PS275 COURSE REVIEW
CHAPTER 1: HISTORY, THEORY AND APPLIED DIRECTIONS
child development: an area of study devoted to understanding constancy and
change from conception through adolescence. Child development is part of a larger,
interdisciplinary field known as Developmental science, which includes all
changes we experience throughout the lifespan
Common goal of all researchers: to describe and identify those factors that
influence the consistencies and changes in young people during the first two
decades of life
Each question in child psychology has scientific, applied and practical importance.
Research about development has been stimulated by social pressures to better the
lives of childen.
Child psychology is interdisciplinary because it has grown through the combined
efforts of people from many fields.
Developmental is often divided into three broad domains: physical, cognitive
and emotional and social.
Physical development: changes in body size, proportions, appearance,
functioning of body systems, perceptual and motor capacities and physical health
Cognitive development: changes in intellectual abilities, including attention
memory, academic and everyday knowledge, problem solving, imagination,
creativity and language
Emotional and social development: changes in emotional communication, self
understanding, knowledge about other people, interpersonal skills, friendships,
intimate relationships, and more reasoning and behaviour
Researchers usually use the following age periods, as each brings new capacities
and social expectations that serve as important transitions in major theories:
1. The prenatal period: from conception to birth. In this nine- month period, the
most rapid time of change, a one- celled organism is transformed into a human
baby with remark-able capacities for adjusting to life in the surrounding world.
2. Infancy and toddlerhood: from birth to 2 years. This period brings dramatic
changes in the body and brain that support the emergence of a wide array of
motor, perceptual, and intellectual capacities; the beginnings of language; and first
intimate ties to others. Infancy spans the first year; toddlerhood spans the second,
during which children take their first independent steps, marking a shift to greater
autonomy. 3. Early childhood: from 2 to 6 years. The body becomes longer and leaner,
motor skills are refined, and children become more self- controlled and self-
sufficient. Make- believe play blossoms, supporting every aspect of psychological
development. Thought and language expand at an astounding pace, a sense of
morality becomes evident, and children establish ties with peers.
4. Middle childhood: from 6 to 11 years. Children learn about the wider world
and master new responsibilities that increasingly resemble those they will perform
as adults. Hallmarks of this period are improved athletic abilities, participation in
organized games with rules, more logical thought processes, mastery of basic
literacy skills, and advances in self- understanding, morality, and friendship.
5. Adolescence: from 11 to 18 years. This period initiates the transition to
adulthood. Puberty leads to an adult- sized body and sexual maturity. Thought
becomes abstract and idealistic, and schooling is increasingly directed toward
preparation for higher education and the world of work. Young people begin to
establish autonomy from the family and define personal values and goals.
For many contemporary youths in industrialized nations, the transition to adult
roles has become increasingly prolonged— so much so that some researchers have
posited a new period of development called:
6. emerging adulthood: which spans ages 18 to 25. Although emerging adults
have moved beyond adolescence, they have not yet fully assumed adult roles.
Rather, during higher edu-cation and sometimes beyond, these young people
intensify their exploration of options in love, career, and personal values before
making enduring commitments.
Research on child development did not begin until the late nineteenth and early
twentieth centuries. But ideas about how children grow and change have a much
A theory is an orderly, integrated set of statements that describes, explains, and
Theories are vital tools for two reasons. First, they provide organizing
frameworks for our observations of children. In other words, they guide and give
meaning to what we see. Second, theories that are verified by research often serve
as a sound basis for practical action. Once a theory helps us understand
development, we are in a much better position to know how to improve the welfare
and treatment of children.
A theory’s continued existence depends on scientific verification. In other
words, every theory must be tested using a fair set of research procedures agreed
on by the scientific community, and its findings must endure, or be replicated over
Although there are many theories, we can easily organize them by looking at the stand they take on three basic issues: ( 1) Is the course of development continuous
or discontinuous? ( 2) Does one course of development characterize all children, or
are there many possible courses? ( 3) Are genetic or environmental factors more
important in influencing development?
