By 9 weeks after conception, the embryo looks unmistakably human It is now a fetus. (Latin for “offspring” or “young one”). During the sixth month, organs such as the stomach have developed enough to allow a prematurely born fetus a chance of survival. At this point, the fetus is also responsive to sound

Immediately after birth, when newborns emerge from living 38 or so weeks underwater, they prefer this voice to another woman’s or to their father’s voice (Busnel et al., 1992; DeCasper et al., 1984, 1986, 1994).

As a flower unfolds in accord with its genetic instructions, so do we, in the orderly sequence of biological growth processes called Maturation. Maturation decrees many of our commonalities—from standing before walking, to using nouns before adjectives. Severe deprivation or abuse can retard development, and ample parental experiences of talking and reading will help sculpt neural connections. Yet the genetic growth tendencies are inborn. Maturation sets the basic course of development; experience adjusts it.

There are, however, individual differences in timing. In the United States, for example, 25 percent of all babies walk by age 11 months, 50 percent within a week after their first birthday, and 90 percent by age 15 months (Frankenburg et al., 1992). The recommended infant back-to-sleep position (putting babies to sleep on their backs to reduce the risk of a smothering crib death) has been associated with somewhat later crawling but not with later walking (Davis et al., 1998; Lipsitt, 2003).

Genes play a major role in motor development. Identical twins typically begin sitting up and walking on nearly the same day (Wilson, 1979). Maturation—including the rapid development of the cerebellum at the back of the brain—creates our readiness to learn walking at about age 1.

Sensorimotor Stage from birth to nearly age 2, babies take in the world through their senses and actions—through looking, hearing, touching, mouthing, and grasping.

When Little Red Riding Hood realizes her “grandmother” is really a wolf, she swiftly revises her ideas about the creature’s intentions and races away. Preschoolers, although still egocentric, develop this ability to infer others’ mental states when they begin forming a theory of mind (a term first coined by psychologists David Premack and Guy Woodruff, to describe chimpanzees’ seeming ability to read intentions).

By about 6 or 7 years of age, said Piaget, children enter the concrete operational stage. Given concrete materials, they begin to grasp conservation. Understanding that change in form does not mean change in quantity, they can mentally pour milk back and forth between glasses of different shapes. They also enjoy jokes that allow them to use this new understanding:

Piaget believed that during the concrete operational stage, children fully gain the mental ability to comprehend mathematical transformations and conservation. When my daughter Laura was 6, I was astonished at her inability to reverse simple arithmetic. Asked, “What is 8 plus 4?” she required 5 seconds to compute “12,” and another 5 seconds to then compute 12 minus 4. By age 8, she could answer a reversed question instantly.

 By age 12, our reasoning expands from the purely concrete (involving actual experience) to encompass abstract thinking (involving imagined realities and symbols). As children approach adolescence, said Piaget, many become capable of solving hypothetical propositions and deducing consequences: If this, then that. Systematic reasoning, what Piaget called formal operational thinking, is now within their grasp.

Although full-blown logic and reasoning await adolescence, the rudiments of formal operational thinking begin earlier than Piaget realized. Consider this simple problem:

If John is in school, then Mary is in school. John is in school. What can you say about Mary?

Formal operational thinkers have no trouble answering correctly. But neither do most 7-year-olds (Suppes, 1982

What remains of Piaget’s ideas about the child’s mind? Plenty—enough to merit his being singled out by Time magazine as one of the twentieth century’s 20 most influential scientists and thinkers and rated in a survey of British psychologists as the greatest psychologist of that century (Psychologist, 2003). Piaget identified significant cognitive milestones and stimulated worldwide interest in how the mind develops. His emphasis was less on the ages at which children typically reach specific milestones than on their sequence. Studies around the globe, from aboriginal Australia to Algeria to North America, have confirmed that human cognition unfolds basically in the sequence Piaget described

However, today’s researchers see development as more continuous than did Piaget. By detecting the beginnings of each type of thinking at earlier ages, they have revealed conceptual abilities Piaget missed. Moreover, they see formal logic as a smaller part of cognition than he did. Piaget would not be surprised that today, as part of our own cognitive development, we are adapting his ideas to accommodate new findings.

Familiarity Contact is one key to attachment. Another is familiarity. In many animals, attachments based on familiarity likewise form during a critical period—an optimal period when certain events must take place to facilitate proper development (Bornstein, 1989). For goslings, ducklings, or chicks, that period falls in the hours shortly after hatching, when the first moving object they see is normally their mother. From then on, the young fowl follow her, and her alone.

