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Discovering Psychology: Updated Edition

Explorations Life Span Development

In this activity you will explore development across the life span. The process begins during the period between conception and birth, as the fetus emerges from a one-celled organism to a full-term infant. As the genetic program within the cells of the body unfolds, important characteristics emerge that will set the stage for the newborn baby's emergence into the world. At the same time, the world around the developing child exerts its influence on growth, and, at critical points, can alter the way these genetic characteristics are expressed. Our exploration begins where this process culminates, at birth, where who we are and will ultimately become is a life-long endeavor.

You will learn about some of the biological, cognitive, and psychosocial developments that take place from birth across the life span. As you explore, keep in mind the following questions that are on the forefront of the developmental psychology: How do innate and environmental factors interact? What relationships exist between development in one period of life and development in another? How might differences in culture and social class shape the course of development?


We will consider development as it occurs across three separate, overlapping domains. Because important relationships exist where these domains overlap, psychologists refer to the process of development as biopsychosocial.

Biological Domain: bodily changes, maturation, and growth

Cognitive Domain: mental processes of knowing, which include imagining, perceiving, reasoning, and problem solving

Psychosocial Domain: emotions, personality, and social interactions and expectations

Periods: 0-2

Infancy and Toddlerhood: Birth – Age 2


•Body doubles in height and quadruples in weight

•Neurons grow in increasingly dense connections, becoming coated with layers of myelin, and enabling faster and more efficient message transmission

•Experiences help to fine tune the brain’s responses to stimulation

•Motor skills progress from simple reflexes to coordinated motor abilities, such as grasping and walking

•Sensory and perceptual abilities develop rapidly


•Basic structure of language learned through baby talk with adults

•First communication emerges through crying, then cooing and babbling

•Language skills progress from speaking a few words by age 1, to constructing sentences by age 2

•Awareness of world progresses through immediate sensorimotor experiences to mental representations of events

•Thinking includes concept of object permanence: objects still exist when out of sight or awareness

•Ability to grasp conceptual categories begins; by age 2 numerous definite concepts develop


•Emotional responses change from basic reactions to more complex, self-conscious responses

•Independent behaviors increase with parental encouragement around feeding, dressing, and toilet training

•Parents and infants respond to each other by synchronizing their behavior

•Development of secure attachment sets stage for child’s increasingly independent exploration

•Ability to relate to playmates emerges by end of period

•Early personality traits, such as introversion and extroversion, develop

Periods: 2-6

Early Childhood: Ages 2 – 6


•Brain attains 90% of its adult weight by age 5, developing faster than any other body part

•Myelination proceeds at different rates in various areas of the brain, resulting in different rates of readiness for certain types of activities

•Physical strength increases and body proportions become more adult-like

•Athletic skills, such as running, jumping, and hopping, dramatically improve

•Fine motors skills, such as writing and drawing, develop slowly

•Gender differences in motor skills begin to emerge


•Use of mental representations and symbols, such as words, begins

•Ideas about the world continue to be somewhat illogical

•Social interactions with parents and playmates teach about the world

•Language abilities develop rapidly, resulting, on average, in a 14,000-word vocabulary and extensive grammatical knowledge by age 6

•Ability to adjust communication to audience begins

•Metacognition, the ability to think about thought, forms


•Play alone or with others becomes increasingly complex and imaginative

•Increased energy fosters ability to initiate new activities, especially if child receives praise for actions

•First awareness of gender roles emerge

•Desire for independence and control over environment increases, making parents’ supervisory role more challenging

•Parenting style influences child’s psychosocial development

•Socialization in school encourages thinking about world outside the home

Periods: 7-9

Middle Childhood: Ages 7 – 9


•Brain growth slows

•Physical growth slows, but slight height spurts occur

•Expansion of heart and lung capacities supports more physical endurance

•Athletic and fine motor skills become more refined


•Ability to understand logical principle develops

•Memory capacity and ability to use mnemonics expands

•Metacognition, the ability to think about thought, enables organization of own learning

•Use of language becomes more analytical

•Proficiency in more than one language code may begin, sometimes resulting in bilingualism


•Peer group becomes more significant as dependence shifts to friends for help, loyalty, and sharing of mutual interests

•Awareness of and involvement in outside world increases awareness of family, economic, and political conditions

•Motivational systems build around achievement, competence, and affiliation

•Coping strategies develop for problem solving and stress tolerance

•Interpersonal strategies develop to aid in understanding others’ behavior

Periods: 10-12

Late Childhood: Ages 10 – 12


•Puberty begins with rising hormone levels

•Girls’ growth spurt begins with gains in height, weight, and musculature

•Gender specific physical changes appear within first year: enlargement of breasts in girls and testes in boys

•In physical maturation, boys lag, on average, 2 years behind girls

•Variations in onset of puberty impact personality development


•Logical thought progresses to abstract thinking

•Planning skills and memory strategies improve

•Long-term knowledge base grows

•Language skills expand to include synonyms, categories, double meanings, metaphors, humor, and complex grammatical structure


•Changes in physique, sexuality, cognitive functioning, and society’s treatment may challenge sense of self

•Appreciation of connection between moral rules and social conventions strengthens

•Peer groups often divide into cliques

•Awareness of gender stereotypes continues to increase

•Issues increase around autonomy, sibling rivalry, and separation from family

Periods: 13-15

Early Adolescence: Ages 13 – 15


•Body continues to grow in height and weight

•Girlsgrowth spurt peaks, while boys typically begin it

•Motor performance gradually increases, but often levels off for girls

•Girls usually start to menstruate and boys to ejaculate


•Formal operational reasoning, the capacity for abstract, scientific thought, emerges

