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The Holistic Nature of Human
Development
Human Development: A Multidisciplinary
Perspective
Key Ideas Guiding the Study of Human Development
Multi-directional : Over time, characteristics change in every direction, not always linearly. Development is thought of as a series of gains and losses, predictable growth, and unexpected transformations.
Multi-contextual : Each person lives a life embedded in many contexts, including a particular historical period, family system, community, and socioeconomic status (level of education, family, social status).
Multi-cultural : Culture impacts patterns of behavior that are passed from one generation to the next.
Multi-disciplinary : Understanding lifespan development and its context requires examination by many academic fields (e.g., psychology, biology, education, sociology).
Plastic : Human traits can be shaped, yet maintain a certain durability of identity. Every individual and trait can be altered at any point. Change is ongoing but gradual.
Domains of Development
Biosocial or Physical Domain : Includes growth and changes in body size, proportions, appearance, and functioning of body systems, as well as the social influences that guide them. Physical development includes perceptual and motor skills/capacities and physical health. Genetic, nutritional, and health factors affect growth and change.
Cognitive Domain : Includes all mental processes a person uses to gain knowledge or think about their environment. Includes changes in intellectual attention, memory, academic and everyday knowledge, problem-solving, imagination, creativity, and language. Encompasses perception, imagination, judgment, memory, and language, as well as education.
Psychosocial Domain : Includes emotions, temperament, and social skills. Changes in emotional communication, self-understanding, self- esteem, personality, and knowledge about others. Social development refers to an interaction between a person and others who are outside of the individual, including interpersonal skills, friendships, intimate
relationships, moral reasoning, and behavior. Central to this domain are family, friends, community, culture, and larger society.
The Scientific Method
Begin with curiosity (Question) Develop a hypothesis Test hypothesis (empirical research) Draw conclusion Report results Replication
Nature-Nurture Debate
Nature refers to the influence of the genes that people inherit. Nurture refers to environmental influences, beginning with the health and diet of the embryo's mother and continuing throughout a lifetime, including family, school, society, and community. The debate centers on how much of any characteristic, behavior, or emotion is the result of genes and how much is the result of specific experiences.
Life-Span Perspective
This approach to the study of human development takes into account all phases of life, not just childhood or adulthood. Ages are a rough guide to "change over time," as development can appear, disappear, increase, decrease, and zigzag over time. Continuity and discontinuity are both evident in human development.
Sensitive Periods
Certain periods in development are more sensitive, where a particular type of development is most likely to happen or happens most easily, although it may still occur later with more difficulty (e.g., early childhood is a sensitive period for language learning).
Ecological Systems Approach
This view considers the person in all contexts and interactions that constitute a life, including microsystems (personal relationships), exosystems (relationships between people and local institutions), macrosystems (broader social settings and influences), mesosystems (connections among all other systems), and the chronosystem (time system).
Socioeconomic Status (SES) and Culture
Socioeconomic status, determined by income, wealth, occupation, education, and place of residence, can significantly impact human development. Culture, a system of shared beliefs, norms, behaviors, and expectations, also shapes development through social constructions and acculturation.
Safety (need to feel safe, secure, and stable) Love and belonging (need to love, be loved, belong, and be accepted) Esteem (need for self-esteem, achievement, competence, and respect from others) Self-actualization (need to live up to one's full and unique potential)
Evolutionary Theory
Evolutionary Theory suggests that nature works to ensure that each species does two things: survive and reproduce (Charles Darwin).
Research Methods
Scientific Method
The scientific method is used when researchers want to examine a particular topic in an objective way, where biases do not influence the process.
Quantitative Research
Quantitative research uses numbers, combines data into categories/groups that can be contrasted and compared with statistical techniques to test hypotheses (e.g., questionnaires, experiments).
Qualitative Research
Qualitative research focuses on words and descriptions of experience/event. Often, no specific hypothesis is tested (e.g., naturalistic observation - watching kids on the playground).
Longitudinal Design
Longitudinal design examines the same group of individuals over various time points (e.g., PHAST). This design has drawbacks, such as people withdrawing, moving to unknown addresses, or dying, which can skew the results. Additionally, people may become more aware of the questions/goals of the study, causing them to change in ways that differ from most people.
Cross-Sectional Design
Cross-sectional design compares groups of individuals from several categories, where the groups differ in age but are similar in other important characteristics.
