Chapter 1 development

1.1: Prelude to Lifespan Development

Developmental Psychology, also known as Human Development or Lifespan Development, is the scientific study of ways in

which people change, as well as stay the same, from conception to death. You will no doubt discover in the course of studying

that the field examines change across a broad range of topics. These include physical and other psychophysiological processes,

cognition, language, and psychosocial development, including the impact of family and peers.

Originally concerned with infants and children, the field has expanded to include adolescence, and more recently, aging and

the entire life span. Previously, the message was once you are 25, your development is essentially completed. Our academic

knowledge of the lifespan has changed, and although there is still less research on adulthood than on childhood, adulthood is

gaining increasing attention. This is particularly true now that the large cohort known as the "baby boomers" are beginning to enter

late adulthood. The assumption that early childhood experiences dictate our future is also being called into question. Rather, we

have come to appreciate that growth and change continues throughout life and experience continues to have an impact on who

we are and how we relate to others. We now recognize that adulthood is a dynamic period of life marked by continued cognitive,

social, and psychological development.

Figure . Source

You will also discover that developmental psychologists investigate key questions, such as whether children are qualitatively

different from adults or simply lack the experience that adults draw upon. Other issues that they deal with is the question of

whether development occurs through the gradual accumulation of knowledge or through shifts from one stage of thinking to

another, or if children are born with innate knowledge or figure things out through experience, and whether development is driven

by the social context or something inside each child. From the above explanation, you may be thinking already that developmental

psychology is related to other applied fields. You are very right. The field informs several applied fields in psychology, including,

educational psychology, psychopathology, and forensic developmental psychology. It also complements several other basic

research fields in psychology including social psychology, cognitive psychology, and comparative psychology. Lastly, it draws from

the theories and research of several scientific fields including biology, sociology, health care, nutrition, and anthropology.

Learning Objectives: Lifespan Perspective

• Explain the lifespan perspective and its assumptions about development.

• Differentiate periods of human development.

• Explain the issues underlying lifespan development.

• Identify the historical and contemporary theories impacting lifespan development.

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3 (1.1.2)1.2: Lifespan Perspective

Paul Baltes identified several underlying principles of the lifespan perspective (Baltes, 1987; Baltes et al., 2006).

Development is lifelong. Lifespan theorists believe that development is life-long, and change is apparent across the lifespan. No

single age period is more crucial, characterizes, or dominates human development. Consequently, the term lifespan development

will be used throughout the textbook.

Development is multidirectional. Humans change in many directions. We may show gains in some areas of development, while

showing losses in other areas. Every change, whether it is finishing high school, getting married, or becoming a parent, entails

both growth and loss.

Development is multidimensional. We change across three general domains/dimensions; physical, cognitive, and psychosocial.

The physical domain includes changes in height and weight, sensory capabilities, the nervous system, as well as the propensity

for disease and illness. The cognitive domain encompasses the changes in intelligence, wisdom, perception, problem-solving,

memory, and language. The psychosocial domain focuses on changes in emotion, self-perception and interpersonal

relationships with families, peers, and friends. All three domains influence each other. It is also important to note that a change

in one domain may cascade and prompt changes in the other domains. For instance, an infant who has started to crawl or walk

will encounter more objects and people, thus fostering developmental change in the child's understanding of the physical and

social world.

Development is multidisciplinary. As mentioned at the start of the chapter, human development is such a vast topic of study

that it requires the theories, research methods, and knowledge base of many academic disciplines.

Development is characterized by plasticity. Plasticity is all about our ability to change and that many of our characteristics

are malleable. For instance, plasticity is illustrated in the brain's ability to learn from experience and how it can recover from

injury.

Development is multicontextual. Development occurs in many contexts. Baltes (1987) identified three specific contextual

influences.

• Normative age-graded influences: An age-grade is a specific age group, such as toddler, adolescent, or senior. Humans

in a specific age-grade share particular experiences and developmental changes.

• Normative history-graded influences: The time period in which you are born (see Table ) shapes your experiences. A

cohort is a group of people who are born at roughly the same period in a particular society. These people travel through life

often experiencing similar circumstances.

Table . Which generation (cohort) are you?

Source

• Non-normative life influences: Despite sharing an age and history with our peers, each of us also has unique experiences

that may shape our development. A child who loses his/her parent at a young age has experienced a life event that is not

typical of the age group.

Another context that influences our lives is our social standing, socioeconomic status, or social class. Socioeconomic status

(SES) is a way to identify families and households based on their shared levels of education, income, and occupation. While there

4 (1.2.1)is certainly individual variation, members of a social class tend to share similar lifestyles, patterns of consumption, parenting

styles, stressors, religious preferences, and other aspects of daily life. All of us born into a class system are socially located, and

we may move up or down depending on a combination of both socially and individually created limits and opportunities.

Families with higher socioeconomic status usually are in occupations (e.g., attorneys, physicians, executives) that not only pay

better, but also grant them a certain degree of freedom and control over their job. Having a sense of autonomy or control is a

key factor in experiencing job satisfaction, personal happiness, and ultimately health and well-being (Weitz, 2007). Those families

with lower socioeconomic status are typically in occupations that are more routine, more heavily supervised, and require less

formal education. These occupations are also more subject to job disruptions, including lay-offs and lower wages.

Poverty level is an income amount established by the federal government that is based on a set of income thresholds that vary

by family size (United States Census Bureau, 2016). If a family's income is less than the government threshold, that family is

considered in poverty. Those living at or near poverty level may find it extremely difficult to sustain a household with this amount

of income. Poverty is associated with poorer health and a lower life expectancy due to poorer diet, less healthcare, greater stress,

working in more dangerous occupations, higher infant mortality rates, poorer prenatal care, greater iron deficiencies, greater

difficulty in school, and many other problems. Members of higher income status may fear losing that status, but the poor may

have greater concerns over losing housing.

