Physical Development

• Psychologists believe infants show certain motor responses (movements) automatically as they grow.
• These movements happen because of maturation—natural growth and changes inside the body.
• No prior learning, practice, or experience is required for these initial movements.

1. Cephalo-Caudal Development

• Growth and control happen from head to toe.
• Example: Babies control their head, then their arms, then their legs.

2. Proximo-Distal Development

• Growth and movement start from the center of the body and move outward.
• Example: Babies first move their shoulders and arms, then their hands and fingers.

• Lymphoid tissue grows quickly and reaches the adult level by age six, doubles at age 12, then declines by maturity.
• Neural growth is fastest after birth, with about eighty percent complete by four years old.
• Genital growth speeds up during puberty.
• Skeletal system grows quickly at birth and during pubescence.
• Vascular and respiratory organs grow along with bones and muscles.​

• Physical growth relates to a person’s behaviour.
• Slow physical development can cause children to have different social experiences than those who develop at a normal rate.
• Changes due to physical growth can impact sociability, popularity, interests, attitudes, and personality.
• During adolescence, hormonal changes alter interests, attitudes, and motivations.​

• Infants show automatic motor responses due to natural growth (maturation), without prior learning.
• Cephalo-caudal development: control grows from head to toe (head → arms → legs).
• Proximo-distal development: control grows from the centre outward (shoulders/arms → hands/fingers).
• Physical growth after birth is rapid in neural, skeletal, genital, lymphoid, and respiratory systems, especially in early childhood and puberty.
• Physical growth affects behaviour, social experiences, interests, attitudes, and personality, with hormones influencing adolescence.