It seems children in other parts of the world are more responsible and self-sufficient than children in the US, probably because of how the US children are "pampered" and guided by their parents. What will this do for their future? 

How to think about development? 

Development means the systematic changes/continuities in a human over their life span. Systematic means they are orderly, patterned and relatively enduring.

There are three domains of interest and they affect each other:

• Physical development (body, organs, physiological systems, signs of aging etc)
• Cognitive development (language, learning, memory etc)
• Psychosocial development (emotions, personality, interpersonal skills, relationships etc)

Growth typically stands for physical changes from conception to maturity. 

The deterioration of organisms that leads to their death is called biological aging. But aging is more than biological aging, it's a range of changes in the 3 upper domains in the mature organism.

The gain-stability-loss model states you gain capacity in your younger years, are stable in your adulthood, and you lose in your elderly years. However: modern thinkers argue any age involves gain and losses (e.g. as a child you gain cognitive abilities, but lose self-esteem). 

Thus: development involves gains, losses, neutral changes, & continuities in each phase of life, and aging is part of it.

Overview of periods in the life span: (remember: age is a rough indicator of developmental status. Also, age means different things in different societies)

1. Prenatal period = conception to birth
2. Infancy = first 2 years of life (first month = neonatal/newborn period)
3. Preschool = 2-5 (toddlers = 1-3)
4. Middle childhood = 6-10 or onset of puberty
5. Adolescence = 10-18 (from puberty to relative independence)
6. Emerging adulthood = 18-25/29 
7. Early adulthood = 25-40 
8. Middle adulthood = 40-65
9. Late adulthood = 65+ 

Emerging adulthood is quite new phenomenon of a transitional period between adolescence and adulthood, from around 18-25 or even 29. In these years people get educated/save money to prepare their adult lives. Arnett says emerging adults: 

• explore their identities
• lead unstable lives (job changes, new relationships)
• self-focused
• feel "in between"
• believe in limitless possibilities 

Furstenberg says there are 5 traditional markers of adulthood: 

• completing education
• financially independent
• leaving home
• marrying
• having children

(Sub)Culture consists of shared understandings and way of life of people. It influences our development and how different age grades (socially defined age groups in a society) are treated.

The Rite of passage is a ritual that marks a person's passage from one age grade to another (e.g. body painting, instruction in sex, celebrations..) which is now less common.

Age norms basically stand for how to act your age, and they form the basis for the social clock: a person's idea of when things should be done (like having kids). Age norms are weakening lately. Socioeconomic status matters as well (e.g. poverty can be damaging to development). 

Historical changes also had their influence on the view of the life span:

• Childhood as age of innocence. The modern concept of kids as innocents to be nurtured and protected only started around 17th century, before that they were viewed more like adults & expected to be economically useful asap. 
• Adolescence. This is a quite new dinstinct life phase (since late 19th century), this had to do with the start of higher education.
• Emerging adulthood (as noted before). 
• Middle age as an emptying of the nest. This emerged in the 20th century: parents got fewer children and lived to see their children grow up and leave home.
• Old age as retirement. Before the 20th century, the elderly worked until they dropped. Now luckily retirement has come. 

In the future the aging experience will be different as well, e.g. because of the "graying" of the world (more elderly people in relation to younger ones). We must view development in its historical, cultural and subcultural context.

The nature-nurture issue: 

• Nature- believers think some aspectes of development are inborn and others occur through maturation (the biological unfolding of the person as sketched out in the genes). The maturational processes guide all of us through the same development, but individual hereditary endowment makes every person different. Nature in order: heredity, maturation, genes, innate/biological predispositions.
• Nurture- believers believe in the external conditions to cause change. Learning (thus, experience bringing the changes) is emphasized. Nurture in order: environment, learning, experience, cultural influences. 

However: it is the interplay between nature and nurture that causes developmental changes.

What does the science say?

Goals of the science of development are: describing, predicting, explaining and optimizing.

The first scientific investigations of development were baby biographies in the late 19th century, for instance by Charles Darwin. His evolutionary perspective influenced the early theories, emphasizing biological changes. But baby biographies were difficult to compare, not really objective and not generalizable. 

The founder of developmental psychology was influenced by Darwin. His name was G. Stanley Hall, and he attempted to get more objective data through a questionnaire. He characterized adolescence as a period of storm and stress and found aging is more than only decline. 

Gerontology is the process of studying aging/old age. 

First, development was mostly viewed as: happening in the infancy, childhood & adolescence, proceeding through universal stages and leading towards mature adult functioning. But in the 1960s/70s a life span perspective on human development emerged. Paul Baltes wrote 7 key assumptions: 

1. Development is a lifelong process. (and should always be looked at in the context of a whole life).
2. Development is multidirectional. Different capacities show different ways of change over time.
3. Development involves both gain and loss. And gain and loss occur jointly. 
4. Development is characterized by lifelong plasticity. This is the capacity to change in response to experience, rooted in neuroplasticity (it is the brain's ability to do this). 
5. Development is shaped by its historical-cultural context. (e.g. the Great Depression had a lot of influence on the development of children in that time, and as of now the social media etc changes development). 
6. Development is multiply influenced. It is the product of interacting nature and nurture. 
7. Development must be studied by multiple disciplines. (because so many things are influential).

How is development studied?

Through the scientific method: finding a theory, then generating hypotheses, which are tested through observation of behavior, and thus finding out if the theory is worth keeping or needs to be revised. A good theory should be internally consistent, falsifiable (thus testable), and supported by data. 

The best approach is to look at a random sample of the population of interest, because this makes it more representative. Overgeneralizing needs to be avoided! 