Today we are more aware of the variations in development and the impact that culture and the environment have on shaping our

lives. Culture is the totality of our shared language, knowledge, material objects, and behavior. It includes ideas about what is

right and wrong, what to strive for, what to eat, how to speak, what is valued, as well as what kinds of emotions are called for in

certain situations. Culture teaches us how to live in a society and allows us to advance because each new generation can benefit

from the solutions found and passed down from previous generations. Culture is learned from parents, schools, houses of worship,

media, friends and others throughout a lifetime. The kinds of traditions and values that evolve in a particular culture serve to help

members function and value their own society. We tend to believe that our own culture's practices and expectations are the right

ones. This belief that our own culture is superior is called ethnocentrism and is a normal byproduct of growing up in a culture.

It becomes a roadblock, however, when it inhibits understanding of cultural practices from other societies. Cultural relativity is

an appreciation for cultural differences and the understanding that cultural practices are best understood from the standpoint of

that particular culture.

Figure . Think of other ways culture may have affected your development. How might cultural differences influence interactions between

teachers and students, nurses and patients, or other relationships? Image source

Culture is an extremely important context for human development and understanding development requires being able to identify

which features of development are culturally based. This understanding is somewhat new and still being explored. Much of what

developmental theorists have described in the past has been culturally bound and difficult to apply to various cultural contexts.

The reader should keep this in mind and realize that there is still much that is unknown when comparing development across

cultures.

Lifespan vs. Life expectancy: At this point you must be wondering what the difference between lifespan and life expectancy is,

5 (1.2.2)according to developmentalists. Lifespan, or longevity, refers to the length of time a species can exist under the most optimal

conditions. For instance, the grey wolf can live up to 20 years in captivity, the bald eagle up to 50 years, and the Galapagos

tortoise over 150 years (Smithsonian National Zoo, 2016). The longest recorded lifespan for a human was that of Jean Calment,

who died in 1994 at the age of 122 years, 5 months, and 14 days (Guinness World Records, 2016). Life expectancy is the predicted

number of years a person born in a particular time period can reasonably expect to live (Vogt & Johnson, 2016).

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6 (1.2.3)1.3: Conceptions of Age

How old are you? Chances are you would answer that question based on the number of years since your birth, or what is called

your chronological age. Ever felt older than your chronological age? Some days we might "feel" like we are older, especially if we

are not feeling well, are tired, or are stressed out. We might notice that a peer seems more emotionally mature than we are, or

that they are physically more capable. So years since birth is not the only way we can conceptualize age.

Biological age: Another way developmental researchers can think about the concept of age is to examine how quickly the body

is aging; this is your biological age. Several factors determine the rate at which our body ages. Our nutrition, level of physical

activity, sleeping habits, smoking, alcohol consumption, how we mentally handle stress, and the genetic history of our ancestors,

to name but a few.

Psychological age: Our psychologically adaptive capacity compared to others of our chronological age is our psychological age.

This includes our cognitive capacity, along with our emotional beliefs about how old we are. An individual who has cognitive

impairments might be 20 years of age, yet have the mental capacity of an 8-year-old. A 70-year-old might be traveling to new

countries, taking courses at college, or starting a new business. Compared to others of our age group, we may be more or less

adaptive and excited to meet new challenges. Remember you are as young or old as you feel.

Figure . You are as young as you feel! Image source

Social age: Our social age is based on the social norms of our culture and the expectations our culture has for people of our

age group. Our culture often reminds us whether we are "on target" or "off target" for reaching certain social milestones, such as

completing our education, moving away from home, having children, or retiring from work. However, there have been arguments

that social age is becoming less relevant in the century (Neugarten, 1979; 1996).

If you look around at your fellow students in your courses at college, you might notice more people who are older than the more

traditional-aged college students of ages 18 to 25. Similarly, the age at which people are moving away from the home of their

parents, starting their careers, getting married or having children, or even whether they get married or have children at all, is

changing. Those who study lifespan development recognize that chronological age does not completely capture a person's age.

Our age profile is much more complex than this. A person may be physically more competent than others in their age group, while

being psychologically immature. So, how old are you?

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7 (1.3.1)1.4: Periods of Development

Table . Age Periods of Development

Age Period Description

Prenatal Starts at conception, continues through implantation in the uterine wall by the embryo, and ends at

birth.

Infancy and Toddlerhood Starts at birth and continues to two years of age

Early Childhood Starts at two years of age until six years of age

Middle and Late

Childhood

Starts at six years of age and continues until the onset of puberty

Adolescence Starts at the onset of puberty until 18

Emerging Adulthood Starts at 18 until 29

Established Adulthood Starts at 30 until 45

Middle Adulthood Starts at 45 until 65

Late Adulthood Starts at 65 onward

Table reflects unique aspects of the various stages of childhood and adulthood that will be explored in this book. So, while

both an 8-month old and an 8-year-old are considered children, they have very different motor abilities, social relationships, and

cognitive skills. Their nutritional needs are different and their primary psychological concerns are also distinctive. The same is

true of an 18-year-old and an 80-year-old, as both are considered adults.

Prenatal Development: Conception occurs and development begins. All of the major structures of the body are forming, and the

health of the mother is of primary concern. Understanding nutrition, teratogens, or environmental factors that can lead to birth

defects, and labor and delivery are primary concerns.

Infancy and Toddlerhood: The first two years of life are ones of dramatic growth and change. A newborn, with a keen sense of

hearing but very poor vision, is transformed into a walking, talking toddler within a relatively short period of time. Caregivers are

also transformed from someone who manages feeding and sleep schedules to a constantly moving guide and safety inspector for

a mobile, energetic child.

Figure . Image source.

Early Childhood: This period is also referred to as the preschool years and consists of the years which follow toddlerhood and

precede formal schooling. As a two- to six-year-old, the child is busy learning language, is gaining a sense of self and greater

8 (1.4.1)independence, and is beginning to learn the workings of the physical world.

Middle and Late Childhood: The ages of six to the onset of puberty comprise middle and late childhood, and much of what

children experience at this age is connected to their involvement in the early grades of school. Now the world becomes one of

learning and testing new academic skills and by assessing one's abilities and accomplishments by making comparisons between

self and others.

Adolescence: Adolescence is a period of dramatic physical change marked by an overall growth spurt and sexual maturation,

known as puberty. It is also a time of cognitive change as the adolescent begins to think of new possibilities and to consider

abstract concepts such as love, fear, and freedom. Ironically, adolescents have a sense of invincibility that puts them at greater

risk of dying from accidents or contracting sexually transmitted infections that can have lifelong consequences.

