 10 months. Piaget said that the 5-month-old who sees a toy does not search for it if it disappears, but a 9-month-old does. Recently, psychologists have found that object permanence seems to develop gradually; young infants gaze where they saw a toy that disappeared. According to Piaget, infants at about 8 months of age also seem to develop
stranger anxiety
, fear of unfamiliar people, indicating that they can differentiate among people they know and people they don’t know.

To Piaget, attainment of object permanence and stranger anxiety indicated that cognitive structures had matured sufficiently for the typical 2-year-old to represent and manipulate objects with symbols such as words, whether or not the objects were present, which characterizes Piaget’s second stage, the
preoperational stage
. From approximately 2 to 7 years, language develops with the ability to think. The child is mainly
egocentric
, seeing the world from his/her own point of view. Egocentrism is consistent with a belief called
animism
, that all things are living just like him/her; and the belief, called
artificialism
, that all objects are made by people. While preoperational, a child uses trial and error to figure out how things work and answers questions intuitively rather than logically. He/she sometimes demonstrates magical thinking, reasoning that something happens because he/she wishes it to happen.

During Piaget’s third stage, the
concrete operational stage
, children between 7 and 12 years develop simple logic and master
conservation concepts
, that changes in the form of an object do not alter physical properties of mass, volume, and number. For example, 12 ounces of juice in a tall, thin glass isn’t more than 12 ounces of juice in a short, fat glass. The child now can logically classify objects into categories mentally. Mathematically and logically, the concrete operational child recognizes reversibility (transformations), for example that 3 + 4 = 4 + 3.

According to Piaget, after about age 12, children reason like adults in the fourth stage, the
formal operational stage
. In this stage, youngsters are able to think abstractly and hypothetically. They can manipulate more information in their heads and make inferences they were unable to make during the previous stage. Teens are able to consider questions involving abstract concepts, such as truth and justice. Some believe that the ability to think abstractly decreases in older adults partially because these skills are not utilized as often.

Piaget emphasized that increases in reasoning skill over time were punctuated by shifts in perspective, which were qualitative from one stage to the next. For example, in moving from the preoperational stage to the concrete operational stage, children decenter their perspective from egocentric to taking other people’s perspectives. With more experience, concrete operational thinkers cognitively reorganize their thinking to become the abstract thinkers of the formal operational stage. Although psychologists agree with the sequence of cognitive development steps and milestones proposed by Piaget, critics fault him for not acknowledging that children go through the stages at different rates, often more quickly than he predicted, and for not understanding that change is more gradual and continuous.

Whereas Piaget emphasized maturation (nature) and development in stages (discontinuity), Russian psychologist Lev Vygotsky emphasized the role of the environment (nurture) and gradual growth (continuity) in intellectual functioning. Vygotsky thought that
development proceeds mainly from the outside in by the process of
internalization
, absorbing information from a specified social environmental context. Children learn from observing the interactions of others and through their own interactions within the environment. Vygotsky’s
sociocultural theory
of cognitive development assigns a significant role to mentors such as parents, teachers, and other students. A key concept is his
zone of proximal development (ZPD
), the range between the level at which a child can solve a problem working alone with difficulty, and the level at which a child can solve a problem with the assistance of adults or more-skilled children. Working close to the upper limit of a child’s capability, the instructor and child work closely together to reach that goal, and then through continued practice, the child is able to attain it more and more independently. When the goal is achieved without help, then that goal becomes the lower limit for a new ZPD. Both Piaget and Vygotsky have influenced the ways that teachers are trained to help children learn.

Piaget did not study changes in cognition as adults age. Adult thought is frequently richer and more adaptive than adolescent thought. Middle-aged adults tend to reason more globally and make more rational decisions than younger people. Gerontologist Warner Schaie has found that while
fluid intelligence
—those abilities requiring speed or rapid learning—generally diminishes with aging,
crystallized intelligence
—learned knowledge and skills such as vocabulary—generally improves with age (at least through the 60s). In situations that access their skills and long-term memories, older adults may show superior functioning to younger people. Decline in mental abilities can be slowed if we stay healthy, live in a favorable environment, engage in stimulating activities, are flexible, have a mentally able partner, maintain perceptual processing speed, and feel satisfied with our earlier accomplishments.
Alzheimer’s disease
, a fatal degenerative disease in which brain neurons progressively die—causing loss of memory, reasoning, emotion, control of bodily functions, then death—strikes 3% of the world’s population by age 75. Strokes, brain tumors, and alcoholism can result in dementia, the loss of mental abilities.

Moral development refers to growth in the ability to tell right from wrong, control impulses, and act ethically. Lawrence Kohlberg, like Piaget, thought that moral thinking develops sequentially in stages as cognitive abilities develop. Kohlberg examined moral development by asking boys, male adolescents, and men how they would solve hypothetical moral problems, the most famous one dealing with Heinz, who must decide whether or not to steal a scarce drug he is unable to pay for in order to possibly save his wife’s life. Kohlberg analyzed the reasoning subjects used to arrive at their answers. Kohlberg concluded that our moral reasoning develops from simple and concrete to more abstract and principled. He suggested three basic levels of moral development consisting of two stages each.

• When at the preoperational stage of cognitive development, children tend to be at the
preconventional
level of morality, in which they do the right thing to avoid punishment (stage 1), or to further their self-interests (stage 2).