There are 3 major methods of data collection for developmental researchers (and the combination of multiple methods is most reliable):

• Verbal reports. Thus interviews, questionnaires, tests etc. Shortcomings include that self-report measures typically can't be used by infants or other individuals who cannot read or understand speech. Second, people of different ages may not understand questions in the same way, thus age differences can give a flawed outcome. Lastly, respondents might give socially desirable answers.
• Behavioral observations. Naturalistic observation has to do with observing people in their everyday environment. This is often used with children as they do not have the verbal skills yet. The shortcomings are that some behaviors happen too infrequently/unexpectedly to study this way, the causes are difficult to conclude because many things can happen at once, and an observer can cause the studied individual to behave differently (this may be fixed by videotaping instead or giving the individual time to get used to the observer). Structured observation gives the researcher more control over the conditions and makes it easier to capture rare events, since now the situations or stimuli are created. This way all participants can face the same situation and thus it is easier to compare the results. However, it is unsure if the participants behave naturally and if the created setting causes the same behavior as the real world would. 
• Physiological measurements. For instance, electrodes to measure brain activity, or the measuring of heart rate. An example is functional magnetic resonance imaging (fMRI) which is a brain-scanning technique, using magnetic forces to study the increase in blood flow to an area of the brain, which happens when that area gets active. This is an useful way of studying with infants since they can not speak (though they have to be very still), and it's also hard to manipulate by the participants. However, it is not always clear what's happening: arousal can come from anger, but maybe from other emotions as well. 

There are different methods to look at the relationships between the variables studied:

• Case study. This is an in-depth study of an individual/small group of individuals, often done by using different methods like interviewing, observation and testing. It is a helpful method to study a rare case, but it is hard to generalize findings this way, so further study is often needed. 
• Experimental method. The researcher then manipulates something to see how this affects the participants. An experiment shows whether the different forms of the independent variable (the manipulated variable, so the effects can be seen, often the hypothesized cause) have different effects on the dependent variable (the behavior expected to be affected, the hypothesized effect). An experiment has 3 critical features: - Random assignment of the participants to a condition (when this does not happen, it is called a quasi experiment because the results can be caused by differences in the groups), - Manipulation of the independent variable, - Experimental control. This means all factors other than the independent variable are controlled so they have no influence on the results. Thus for instance the same room is used, the same researcher, etc. The experimental method can show cause and effect nicely, however they have shortcomings. Firstly, experiments are often conducted in laboratory settings or other unusual situations, so it is not like the real world. Secondly ethics are often interfering, so many experiments can not be conducted. 
• Correlational method. This involves determining whether 2 or more variables are related systematically. It's not about random assignment and manipulating, but taking people as they are and determining relationships. Statistical control can be used to get rid of the possible uncontrolled differences. In correlational research the strength of a relationship is often determined using a correlation coefficient (r), which can range from -1 to 1. Thus, a +0.90 would indicate a strong relationship between the 2, but whether its a cause-effect relationship is harder to establish than with an experiment, which is a limitation. Watch out for the directionality problem, which means the cause-effect relationship could be reversed. And watch out for the third variable problem: the relation may be caused by some third variable the researcher did not control for. Correlation is not causation! 

Again, these methods are more reliable when combined: e.g. experiments demonstrate a cause-effect, and correlational research shows the same relationship seems to be there in real life. And you need more studies on the same subject to be reliable. The results of multiple studies with the same research question can be viewed with the method of meta-analysis. 

When it comes to studying development, there are 2 types of research designs:

• Cross-sectional design: in this quick and easy design the performances of people of different age groups (or cohorts, which means a group born at approx. the same time, e.g. in the same year or in a number of years, like a generation) are compared. It provides info about age differences. If these studies feature big age differences between people, age effects (= relationships between age and an aspect of development) and cohort effects (= effects of being born as a member of a particular cohort/generation) are entangled, so a study can show how people of different ages differ but not how people normally change as they get older since the people belong to different cohorts. You have to be careful whether its an age effect or a cohort effect. A second limitation is that each person is observed at one point, so it is not found how individuals change over time.
• Longitudinal design: in this design one cohort of the same individuals is studied repeatedly over time. Thus it can provide info about age changes, instead of age differences, and show how people change as they grow older and if earlier experiences predict later behavior. In this design you have to be careful with time-of-measurement effects (the effects of historical events/trends occuring as the data is collected) getting entangled with age effects. Longitudinal studies are also costly and time-consuming, a lot of participants may drop out and the methods can seem outdated at the end of the study. 

A new design is found to overcome the limitations of the upper designs: namely the sequential design. This combines both approaches in one study, thus using different cohorts and then testing them repeatedly. A sequential design can tell researchers: 1. which age-related trends are truly developmental and show how most people (regardless of cohort) will change over time (so the true age effects), 2. which age trends differ in different cohorts and suggest that each generation is affected by its growing-up experiences (so the cohort effects), and 3. which trends suggest that events that happened affect the alive cohorts (so the time-of-measurement effects). These designs unfortunately are expensive and complex. 

What special challenges do developmental scientists face?

Joseph Henrich says psychology is the study of WEIRD people (Western, Educated, Industrialized, Rich and Democratic) since most research focuses on those. It is a challenge to carry out research in a variety of cultures and keeping the procedures meaningful for each culture. Also ethnocentrism (belief that one's own culture is superior) or other bias can get in the way. 

Also challenging is to keep living up to the research ethics, the standards that researchers have to honor to protect their participants from harm. The benefits have to be weighed against the risks. Concepts of consent, privacy and harm also differ in cultures which makes it extra challenging. Important ethical responsibilities are: the use of informed consent, debriefing afterwards, protecting from harm and treating information confidentially.