06 Human Development I: Physical, Cognitive, & Language Development

Dicephalic twins Abigail and Brittany Hensel share two arms and two legs,as well as most of their organs from the waist down. They have identical genes and grew up in an identical environment, yet their personalities are very different.

How do our biology and our environments influence our development?

• During pregnancy, teratogens can pass through the placenta and cause irreparable harm to an embryo or fetus.
• Increased food intake and a decrease in disease may contribute to the earlier onset of puberty in industrialized countries.

What universal changes do we experience at different stages in our lives?

• Newborn babies exhibit reflexes including rooting, sucking, swallowing, grasping, and stepping.
• Motor skills tend to develop in sequence from top to bottom and from inside to outside.
• During puberty, the body develops primary and secondary sex characteristics.
• The gradual loss of brain cells as we age leads to a decline in memory.

What are some of the landmarks of physical, cognitive, and language development?

• Physical landmarks include the germinal, embryonic, and fetal stages, newborn reflex actions, motor development, puberty, menopause and andropause, and the physical decline of old age.
• Piaget theorized that children use assimilation and accommodation to adjust their informational schemas. Vygotsky believed children’s cognitive development is influenced by cultural experiences.
• Language development landmarks include cooing and babbling, producing vocabulary, and learning grammatical rules.

How do psychologists study human development, and what questions have yet to be answered?

• Developmental psychologists study the physical, cognitive, and social changes we experience by examining three issues: stability/change, nature/nurture, and continuity/stages.
• Researchers perform both cross-sectional and longitudinal developmental studies.
• Normative investigations enable researchers to distinguish between chronological age and developmental age.