Konrad Lorenz (1937) explored this rigid attachment process, called imprinting. He wondered: What would ducklings do if he was the first moving creature they observed? What they did was follow him around: Everywhere that Konrad went, the ducks were sure to go. Further tests revealed that although baby birds imprint best to their own species, they also will imprint to a variety of moving objects—an animal of another species, a box on wheels, a bouncing ball (Colombo, 1982; Johnson, 1992). And, once formed, this attachment is difficult to reverse.

Developmental theorist Erik Erikson (1902–1994), working in collaboration with his wife, Joan Erikson, said that securely attached children approach life with a sense of basic trust—a sense that the world is predictable and reliable. He attributed basic trust not to environment or inborn temperament, but to early parenting. He theorized that infants blessed with sensitive, loving caregivers form a lifelong attitude of trust rather than fear.

Although debate continues, many researchers now believe that our early attachments form the foundation for our adult relationships and our comfort with affection and intimacy (Birnbaum et al., 2006; Fraley, 2002). Adult styles of romantic love do tend to exhibit secure, trusting attachment; insecure, anxious attachment; or the avoidance of attachment (Feeney & Noller, 1990; Shaver & Mikulincer, 2007; Rholes & Simpson, 2004). Moreover, these adult attachment styles in turn affect relationships with our children, as avoidant people find parenting more stressful and unsatisfying (Rholes et al., 2006). Attachment style is also associated with motivation, note Andrew Elliot and Harry Reis (2003). Securely attached people exhibit less fear of failure and a greater drive to achieve.

1. Authoritarian parents impose rules and expect obedience: “Don’t interrupt.” “Keep your room clean.” “Don’t stay out late or you’ll be grounded.” “Why? Because I said so.”

2. Permissive parents submit to their children’s desires. They make few demands and use little punishment.

3. Authoritative parents are both demanding and responsive. They exert control by setting rules and enforcing them, but they also explain the reasons for rules. And, especially with older children, they encourage open discussion when making the rules and allow exceptions.

In girls, puberty starts with breast development, which now often begins by age 10 (Brody, 1999). But puberty’s landmarks are the first ejaculation in boys, usually by about age 14, and the first menstrual period in girls, usually within a year of age 12½ (Anderson et al., 2003). The first menstrual period, called menarche (meh-NAR-key), is a memorable event. Nearly all adult women recall it and remember experiencing a mixture of feelings—pride, excitement, embarrassment, and apprehension (Greif & Ulman, 1982; Woods et al., 1983). Girls who have been prepared for menarche usually experience it as a positive life transition. Most men similarly recall their first ejaculation (spermarche), which usually occurs as a nocturnal emission (Fuller & Downs, 1990).

• Preconventional morality Before age 9, most children’s morality focuses on self-interest: They obey rules either to avoid punishment or to gain concrete rewards.

• Conventional morality By early adolescence, morality focuses on caring for others and on upholding laws and social rules, simply because they are the laws and rules.

• Postconventional morality With the abstract reasoning of formal operational thought, people may reach a third moral level. Actions are judged “right” because they flow from people’s rights or from self-defined, basic ethical principles.

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  1.Preconventional Morality: Before age 9, children show morality to avoid punishment or gain reward.

   

  2.Conventional Morality: By early adolescence, social rules and laws are upheld for their own sake.

  Postconventional Morality: Affirms people’s agreed-upon rights or follows personally perceived ethical principles

To refine their sense of identity, adolescents in individualistic cultures usually try out different “selves” in different situations. They may act out one self at home, another with friends, and still another at school or on Facebook. If two situations overlap—as when a teenager brings home friends—the discomfort can be considerable. The teen asks, “Which self should I be? Which is the real me?” The resolution is a self-definition that unifies the various selves into a consistent and comfortable sense of who one is—an identity.

For both adolescents and adults, group identities often form around how we differ from those around us. When living in Britain, I became conscious of my Americanness. When spending time with my daughter in Africa, I become conscious of my minority (White) race. When surrounded by women, I am mindful of my gender identity. For international students, for those of a minority ethnic group, for people with a disability, for those on a team, a social identity often forms around their distinctiveness.

Especially for those still in school, the time from 18 to the mid-twenties is an increasingly not-yet-settled phase of life, which some now call emerging adulthood  (Arnett, 2006, 2007; Reitzle, 2006). Unlike some other cultures with an abrupt transition to adulthood, Westerners typically ease their way into their new status. Those who leave home for college, for example, are separated from parents and, more than ever before, managing their time and priorities. Yet they may remain dependent on their parents’ financial and emotional support and may return home for holidays. For many others, their parents’ home may be the only affordable place to live. No longer adolescents, these emerging adults have not yet assumed full adult responsibilities and independence, and they feel “in between.” But adulthood emerges gradually, and often with diminishing bouts of depression or anger and increased self-esteem (Galambos et al., 2006).