Cross-Sequential Design
Cross-sequential design combines both longitudinal and cross-sectional approaches.
Correlation vs. Causation
An important issue in the interpretation of quantitative research findings is the distinction between correlation and causation. Correlation studies measure relationships between variables, providing an index called the correlation coefficient ("r") indicating the strength of the relationship between variables. However, the results do not show cause-effect relationships.
Scientific Observation
Scientific observation is a method of testing a hypothesis by unobtrusively watching and recording participants' behavior in a systematic and objective manner, either in a natural setting, in a lab, or through searches of archival data. Observation is crucial in developing hypotheses but provides issues to explore, not proof.
Experiments
Experiments are a research method where the researcher tries to determine a cause-and-effect relationship between two variables by manipulating one (i.e., what causes what). The independent variable is the variable introduced to see what effect it has on the dependent (or experimental) variable.
Surveys
Surveys are a research method where information is collected from a large number of people by interviews, questionnaires, etc. They are a quick, direct way to obtain data, but not all surveys are accurate. Factors affecting surveys include respondents presenting themselves as they'd like to be perceived, leading to deception in these tests.
Case Studies
Case studies are in-depth studies of one person, usually requiring personal interviews to collect background information and various follow-up discussions, tests, questionnaires, and so on. Case studies are more likely to have biased results than surveys due to assumptions and interpretations.
Correlation
Correlation is a number that indicates the degree of relationship between two variables, expressed in terms of the likelihood that one variable will (or will not) occur when the other variable does (or does not). A correlation indicates only that two variables are related, not that one variable causes the other to occur.
Genes and Chromosomes
Cells promote growth and sustain life according to DNA, and each molecule of DNA is a chromosome that contains instructions called genes. Methylation can enhance, transcribe, connect, empower, silence, and alter genes.
Variations Among People
Variations in genes are called alleles, and genes that have various alleles are called polymorphic. Each variation is a single-nucleotide polymorphism. The entire packet of instructions to make a living organism is the genome.
The 23rd Pair
Humans have 22 pairs of chromosomes called autosomes, and the 23rd pair is the sex chromosomes.
Genetic Interactions
No gene functions alone, and almost every trait is polygenic (affected by many genes) and multifactorial (influenced by many factors). Some genes are additive, while others are non-additive and exhibit a dominant-recessive pattern.
Prenatal Development
Prenatal development is often divided into three main periods: the germinal period (the first 14 days), the embryonic period (the third through eighth week), and the fetal period (the ninth week until birth).
Germinal Period
During the germinal period, the zygote begins duplication and division, and the first cells are stem cells. After the eight-cell stage, differentiation begins, and cells start to specialize.
Embryonic Period
In the embryonic period, the formless mass of cells becomes a distinct being, and the head, eyes, ears, nose, mouth, arms, and legs start to form.
Fetal Period
In the fetal period, the dramatic change from a tiny, sexless creature to a boy or girl occurs. The cardiovascular, digestive, and excretory systems develop, and the brain increases in size, enabling the regulation of all body functions.
From Zygote to Newborn
The Newborn
Newborns are responsive social creatures, and they have three sets of protective reflexes: reflexes that maintain oxygen supply, reflexes that maintain constant body temperature, and reflexes that manage feeding.
New Fathers
Fathers' involvement in their children's lives is vitally important and has a strong impact on children's development. Some fathers-to-be even have their own biological and psychological experiences with pregnancy and birth, in a condition known as couvade.
New Mothers
When the birth hormones decrease, between 8 and 15 percent of women experience postpartum depression, which can have a long-term impact on the child.
Bonding
The active involvement of both parents in pregnancy, birth, and newborn care helps establish the parent-infant bond, the strong, loving connection that forms as parents hold, examine, and feed their newborn. Early skin-to- skin contact helps establish this bond.
Problems and Solutions
Abnormal Genes and Chromosomes
Chromosomal miscounts, such as Down syndrome, and gene disorders can lead to serious diseases or disabilities in the next generation.
Teratogens
Teratogens, which are anything that increases the risk of prenatal abnormalities, can cause physical defects or affect the brain (behavioral teratogens). The timing and dose of exposure to a teratogen are crucial factors in the effect.
Genetic Vulnerability
Genes are a third factor that influences every aspect of conception, pregnancy, and birth, and the X chromosome seems to be a protective factor.