Emerging Adulthood: The period of emerging adulthood is a transitional time between the end of adolescence and before

individuals acquire all the benchmarks of adulthood. Continued identity exploration and preparation for full independence from

parents are demonstrated. Although at one's physiological peak, emerging adults are most at risk for involvement in violent crimes

and substance abuse.

Established Adulthood: The thirties and early forties are identified as established adulthood. Intimate relationships, establishing

families, and work are primary concerns at this stage of life.

Middle Adulthood: The mid-forties through the mid-sixties is referred to as middle adulthood. This is a period in which aging

becomes more noticeable and when many people are at their peak of productivity in love and work.

Figure . Image source

Late Adulthood: Late adulthood is sometimes subdivided into two categories: The young-old who are from 65-84 years and

the oldest-old who are 85 years and older. One of the primary differences between these groups is that the young-old are still

relatively healthy, productive, active, and the majority continue to live independently. With both age groups the risks of diseases

such as, arteriosclerosis, cancer, and cerebral vascular disease increases substantially.

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9 (1.4.2)1.5: Issues in Lifespan Development

Nature and Nurture: Why are you the way you are? As you consider some of your features (height, weight, personality, being

diabetic, etc.), ask yourself whether these features are a result of heredity or environmental factors, or both. Chances are, you

can see the ways in which both heredity and environmental factors (such as lifestyle, diet, and so on) have contributed to these

features. For decades, scholars have carried on the "nature/nurture" debate. For any particular feature, those on the side of nature

would argue that heredity plays the most important role in bringing about that feature. Those on the side of nurture would argue

that one's environment is most significant in shaping the way we are. This debate continues in all aspects of human development,

and most scholars agree that there is a constant interplay between the two forces. It is difficult to isolate the root of any single

behavior as a result solely of nature or nurture.

Continuity versus Discontinuity: Is human development best characterized as a slow, gradual process, or is it best viewed as

one of more abrupt change? The answer to that question often depends on which developmental theorist you ask and what topic

is being studied. The theories of Freud, Erikson, Piaget, and Kohlberg are called stage theories. Stage theories or discontinuous

development assume that developmental change often occurs in distinct stages that are qualitatively different from each other,

and in a set, universal sequence. At each stage of development, children and adults have different qualities and characteristics.

Thus, stage theorists assume development is more discontinuous. Others, such as the behaviorists, Vygotsky, and information

processing theorists, assume development is a more slow and gradual process known as continuous development. For instance,

they would see the adult as not possessing new skills, but more advanced skills that were already present in some form in the

child. Brain development and environmental experiences contribute to the acquisition of more developed skills.

Figure . The tree represents continuous development, while the ladybug represents discontinuous/stage development. Image source.

Active versus Passive: How much do you play a role in your own developmental path? Are you at the whim of your genetic

inheritance or the environment that surrounds you? Some theorists see humans as playing a much more active role in their own

development. Piaget, for instance, believed that children actively explore their world and construct new ways of thinking to explain

the things they experience. In contrast, many behaviorists view humans as being more passive in the developmental process.

Stability versus Change: How similar are you to how you were as a child? Were you always as out-going or reserved as you are

now? Some theorists argue that the personality traits of adults are rooted in the behavioral and emotional tendencies of the infant

and young child. Others disagree, and believe that these initial tendencies are modified by social and cultural forces over time.

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10 (1.5.1)1.6: Historical Theories on Development

Preformationist View: Well into the century, children were merely thought of as little adults. Preformationism, or the belief

that a tiny, fully formed human is implanted in the sperm or egg at conception and then grows in size until birth, was the

predominant early theory. Children were believed to possess all their sensory capabilities, emotions, and mental aptitude at birth,

and as they developed these abilities unfolded on a predetermined schedule (Thomas, 1979). The environment was thought to

play no role in determining development.

Figure . A tiny person inside a sperm. Image source.

John Locke (1632-1704): Locke, a British philosopher, refuted the idea of innate knowledge and instead proposed that children

are largely shaped by their social environments, especially their education as adults teach them important knowledge. He

believed that through education a child learns socialization, or what is needed to be an appropriate member of society. Locke

advocated thinking of a child's mind as a tabula rasa or blank slate, where whatever comes into the child's mind comes from the

environment. Locke emphasized that the environment is especially powerful in the child's early life because he considered the

mind the most pliable then. Locke indicated that the environment exerts its effects through associations between thoughts and

feelings, behavioral repetition, imitation, and rewards and punishments (Crain, 2005). Locke's ideas laid the groundwork for the

behavioral perspective and subsequent learning theories of Pavlov, Skinner and Bandura.

Jean-Jacques Rousseau (1712-1778): Like Locke, Rousseau also believed that children were not just little adults. However, he

did not believe they were blank slates, but instead developed according to a natural plan which unfolded in different stages

(Crain, 2005). He did not believe in teaching them the correct way to think, but believed children should be allowed to think

by themselves according to their own ways and an inner, biological timetable. This focus on biological maturation resulted in

Rousseau being considered the father of developmental psychology. Followers of Rousseau's developmental perspective include

Gesell, Montessori, and Piaget.

Arnold Gesell (1880-1961): Gesell spent 50 years at the Yale Clinic of Child Development, and with his colleagues he studied

the neuromotor development of children. Gesell believed that the child's development was activated by genes and he called this

process maturation (Crain, 2005). Further, he believed that development unfolded in fixed sequences, and he opposed efforts

to teach children ahead of schedule as he believed they will engage in behaviors when their nervous systems had sufficiently

matured.

Sigmund Freud (1856-1939): Freud was a very influential figure in the area of development. Freud emphasized the importance of

early childhood experiences in shaping our personality and behavior. In our natural state, we are biological beings and are driven

primarily by instincts. During childhood, however, we begin to become social beings as we learn how to manage our instincts

and transform them into socially acceptable behaviors. His assumptions were that personality formed during the first few years

of life. The ways in which parents or other caregivers interacted with children were assumed to have a long-lasting impact on

11 (1.6.1)children's emotional states. His beliefs formed the psychodynamic perspective and his theories of psychosexual development and

psychopathology dominated the field of psychiatry until the growth of behaviorism in the 1950s.