Prospective memory (“Remember to…”) remains strong when events help trigger memories, as when walking by a convenience store triggers a “Pick up milk!” memory. Time-based tasks (“Remember the 3 P.M. meeting”) prove somewhat more challenging for older people. Habitual tasks, such as remembering to take medications three times daily, can be especially challenging (Einstein et al., 1990, 1995, 1998). Teens and young adults surpass both young children and 70-year-olds at remembering to do something (Zimmerman & Meier, 2006). To minimize problems associated with declining prospective memory, older adults rely more on time management and on using reminder cues, such as notes to themselves (Henry et al., 2004).

Phase I: Cross-Sectional Evidence for Intellectual Decline In cross sectional studies, researchers at one point in time test and compare people of various ages. When giving intelligence tests to representative samples of people, researchers consistently find that older adults give fewer correct answers than do younger adults. David Wechsler (1972), creator of the most widely used adult intelligence test, therefore concluded that “the decline of mental ability with age is part of the general [aging] process of the organism as a whole.”

For a long time, this rather dismal view of mental decline went unchallenged. Many corporations established mandatory retirement policies, assuming the companies would benefit by replacing aging workers with younger, presumably more capable, employees. As everyone “knows,” you can’t teach an old dog new tricks.

So the answers to our age-and-intelligence questions depend on what we assess and how we assess it. Crystalized—our accumulated knowledge as reflected in vocabulary and analogies tests—increases up to old age. Fluid intelligence—our ability to reason speedily and abstractly, as when solving novel logic problems—decreases slowly up to age 75 or so, then more rapidly, especially after age 85 (Cattell, 1963; Horn, 1982). We can see this pattern in the intelligence scores of a national sample of adults (Kaufman et al., 1989). After adjustments for education, verbal scores (reflecting crystallized intelligence) held relatively steady from ages 20 to 74. Nonverbal, puzzle-solving intelligence declined. With age we lose and we win. We lose recall memory and processing speed, but we gain vocabulary and knowledge (Park et al., 2002). Our decisions also become less distorted by negative emotions such as anxiety, depression, and anger (Blanchard-Fields, 2007; Carstensen & Mikels, 2005).

Life events trigger transitions to new life stages at varying ages. The—the definition of “the right time” to leave home, get a job, marry, have children, and retire—varies from era to era and culture to culture. In Western Europe, fewer than 10 percent of men over 65 remain in the work force, as do 16 percent in the United States, 36 percent in Japan, and 69 percent in Mexico (Davies et al., 1991). And the once-rigid sequence for many Western women—of student to worker to wife to at-home mom to worker again—has loosened. Contemporary women occupy these roles in any order or all at once. The social clock still ticks, but people feel freer about being out of sync with it.

Conditioning is the process of learning associations. In classical conditioning, we learn to associate two stimuli and thus to anticipate events. We learn that a flash of lightning signals an impending crack of thunder, so when lightning flashes nearby, we start to brace ourselves

In operant conditioning, we learn to associate a response (our behavior) and its consequence and thus to repeat acts followed by good results and avoid acts followed by bad results.

Because salivation in response to food in the mouth was unlearned, Pavlov called it an UR. Food in the mouth automatically, unconditionally, triggers a dog’s salivary reflex. Thus, Pavlov called the food stimulus an US.

To understand the acquisition, or initial learning, of the stimulus-response relationship, Pavlov and his associates had to confront the question of timing: How much time should elapse between presenting the neutral stimulus (the tone, the light, the touch) and the unconditioned stimulus? In most cases, not much—half a second usually works well.

Through higher order condition, a new neutral stimulus can become a new conditioned stimulus. All that’s required is for it to become associated with a previously conditioned stimulus. If a tone regularly signals food and produces salivation, then a light that becomes associated with the tone may also begin to trigger salivation. Although this higher-order conditioning (also called second-order conditioning) tends to be weaker than first-stage conditioning, it influences our everyday lives. Imagine that something makes us very afraid (perhaps a pit bull dog associated with a previous dog bite). If something else, such as the sound of a barking dog, brings to mind that pit bull, the bark alone may make us feel a little afraid

Conditioning helps an animal survive and reproduce—by responding to cues that help it gain food, avoid dangers, locate mates, and produce offspring (Hollis, 1997).

