Developmental Pyschology

Genome: This term refers to the complete set of DNA and genes an individual inherits from their biological parents.
Dominant Genes: These genes are expressed every time they are paired with any other gene.
- Example: Brown eyes are a dominant gene. If a person inherits a brown eye gene, they will have brown eyes, regardless of the other gene.
Recessive Genes: These genes only manifest if paired with another identical recessive gene.
- Example: Blue eyes are a recessive gene. To have blue eyes, a person must inherit a blue eye gene from both parents.
  - Scenario: A person with blue eyes ( $bb$ ) and a spouse with brown eyes ( $B?$ ). If their child has blue eyes ( $bb$ ), it indicates the spouse must carry a recessive blue gene ( $Bb$ ).
Polygenetic Traits: Most human characteristics, such as height, are determined by multiple genetic variations (e.g., height is influenced by approximately $200$ genetic variations). This is a more complex inheritance pattern than simple dominant/recessive traits.

Definition: While genes provide the blueprint (like for identical twins), epigenetics refers to external factors that can turn our genes on or off or tag them, leading to differences even among individuals with identical DNA.
Identical Twins Example: Identical twins have the exact same genes, yet as they age, their epigenomes diverge, affecting their aging process and susceptibility to diseases like heart disease.
Mechanism: Genes in DNA are expressed when they are read and transcribed into RNA, which then leads to protein synthesis by ribosomes. Proteins determine a cell's characteristics and function.
- Epigenetic Changes: These changes can either boost or interfere with the transcription of specific genes.
- Process: The most common interference mechanism involves DNA or the proteins it's wrapped around being labeled with small chemical tags. These tags constitute the epigenome.

Stages: Development begins in the prenatal period before birth.
- Zygote: The initial stage after conception.
- Embryo: The developing organism from implantation through the $8$ th week.
- Fetus: From the $9$ th week until birth.
Factors Impacting Development In Utero: Various external factors can influence a baby's development while in the womb.
- Diet: Maternal diet is a significant factor.
- Medications: Concerns exist regarding certain medications; for example, Tylenol has been controversially linked to autism in some research.

Historically, children were not viewed as having distinct developmental stages; they were often seen as little adults.

Babies are not little slugs but possess inherent abilities.
Moro Reflex: A survival reflex where babies automatically make a hugging motion or grab if they experience a sudden change in direction or a falling sensation. This helps them hang on and prevents them from getting lost.

Babies follow a general sequence of motor development, though timing can vary:
- Lifting head
- Holding chest up
- Sitting
- Standing with help
- Crawling
- Standing alone
- Walking alone
Developmental Milestones: While these are not exact timeframes, significant delays (e.g., not holding chest up by $7$ months) can indicate concerns.

Vision: Babies are born with the ability to see, though their vision is initially blurry. They can discern edges and faces and show preference for looking at a person's face even at $2-5$ days old.

Readiness Period: A time when the brain and body are cognitively and physiologically prepared to learn a particular skill.
- Example: A one-year-old cannot read because they lack language and the ability to associate symbols with words. Expecting skills before readiness can be detrimental in education.
Sensitive Period: A critical window during which the brain is optimally primed to absorb a lot of new information for specific skills.
- Example: Learning two languages from a young age is significantly easier due to a sensitive period for language acquisition. Waiting too long (missing this period) makes learning harder.

Skills Expected Too Early: Examples include demanding complex physical activities (like crawling before ready), expecting advanced communication skills (talking clearly, knowing names), proficient use of technology (abstract thought), full emotional expression and control, understanding right/wrong, not asking clarifying questions, emotional regulation, tying shoes (fine motor skills, sequencing).
Skills Taught Too Late (Missing Sensitive Periods): Examples include scheduling/routine creation, swimming (baby classes show early learning is possible), relationship skills (impacting others, emotional development), making friends, being respectful, sexuality education (comfortable, truthful answers), identifying emotions/feelings, public speaking, learning from mistakes, hygiene.

Babies are born with basic emotions (e.g., interest, anger, sadness, happiness) that aid survival and communication with caregivers.
Absent Emotions in Infants: Complex emotions like envy and jealousy are not present at birth; they develop later.

Research suggests that individuals are born with an innate temperament (e.g., easy or difficult babies), which contributes to their developing personality.

Background: Mid- $1950$ s research investigated whether infants bond with caregivers solely for food (behaviorist view) or for comfort and security (Bowlby's view).
Experimental Design: Harry Harlow used rhesus macaque monkeys, isolating them and testing their behavior with surrogate mothers:
- Wire Mother: Provided food (milk).
- Cloth Mother: Offered comfort (soft texture).
Findings (First Studies):
- Monkeys went to the wire mother for food but spent the vast majority of their time cuddling with the cloth mother.
- When scared by a motorized toy, monkeys consistently ran to the cloth mother for comfort and security, regardless of which surrogate provided food.
- Conclusion: Provided solid evidence against the behaviorist perspective, supporting the idea that monkeys (and by extension, infants) have emotional and attachment needs beyond simple sustenance, termed contact comfort.
Ethical Concerns: Harlow's methods are now considered inherently unethical due to the unjustifiable amount of pain and distress caused to the subjects.
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