Chapter 9

Genetic and Environmental Influences on Intelligence

Mary Anne discusses the interplay between genetic and environmental factors in determining intelligence. It is established that intelligence is strongly genetic but not entirely determined by genetics. Environmental variables, such as the type of schooling and enrichment a child receives, play a significant role in shaping their intelligence.

Average Intelligence

The definition of average intelligence is framed with the score of IQ 100.

  • 50% of individuals score above 100.
  • 50% score below 100.
Giftedness

To classify as gifted, an individual must score an IQ of above 130, which is two standard deviations above the mean IQ of the population.

  • This classification applies to roughly 2.5% of the population.
  • Gifted individuals typically exhibit:
    • Curiosity: They ask numerous questions, demonstrating a desire to understand and learn.
    • Creativity: They solve problems uniquely and approach tasks differently from their peers.
    • Passion for Mastery: Intrinsically motivated learners who strive for success in their academic pursuits.
School Environments for Gifted Children

Gifted children thrive in settings that allow for self-directed exploration, such as Montessori schools. These schools support intrinsic motivation and mastery, unlike rigid traditional education systems.

Intellectual Disabilities

Intellectual disabilities, previously referred to as mental retardation, are now classified as such in the DSM (Diagnostic and Statistical Manual of Mental Disorders).

  • The terminology change reflects an evolving understanding of these conditions.

Classification of Intellectual Disabilities

Historically, intellectual disability was defined with a strict IQ cutoff of 70, aligning similarly with the giftedness cutoff.

  • 2.5% of individuals also fall below this threshold, indicating that the rates of giftedness and intellectual disability are statistically similar.
Diagnosis Criteria

According to the DSM:

  • An IQ below 70 is necessary, but additional criteria include:
    • Deficit in Adaptive Functioning: Impairments in daily skills (e.g., inability to live independently).
    • Onset During Developmental Period: Symptoms must be evident from early childhood to avoid confounding with other diagnoses arising from events like injuries.

Most individuals with intellectual disabilities are classified as mild, with IQs typically ranging from 60 to 70. These individuals can maintain employment in supportive roles.

Causes of Intellectual Disability

The causes of intellectual disabilities can be both known and unknown, with approximately 25% of cases traced to:

  • Genetic conditions (e.g., Fragile X syndrome, Down syndrome).
  • Prenatal factors such as fetal alcohol syndrome, infections like meningitis, or maternal high fevers during pregnancy.

The impact of environment on developmental potential is also noted, where intellectual capacity can fluctuate between lower bounds in neglectful settings versus higher bounds in enriched environments.

Theories of Intelligence

Sternberg’s Triarchic Theory

Robert Sternberg posits that intelligent behavior can be categorized into three types:

  1. Analytical Intelligence: Traditional book smarts associated with academic success.
  2. Creative Intelligence: The ability to think outside the box, a quality found in designers and innovators (e.g., Steve Jobs).
  3. Practical Intelligence: Common sense or street smarts, understanding social dynamics and real-world tasks.

Gardner’s Multiple Intelligences

Howard Gardner expands the notion of intelligence beyond Sternberg's triadic model to identify nine distinct intelligences:

  1. Interpersonal Intelligence: Recognizing and interpreting emotions in others; essential for fields like nursing and social work.
  2. Intrapersonal Intelligence: Self-awareness and the ability to reflect on one’s self.
  3. Bodily-Kinesthetic Intelligence: Proficiency in physical activities like sports and dance.
  4. Verbal-Linguistic Intelligence: High proficiency in reading, writing, and communication skills.
  5. Logical-Mathematical Intelligence: Skills in logical reasoning and quantification, highlighted by early calculus learners.
  6. Naturalistic Intelligence: Understanding and engaging with nature and ecological systems.
  7. Visual-Spatial Intelligence: Aptitude in visualizing spatial relationships and artistic expression.
  8. Musical Intelligence: Sensitivity to rhythm and tone, enabling musical abilities.
  9. Existential Intelligence: The capacity to ponder deep questions about life, purpose, and philosophy.

Gardner's argument centers on the idea that educational systems often neglect diverse intelligences, and the hope is to celebrate all forms of intelligence in education.

Educational Implications and Changing Landscape

The conversation on educational systems highlights that creativity should be regarded with equal importance as literacy.

  • Sir Ken Robinson stresses that creativity is critical for our future, yet educational systems worldwide prioritize traditional academic abilities.
  • He argues that systems currently favor the production of university professors, while many forms of intelligence crucial for innovation and real-world problem-solving are marginalized.

Current Trends in Education

Robinson discusses the evolving nature of education in response to societal changes, with increasing academic inflation where higher degrees are required for jobs that previously did not need them.

  • This inflation affects perceptions of intelligence and capability, often sidelining individuals with non-academic strengths.

Autism Spectrum Disorder (ASD)

A recent discussion indicates that the DSM now recognizes autism under the wider classification of Autism Spectrum Disorder (ASD).

  • This replacement includes previous diagnoses like Asperger’s Syndrome.

Characteristics of Autism

ASD is defined by:

  1. Deficits in Social Communication: Challenges in reciprocal conversation and interpreting nonverbal cues.
  2. Restricted and Repetitive Patterns of Behavior: Stereotypic movements (e.g., hand-flapping), insistence on sameness, and narrow focus of interests.
Eye-Movement Studies in Autism

Studies reveal distinctive patterns in eye contact among individuals with autism, with equal attention to facial features and objects, as opposed to typical human attention favoring the eyes.

  • This may be a potential marker for early diagnosis.

Increasing Diagnosis Rates

The rates of autism diagnoses have risen sharply:

  • Born in 1992: 1 in 150 affected.
  • Born in 2016: 1 in 31 affected.

This rise primarily results from heightened awareness and better diagnostic practices, though environmental factors cannot be discounted.

Genetic Factors

While the precise causes of autism remain nebulous, research suggests a significant genetic component:

  • Identical twin studies show that if one twin is diagnosed, there is a 90% likelihood that the other will be as well.

Overall, understanding intelligence and autism requires acknowledging diverse forms of intelligence and the complexities inherent in mental development.