Brain Development
Brain Basics
Communication within the central nervous system (CNS)—the brain and spinal cord—begins with nerve cells called neurons. The human brain has billions of neurons, most of them in the cortex, the brain's six outer layers. The cortex is crucial: most thinking, feeling, and sensing occur in the cortex. The final part of the brain to mature is the prefrontal cortex: the area for anticipation, planning, and impulse control. It is inactive for the first months of infancy. The brain has specialized areas, such as the visual cortex, auditory cortex, and an area dedicated to the sense of touch for each body part. Neurons are linked to other neurons by intricate networks of nerve fibers called axons and dendrites. Each neuron has a single axon and numerous dendrites that spread out like branches of a tree. The axons of one neuron meet the dendrites of another at intersections called synapses: tiny gaps that are critical communication links within the brain. Axons and dendrites do not touch at synapses; instead, neurons communicate by sending electrochemical impulses (neurotransmitters) through their axons to synapses, to be picked up by the dendrites. The dendrites bring messages to the cell bodies of their neurons, which, in turn, convey the messages via their axons to the dendrites of other neurons.
Experiences and Pruning
During the first months and years, rapid growth and refinement in axons, dendrites, and synapses occur, especially in the cortex. Transient exuberance: early dendrite growth is followed by pruning, which increases brain power. The space between neurons in the human brain is far greater than the space in chimp brains, and the densely packed neurons of chimps make them less intelligent than people. More space allows more synapses and more complex thinking. Children with intellectual disabilities have a 'persistent failure of normal synapse pruning,' which makes thinking difficult. Lack of normative experiences may lead to overpruning, which can also lead to a reduction of brain activity.
Plasticity of the Brain
The brain is high in plasticity, meaning that it can be modified and changed by environmental circumstances. An advantage of this is the ability to compensate or take over the functions of certain areas that may have been damaged by disease or accident.
However, the brain is also highly vulnerable to impoverished or restricted environments, and this can lead to damage that is significant enough to have serious implications for future development.
Face Recognition
A part of your brain, the fusiform face area, is adept at face recognition.
Harm and Protection
Most infants develop well within their culture, and head-sparing usually ensures that baby brains are sufficiently nourished. Because of brain plasticity and its consistent development, parents and others in the infant's social world play an important role in the baby's brain development. Parents need to provide a stimulating environment.
Shaken Baby Syndrome (SBS)
SBS occurs when infants are shaken back and forth sharply and quickly. Because the brain is still developing, shaking stops the crying because blood vessels in the brain rupture and fragile neural connections break. Lifelong intellectual impairment is most likely. One study showed that 364 injured children under 5 years who were admitted to pediatric hospitals across Canada, 19% of the children died outright of their injuries. Of those who survived, 55% suffered long- term neurological damage and 65% had visual impairments. Only 22% of survivors showed no signs of continuing developmental impacts.
Self-Righting and Sleep
Self-righting is an inborn drive to remedy deficits, which is built into the human system. A consequence of brain maturation is the ability to sleep through the night. Newborns cannot do this and sleep 15-17 hours a day, in 1-3 hour segments.
Perceiving and Moving
The Senses
Every sense functions at birth—babies need to begin responding to sensory input in order to learn. Sensation is the response of a sensory system (eyes, ears, skin, tongue, nose) when it detects a stimulus. Perception is the mental processing of sensory information when the brain interprets a sensation, which happens in the cortex. The process goes from sensation to perception to cognition.
At 5 months, infants use their arms and legs to move forward, which is affected by culture and the amount of tummy time. At 8-10 months, infants lift their mid-sections and crawl, but it is not true that they must crawl to develop normally. Infants typically walk by one year.
Fine Motor Skills
Fine motor skills are physical abilities involving small body movements, especially of the hands and fingers, such as drawing and picking up a coin. Hand-eye coordination is limited at 3 months, but infants can reach, grab, and hold by 6 months. From 6-9 months, infants practice enthusiastically on objects within arm's reach. Infants master the pincer movement (using the thumb and forefinger to pick up objects) by the end of the first year and throughout the second year. During the second year, grabbing becomes more selective.
Dynamic Sensory-Motor Systems
Sensation and motor skills further three goals: social interaction, comfort, and learning. Sensory-motor development is a prerequisite for growth and staying alive.