After conditioning, what happens if the CS occurs repeatedly without the US? Will the CS continue to elicit the CR? Pavlov discovered that when he sounded the tone again and again without presenting food, the dogs salivated less and less. Their declining salivation illustrates extinction, the diminished responding that occurs when the CS (tone) no longer signals an impending US (food).

extinction the diminishing of a conditioned response; occurs in classical conditioning when an unconditioned stimulus (US) does not follow a conditioned stimulus (CS); occurs in operant conditioning when a response is no longer reinforced.

Pavlov found, however, that if he allowed several hours to elapse before sounding the tone again, the salivation to the tone would reappear spontaneously. This spontaneous recovery—the reappearance of a (weakened) CR after a pause—suggested to Pavlov that extinction was suppressing the CR rather than eliminating it.

Pavlov and his students noticed that a dog conditioned to the sound of one tone also responded somewhat to the sound of a different tone that had never been paired with food. Likewise, a dog conditioned to salivate when rubbed would also drool a bit when scratched (Windholz, 1989) or when touched on a different body part. This tendency to respond to stimuli similar to the CS is called generalization.

Generalization can be adaptive, as when toddlers taught to fear moving cars also become afraid of moving trucks and motorcycles. So automatic is generalization that one Argentine writer who underwent torture still recoils with fear when he sees black shoes—his first glimpse of his torturers as they approached his cell. Generalization of anxiety reactions has been demonstrated in laboratory studies comparing abused with nonabused children. Shown an angry face on a computer screen, abused children’s brain-wave responses are dramatically stronger and longer lasting (Pollak et al., 1998).

Pavlov’s dogs also learned to respond to the sound of a particular tone and not to other tones. Discrimination is the learned ability to distinguish between a conditioned stimulus (which predicts the US) and other irrelevant stimuli. Being able to recognize differences is adaptive. Slightly different stimuli can be followed by vastly different consequences. Confronted by a pit bull, your heart may race; confronted by a golden retriever, it probably will not.

Why does Pavlov’s work remain so important? If he had merely taught us that old dogs can learn new tricks, his experiments would long ago have been forgotten. Why should we care that dogs can be conditioned to salivate at the sound of a tone? The importance lies first in this finding: Many other responses to many other stimuli can be classically conditioned in many other organisms—in fact, in every species tested, from earthworms to fish to dogs to monkeys to people (Schwartz, 1984). Thus, classical conditioning is one way that virtually all organisms learn to adapt to their environment.

Second, Pavlov showed us how a process such as learning can be studied objectively. He was proud that his methods involved virtually no subjective judgments or guesses about what went on in a dog’s mind. The salivary response is a behavior measurable in cubic centimeters of saliva. Pavlov’s success therefore suggested a scientific model for how the young discipline of psychology might proceed—by isolating the basic building blocks of complex behaviors and studying them with objective laboratory procedures.

• Classical conditioning forms associations between stimuli (a CS and the US it signals). It also involves respondent behavior —actions that are automatic responses to a stimulus (such as salivating in response to meat powder and later in response to a tone).

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• In operant conditioning, organisms associate their own actions with consequences. Actions followed by reinforcers increase; those followed by punishers decrease. Behavior that operates on the environment to produce rewarding or punishing stimuli is called operant behavior.

   

We can therefore distinguish classical from operant conditioning by asking: Is the organism learning associations between events it does not control (classical conditioning)? Or is it learning associations between its behavior and resulting events (operant conditioning)?

People often refer rather loosely to the power of “rewards.” This idea gains a more precise meaning in Skinner’s concept of a reinforcer. any event that strengthens (increases the frequency of) a preceding response. A reinforcer may be a tangible reward, such as food or money. It may be praise or attention—even being yelled at, for a child hungry for attention. Or it may be an activity—borrowing the family car after doing the dishes, or taking a break after an hour of study.

Up to now, we’ve really been discussing PR which strengthens a response by presenting a typically pleasurable stimulus after a response. But there are two basic kinds of reinforcement NR strengthens a response by reducing or removing something undesirable or unpleasant, as when an organism escapes an aversive situation. Taking aspirin may relieve your headache, and pushing the snooze button will silence your annoying alarm. These welcome results (end of pain, end of alarm) provide negative reinforcement and increase the odds that you will repeat these behaviors. For drug addicts, the negative reinforcement of ending withdrawal pangs can be a compelling reason to resume using (Baker et al., 2004). Note that contrary to popular usage, negative reinforcement is not punishment. (Advice: Repeat the last five words in your mind, because this is one of psychology’s most often misunderstood concepts.) Rather, negative reinforcement removes a punishing (aversive) event