Continuous or discontinuous development
continuous— a process of gradually add-ing more of the same types of skills that
were there to begin with. Infants and preschoolers respond to the world in much
the same way adults do. The difference between the immature and mature being is
simply one of amount or complexity.
discontinuous— a process in which new ways of understanding and responding to
the world emerge at specific times. From this perspective, Angelo is not yet able to
organize objects or remember and interpret experiences as we do. Instead, he will
move through a series of developmental steps, each with unique features, until he
reaches the highest level of functioning.
Is development continuous or discontinuous? ( a) Some theorists believe that
development is a smooth, continuous process. Children gradually add more of the
same types of skills. ( b) Other theorists think that development takes place in
discontinuous stages. Children change rapidly as they step up to a new level of
development and then change very little for a while. With each step, the child
interprets and responds to the world in a qualitatively different way.
Theories that accept the discontinuous perspective regard development as taking
place in stages— qualitative changes in thinking, feeling, and behaving that
characterize specific periods of development. In stage theories, development is
much like climbing a staircase, with each step corresponding to a more mature,
reorganized way of functioning. The stage concept also assumes that children
undergo periods of rapid transformation as they step up from one stage to the next,
alternating with plateaus during which they stand solidly within a stage.
Stage theorists assume that people everywhere follow the same sequence of
Nature Vs. Nurture
Are genetic or environmental factors more important in influencing development?
This is the age- old nature– nurture controversy. By nature, we mean inborn
biological givens— the hereditary information we receive from our parents at the
moment of conception. By nurture, we mean the complex forces of the physical and
social world that influence our biological makeup and psychological experiences
before and after birth.
Some theorists emphasize stability— that children who are high or low in a
characteristic ( such as verbal ability, anxiety, or sociability) will remain so at later
ages. These theorists typically stress the importance of heredity. If they regard environment as important, they usually point to early experiences as establishing a
lifelong pattern of behaviour. Powerful negative events in the first few years, they
argue, cannot be fully overcome by later, more positive ones
Other theorists, taking a more optimistic view, emphasize that change is possible
and even likely if new experiences support it
Biology and Environment
resilience— the ability to adapt effectively in the face of threats to
development— is receiving increasing attention as investigators look for ways to
protect young people from the damaging effects of stressful life conditions
A child’s biologically endowed characteristics can reduce exposure to risk or
lead to experiences that compensate for early stressful events. High intelligence
and socially valued talents ( in music or athletics, for example) increase the
chances that a child will have rewarding experiences in school and in the
community that offset the impact of a stressful home life
Temperament is particularly powerful. Children who have easygoing, sociable
dispositions and who can readily inhibit negative emotions and impulses tend to
have an optimistic outlook on life and a special capacity to adapt to change—
qualities that elicit positive responses from others. In contrast, emotionally reactive
and irritable children often tax the patience of people around them
A close relationship with at least one parent who provides warmth,
appropriately high expectations, monitoring of the child’s activities, and an
organized home environment fosters resilience
The most consistent asset of resilient children is a strong bond with a
competent, caring adult.
Community supports— good schools, convenient and affordable health care and
social services, libraries, and recreation centers— foster both parents’ and
children’s well- being. In addition, opportunities to participate in community life
help older children and adolescents overcome adversity.
Contemporary theories of child development are the result of centuries of change
in Western cultural values, philosophical thinking about children, and scientific
Historical artifacts and writings show that childhood was regarded as a separate
period of life as early as medieval Europe— the sixth through the fifteenth
centuries. Medieval painters often depicted children wearing loose, comfortable
gowns, playing games, and looking up to adults. Written texts contained terms that
distinguished children under age 7 or 8 from other people and that recognized even
young teenagers as not fully mature. By the fourteenth cen-tury, manuals offering
advice on many aspects of child care, including health, feeding, cloth-ing, and games, were common. Laws recognized that children needed protection from
people who might mistreat them, and courts exercised leniency with lawbreaking
youths because of their tender years. In sum, in medieval times, if not before, clear
awareness existed of children as vulnerable beings.
