2.2 psych

2.2.1 Hereditary and Environmental Factors

• Heredity: Transmission of characteristics from biological parents to offspring through genes at conception.

  • Male's sperm fertilizes female's egg (ovum).

  • Chromosomes in sperm and ovum carry genes from each parent, forming a unique zygote.

• Influence of Genes: Genes affect physical traits (blood type, eye/hair color) and biological processes (growth of brain, hormonal changes).

  • Psychological development is also influenced by genetics, impacting traits like intelligence and personality.

  • Mental health disorders (e.g., schizophrenia, depression) have genetic components but are not solely inherited.

• Environmental Factors: Experiences and contexts affect psychological development.

  • Influential factors include siblings, upbringing, friendship groups, education, job, income, housing, and media exposure.

  • Environmental influences can impact individual and collective development throughout life.

2.2.2 Nature Versus Nurture

• Historical Perspectives:

  • Early psychologists debated nature (heredity) vs. nurture (environment).

  • Biological View: Heredity regarded as the primary determinant of psychological development.

    • Skills, personality, and intelligence seen as inherited traits.

  • Behaviorist View: Environmental factors viewed as the main determinants, emphasizing learning.

    • Assumed a newborn's mind is a blank slate, shaped entirely by experiences.

• Nature and Nurture Debate: Ongoing discussion clarified over time.

  • Both hereditary and environmental factors contribute to development.

  • Psychology now focuses on how these factors interact to influence behavior and mental processes.

• Genetic Blueprint: Genetic information from conception outlines physical and psychological traits.

  • Environmental interactions affect the expression of these traits.

2.2.3 Environmental Influences on Psychological Development

• Major experiences can either positively or negatively influence development, depending on timing.

  • Example: Genetic predisposition for schizophrenia may require a major life stressor for onset.

  • Individual experiences vary significantly in their impact on development.

• Two-Hit Model of Schizophrenia: Illustrates the interaction between genetic predisposition and environmental stressors.

• Current Understanding: Shift from nature vs. nurture to nature and nurture debate.

  • Both factors are crucial for psychological growth.

  • Individuals actively shape their development from birth, not merely passive recipients of their environment.