Intelligence, Fluid vs. Crystalized & Animal Inteligence

Intelligence Testing and Its Implications

Variability in Test Performance

  • Intelligence tests vary in difficulty across individuals.
  • Some tasks, like identifying similarities, may be easy for some (e.g., Maddie), indicating abstract thinking skills.
  • Other tasks, like manipulating blocks, may be more challenging.

Norming of Intelligence Tests

  • Intelligence tests are normed, meaning they have been administered to large populations.
  • This allows comparison of an individual's performance to a broader population.
  • For example, "this person performed better than sixty seven percent of people her age in The United States".
  • It allows the possibility of making fine-grained distinctions about a person's abilities compared to others.

Domains of Intelligence

  • Different domains exist, such as language and spatial manipulation.
  • Two major domains are crystallized and fluid intelligence.

Crystallized Intelligence

  • Crystallized intelligence: abilities that develop through experience, schooling, and knowledge gained from the environment.
  • Examples: vocabulary, understanding relationships between concepts.

Fluid Intelligence

  • Fluid intelligence: the ability to manipulate abstract information in one's mind.
  • Example: solving puzzles with blocks without prior instruction.

Experiencing Fluid Intelligence

  • Raven's Progressive Matrices: A test of fluid intelligence where the difficulty increases progressively.
  • The test involves abstract thinking about complex problems.

The Importance of Measuring Intelligence

  • Intelligence predicts real-world outcomes that people care about, such as performance in school and on the job.
  • Even after controlling for family background, children who score higher on IQ tests do better in school and the workplace compared to their siblings.

Job Performance

  • Intelligence tests predict job performance, even in manual labor or blue-collar jobs.
  • They also predict high levels of achievement like scientific discoveries and inventions.

Differential Prediction of Fluid and Crystallized Intelligence

  • Fluid intelligence is more predictive of performance in math, science, engineering, and technical trades.
  • Crystallized intelligence is more predictive of writing quality and success in humanities, law, and related fields.

Prediction of Health Outcomes

  • Intelligence at ages 10 or 11 can predict health in adulthood, including risk for heart disease, mental health, and longevity.
  • There is a correlation between IQ points and extra years of life, though it's not a strong relationship.
  • IQ \uparrow \implies Longevity \uparrow

Mechanisms Linking Intelligence and Health

  • Smarter people tend to have better healthcare, live in safer neighborhoods, and have more public resources due to socioeconomic status.
  • Intelligence is correlated with health behaviors like following medication instructions and maintaining a healthy lifestyle.
  • Intelligence may represent overall system integrity, reflecting both neural and bodily health.

Brain Structure and Intelligence

  • Neural connections between brain regions are related to intelligence test scores and change together with intelligence as people age.
  • Declining brain wiring is associated with cognitive decline.

The Lothian Birth Cohort Study

  • A Scottish study that has provided insights into intelligence and aging.
  • IQ tests were administered to 11-year-olds in Scotland in 1947.
  • Researchers followed up with these individuals in their retirement age, conducting psychological testing and brain imaging.
  • The study has contributed to understanding the stability and aging of intelligence and its relationship to brain structure.

Changes in Intelligence Over the Lifespan

  • Crystallized intelligence increases until about age 65 or 70 and then may decline slightly.
  • Fluid intelligence peaks in late adolescence and early adulthood (around age 20) and then slowly declines throughout life.
  • The decline in fluid intelligence begins in early adulthood, even in the absence of dementia.

The Effects of Substance Use on Intelligence

  • Stimulants like Adderall and Ritalin can temporarily boost cognitive performance.
  • Hallucinogens and alcohol impair cognitive performance during intoxication.
  • The long-term effects of persistent drug use on intelligence are being studied.
  • Longitudinal studies are following children into adolescence and young adulthood to determine whether lower intelligence is a cause or consequence of drug use.

Intelligence in Non-Human Animals

  • Intelligence is the ability of an organism to deal with and cope with the world and negotiate it successfully.
  • Tests for intelligence vary across species.
  • Dogs have evolved to attend to humans and use human cues.

Example: Dog vs. Wolf

  • Dogs and wolves raised in the same environment learn to pull a rope for food.
  • When the rope stops working, wolves keep pulling, while dogs look to humans for help.

Testing Intelligence in Dogs: Chaser the Border Collie

  • Chaser, a border collie, was tested on her ability to identify a new toy.
  • She was asked to find a toy she had never seen or heard the name of before (a Charles Darwin doll).
  • Chaser was able to pick out the Darwin doll, demonstrating the ability to infer the name based on exclusion.
  • Dogs like Chaser can remember the connection made between a new toy and its name.