In the sixteenth century, the Puritan belief in original sin gave rise to the view that
children were born evil and stubborn and had to be civilized. Harsh, restrictive
child- rearing practices were recommended to tame the depraved child. Children
were dressed in stiff, uncomfortable clothing that held them in adultlike postures,
and dis-obedient students were routinely beaten by their schoolmasters. The
Puritans were the first to devise special reading materials for children that
instructed them in religious and moral ideals.
The Philosophies of the Enlightenment
The seventeenth- century Enlightenment brought new philosophies that emphasized
ideals of human dignity and respect. Conceptions of childhood were more humane
than those of the past.
John Locke viewed the child as a tabula rasa— Latin for “ blank slate.”
According to this idea, children begin as nothing at all; their characters are
shaped entirely by experience. Locke saw parents as rational tutors who can mold
the child in any way they wish through care-ful instruction, effective example, and
rewards for good behaviour. He was ahead of his time in recommending child-
rearing practices that present- day research supports— for example, the use of
praise and approval as rewards, rather than money or sweets. He also opposed
physical punishment: “ Locke’s philosophy led to a change from harshness toward
children to kindness and compassion. He viewed development as continuous. His
view of the child as a tabula rasa led him to champion nurture— the power of the
environment to shape the child. And his faith in nurture suggests the possibility of
many courses of development and of change at later ages due to new
experiences. Finally, Locke’s philosophy characterizes children as doing little to
influence their own destiny, which is written on “ blank slates” by others.
Jean Rousseau introduced a new view of childhood. He claimed, are not blank
slates and empty containers to be filled by adult instruction. Instead, they are
noble savages, naturally endowed with a sense of right and wrong and with an
innate plan for orderly, healthy growth. Unlike Locke, Rousseau believed that
children’s built-in moral sense and unique ways of thinking and feeling would only
be harmed by adult training. His was a child- centered philosophy in which adults
should be receptive to the child’s needs at each of four stages: infancy, childhood,
late childhood, and adolescence.
Rousseau’s philosophy includes two influential concepts. The first is the concept
of stage, which we discussed earlier. The second is the concept of maturation,
which refers to a genetically determined, naturally unfolding course of growth. He viewed development as a discontinuous, stagewise process that follows a single,
unified course mapped out by nature.
The study of child development evolved quickly in the late nineteenth and early
Darwin's theory of evolution:
The theory emphasized two related principles: natural selection and survival of
the fittest. Darwin explained that certain species survive in particular parts of the
world because they have characteristics that fit with, or are adapted to, their
-scientific child study was born through darwins study
-early recordings of child studies were emotionally invested and the recorders often
did not know what they were looking for
G Stanley Hall is regarded as the founder of the child study movement. He
regarded child development as a maturational process— a genetically deter-mined
series of events that unfold automatically, much like a flower
Alfred Binet took a normative approach to studying child development. In 1916, at
Stanford University, Binet’s test was adapted for use with English- speaking
children. Since then, the English version has been known as the Stanford- Binet
Intelligence Scale. Besides providing a score that could successfully predict school
achievement, the Binet test sparked tremendous interest in individual differences in
James Mark Baldwin: He believed that children’s understanding of their physical
and social worlds develops through a sequence of stages, beginning with the
simplest behaviour patterns of the newborn infant and concluding with the adult’s
capacity to think abstractly and reflectively. He granted nature and nurture equal
importance. Children, he argued, actively revise their ways of thinking about the
world, but they also learn through habit, or by copying others’ behaviours. As
development proceeds, the child and her social surroundings influence each other,
forming an inseparable, interwoven network.
Mid 20th Century Theories
-mid 20th century the child development field expanded into a legitimate field
- The Society for Research in Child Development (SRCD) was stabled in 1933
The Psychoanalytic Perspective:
- In the 1930s-40s parents were seeking professional help in dealing with children's
According to the psychoanalytic perspective- children move through a series of stages in which they confront conflicts between biological drives and social
expectations. How these conflicts are resolved determines the person's ability to
learn, to get along with others and to cope with anxiety.