Primary Reinforcers—getting food when hungry or having a painful headache go away—are unlearned. They are innately satisfying.Conditioned reinforcers also called secondary reinforcers, get their power through learned association with primary reinforcers. If a rat in a Skinner box learns that a light reliably signals that food is coming, the rat will work to turn on the light. The light has become a conditioned reinforcer associated with food. Our lives are filled with conditioned reinforcers—money, good grades, a pleasant tone of voice—each of which has been linked with more basic rewards. If money is a conditioned reinforcer—if people’s desire for money is derived from their desire for food—then hunger should also make people more money-hungry, reasoned one European research team (Briers et al., 2006). Indeed, in their experiments, people were less likely to donate to charity when food deprived, and less likely to share money with fellow participants when in a room with hunger-arousing aromas.

Fixed Ratio Schedules  reinforce behavior after a set number of responses. Just as coffee shops reward us with a free drink after every 10 purchased, laboratory animals may be reinforced on a fixed ratio of, say, one reinforcer for every 30 responses. Once conditioned, the animal will pause only briefly after a reinforcer and will then return to a high rate of responding.

Fixed Interval schedules reinforce the first response after a fixed time period. Like people checking more frequently for the mail as the delivery time approaches, or checking to see if the Jell-O has set, pigeons on a fixed-interval schedule peck a key more frequently as the anticipated time for reward draws near, producing a choppy stop-start pattern rather than a steady rate of response.

1. Punished behavior is suppressed, not forgotten. This suppression, though temporary, may (negatively) reinforce parents’ punishing behavior. The child swears, the parent swats, the parent hears no more swearing and feels the punishment successfully stopped the behavior. No wonder spanking is a hit with so many U.S. parents of 3- and 4-year-olds—more than 9 in 10 of whom acknowledge spanking their children (Kazdin & Benjet, 2003).

2. Punishment teaches discrimination. Was the punishment effective in putting an end to the swearing? Or did the child simply learn that it’s not okay to swear around the house, but it is okay to swear elsewhere?

3. Punishment can teach fear. The child may associate fear not only with the undesirable behavior but also with the person who delivered the punishment or the place it occurred. Thus, children may learn to fear a punishing teacher and try to avoid school. For such reasons, most European countries now ban hitting children in schools and child-care institutions (Leach, 1993, 1994). Eleven countries, including those in Scandinavia, further outlaw hitting by parents, giving children the same legal protection given to spouses (EPOCH, 2000).

4. Physical punishment may increase aggressiveness by modeling aggression as a way to cope with problems. We know that many aggressive delinquents and abusive parents come from abusive families (Straus & Gelles, 1980; Straus et al., 1997). But some researchers note a problem with studies that find that spanked children are at increased risk for aggression (and depression and low self-esteem). Well, yes, they say, just as people who have undergone psychotherapy are more likely to suffer depression—because they had preexisting problems that triggered the treatments (Larzelere, 2000, 2004). Which is the chicken and which is the egg? The correlations don’t hand us an answer.

Excessive rewards can undermine intrinsic motivation—the desire to perform a behavior effectively and for its own sake. Extrinsic motivation  is the desire to behave in certain ways to receive external rewards or avoid threatened punishment.

Classical conditioning

UCS makes behavior happe

Operant conditioning

Escape conditioning is a form of aversive conditioning. The word aversive refers to stimuli that are avoided. Generally, those stimuli are unpleasant or painful. Escape conditioning occurs when an aversive stimulus is presented and an animal responds by leaving the stimulus situation.

In the lab, escape conditioning can be demonstrated with a shuttle box. A shuttle box is an enclosure with two sections separated by a partition. For example, a dog shuttle box might have a low barrier separating the two halves. To demonstrate escape conditioning all that is necessary is to shock the dog's feet. The dog then jumps to the other side of the box. Then, after a time, the dog is shocked again. It then jumps over the barrier again, escaping the shock.

Someone who finds school aversive may escape that situation. Most states require attendance until age 16. However, once students turn 16 they no longer must attend. So, some drop out at that point. Dropping out is a form of escape conditioning.

Avoidance conditioning is similar to escape conditioning. The difference is that a CS is given before the presentation of an aversive stimulus. For example, a light may precede the shock by a few seconds. What does the animal do under this new setup? At first, its behavior is no different than it was for escape conditioning. Namely, it jumps the barrier when the shock is delivered. Soon, however, it begins to jump before the shock. It jumps when the light comes on and thus avoids the shock. Also, unlike escape conditioning, the animal settles down emotionally. Dogs quit yelping, and calmly jump to the other side when the CS comes on.