Figure . Sigmund Freud.

However, Freud's theory has been heavily criticized for several reasons. One is that it is very difficult to test scientifically (Crews,

1998). Freud suggested that much of what determines our actions were unknown to us, and as scientists we cannot measure

these unconscious concepts. A second criticism is that Freud's case studies were not validated and cannot be used as evidence

for his theories. Many later theories, particularly behaviorism and humanism, came about as challenges to Freud's views.

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12 (1.6.2)1.7: Contemporary Theories on Development

Erikson (1902-1994) and Psychosocial Theory:

Now, let's turn to a less controversial psychodynamic theorist, Erik Erikson. Erikson presents eight developmental stages that

encompass the entire lifespan. For that reason, Erikson's psychosocial theory forms the foundation for much of our discussion of

psychosocial development.

Figure . Erik Erikson.

Erikson (1950) proposed a model of lifespan development that provides a useful guideline for thinking about the changes we

experience throughout life. Erikson broke with Freud's emphasis on sexuality as the cornerstone of social-emotional development

and instead suggested that social relationships fostered development. Erikson proposed that each period of life has a unique

challenge or crisis that the person who reaches it must face, referred to as psychosocial crises. According to Erikson, successful

development involves dealing with and resolving the goals and demands of each of these psychosocial crises in a positive

way. These crises are usually called stages, although that is not the term Erikson used. If a person does not resolve a stage

successfully, it may hinder their ability to deal with later stages. For example, the person who does not develop a sense of

trust (Erikson's first stage) may find it challenging as an adult to form a positive intimate relationship (Erikson's sixth stage).

Or an individual who does not develop a clear sense of purpose and identity (Erikson's fifth stage) may become self-absorbed

and stagnate rather than work toward the betterment of others (Erikson's seventh stage). However, most individuals are able to

successfully complete the eight stages of his theory (See Table ).

Table . Erikson’s Psychosocial Stages.

13 (1.7.1)Age range Psychosocial crisis Positive resolution of crisis

12 to 18 years Identity versus Role

Confusion

The adolescent develops a well-defined and positive sense of self in relationship to

others.

19 to 40 years Intimacy versus

Isolation

The person develops the ability to give and receive love and to make long-term

commitments.

40 to 65 years Generativity versus

Stagnation

The person develops an interest in guiding the development of the next generation,

often by becoming a parent.

65 to death Ego Integrity versus

Despair

The person develops acceptance of how one has lived.

Erikson's theory has been criticized for focusing so heavily on crises and assuming that the completion of one crisis is a

prerequisite for the next crisis of development. His theory also focused on the social expectations that are found in certain

cultures, but not in all. For instance, the idea that adolescence is a time of searching for identity might translate well in the

middle-class culture of the United States, but not as well in cultures where the transition into adulthood coincides with puberty

through rites of passage and where adult roles offer fewer choices.

Learning Theory:

Also known as Behaviorism, this theory is based on the premise that it is not possible to objectively study the mind, and therefore

psychologists should limit their attention to the study of behavior itself. The most famous behaviorist was Burrhus Frederick (B. F.)

Skinner (1904–1990), who expanded the principles of behaviorism and also brought them to the attention of the public at large.

Skinner used the ideas of stimulus and response, along with the application of rewards or reinforcements, to train pigeons and

other animals. In addition, he used the general principles of behaviorism to develop theories about how best to teach children

and how to create societies that were peaceful and productive (Skinner, 1957, 1968, 1972).

The behaviorists made substantial contributions to psychology by identifying the principles of learning. Although the behaviorists

were incorrect in their beliefs that it was not possible to measure thoughts and feelings, their ideas provided new insights

that helped further our understanding regarding the nature-nurture debate as well as the question of free will. The ideas of

behaviorism are fundamental to psychology and have been developed to help us better understand the role of prior experiences

in a variety of areas of psychology.

Social Learning Theory:

Social learning theory, or learning by watching others, was developed by Albert Bandura (1977). His theory calls our attention to

the ways in which many of our actions are not learned through conditioning, as suggested by Skinner. Young children frequently

learn behaviors through imitation. Especially when children do not know what else to do, they learn by modeling or copying the

behavior of others.

Bandura (1986) suggests that there is interplay between the environment and the individual. We are not just the product of our

surroundings; rather, we influence our surroundings. There is interplay between our personality and the way we interpret events

and how they influence us. This concept is called reciprocal determinism. An example of this might be the interplay between

parents and children. Parents not only influence their child's environment, perhaps intentionally through the use of reinforcement,

etc., but children influence parents as well. Parents may respond differently with their first child than with their fourth. Perhaps they

try to be the perfect parents with their firstborn, but by the time their last child comes along they have very different expectations,

both of themselves and their child. Our environment creates us and we create our environment.

Other social influences: TV or not TV? Bandura, Ross and Ross (1963) began a series of studies to look at the impact of television

on the behavior of children. Bandura began by conducting an experiment in which he showed children a film of a woman hitting

an inflatable clown or "bobo" doll. Then the children were allowed in the room, where they found the doll and during their play

they began to hit it. The children also demonstrated novel ways of being aggressive toward the doll that were not demonstrated

by those children who did not see the aggressive model. Bandura's research raised concerns about the impact of violence on

young children. Since then, considerable research has been conducted on the impact of violent media on children's aggression

including playing video games.

14 (1.7.2)Figure . The Bobo Doll. Image source.

Cognitive Theory:

The cognitive theories focus on how our mental processes or cognitions change over time. Three important theories are Jean

Piaget's, Lev Vygotsky's, and Information-processing.

Jean Piaget (1896-1980) was one of the most influential cognitive theorists in development. He was inspired to explore children's

ability to think and reason by watching his own children's development. He was one of the first to recognize and map out the ways

in which children's intelligence differs from that of adults (Piaget, 1929). He became interested in this area when he was asked to

test the IQ of children and began to notice that there was a pattern in their wrong answers. He believed that children's intellectual

skills change over time and that maturation, rather than training, brings about that change. Children of differing ages interpret

the world differently. Piaget theorized that children progressed through four stages of cognitive development (see Table ).