Freud's psychosexual theory- this emphasizes how parents manage their chid's
sexual aggressive drive in the first few years is crucial for healthy personality
development. His theory consisted of three parts: id, ego, and superego. The id is
the largest portion of the mind, is the source of biological needs and desires. The
ego, the conscious, rational part of personality, emerges early in infancy to redirect
the id's impulses so they are discharged in acceptable ways. Between 3-6 years the
superego, or conscience develops through interactions with parents, who insists
that children conform to the values of society. According to Freud, the relations
established between the id, ego and superego during the preschool years
determine the individual's basic personality.
Erickson's theory: expanded Freud's theory at each stage.
In his psychosocial theory, Erikson emphasized that in addition to mediating
between id impulses and superego demands, the ego makes a positive contribu-tion
to development, acquiring attitudes and skills at each stage that make the
individual an active, contributing member of society. Unlike Freud, Erikson pointed
out that normal development must be understood in relation to each culture’s life
situation. He was the first to recognize the lifespan nature of development
His stages include:
Basic trust- mistrust: 0-1
Autonomy- shame: 1-3
Initiative- guilt: 3-6
Industry- inferiority: 6-11
Identity- confusion: adolescence
Intimacy-isolation: young adult
Generativity- stagnation: middle adult
Integrity- despair: old age
Strengths of Psychoanalytic perspective:
- the emphasis on the individual's unique life history as worthy of study and
-accepts the clinical, case study or method which synthesizes information from a
variety of sources into a detailed picture of the personality of a single child
-they failed to consider other methods
-subjects are so vague they are difficult or impossible to test
Behaviourism and Social Leaning Theory
According to behaviourism, directly observable events— stimuli and
responses— are the appropriate focus of study. North American behaviourism
began in the early twentieth century with the work of psychologist John Watson ( 1878– 1958), who, rejecting the psychoanalytic concern with the unseen workings
of the mind, set out to create an objective science of psychology. Watson concluded
that environment is the supreme force in development and that adults can
mold children’s behaviour by carefully con-trolling stimulus– response
associations. He viewed development as a continuous process, consisting of a
gradual increase with age in the number and strength of these associations.
Another form of behaviourism was American psychologist B. F. Skinner’s ( 1904–
1990) operant conditioning theory. According to Skinner, the frequency of a
behaviour can be increased by following it with a wide variety of
reinforcers— food, drink, praise, a friendly smile, or a new toy— or decreased
through punishment, such as disapproval or withdrawal of privileges.
Observational learning- Albert Bandura: what a child sees a child does
The most recent revision of Bandura’s ( 1992, 2001) theory places such strong
emphasis on how children think about themselves and other people that he calls it
a social-cognitive rather than a social learning approach. From watching
others engage in self- praise and self- blame and through feedback about the worth
of their own actions, children develop personal standards for behaviour and a sense
of self- efficacy— the belief that their own abilities and characteristics will help
Contributions and Limitations
Behaviour modification consists of procedures that combine conditioning and
modelling to eliminate undesirable behaviours and increase desirable responses.
Limitations: offers to narrow a view of important environmental influences. These
extend beyond immediate reinforcements, punishments and modelled behaviours to
children's rich physical and social worlds.
-It also underestimates children's contributions to their own learning
Piaget's cognitive developmental theory
Piaget did not believe that children’s learning depends on reinforcers, such
as rewards from adults. According to his cognitive- developmental theory,
children actively construct knowledge as they manipulate and explore their world.
Sensorimotor Birth– 2 years: Infants “ think” by acting on the world with their
eyes, ears, hands, and mouth. As a result, they invent ways of solving sensorimotor
problems, such as pulling a lever to hear the sound of a music box, finding hidden
toys, and putting objects into and taking them out of containers.
Preoperational 2– 7 years: Preschool children use symbols to represent their
earlier sensori-motor discoveries. Development of language and make- believe play
takes place. However, thinking lacks the logic of the two remaining stages. Concrete operational 7– 11 years: Children’s reasoning becomes logical and
better organized. School- age children understand that a certain amount of
lemonade or play dough remains the same even after its appearance changes. They
also organize objects into hierarchies of classes and subclasses. However, thinking
falls short of adult intelligence. It is not yet abstract.
Formal operational 11 years on: The capacity for abstract, systematic thinking
enables adolescents, when faced with a problem, to start with a hypothesis, deduce
testable inferences, and isolate and combine variables to see which inferences are
confirmed. Adolescents can also evaluate the logic of verbal statements without
referring to real- world circumstances.
