3.2 Physical Development Across the Lifespan
- Syllabus
- 2025
- Topic
- 3.2
- Level
- —
Learning objectives
3.2A—Explain how physical development before birth applies to behavior and mental processesExplain how physical development before birth applies to behavior and mental processes.• T eratogens, maternal illness, genetic mutations, hormonal, and environmental factors can influence the major physical and psychological milestones that occur during prenatal development.- Exclusion: The stages of prenatal development (zygote, embryo, and fetus) are outside the scope of the AP Psychology Exam.3.2B—Explain how physical development in infancy and childhood apply to behavior and mental processesExplain how physical development in infancy and childhood apply to behavior and mental processes.• Physical development in infancy and childhood happens in generally the same order, but the timing of the development can vary. The development of fine and gross motor coordination is among the major physical and psychological milestones that define infancy and childhood. These physical skills develop as children mature, allowing children to develop critical skills needed to become more independent.• Infants possess reflexes, like the rooting reflex, that indicate on-track physical and psychological milestone development.• Research using the visual cliff apparatus demonstrates an early ability in infants to perceive depth and an innovative way to assess infant responses.• Research suggests that critical or sensitive periods in infancy and childhood have strong developmental effects, especially for skills such as language. Some non-human animals will imprint on the first object they encounter as a means of survival.3.2C—Explain how physical development in adolescence applies to behavior and mental processesExplain how physical development in adolescence applies to behavior and mental processes.• The main physical and psychological milestones that occur in adolescence are the adolescent growth spurt and puberty, in which reproductive ability develops. Adolescents develop primary and secondary sex characteristics during this time, such as menarche and spermarche.3.2D—Explain how physical development in adulthood applies to behavior and mental processesExplain how physical development in adulthood applies to behavior and mental processes.• Adulthood spans most of the lifespan and is characterized by a general leveling off and then a varying decline in reproductive ability (i.e., menopause), mobility, flexibility, reaction time, and visual and auditory sensory acuity.
Influences on Prenatal Development
Before birth, developing physical systems create conditions for later behavior and mental processes. Teratogens, maternal illness, genetic mutations, hormonal factors, and environmental conditions can influence whether major physical and psychological milestones develop as expected.
| Influence | Developmental connection |
|---|---|
| Teratogens or maternal illness | Prenatal exposure or illness may disrupt developing systems |
| Genetic mutations | Altered genetic information may change physical or psychological development |
| Hormonal factors | Chemical signals can affect developmental processes |
| Environmental factors | Conditions surrounding prenatal development can influence outcomes |
The correct causal claim is that these factors can influence development. Their presence identifies a possible developmental influence; it does not by itself prove one inevitable behavioral or mental outcome.
For the AP Psychology Exam, do not label or describe the prenatal stages called zygote, embryo, and fetus. Focus on influences on prenatal physical and psychological milestones.
Physical Development in Infancy and Childhood
Physical development in infancy and childhood usually follows a similar order, while the timing can vary. This distinction lets psychologists recognize a developmental sequence without assuming every child reaches each milestone at exactly the same age.
| Developmental feature or evidence | What it shows |
|---|---|
| Fine motor coordination | Increasing control of small, precise movements supports independence |
| Gross motor coordination | Increasing control of large movements supports mobility and independence |
| Rooting reflex | An infant reflex can indicate on-track milestone development |
| Visual cliff | Infant responses provide evidence of an early ability to perceive depth |
| Critical or sensitive periods | Experience during some periods can have especially strong effects, including on language |
| Imprinting in some non-human animals | Following the first encountered object can support survival |
These examples connect physical maturation with behavior: greater coordination expands what a child can do independently, while apparatuses such as the visual cliff let researchers infer abilities from infant responses when verbal reports are unavailable.
Variable timing is not the same as random order. Also, imprinting is presented here for some non-human animals; do not automatically treat it as the human pattern for attachment or language.
Adolescent Growth and Puberty
Adolescence includes an adolescent growth spurt and puberty. Puberty is the period in which reproductive ability develops, so physical maturation is connected with major psychological and behavioral adjustments during this life stage.
| Developmental feature | Meaning |
|---|---|
| Primary sex characteristics | Physical structures directly involved in reproduction mature |
| Secondary sex characteristics | Other physical traits associated with sexual maturation develop |
| Menarche | The onset of menstruation |
| Spermarche | The first ejaculation |
Growth, puberty, and reproductive milestones help define adolescent physical development. They identify a developmental transition, but the exact timing and personal experience of that transition can vary.
Puberty and the adolescent growth spurt are related but not identical: puberty specifically concerns reproductive maturation, while the growth spurt concerns rapid physical growth.
Physical Change Across Adulthood
Adulthood spans most of the lifespan. Its broad physical pattern is a general leveling off followed by variable decline, rather than one sudden change occurring at the same age for everyone.
| Domain | Lifespan pattern named in the CED |
|---|---|
| Reproductive ability | May decline; menopause is one example |
| Mobility and flexibility | May decrease to varying degrees |
| Reaction time | May become slower |
| Visual and auditory sensory acuity | May decline |
A developmental explanation links a physical change to possible behavior or mental processes. For example, reduced sensory acuity can alter the information available for perception, while slower reaction time can affect how quickly a person responds.
A group trend is not an exact prediction for one adult. The timing and degree of change vary among people and across domains, so aging should not be described as uniform loss.