Lifespan

Studying the Lifespan of Humans

Longitudinal Research

This method allows the continual measurement of individual development differences within a defined timetable. Participants in this kind of study are all the same age and have long-term contact with the researchers, which might last months or years. Longitudinal studies help determine stability and change across time.

Cross-Sectional Research

This strategy entails collecting data from people of various ages simultaneously. Cross-sectional studies are beneficial for comparing features among people of different ages in a community or obtaining data for future studies and research. This research method is less time-consuming than longitudinal research because no participant follow-up is required. It is also less costly.

Cohort-Sequential Research

Cohort-sequential research combines longitudinal and cross-sectional analysis. It involves the study and follow-up of participants through time within groups based on age. This method allows researchers to look at individual changes across time compared to others of different ages and times in history. The researchers can determine if development occurs differently across different ages at the same time interval and check for distinctions due to being born within a specific time period.

Retrospective Research

In retrospective research, participants give information about their past and other important data relevant to the study. Data gathering includes interviews, questionnaires, or medical records.

Lifespan: Human Development Stages

There are different ways to categorize the stages of human development, but one common way is in eight stages, from prenatal to late adulthood.

1. Prenatal Stage: This is the stage in which a fertilized egg develops inside the womb.

2. Infancy and Toddler Stage: from birth to three years of age. This stage displays rapid changes in different areas, including physical, socio-emotional, language, and cognitive development. Completing milestones helps lay the foundation for independence and a healthy sense of self.

3. Early Childhood Stage: the preschool years from birth to six years old. Experts say that this phase is crucial in human development since it can determine overall life outcomes.

4. Middle Childhood Stage: Children between the ages of six to 12 display greater control and mastery of body movements and motor skills. They learn how to reason better and adapt their thoughts to different situations.

5. Adolescent Stage:Adolescence is a phase of rapid physical and socio-emotional transformation brought about by puberty. Also called the "teenager phase" between the ages of 13 to 19 years, the adolescent stage is defined as the transition from childhood to adulthood.

6. Early Adulthood Stage: Early adulthood typically spans from ages 20 to 35, where individuals explore open doors in many areas of life such as career, romance, building families, and forming close relationships. It is also the stage where humans achieve milestones in independence as they venture out in life, seeking to make their own choices.

7. Middle Adulthood Stage: Middle adulthood is generally defined as ages 35 to 65. Some key features of this phase include maintaining stability in relationships, careers, hobbies, parenting, and preparation for late adulthood. Most people experience love and work at their peak during this stage. Signs of aging also become more apparent such as graying hair, muscle loss, visual changes, and hearing problems.

8. Late Adulthood Stage: the ages of 65 to the very last year of life. This stage can reach up to 120 years for those who have a longer lifespan. The late adulthood stage has features of physical decline due to aging and a host of emotions about death and dying. Aside from these changes, this period is also marked by a decrease in cognitive abilities, affecting short-term memory and the ability to acquire new information.

Fig. 3 Human development over time, Pixabay.

Human Development Across the Lifespan

There are many different ways to consider how humans develop, but there are a few key ideas in developmental psychology that help us understand this better. They are maturation, assimilation, accommodation, and critical periods in development.

Maturation

Maturation is a natural physical and mental development process that occurs over time until a person reaches full maturity. Maturity, in this sense, can also mean when a person starts to act like a grown-up. One example of this is when a person seeks emotional stability, which is a sign of maturity.

During a child's life, maturation also involves learning and body movements, including gross and fine motor skills. Maturation is also essential in learning as certain maturity levels indicate readiness to acquire new knowledge and skills.

Assimilation and Accommodation

Assimilation and accommodation are about cognitively organizing information as you learn and grow.

When a child sees a dog for the first time, the child learns that a dog has four legs and a tail. This is the child's dog schema. A schema is a collection of information that provides a framework for organizing and acquiring new knowledge.

If the same child sees a horse during his first time visiting the zoo, the child might call it a dog, demonstrating assimilation. Assimilation is piecing new information into an old schema. In this case, the child puts the horse into the dog schema of an animal with four legs and a tail.

On the other hand, accommodation is creating space in a body of knowledge to insert new information. A child accommodates new words such as horse and cat and understands that not all animals with four legs and a tail are dogs. New schemas are created in the child's mind to organize this information. Assimilating involves using old knowledge to understand new situations, while accommodation involves redesigning old knowledge and understandings to include new knowledge.

Critical Periods in Development

A critical period applies to many vital areas in development, such as language, social interactions, hearing, and vision. Exposure to appropriate and specific influences significantly affects development during its critical periods. A critical period is a window of opportunity for optimal growth and proper functioning. If the right conditions are present, the individual will develop normally. If not, they will exhibit impairments in development.

Psychosexual Theory of Development

Sigmund Freud introduced the Psychosexual Theory of Development. He believed that our personality is shaped by our experiences in early childhood and that there are certain fixations that happen during each stage: Oral, Anal, Phallic, Latency, and Genital. His theory is an example of discontinuity.

Ainsworth's Attachment Theory

Psychologist Mary Ainsworth built upon British psychologist John Bowlby's original study on attachment theory in her 1970s research. Ainsworth classified attachment into three types: secure attachment, ambivalent-insecure attachment, and avoidant-insecure attachment.

Erikson's Psychosocial Theory of Development

Erik Erikson introduced the Psychosocial Theory of Development as a modification of Sigmund Freud's Psychosexual Theory. He proposed that social connection throughout the lifespan fosters development. According to Erikson, each stage in life consists of certain tasks that must be completed, and the inability to do so elicits feelings of insufficiency.

The stages in Erikson's Psychosocial Theory include:

1. Trust vs. Mistrust (birth to 12 to 18 months).

2. Autonomy vs. Shame (18 months to 3 years).

3. Initiative vs. Guilt (3 to 6 years).

4. Industry vs. Inferiority (6 to 12 years).

5. Identity vs. Confusion (12 to 18 years).

6. Intimacy vs. Isolation (19 to 40 years).

7. Generativity vs. Stagnation (40 to 65 years).

8. Integrity vs. Despair (65 to death).

Cognitive Theory of Development