Contributions and Limitations:
Piaget’s theory encouraged the development of educational philosophies and
programs that emphasize children’s discovery learning and direct contact with the
Research indicates that Piaget underestimated the competencies of infants and
Recent Theoretical Perspectives
Information processing: the human mind might also be viewed as a symbol-
manipulating system through which information flows— a perspective called
information processing. From the time information is presented to the senses at
input until it emerges as a behavioural response at output, information is actively
coded, transformed, and organized. Information- processing researchers often use
flow-charts to map the precise steps individuals use to solve problems and
complete tasks, much like the plans devised by programmers to get computers to
perform a series of “ mental operations”. Like Piaget’s theory, the information-
processing approach views children as actively making sense of their experiences
and as modifying their own thinking in response to environ-mental demands. But
unlike Piaget’s theory, it does not divide development into stages. Rather, the
thought processes studied— perception, attention, memory, categorization of
information, planning, problem solving, and comprehension of written and spoken
prose— are regarded as similar at all ages but present to a lesser or greater extent.
Therefore, the view of development is one of continuous change.
developmental cognitive neuroscience: It brings together researchers from
psychology, biology, neuroscience, and medicine to study the relationship between
changes in the brain and the developing child’s cognitive processing and behaviour
Ethology is concerned with the adaptive, or survival, value of behaviour and its
evolutionary history. Its roots can be traced to the work of Darwin. Imprinting:
the early following behaviour of certain baby birds, such as geese, which ensures that the young will stay close to the mother and be fed and protected from danger.
Imprinting takes place during an early, restricted period of development.
A sensitive period is a time that is optimal for certain capacities to emerge and in
which the individual is especially responsive to environmental influences. However,
its boundaries are less well- defined than those of a critical period. Development
can occur later, but it is harder to induce.
John Bowlby ( 1969) applied ethological theory to the understanding of the
human infant– caregiver relationship. He argued that infant smiling,
babbling, grasping, and crying are built- in social signals that encourage
the caregiver to approach, care for, and interact with the baby. By keeping
the parent near, these behaviours help ensure that the infant will be fed, protected
from danger, and provided with stimulation and affection necessary for healthy
evolutionary developmental psychology: seeks to understand the adaptive
value of species- wide cognitive, emotional, and social competencies as those
competencies change with age
Vygotsky’s perspective, known as sociocultural theory, focuses on how culture
— the values, beliefs, customs, and skills of a social group— is transmitted to the
next generation. According to Vygotsky, social interaction— in particular,
cooperative dialogues between children and more knowledgeable members of
society— is necessary for children to acquire the ways of thinking and behaving that
make up a community’s culture. Vygotsky believed that as adults and more- expert
peers help children master culturally meaningful activities, the communication
between them becomes part of children’s thinking. Vygotsky agreed with Piaget
that children are active, constructive beings. But whereas Piaget emphasized
children’s independent efforts to make sense of their world, Vygotsky viewed
cognitive development as a socially mediated process, in which children depend on
assistance from adults and more- expert peers as they tackle new challenges.
Urie Bronfenbrenner- Ecological systems theory: views the child as developing
within a complex system of relationships affected by multiple levels of the
surrounding environment. Because the child’s biologically influenced dispositions
join with environmental forces to mould development, Bronfenbrenner recently
characterized his perspective as a bio-ecological model.
all relationships are bidirectional: Adults affect children’s behavior, but children’s
biologically and socially influenced characteristics— their physical attributes,
personalities, and capacities— also affect adults’ behavior.
Different levels of this model include:
The innermost level of the environment, the microsystem, consists of activities
and interaction patterns in the child’s immediate surroundings.
The second level of Bronfenbrenner’s model, the mesosystem, encompasses connections between microsystems, such as home, school, neighborhood, and
child- care center.
The exosystem consists of social settings that do not contain children but that
nevertheless affect children’s experiences in imme-diate settings.