Table . Piaget’s Stages of Cognitive Development.

Stage Approximate

age range

Characteristics Stage attainments

Sensorimotor Birth to

about 2 years

Children experience the world through their fundamental senses of

seeing, hearing, touching, and tasting.

Object permanence

Preoperational 2 to 7 years Children acquire the ability to internally represent the world through

language and mental imagery. They also start to see the world from other

people's perspectives.

Theory of mind; rapid

increase in language

ability

Concrete 7 to 11 years Children become able to think logically. They can increasingly perform

operations on objects that are real.

Conservation

Formal

operational

11 years to

adulthood

Adolescents can think systematically, can understand ethics and

scientific reasoning.

Abstract logic

Piaget has been criticized for overemphasizing the role that physical maturation plays in cognitive development and in

underestimating the role that culture and experience plays. Looking across cultures reveals considerable variation in what

children are able to do at various ages. Research has shown considerable overlap among the four stages and that development is

more continuous.

Lev Vygotsky (1896-1934) was a Russian psychologist who wrote in the early 1900s, but whose work was not discovered by

researchers in the United States until the 1960s and became more widely known in the 1980s (Crain, 2005). His sociocultural

theory emphasizes the importance of culture and interaction in the development of cognitive abilities. Vygotsky differed with

Piaget in that he believed that a person not only has a set of abilities, but also a set of potential abilities that can be realized if

15 (1.7.3)given the proper guidance from others. Vygotsky developed theories on teaching that have been adopted by educators today.

Information Processing is not the work of a single theorist, but based on the ideas and research of several cognitive scientists

studying how individuals perceive, analyze, manipulate, use, and remember information. This approach assumes that humans

gradually improve in their processing skills; that is, cognitive development is continuous rather than stage-like. The more complex

mental skills of adults are built from the primitive abilities of children. We are born with the ability to notice stimuli, store, and

retrieve information. Brain maturation enables advancements in our information processing system. At the same time, interactions

with the environment also aid in our development of more effective strategies for processing information.

Urie Bronfenbrenner (1917-2005) developed the Ecological Systems Theory, which provides a framework for understanding

and studying the many influences on human development (Bronfenbrenner, 1979). Bronfenbrenner recognized that human

interaction is influenced by larger social forces and that an understanding of these forces is essential for understanding an

individual. The individual is impacted by several systems including:

• Microsystem includes the individual's setting and those who have direct, significant contact with the person, such as parents

or siblings. The input of those is modified by the cognitive and biological state of the individual as well. These influence the

person's actions, which in turn influence systems operating on the person.

• Mesosystem includes the larger organizational structures, such as school, the family, or religion. These institutions impact

the microsystems just described. The philosophy of the school system, daily routine, assessment methods, and other

characteristics can affect the child's self-image, growth, sense of accomplishment, and schedule thereby impacting the child,

physically, cognitively, and emotionally.

• Exosystem includes the larger contexts of community. A community's values, history, and economy can impact the

organizational structures it houses. Mesosystems both influence and are influenced by the exosystem.

• Macrosystem includes the cultural elements, such as global economic conditions, war, technological trends, values,

philosophies, and a society's responses to the global community.

• Chronosystem is the historical context in which these experiences occur. This relates to the different generational time

periods previously discussed, such as the baby boomers and millennials.

In sum, a child's experiences are shaped by larger forces, such as the family, schools, religion, culture, and time period.

Bronfenbrenner's model helps us understand all of the different environments that impact each one of us simultaneously. Despite

its comprehensiveness, Bronfenbrenner's ecological system's theory is not easy to use. Taking into consideration all the different

influences makes it difficult to research and determine the impact of all the different variables (Dixon, 2003). Consequently,

psychologists have not fully adopted this approach, although they recognize the importance of the ecology of the individual.

Figure is a model of Bronfenbrenner's Ecological Systems Theory.

Figure . Visual model of Bronfenbrenner's Ecological Systems Theory. Image source.

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16 (1.7.4)1.8: Research Methods

Learning Objectives: Research Methods

• Define the scientific method.

• Compare research methods, noting the advantages and disadvantages of each.

• Explain research involving time spans.

• Explain ways to conduct ethical research.

An important part of learning any science, including psychology, is having a basic knowledge of the techniques used in gathering

information. The hallmark of scientific investigation is that of following a set of procedures designed to keep questioning

or skepticism alive while describing, explaining, or testing any phenomenon. Science involves continuously renewing our

understanding of the subjects in question and an ongoing investigation of how and why events occur. The scientific method is

the set of assumptions, rules, and procedures scientists use to conduct research.

A research design is the specific method a researcher uses to collect, analyze, and interpret data. Psychologists use three

major types of research designs in their research, and each provides an essential avenue for scientific investigation. Descriptive

research is research that describes what is occurring at a particular point in time. Correlational research is research designed

to discover relationships among variables and to allow the prediction of future events from present knowledge. Experimental

research is research in which a researcher manipulates one or more variables to see their effects. Each of the three research

designs varies according to its strengths and limitations.

Descriptive Research

Case Study: Sometimes the data in a descriptive research project are based on only a small set of individuals, often only one

person or a single small group. These research designs are known as case studies, which are descriptive records of one or

a small group of individuals' experiences and behavior. Sometimes case studies involve ordinary individuals. Developmental

psychologist Jean Piaget observed his own children. More frequently, case studies are conducted on individuals who have unusual

or abnormal experiences. The assumption is that by carefully studying these individuals, we can learn something about human

nature. Case studies have a distinct disadvantage in that, although it allows us to get an idea of what is currently happening,

it is usually limited to static pictures. Although descriptions of particular experiences may be interesting, they are not always

transferable to other individuals in similar situations. They are also time-consuming and expensive as many professionals are

involved in gathering the information.

Observations: Another type of descriptive research is known as observation. When using naturalistic observation,

psychologists observe and record behavior that occurs in everyday settings. For instance, a developmental psychologist might

watch children on a playground and describe what they say to each other. However, naturalistic observations do not allow the

researcher to have any control over the environment.

