Developmental Psychology Notes

Week Three Development

• Zygote develops into about 50 cells by week three.
• Zygote travels down the fallopian tubes and implants in the uterus lining; this marks the transition from a zygote to an embryo.

Embryonic Stage (Weeks 3-8)

• Heart begins to beat.
• Formation of structures: head, chest, abdomen.
• Embryo receives nourishment and oxygen through the placenta and umbilical cord.
• Timeline:
• First two weeks: zygote (germinal stage).
• Next six weeks: embryo (embryonic stage).
• Last thirty-two weeks: fetus (fetal stage).

Fetal Stage Development (Weeks 9-40)

• 12 weeks: sex organs start differentiating.
• 16 weeks: fingers and toes form.
• 20 weeks: fetal hearing begins.
• 24 weeks: lungs develop.
• 28 weeks: rapid brain growth.
• 32 weeks: bones fully developed.
• 36 weeks: muscles fully developed.
• 40 weeks: full-term development; gestation period = 40 weeks (approximately 265 days).

Teratogens

• Harmful factors affecting embryo/fetus include biological, chemical, or physical agents called teratogens.
• Alcohol:
• Heavy consumption can cause fetal alcohol syndrome (FAS), leading to intellectual disability and physical abnormalities.
• Lesser amounts lead to fetal alcohol effects, which still cause issues.
• Smoking:
• Can lead to low birth weight, stillbirth, premature birth, and SIDS (sudden infant death syndrome).
• Other Drugs:
• Includes illicit drugs (heroin, cocaine) and prescription medications that can harm the fetus.
• Historical Example:
• Thalidomide in the 1960s caused birth defects including facial deformities.
• Radiation:
• X-rays pose risks to developing fetus.
• Infectious Agents:
• HIV and rubella can cause significant harm during pregnancy.
• Dietary Restrictions:
• Pregnant women advised to avoid lunch meat, raw fish (due to mercury content).

Impact of Prenatal Development

• Harmful effects due to teratogens are particularly concerning for the embryo and fetus phases (post-embryonic development is not the focus here).

Reflexes at Birth

• Newborns exhibit numerous reflexes (approximately 36), some lasting a lifetime (e.g., sneezing).
• Reflexes are involuntary automatic responses; examples:
• Rooting Reflex: Turn towards touch on the cheek.
• Sucking Reflex: Suckle when something is near mouth.
• Swallow Reflex: Triggered when liquid enters mouth.
• Grasping Reflex: Strong grip when something touches palm.
• Moro Reflex: Startle response causing arms to fling out then retract.
• Babinski Reflex: Splaying of toes when the foot is stroked.

Sensory Development

• Vision is functional at birth, developing into 20/20 vision around age one.
• Infants prefer human voices, especially their mother's.
• Olfactory senses also present, with a preference for sweet tastes often established.

Growth Patterns in Infancy

• Newborns often weigh between 6-8 lbs, typically tripling their weight by year one (21 lbs).
• Length increases approximately by half during the first year (e.g., from 20 inches to 30 inches).

Neural Development

• Rapid formation of neural pathways occurs throughout infancy and childhood.
• By age six, a child's brain is about 90% of adult size.
• Motor Skill Development:
• Fine Motor Skills: Small movements, develop later through the manipulation of objects (writing).
• Gross Motor Skills: Larger movements, requiring muscle control in a sequential order (e.g., rolling over before walking).

Cognitive Milestones

• Development stages (e.g., object permanence begins at around 8 months).
• Growth in logical thought begins between ages 6 to 11.

Psychosocial Development: Attachment

• Development of attachment bonds primarily between infants and caregivers (often mothers).
• Harry Harlow's Research: Suggested comfort is often more important than nourishment (Rhesus monkey studies).
• John Bowlby: Emphasized the necessity of attachment for emotional and social development.
• Mary Ainsworth's Strange Situation: Identified three attachment styles:
• Secure Attachment: Healthy bond; child explores and is upset when caregiver leaves.
• Avoidant Attachment: Little emotional response to caregiver’s absence.
• Resistant Attachment: Clingy, upset by absence, inadequate comfort upon return.
• Later designated a fourth type: Disorganized Attachment among abused children.

Parenting Styles Impacting Attachment

• Authoritative: Parents provide rules but show warmth and listen to children's perspectives; children often do well under this style.
• Authoritarian: Lack warmth; emphasize obedience and control; can lead to less competent children.
• Permissive: Parents act more like friends than authority figures; lack structure can hinder development.
• Uninvolved: Caregivers provide basic needs but lack emotional involvement; can lead to neglect.

Impact of Child Temperament on Parenting

• Some children display easier temperaments, while others may be more difficult, influencing parenting approaches.

Adolescence and Physical Development

• Puberty transforms individuals from non-reproductive to reproductive capability.
• Primary Sexual Characteristics: Necessary for reproduction; develops during puberty.
• Secondary Sexual Characteristics: Develop during puberty; e.g., for girls, breast development; for boys, facial hair.
• Menarche and Spermarch:
• Menarche (first menstruation) occurs around age 12-13.
• Spermarch (first ejaculation) occurs around age 13-14.

Brain Development in Adolescence

• Brain continues to develop into the twenties, particularly the prefrontal cortex which contributes to executive functions.
• Adolescents may not always make the best decisions due to ongoing brain maturation.

Summary of Key Concepts

• The processes of prenatal development and after birth are critical in determining an individual’s physical, cognitive, and psychosocial capabilities for life.
• The significance of nurturing and responsive caregiving is paramount to promoting healthy development in infants and children.