Surviving in Good Health
Immunization
Immunization is the process that stimulates the body's immune system to defend against particular contagious diseases. Vaccination has had the greatest impact on human mortality reduction. Successful immunization has led to the eradication of smallpox and a significant decrease in the number of cases of polio, measles, and varicella (chickenpox). However, certain groups, such as newborns, people with impaired immune systems, and unvaccinated individuals, remain vulnerable to these diseases. Herd immunity, where the vaccination of children stops the spread of disease and protects others, is an important concept. Problems with immunization include temporary irritability and fever in babies, as well as the debunked claim that the MMR (measles, mumps, rubella) vaccine causes autism.
Nutrition
Breast milk is the best source of nutrition for infants.
Colostrum, the thick, high-calorie fluid from the mother's breast, is sterile, always body temperature, and rich in iron and vitamins. Breastfeeding exclusively for the first 6 months is recommended, as it provides antibodies, easier-to-digest fats and sugars, and protection against obesity. However, some mothers, such as those with HIV or who use addictive drugs, cannot breastfeed. Malnutrition, including protein-calorie malnutrition, stunting, and wasting, affects one-third of children in developing nations and can lead to severe illness, weight loss, and death.
Malnutrition and Its Effects
Some diseases can result directly from malnutrition. Two notable examples are:
Marasmus
This condition occurs in early infancy when the body's tissue wastes away.
Kwashiorkor
In this condition, the hair thins, the skin becomes splotchy, and the face and legs swell with fluid (edema).
Prevention of these conditions involves providing proper prenatal nutrition and promoting breastfeeding. Supplementation of iron and vitamin A can also help.
Poverty and Nutrition
Prevalence of Poverty
14.5% of children in Canada live in poverty. 25% of Aboriginal children in Canada live in poverty.
Impact of Poverty on Child Development
Children living in poverty are at risk for: - Lower scores on vocabulary, reading comprehension, arithmetic, and general knowledge - Maternal drug abuse and depression - Impaired motor development - Emotional issues, such as withdrawal and a mistrusting personality - Increased stress levels, leading to higher cortisol levels and brain cell damage
Stage 6 (18-24 months)
Infants use mental combinations, memory, and pretend play to solve problems.
Piaget Re-evaluated
Piaget's evidence relied on observable behaviors. Recent research using brain scans and other methods shows that infants reach the sensorimotor stage earlier than Piaget suggested. Brain scans have identified mirror neurons, which respond in an observer's brain to an action performed by someone else, similar to how the observer's brain would respond if they had performed the action themselves.
Information Processing
Information-Processing Theory
This perspective compares human thinking processes to computer data analysis, including sensory input, connections, stored memories, and output.
Infant Cognition and Information Processing
Math concepts may begin as early as 6 months, with infants able to differentiate between 8 and 16 dots, but not between 8 and 12 dots until 9 months. Infant amnesia: Adults forget what happened before age 2, but research suggests infants have some memory.
Infant Memory
3-month-olds learned to kick to make a mobile move, and remembered this a week later, but forgot after 2 weeks. Infants needed a "reminder session" to reactivate the stored memory. Memories are evident when experimental conditions are similar to real life, motivation is high, and retrieval is strengthened by reminders and repetition.
The Active Brain
6-month-olds remembered a novel puppet a month later after two 30- minute sessions. 15-month-olds tried to play with a new toy in the same way they had seen an adult play with a different toy the day before, showing they don't just copy what they see but think about it.
Language Development
The Universal Sequence
Listening and Responding
a. Infants begin learning language at birth, preferring the language their mother speaks. b. Infants closely look at facial expressions to understand communication. c. Infants can differentiate their native language just by looking at mouth movements by 6 months. d. Infants respond to child- directed speech, which is high-pitched, simplified, and repetitive. e. Infants prefer their own native music best from 4-8 months.
Babbling
a. The extended repetition of certain syllables, such as "ba-ba-ba," begins between 6-9 months. b. Responses from others encourage babbling. c. Infants express concepts with gestures, such as pointing, sooner than speech, starting around 10 months.
First Words
a. Hearing infants start talking at 12-18 months. b. Infants understand 10 times more words than they can say between 6-15 months. c. Holophrase: A single word used to express a complete, meaningful thought. d. With new perceptual understanding, it takes time for verbal output to reflect the neurological advance. e. Once infants reach a 50-word vocabulary, the rate of word learning increases to 50-100 words per month, known as the "naming explosion."