The microsystem concerns relations between the child and the immediate
environment; the mesosystem, connections among immediate settings; the
exosystem, social settings that affect but do not contain the child; and the
macrosystem, the values, laws, customs, and resources of the culture that affect
activities and interactions at all inner layers. The chrono-system is not a specific
context. Instead, it refers to the dynamic, ever- changing nature of the person’s
The macrosystem consists of cultural values, laws, customs, and resources.
Rather than envisioning a single line of stagewise or continuous change, dynamic
systems theorists conceive of development as a web of fibers branching out in
many directions. Each strand in the web represents a skill within the major
domains of development— physical, cognitive, and emotional/ social. The
differing directions of the strands signify possible variations in paths and outcomes
as the child masters skills necessary to participate in diverse contexts. The
interconnections of the strands at each row of “ hills” portray stagelike changes—
periods of major transformation in which various skills work together as a
functioning whole. As the web expands, skills become more numerous, complex,
dynamic systems perspective: According to this view, the child’s mind, body,
and physical and social worlds form an integrated system that guides mastery of
new skills. The system is dynamic, or constantly in motion. A change in any part of
it— from brain growth to physical and social surroundings— disrupts the current
organism– environment relation-ship. When this happens, the child actively
reorganizes her behavior so the components of the system work together again but
in a more complex, effective way
The dynamic systems perspective views the child’s mind, body, and
physical and social worlds as a continually reorganizing, integrated
system. A change in any part of the system disrupts the current organism–
environment relationship. As he experiences the physical, cognitive, and emotional
changes of early adolescence, this boy and his father must devise new, more
mature ways of relating to one another.
First, they focus on different domains of development. Some, such as the
psychoanalytic perspective and ethology, emphasize emotional and social
development. Others, such as Piaget’s cognitive- developmental theory, information
processing, and Vygotsky’s sociocultural theory, stress changes in thinking. The
remaining approaches— behaviorism, social learning theory, evolutionary developmental psychology, ecological systems theory, and the dynamic systems
perspective— discuss many aspects of children’s functioning. Second, every
theory contains a point of view about child development.
Read page 31 for comparison of all theories
Child development and Social Policy
Social policy is any planned set of actions by a group, institution, or governing
body directed at attaining a social goal. When widespread social problems arise,
nations attempt to solve them through a special type of social policy called public
policy— laws and govern-ment programs aimed at improving current conditions.
Chapter 2: Research Strategies
Research usually begins with a prediction drawn from a theory, called a
Why learn about research strategies:
There are two reasons. First, each of us must be a wise and critical consumer of
knowledge. Knowing the strengths and limitations of var-ious research strategies is
important in separating dependable information from misleading results. Second,
individuals who work directly with children may be in a unique position to build
bridges between research and practice by conducting studies, either on their own or
in partnership with experienced investigators.
How does a researcher choose a basic approach to gathering information
about children? Common methods include systematic observation, self- reports
(such as questionnaires and interviews), clinical or case studies of a single child,
and ethnographies of the life circumstances of a specific group of children.
One approach is to go into the field, or natural environment, and record the
behavior of interest— a method called naturalistic observation. This is the
observation of behaviour in natural contexts
Naturalistic observation also has a major limitation: Not all children have the
same opportunity to display a particular behavior in everyday life.
Structured observation: Observation of behavior in a laboratory, where
conditions are the same for all participants
event sampling: the observer records all instances of a particular behavior during
a specified time period.
time sampling: In this procedure, the researcher records whether certain
behaviors occur during a sample of short intervals.
A major problem with systematic observation is observer influence— the effects of the observer on the behavior studied.
To Minimize this:
-researchers have observers visit the research setting so participants get use to
-asks an individual who is part of child's environment to do observing
Another serious danger is observer bias. When observers are aware of the
purposes of a study, they may see and record what they expect to see rather than
what participants actually do.
-finally systematic observation does not explain underlying reasons for
Clinical interview: Flexible interviewing procedure in which the investigator
obtains a complete account of the participant’s thoughts
The clinical interview has two major strengths. First, it permits people to
display their thoughts in terms that are as close as possible to the way they think in
everyday life. Second, the clinical interview can provide a large amount of
information in a fairly brief period.
