Children develop from little blobs to complex, active, communicative creatures in a matter of a few years.
There are many differences between kids in how they interact with others, what they like to do, and their physical attributes.
Understanding human development depends on what accounts for the variability across individuals.
There are sometimes striking differences between identical twins.
Case studies are usually better suited to raising questions than answering them.
We'll soon learn that psychologists have developed ingenious methods for unraveling the causes of development over time.
Nature and nurture can contribute to development.
Change can occur due to physical maturation, be shaped by experience, or a combination of study of how behavior changes over both.
Powerful roles are played in shaping development.
Disentangling their effects is not easy because nature and nurture intersect in a variety of fascinating ways.
In the mid 1990s, Betty Hart and Todd Risley published a study that showed that parents who speak a lot to their children have larger vocabularies than parents who don't.
People who talk less have children who don't learn as much.
Parents and children share genes in intact families.
Have an alternative genetically inclined to have higher vocabulary.
Avshalom Caspi and his colleagues conducted a longitudinal study of children who possessed this gene, some of whom committed violent crimes and others who didn't.
If children were exposed to a specific environmental factor, the genetic risk factor could be associated with violent behavior.
Children with the low MAO gene were not at heightened risk even when they were maltreated.
Nature can affect the environment children are in.
Children can express their genetic tendencies to seek cies through nurture.
Highly fearful children tend to seek out environments that protect them from their fears as they grow older.
Growing up in a safe environment may appear to help create fearfulness, when in fact the environment is a consequence of children's genetic predispositions.
Every one of the 100 trillion or so cells in our bodies contains at least one of our genes.
If the death of a parent early in development causes the children's genes to become active, they will never become anxious.
One of the most surprising aspects of genetic expression is that genes that are turned on don't stay on for long.
Environmental factors may result in month-by-month or even day-by-day adjustments in which genes are actively impacting development and behavior at any given time.
Epigenetics has been important in understanding physical and mental health.
The field will be learning more about how epigenetics influences behaviors in the future as research on how epigenetics impact children's behavioral development is just getting rolling.
Nature is affected by nurture.
Nature affects how we react to nurture.
It's easy to mistake an environmental effect for a genetic effect when it comes to nature and nurture.
It is difficult to separate out the influence of genes and environment because of the ways they intersect.
The environment in which the behavior develops affects the impact of genes on it.
The mistaken appearance of a pure effect of nature can be caused by genetic predispositions.
Some genes turn on in response to certain environmental stimuli.
Environmental conditions regulate whether genes are active.
Early life experiences can shape later development in powerful ways.
Early input from the outside world has a significant impact on brain development.
The influences on brain and behavior don't stop after the first few years.
We should not underestimate the impact of experiences during infancy on long-term development.
Although they are influential, they can often be reversed.
Most children are more resilient than we think.
The separation of an infant from its mother during the first few hours after birth has no negative consequences for children's emotional adjustment.
Early experience is an important part of children's physical, cognitive, and social development.
There is no reason to believe that later experiences are less important than early experiences.
Positive experiences can counteract the effects of early deprivation.
During the first year of life, the baby's brain undergoes massive growth and changes.
Neuroscience research shows that the brain changes in important ways in response to experience throughout childhood and well into early adulthood, supporting the idea that later experiences in life can be as influential as those in early childhood.
In surprisingly good shape, most children are capable of withstanding stress and trauma, emerging from potentially traumatic experiences, including kidnappings and even sexual abuse.
Some children experience long-term negative outcomes, including changes in behavior or sleep routines, and it's not uncommon for these children to show some short-term negative effects.
Most children bounce back from these events with little damage to their well-being.
We could conduct a study to find out how people's knowledge of computers changes with age.
Our hypothesis is that people's knowledge of computers should increase from adolescence to early adulthood, and then level off at age 30.
Knowledge of computers should not change much after 30.
100,000 people have a range of ages from 14 to 80.
We screen out people with brain damage to make sure we don't accidentally include people with cognitive impairment.
We found that people's knowledge of computers decreases with age, especially between the ages of 60 and 80.
We didn't consider an alternative explanation for our findings.
We asked a perfectly sensible question.
Make sure the design we choose is the right one to answer the question.
There were explanations for the findings.
The cohort effects are a serious shortcoming because before the late 1980s, few Americans used computers.
In a longitudinal design, psychologists track the development of the same group of participants over time.
Longitudinal designs can be used to draw faulty conclusions.
There are some unanswered questions about why parents with male children who engage in problem behaviors are more likely to get divorced than other parents.
The longitu Ruling Out Rival Hypotheses dinal nature of the design allowed us to rule out the plausible explanation that the boys' behaviors are a reaction to the divorce.
Although longitudinal designs are ideal for studying change over time, they can be difficult to explain.
People dropping out of a study before it's over.
It can be a problem when participants who drop out differ in ways from those who stay in.
When longitudinal designs aren't feasible, we should be careful with the results of cross-sectional studies.
Cross-sectional designs are more useful than longitudinal designs in some research questions.
When comparing the performance of older adults with two-year-olds on a memory test, the potential for cohort effects or skilled with technology seems low.
In such a study, a longitudinal design could be problematic because they weren't around when they were administering the same memory task to the same children twice so close together would up, limiting our ability to compare probably result in better performance on the second test.
Most longitudinal studies use observational adults in a cross-sectional study.
Most of the studies can't be used to infer cause-and-effect relationships.
There are a few unique challenges when investigating psychological development.
The equipment we need to evaluate the causes of physical, cognitive, emotional, and social changes from childhood to old age will be provided by understanding these challenges, along with the scientific thinking principles we've encountered throughout this text.