Cultural Differences in Language Development
The ratio of nouns to verbs varies across cultures. English-speaking infants use more nouns than verbs, compared to Chinese or Korean infants. This may be due to differences in sentence structure, with verbs appearing at the beginning or end in Mandarin and Korean, making them easier to learn. Cultural differences in emphasis, such as East Asian focus on human interaction versus North American focus on playing with toys, may also influence language development. Verbs that sound like the action they represent may be more common in some languages, making them easier to learn.
Putting Words Together
Grammar: The methods, such as word order, verb forms, and so on, that languages use to communicate meaning beyond just the words themselves. 18-24 months: Infants begin using two-word combinations.
Emotional Development in Infants and
Toddlers
Fear and Self-Awareness
At 12 months, infants develop a fear of unexpected sights and sounds. At 18 months, infants develop self-awareness, realizing that they are distinct individuals with their own body, mind, and actions separate from others. At 18 months, infants also begin to experience emotions such as pride, shame, embarrassment, and empathy. Infants develop a sense of disgust, a physical reaction to unpleasant tastes or smells.
Anger, Sadness, and Separation Anxiety
Anger is a healthy response to frustration, while sadness indicates withdrawal and is accompanied by an increase in the body's production of the stress hormone cortisol. Separation anxiety is normal at around 1 year of age, intensifies by age 2, and subsides after that. If it remains strong after age 3, it may indicate an emotional disorder.
Self-Recognition and Pretending
The Mirror/Rouge Test (Lewis & Brooks, 1978) shows that infants younger than 12 months sometimes smile at the "other" baby in the mirror, but do not show self-recognition. Between 15-24 months, infants become self-aware and touch their own nose with curiosity and puzzlement. Self-recognition emerges around 18 months, along with the use of first- person pronouns (I, me, mine, myself, my) and the ability to pretend.
Brain and Emotional Development
The maturation of the anterior cingulate gyrus, a part of the cortex, is directly connected to a child's emotional self-regulation, allowing them to express or hide their feelings. Infants' early emotional experiences guide how they deal with those feelings in the future. Positive experiences with trusted adults help them develop constructive ways of dealing with negative events, while repeated high levels of stress without adult support can lead to increased fear, anger, and frustration. Parents greatly affect the "wiring" of an infant's brain, and the unique way of interaction through culture determines the infant's developmental characteristics.
Early Childhood Development
Cultural Differences and Brain Development
Cultural differences become encoded in infants' brains, making them a "cultural sponge." It is difficult to measure how infants' brains are influenced by their context. A study of adults (Zhu, 2007) found that both Americans and Chinese participants activated the medial prefrontal cortex when judging whether certain adjectives applied to them. However, the Chinese participants also activated this brain region when asked whether the adjectives applied to their mothers. Researchers speculate that this brain activation in Chinese participants occurred because they learned as babies to be closely aligned with their mothers, whereas Americans learned to be more independent.
Recommendations for Healthy Brain Development
The research and advocacy organization "From Zero to Three" provides the following suggestions for optimal brain development in infants: Respond to the infant's initiated acts (smiles, cries, babbles) Praise the infant when a new skill or ability is mastered Talk, sing, read, and play with the infant Provide interesting things for the infant to touch, smell, and chew on Encourage the infant to vocalize and babble
Temperament
Temperament is biologically based, meaning that these traits originate from nature rather than nurture. It refers to the core of individual differences in style of approach and response to the environment, which is stable across time and situations. Temperament represents inborn differences between individuals in emotions, activity, and self-regulation. Confirmation that temperament arises from the inborn brain comes from the analysis of the tone, duration, and intensity of infant cries after the first inoculation, before much experience outside the womb. Temperamental traits are genetic (e.g., shyness, aggression), while personality traits are learned and influenced by an individual's environment (e.g., honesty, humility). The expression of emotions over the lifespan is modified by experience, including child-rearing methods, culture, and learning.
The New York Longitudinal Study (NYLS)
The NYLS, initiated in 1956, was the first study to recognize that each newborn has distinct inborn traits. The study identified nine characteristics of infant temperament: motor activity, rhythmicity or regularity of functions (eating, sleeping, wakefulness), response to new people or objects, adaptability to a