Weaknesses: People report more favourably about instances, and sometimes do
not understand question. The questions are also flexible so one question may evoke
one answer but another may evoke a different answer.
Structured interview, questionnaires, and tests: Self- report instruments in
which each participant is asked the same questions in the same way. Structured
interviews do not yield the same depth of information as a clinical
interview. And they can still be affected by the problem of inaccurate
Psychophysiological Methods: Methods that measure the relationship between
physiological processes and behavior. Investigators who rely on these methods
want to find out which central nervous system structures contribute to
development and individual differences. Psychophysiological methods also help
investigators infer the perceptions, thoughts, and emotions of infants and young
children, who cannot report their psychological experiences clearly.
In preparing for an EEG, a researcher applies gel to electrodes before attaching
them to a baby’s scalp. This method records the stability and organization of
electrical brain-wave activity in the cerebral cortex. It can also be used to measure
ERPs, the frequency and amplitude of brain waves in particular areas of the cerebral
cortex in response to specific stimuli, such as music or speech.
PET and fMRI are not suitable for infants and young children because they require that the child remain as motionless as possible on a narrow plank in an
enclosed space filled with the noise of the surrounding machine for an extended
time— often up to an hour. A new brain-imaging method that works well in
infancy and early childhood is near- infrared optical topography ( NIROT),
in which infrared ( invisible) light is beamed at regions of the cerebral cortex to
measure blood flow and oxygen metabolism while the child attends to a stimulus
Clinical, or Case Study, Method: A full picture of one individual’s psychological
functioning, obtained by combining interviews, observations, test scores, and
sometimes psycho-physiological assessments
Ethnography: Participant observation of a culture or distinct social group; by
making extensive field notes, the researcher tries to capture the culture’s unique
values and social processes
Reliability and Validity: Keys to Scientifically Sound Research
Reliability refers to the consistency, or repeatability, of measures of
behavior. To be reliable, observations and evaluations of peoples’ actions cannot
be unique to a single observer. Instead, observers must agree on what they see.
And an interview, test, or questionnaire, when given again within a short time
(before participants could reasonably be expected to change their opinions or
develop new responses), must yield similar results on both occasions.
Two ways to make sure that research is reliable: test-retest reliability & inter-
For research methods to have high validity, they must accurately measure
characteristics that the researcher set out to measure.
Two types of validity: The first, internal validity, is the degree to which
conditions internal to the design of the study permit an accurate test of the
researcher’s hypothesis or question. Second, researchers must consider
external validity, the degree to which their findings generalize to settings and
participants outside the original study.
General Research Designs
Correlational designs: researchers gather information on individuals, generally in
natural life circumstances, and make no effort to alter their experiences. Then they
look at relation-ships between participants’ characteristics and their behavior or
An experimental design permits inferences about cause and effect because
researchers use an evenhanded procedure to assign people to two or more
treatment conditions. In an experiment, the events and behaviors of interest are
divided into two types: independent and dependent variables. The independent
variable is the one the investigator expects to cause changes in another variable. The dependent variable is the one the investigator expects to be influenced by
the independent variable.
Researchers use random assignment of participants to treatment conditions. By
using an un-biased procedure, such as drawing numbers out of a hat or flipping a
coin, investigators increase the chances that participants’ characteristics will be
equally distributed across treatment groups.
matching: In this procedure, participants are measured ahead of time on the
factor in question— in our example, exposure to parental conflict. Then children
high and low on that factor are assigned in equal numbers to each treatment
condition. In this way, the experimental groups are deliberately matched, or made
equivalent, on characteristics that are likely to distort the results.
In field experiments, researchers capitalize on opportunities to randomly assign
participants to treatment conditions in natural settings.
natural, or quasi-, experiments: comparing treatments that already exist, such
as different family environments, schools, child- care centers, and preschool
programs. These studies differ from correlational research only in that groups of
people are carefully chosen to ensure that their characteristics are as much alike as
Designs for studying development
In a longitudinal design, participants are studied repeatedly at different ages,
and changes are noted as they get older.