Laboratory observation, unlike the naturalistic observation, is conducted in a setting created by the researcher. This permits

the researcher to control more aspects of the situation. One example of laboratory observation involves a systematic procedure

known as the strange situation test, which you will learn about in Chapter 3. Concerns regarding laboratory observations are

that the participants are aware that they are being watched, and there is no guarantee that the behavior demonstrated in the

laboratory will generalize to the real world.

Survey: In other cases, the data from descriptive research projects come in the form of a survey, which is a measure

administered through either a verbal or written questionnaire to get a picture of the beliefs or behaviors of a sample of people

of interest. The people chosen to participate in the research, known as the sample, are selected to be representative of all

the people that the researcher wishes to know about, called the population. A representative sample would include the same

percentages of males, females, age groups, ethnic groups, and socio-economic groups as the larger population.

17 (1.8.1)Figure . How many surveys have you taken? Image source.

Surveys gather information from many individuals in a short period of time, which is the greatest benefit for surveys. Additionally,

surveys are inexpensive to administer. However, surveys typically yield surface information on a wide variety of factors but may not

allow for in-depth understanding of human behavior. Another problem is that respondents may lie because they want to present

themselves in the most favorable light, known as social desirability. They also may be embarrassed to answer truthfully or are

worried that their results will not be kept confidential. Additionally, questions can be perceived differently than intended.

Interviews: Rather than surveying participants, they can be interviewed, which means they are directly questioned by a

researcher. Interviewing participants on their behaviors or beliefs can solve the problem of misinterpreting the questions posed

on surveys. The examiner can explain the questions and further probe responses for greater clarity and understanding. Although

this can yield more accurate results, interviews take longer and are more expensive to administer than surveys. Participants can

also demonstrate social desirability, which will affect the accuracy of the responses.

Psychophysiological Assessment: Researchers may also record psychophysiological data, such as measures of heart rate,

hormone levels, or brain activity, to help explain development. These measures may be recorded by themselves or in combination

with behavioral data to better understand the bidirectional relations between biology and behavior. Special equipment has

been developed to allow researchers to record the brain activity of very young and very small research subjects. One manner

of understanding associations between brain development and behavioral advances is through the recording of event-related

potentials (ERPs). ERPs are recorded by fitting a research participant with a stretchy cap that contains many small sensors or

electrodes. These electrodes record tiny electrical currents on the scalp of the participant in response to the presentation of

stimuli, such as a picture or a sound.

18 (1.8.2)Figure

.

Special equipment has been developed to allow researchers to record the brain activity of very young research subjects.

Image source.

The use of ERPs has provided important insight as to how infants and children understand the world around them. Webb, Dawson,

Bernier, and Panagiotides (2006) examined face and object processing in children with autism spectrum disorders, those with

developmental delays, and those who were typically developing. The children wore electrode caps and had their brain activity

recorded as they watched still photographs of faces of their mother or of a stranger, and objects, including those that were familiar

or unfamiliar to them. The researchers examined differences in face and object processing by group by observing a component of

the brainwaves. Findings suggest that children with autism are in some way processing faces differently than typically developing

children and those with more general developmental delays.

Secondary/Content Analysis involves analyzing information that has already been collected or examining documents or media

to uncover attitudes, practices or preferences. There are a number of data sets available to those who wish to conduct this type

of research. For example, the U. S. Census Data is available and widely used to look at trends and changes taking place in the

United States. The researcher conducting secondary analysis does not have to recruit subjects, but does need to know the quality

of the information collected in the original study.

Correlational Research

In contrast to descriptive research, which is designed primarily to provide static pictures, correlational research involves the

measurement of two or more relevant variables and an assessment of the relationship between or among those variables. For

instance, the variables of height and weight are systematically related (correlated) because taller people generally weigh more

than shorter people.

The Pearson Correlation Coefficient, symbolized by the letter , is the most common statistical measure of the strength of

linear relationships among variables. The value of the correlation coefficient ranges from to . The strength

of the linear relationship is indexed by the distance of the correlation coefficient from zero (its absolute value). For instance,

is a stronger relationship than , and is a stronger relationship than . The direction of the linear

relationship is indicated by the sign of the correlation coefficient. Positive values of (such as or ) indicate that

the relationship is positive (i.e., the pattern of the dots on the scatter plot runs from the lower left to the upper right), whereas

negative values of (such as or ) indicate negative relationships (i.e., the dots run from the upper left to the

lower right).

When the straight line indicates that individuals who have high values for one variable also tend to have high values for the other

variable, as in part (a) of Figure , the relationship is said to be a positive correlation. Examples of positive correlations

include those between education and income, and between age and mathematical abilities in children. In each case people

who score higher on one of the variables also tend to score higher on the other variable. Negative correlations, in contrast, as

19 (1.8.3)shown in part (b) of Figure , occur when high values for one variable tend to be associated with low values for the other

variable. Examples of negative correlations include those between the age of a child and the number of diapers the child uses,

and between practice and errors made on a learning task. In these cases, people who score higher on one of the variables tend

to score lower on the other variable.

Figure . Some examples of relationships between two variables, as shown in scatterplots.

An important limitation of correlational research designs is that they cannot be used to draw conclusions about the causal

relationships among the measured variables. Consider, for instance, a researcher who has hypothesized that viewing violent

behavior will cause increased aggressive play in children. He has collected, from a sample of fourth-grade children, a measure

of how much violent television each child views during the week, as well as a measure of how aggressively each child plays. The

researcher discovers a positive correlation between the two measured variables. Although this positive correlation appears to

support the hypothesis, it cannot be taken to indicate that viewing violent television causes aggressive behavior as there are

other possible explanations. One alternative is that children who behaved aggressively at school want to watch violent television

shows. Still another possible explanation for the observed correlation is that it has been produced by the presence of a third

variable.

A third variable is a variable that is not part of the research hypothesis but produces the observed correlation between them.

In our example a potential third variable is the discipline style of the children's parents. Parents who use a harsh and punitive

discipline style may produce children who both like to watch violent television and who behave aggressively in comparison to

children whose parents use less harsh discipline.