•Thinking becomes more self-conscious, idealistic, and critical

•Metacognition and self-regulation further develop

•Vocabulary expands to include abstract words

•Understanding and grasp of complex grammar continues to improve

•Ability to grasp irony and sarcasm develops


•Issues of identity emerge, potentially leading to crisis in sense of self

•Sexual orientation begins to emerge

•Psychological disorders and sociocultural-adaptational disorders may emerge

•Strives for autonomy in relation to family continues to increase, and parent-child conflicts more likely to occur

•Friendships have greater emphasis on intimacy and loyalty

•Conformity to peer pressure increases

Periods: 16-19

Late Adolescence: Ages 16 – 19


•Boys’ growth spurt peaks, and growth is mostly complete by end of this period

•Boys develop deeper voices and patterns of facial hair, and typically grow taller than their female peers

•Girls tend to grow wider in the hips, and breast development continues for several years

•Girls’ motor performance peaks, while boys’ continues to improve


•Reasoning through problems in symbolic terms and through use of formal logic improves

•Fluid intelligence, the ability to cope with new problems and situations, is reached by the end of this period

•Ability to understand and integrate rules into sense of self becomes basis for character development


•Development of identity continues in relation to adult world

•First dating begins process of developing and maintaining intimate relationships

•Cliques decline in importance

•Identity achievement greatly influenced by personal factors, including family and peer relationships with family and peers, and economic and political circumstances

•Increased assertiveness and lack of self-discipline often create conflicts with parents

•Sexual orientation continues to develop

•Introduction begins to the world of work and career planning

Periods: 20-40

Early Adulthood: Ages 20 – 40


•Physical functioning increases through the 20’s and peaks at about age 30, but can be maintained through exercise

•Body shape changes, with gradual increases in weight and body fat and decreases in lean muscle mass

•Efficiency of many organ systems begins to diminish at the rate of about 1% a year

•Sexual responsiveness remains high throughout this period, with some slowing in men

•Physical appearance changes; gray hair and wrinkles develop toward end of this period


•Thinking may become practical and dialectical to adapt to the inconsistencies and complexities in daily experiences

•Short-term memory peaks

•Wisdom and expertise begin to develop

•Vocabulary and knowledge continue to grow through work interactions and everyday problem-solving


•Issues of identity and intimacy peak by age 30

•Need for affiliation filled by friends and often a marriage/partner

•Friendships become particularly important for people who are single

•Need for achievement often met through satisfactory work consistent with personality and abilities

•Personality traits most likely to change up to age 30, with additional maturation continuing into the 40’s

Periods: 41-65

Middle Adulthood: Ages 40 – 65


•Gradual changes continue in appearance of skin, hair, and body shape

•Gradual changes occur in hearing and vision, including presbyopia, the inability to focus on near objects

•Menopause begins in women

•Health and potential onset of disease affected by preventive behaviors, many of which vary by social class


•Fluid intelligence declines while crystallized intelligence remains steady or increases

•Intellectual abilities dependent on speed and novelty decrease, while abilities involving knowledge about the world and vocabulary increase

•Reaction time and mental processing speed slow

•Short and long-term memory remain relatively stable

•Cognitive abilities related to experience and intelligence flourish, leading to further formation of expertise

•Maintenance of cognitive skills as well as opportunities for intellectual growth impacted by social class


•Mid-life crisis occurs in a small minority of cases, because most men and women experience gradual transitions in sense of self and in relationship with the world

•Personality traits tend to remain stable

•Friendship and marriage/partnership continue as primary sources of affiliation

•Marital satisfaction often rises as children move away from home

•Maintenance phase in career may allow for greatest productivity at work, may also cause burn-out

•Experiences of facing age discrimination more likely

Periods: 65+

Late Adulthood: Ages 65 – Onward


•Brain becomes physically smaller and functions more slowly

•Gradual changes continue in appearance, along with weakening of the body sense organs and major body systems

•Losses continue in visual and hearing abilities

•Decreases in immune system and overall muscle strength put older adults at risk of chronic and acute illness

•Short-term memory may decline, but active exercise of mental abilities helps to maintain functioning

•Age-related changes impact sexual functioning, but not pleasure


•Abilities to receive information, store it in memory, and organize and interpret it decline

•Some short-term memory abilities declined, but methods can help compensate for memory loss and slower thinking

•Aesthetic, philosophical, or spiritual interests emerge or intensify

•Language abilities based on memory and processing speed decline, but overall vocabulary continues to grow

•Driving-related abilities dependent on information-processing speed decrease, while skills based on experience increase

•Wisdom, experience-based problem solving, and semantic knowledge increase


•Retirement experience shaped by social class and gender factors, including income, health, and amount of previous planning

•Abilities to cope with stress, reduce negative emotions, and manage personal relationships improve broader perspective on life

•Subjective sense of well-being tends to be higher than at all previous periods

•Satisfaction with life largely dependent on family involvement

•Bereavement for spouse, friends, and families stressful, but most people are able to integrate a loss into their lives within one year after it happens

•End-of-life care that incorporates pain management and psychological support greatly impacts well-being


Life consists not in holding good cards but in playing those you hold well.
 — Josh Billings
Adaptation throughout life depends on how each of us negotiates the internal and external factors that enhance or constrain our abilities to reach our full potentials. The essence of life span development is in how we build on our strengths to transcend these limitations over time.