The longitudinal approach has two major strengths. First, because it tracks
the performance of each person over time, researchers can identify common
patterns as well as individual differences in development. Second, longitudinal
studies permit investigators to examine relationships between early and later
events and behaviors.
Weaknesses of these studies:
Biased sampling— the failure to enlist participants who represent the population
of interest— is a common problem.
selective attrition: Participants may move away or drop out for other reasons,
and the ones who remain are likely to differ in important ways from the ones who
do not continue.
In addition, with repeated testing, participants may become “ test- wise.” Their
performance may improve as a result of practice effects— better test- taking
skills and increased familiarity with the test— not because of factors commonly
associated with development.
cohort effects: Longitudinal studies examine the development of cohorts—
children developing in the same time period who are influenced by particular cultural and historical conditions. Results based on one cohort may not apply to
children developing at other times.
cross- sectional design: groups of people differing in age are studied at the same
point in time.
Advantages: The cross- sectional design is an efficient strategy for describing age-
related trends. And because participants are measured only once, researchers need
not be concerned about such difficulties as selective attrition, practice effects, or
changes in the field that might make the findings obsolete by the time the study is
Weaknesses: Despite its convenience, cross-sectional research does not provide
evidence about development at the level at which it actually occurs: the individual.
It can also be threatened by cohort effects
sequential designs: in which they conduct several similar cross- sectional or
longitudinal studies ( called sequences) at varying times.
The microgenetic design, an adaptation of the longitudinal approach, presents
children with a novel task and follows their mastery over a series of closely spaced
sessions. Within this “ microcosm” of development, researchers observe how
Limitation: Requires intensive study of participants’ moment- by- moment
behaviors; the time required for participants to change is difficult to anticipate;
practice effects may distort developmental trends.
By age 7 children must give their own consent as well as their parents when
involved in an experiment
Chapter 3: Biological Foundations and Prenatal development at birth
These directly observable characteristics are called phenotypes. They depend in
part on the individual’s genotype— the complex blend of genetic information that
determines our species and influences all our unique characteristics.
Within every cell is a control center, or nucleus, containing rodlike structures called
chromosomes, which store and transmit genetic information.
Chromosomes are made up of a chemical substance called deoxyribonucleic acid,
Genes can be of different lengths— perhaps 100 to several thousand ladder rungs
long. An estimated 20,000 to 25,000 genes lie along the human chromosomes A unique feature of DNA is that it can duplicate itself through a process called
mitosis. This special ability permits a single cell, formed at conception, to develop
into a complex human being composed of a great many cells. During mitosis, the
chromosomes copy themselves. As a result, each new body cell contains the same
number of chromosomes and the identical genetic information. Genes accomplish
their task by sending instructions for making a rich assortment of proteins to the
cytoplasm, the area surrounding the cell nucleus. Proteins, which trigger chemical
reactions throughout the body, are the biological foundation on which our
characteristics are built.
New individuals are created when two special cells called gametes, or sex cells—
the sperm and ovum— combine. Gametes are formed through a cell division
process called meiosis, which halves the number of chromosomes normally
present in body cells. When sperm and ovum unite at fertilization, the cell that
results, called a zygote, will again have 46 chromosomes.
Special event called crossing over occurs, in which chromosomes next to each
other break at one or more points along their length and exchange segments, so
that genes from one are replaced by genes from another. This shuffling of genes
creates new hereditary combinations.
The genetic variability produced by meiosis is important in an evolutionary sense:
Because it generates offspring that vary in phenotype, it increases the chances
that at least some members of a species will cope with ever- changing
environments and will survive.
twinning happens because of: temperature changes, variation in oxygen levels,
and late fertilization of the ovum. In a minority of cases, the identical twinning runs
in families, suggesting a genetic influence. Fraternal, or dizygotic, twins, the most
common type of multiple birth, result from the release and fertilization of two ova.
In many heterozygous pairings, dominant– recessive inheritance occurs:
Only one allele affects the child’s characteristics. It is called dominant; the second
allele, which has no effect, is called recessive. Hair color is an example.
incomplete dominance: a pattern of inheritance in which both alleles are
expressed in the phenotype, resulting in a combined trait, or one that is
intermediate between the two.
But when a harmful