20 (1.8.4)Figure . The discipline style of a child's parents may act as a third variable to the observed correlational variables of viewing violent TV

and aggressive play.

For this reason, we are left with the basic limitation of correlational research: Correlation does not demonstrate causation! It

is important that when you read about correlational research projects, you keep in mind the possibility of third variables.

Strengths and limitations: Correlational research can be used when experimental research is not possible because the variables

cannot be manipulated or it would be unethical to use an experiment. Correlational designs also have the advantage of allowing

the researcher to study behavior as it occurs in everyday life. We can also use correlational designs to make predictions. For

instance, we can predict from the scores on a battery of tests the success of job trainees during a training session. However, we

cannot use such correlational information to determine whether one variable caused another variable. For that, researchers rely

on an experiment.

Experimental Research

The goal of the experimental method is to provide more definitive conclusions about the causal relationships among the variables

in a research hypothesis than what is available from correlational research. Experiments are designed to test hypotheses, or

specific statements about the relationship between variables. Experiments are conducted in a controlled setting in an effort

to explain how certain factors or events produce outcomes. A variable is anything that changes in value. In the experimental

research design, the variables of interest are called the independent variable and the dependent variable. The independent

variable in an experiment is the causing variable that is created or manipulated by the experimenter. The dependent variable

in an experiment is a measured variable that is expected to be influenced by the experimental manipulation.

A good experiment randomly assigns participants to at least two groups that are compared. The experimental group receives

the treatment under investigation, while the control group does not receive the treatment the experimenter is studying as a

comparison. For instance, to assess whether violent TV affects aggressive behavior the experimental group might view a violent

television show, while the control group watches a non-violent show. Additionally, experimental designs control for extraneous

variables, or variables that are not part of the experiment that could inadvertently affect either the experimental or control group,

thus distorting the results.

Despite the advantage of determining causation, experiments do have limitations. One is that they are often conducted in

laboratory situations rather than in the everyday lives of people. Therefore, we do not know whether results that we find in a

laboratory setting will necessarily hold up in everyday life. Second, and more important, is that some of the most interesting and

key social variables cannot be experimentally manipulated because of ethical concerns. If we want to study the influence of abuse

on children's development of depression, these relationships must be assessed using correlational designs because it is simply

not ethical to experimentally manipulate these variables. Characteristics of descriptive, correlational, and experimental research

designs can be found in Table .

21 (1.8.5)Table . Characteristics of the Three Research Designs.

Research

Design

Goal Advantages Disadvantages

Descriptive To create a snapshot of the

current state of affairs

Provides a relatively complete picture of what

is occurring at a given time. Allows the

development of questions for further study.

Does not assess relationships

among variables. May be unethical

if participants do not know they

are being observed.

Correlational To assess the relationships

between and among two or

more variables

Allows testing of expected relationships

between and among variables and the making

of predictions. Can assess these relationships

in everyday life events.

Cannot be used to draw inferences

about the causal relationships

between and among the variables.

Experimental To assess the causal impact

of one or more experimental

manipulations on a

dependent variable

Allows drawing of conclusions about the

causal relationships among variables.

Cannot experimentally manipulate

many important variables. May be

expensive and time-consuming.

Source: Stangor, C. (2011). Research methods for the behavioral sciences (4th ed.). Mountain View, CA: Cengage.

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22 (1.8.6)1.9: Research Involving Time-Spans

Cross-sectional research compares samples that represent a cross-section of the population who vary in age. Participants

might be asked to complete a survey or take a test of some physical or cognitive skill. The attitudes or skill levels based on age

are compared. In cross-sectional research, respondents are measured only once, and consequently this method is not expensive

or time consuming. In addition, because participants are only tested at one point in time, practice effects are not an issue as

children do not have the opportunity to become better at the task over time. There is also no need to keep in contact with, or

follow-up with, participants over time.

Figure . An example of cross-sectional research design. Image source.

However, cross-sectional research does not allow the researcher to look at the impact of having been born in a certain time-

period, which is known as the cohort effect. For example, those born during the Great Depression have very different views about

and experiences with the Internet than those born in the last twenty years. Different attitudes about the Internet, for example,

might not be due to a person's biological age as much as their life experiences as members of a cohort.

Longitudinal research involves studying a group of people who are the same age, and measuring them repeatedly over a period

of time. This type of design allows researchers to study individual differences in development. Longitudinal studies may be

conducted over the short term, such as a span of months, or over much longer durations including years or decades. For these

reasons, longitudinal research designs are optimal for studying stability and change over time.

Figure . An example of longitudinal research design. Image source.

Problems with longitudinal research include being very time-consuming and expensive. Researchers must maintain continued

contact with participants over time, and these studies necessitate that scientists have funding to conduct their work over

extended durations. An additional risk is attrition. Attrition occurs when participants fail to complete all portions of a study.

Participants may move, change their phone numbers, or simply become disinterested in participating over time. Researchers

should account for the possibility of attrition by enrolling a larger sample into their study initially, as some participants will likely

23 (1.9.1)drop out over time. Even with a large sample size, the experimenter never knows if there was something different about the

individuals who dropped out versus those that remained in the study.

The results from longitudinal studies may also be impacted by repeated assessments. Consider how well you would do on a

math test if you were given the exact same exam every day for a week. Your performance would likely improve over time not

necessarily because you developed better math abilities, but because you were continuously practicing the same math problems.

This phenomenon is known as a practice effect. Practice effects occur when participants become better at a task over time

because they have done it again and again, not due to natural psychological development.

Sequential research includes elements of both longitudinal and cross-sectional research designs. Similar to longitudinal

designs, sequential research features participants who are followed over time; similar to cross-sectional designs, sequential work

includes participants of different ages. This research design is also distinct from those that have been discussed previously in

that individuals of different ages are enrolled into a study at various points in time to examine age-related changes, development

within the same individuals as they age, and account for the possibility of cohort effects.

Figure . An example of sequential research design. Image source.

For example, in a study with a sequential design, a researcher might enroll three separate groups of children (Groups A, B, and

C). Children in Group A would be enrolled when they are 2 years old and would be tested again when they are 4 and 6 years

old. This is similar in design to the longitudinal study described previously. Children in Group B would also be enrolled when

they are 2 years old, but this would occur two years later when Group A is now 4 years old. Finally, children in Group C would be

enrolled when they are 2 years old and Group A is now 6 and Group B is now 4. At this time, the children would represent a cross-

sectional design (2, 4, and 6 years of age). Further, along the diagonal children of the same age can be compared to determine if

cohort effects are evident. Sequential designs are appealing because they allow researchers to learn a lot about development in

a relatively short amount of time.

Because they include elements of longitudinal and cross-sectional designs, sequential research has many of the same strengths

and limitations as these other approaches. For example, sequential work may require less time and effort than longitudinal

research, but more time and effort than cross-sectional research. Although practice effects may be an issue if participants

are asked to complete the same tasks or assessments over time, attrition may be less problematic than what is commonly

experienced in longitudinal research since participants may not have to remain involved in the study for such a long period-of-

time. Table identifies advantages and disadvantages for each of the described time span research designs.

24 (1.9.2)Table . Time Span Research Designs Advantages and Disadvantages.

Advantages Disadvantages

Longitudinal

• Examines changes within individuals over time

• Provides a developmental analysis

• Expensive

• Takes a long time

• Participant attrition

• Possibility of practice

effects

• Cannot examine cohort

effects

Cross-

sectional • Examines changes between participants of different ages at the same

point in time

• Provide information on age-related change

• Cannot examine change

over time

• Cannot examine cohort

effects

Sequential

• Examines changes within individuals over time

• Examines changes between participants of different ages at the same

point in time

• Can be used to examine cohort effects

• May be expensive

• Possibility of practice

effects

Source

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25 (1.9.3)1.10: Conducting Ethical Research

One of the issues that all scientists must address concerns the ethics of their research. Research in psychology may cause

some stress, harm, or inconvenience for the people who participate in that research. Psychologists may induce stress, anxiety, or

negative moods in their participants, expose them to weak electrical shocks, or convince them to behave in ways that violate their

moral standards. Additionally, researchers may sometimes use animals, potentially harming them in the process.

Decisions about whether research is ethical are made using established ethical codes developed by scientific organizations, such

as the American Psychological Association, and federal governments. In the United States, the Department of Health and Human

Services provides the guidelines for ethical standards in research. The following are the American Psychological Association code

of ethics when using humans in research (APA, 2016).

• No Harm: The most direct ethical concern of the scientist is to prevent harm to the research participants.

• Informed Consent: Researchers must obtain informed consent, which explains as much as possible about the true nature

of the study, particularly everything that might be expected to influence willingness to participate. Participants can withdraw

their consent to participate at any point.

Infants and young children cannot verbally indicate their willingness to participate, much less understand the balance of

potential risks and benefits. As such, researchers are oftentimes required to obtain written informed consent from the parent

or legal guardian of the child participant. Further, this adult is almost always present as the study is conducted. Children

are not asked to indicate whether they would like to be involved in a study until they are approximately seven years old.

Because infants and young children also cannot easily indicate if they would like to discontinue their participation in a

study, researchers must be sensitive to changes in the state of the participant, such as determining whether a child is too

tired or upset to continue, as well as to what the parent desires. In some cases, parents might want to discontinue their

involvement in the research. As in adult studies, researchers must always strive to protect the rights and wellbeing of the

minor participants and their parents when conducting developmental research.

• Confidentiality: Researchers must also protect the privacy of the research participants' responses by not using names or

other information that could identify the participants.

• Deception: Deception occurs whenever research participants are not completely and fully informed about the nature of the

research project before participating in it. Deception may occur when the researcher tells the participants that a study is

about one thing when in fact it is about something else, or when participants are not told about the hypothesis.

• Debriefing: At the end of a study debriefing, which is a procedure designed to fully explain the purposes and procedures of

the research and remove any harmful aftereffects of participation, must occur.

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26 (1.10.1)1.C: COVID-19 Impact on Lifespan Development

Coronaviruses are a large family of viruses that are known to cause illness ranging from the common cold to more severe

diseases such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) (CDC, 2021).

Coronavirus Disease 2019 (COVID-19) is a new strain of coronavirus that had not been previously identified in humans. The

COVID-19 virus spreads primarily through droplets of saliva or discharge from the nose when an infected person coughs or

sneezes.

COVID-19 has dominated the world's attention since it was first declared a public health emergency by the World Health

Organization (WHO) on January 31, 2020 (AJMC Staff, 2021). Three days later on February 3, the United States also declared a

public health emergency as more than 9800 cases of the virus and 200 plus deaths had been confirmed worldwide. By March 11,

2020, WHO declared COVID-19 a pandemic due to the severity of the outbreak and how quickly it was spreading. Subsequently,

on March the United States declared COVID-19 a national emergency, and billions of dollars in federal funding were released

to fight the spread of the disease. California became the first state to issue a stay-at-home order on March , which mandated

that all residents stay at home except to go to an essential job or shop for essential needs. Other states quickly followed, and

Illinois issued the stay-at-home order on March 21, 2020. The impact of COVID-19 on lifespan development has been significant,

and consequently each chapter will address important effects on the age range highlighted.

Life Expectancy: As stated at the beginning of this chapter, life expectancy refers to the predicted number of years a person

born in a particular time period can reasonably expect to live. Due to COVID's impact, the National Center for Health Statistics

(NCHS) for the first time released provisional vital statistics data for the months January through June 2020 to determine current

life expectancy (Arias et al., 2021). Mortality data included over 99% of the deaths that occurred during these 6 months. Results

indicated that life expectancy at birth for the entire U.S. population declined 1.0 years from 78.8 years in 2019 to 77.8 years

in 2020. For males, life expectancy was 75.1 years and declined 1.2 years from 2019, while females' life expectancy was 80.5

years and declined 0.9 years from 2019. Comparing Hispanic (1.9 years decline), non-Hispanic black (2.7 years decline), and non-

Hispanic white (0.8 years decline) populations demonstrated worsening life expectancies for racial and ethnic minorities. Reasons

for these gender and ethnic differences in life expectancy will be explored in subsequent chapters.

Figure . Changes in life expectancies due to COVID-19, based on ethnicity.

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