D

Introduction to Intelligence Testing

  • Early Intelligence Tests and Concepts:

    • Alfred Binet: Designed the first intelligence test for children.

    • Focused on mental age to determine if children were developing on pace or slowly.

    • Primarily concerned with children developing slowly, aiming for early intervention.

    • Mental age compared a child's problem-solving abilities to other children their same chronological age.

    • Binet believed intelligence was not permanent, viewing his test as a "snapshot in time."

    • Lewis Terman: Revised Binet's test.

    • Developed the Stanford-Binet Intelligence Test, which was widely used for a long time.

    • Introduced the term IQ (Intelligent Quotient), which is still in use today.

    • Terman believed intelligence could be measured across multiple domains, not just a single factor.

    • His idea was to assign a numerical score after the test.

  • Early Applications and Biases of Intelligence Tests:

    • World War I: The U.S. Army needed to group recruits based on learning skills.

    • Stanford helped by adapting the Stanford-Binet test into two versions:

      • Army Alpha: A written test.

      • Army Beta: An oral test for soldiers who could not read or write.

    • While it worked reasonably well and measured perceived intelligence, it was not perfect.

    • Immigrant Testing (Ellis Island, 1917):

    • Immigrants were tested in English, a language many did not speak.

    • Tests included cultural biases, such as a picture of children burying a rabbit.

      • American interpretation: Burying a pet, sad.

      • Immigrant interpretation (from countries with food scarcity): Preparing for supper, digging a hole for a fire to cook the rabbit.

      • These answers were marked incorrect, despite being logical based on the immigrants' experiences.

    • This highlights significant bias in testing due to differences in thought processes and backgrounds.

    • Historical Bias and Misinterpretation:

    • An expert, influenced by these biased test results, claimed that 80\% of Hungarians, 79\% of Italians, and 87\% of Russians were "feeble-minded." This was a direct result of their poor performance on culturally biased tests, not actual intellectual deficit.

  • Modern Intelligence Tests:

    • Wechsler Tests: Currently used, revised multiple times.

    • WAIS (Wechsler Adult Intelligence Scale): For adults (currently on the Fourth Edition).

    • WISC (Wechsler Intelligence Scale for Children): For younger children.

    • These tests are designed for specific age groups and focus on age-appropriate learning and decision-making (e.g., WISC focuses on experiential learning, memory, rather than questions about owning a house).

  • Types of Psychological Tests:

    • Achievement Tests: Measure what you have already learned or your knowledge in a specific area.

    • Example: Most academic tests taken in school.

    • Aptitude Tests: Assess your potential or ability to learn a new skill or subject, without requiring prior knowledge.

    • Example: ASVAB (Armed Services Vocational Aptitude Battery), used by the military to assign roles based on aptitude (e.g., mechanics, computer skills).

  • Key Principles of Good Test Design:

    • Standardization:

    • The test can be generalized across populations.

    • Enough people have been tested (normed) for scores to be reliably compared.

    • Ensures everyone has the same opportunity to score well.

    • Examples: ACTs, SATs, GREs.

    • Reliability:

    • The test measures the same thing consistently every time.

    • Multiple versions of the same test should yield roughly the same score for an individual.

    • Example: Taking five different versions of the ACT should result in similar scores.

    • Validity:

    • The test measures what it claims to measure.

    • A test can be reliable but not valid (e.g., a math test given in a psychology class might reliably measure math skills but is not valid for a psychology course).

    • A test cannot be valid unless it is also reliable; it must consistently measure what it's supposed to measure.

  • IQ Distribution and Interpretation:

    • Normal Distribution: IQ scores typically follow a bell curve.

    • Standard Deviation: For IQ, it is 15 points.

    • Average Score: 100.

    • Classifications of Intelligence:

    • Scores between 90 and 110 are considered within the normal range.

    • A score of 125 is one full standard deviation above normal, indicating significantly higher abilities.

    • IQ Calculation Example: If a 10-year-old (chronological age) scores like a 13-year-old (mental age), their IQ is \frac{\text{Mental Age}}{\text{Chronological Age}} \times 100 = \frac{13}{10} \times 100 = 130.

    • Stability over Time: IQ scores generally remain stable over a person's life, with some minor variations.

    • Population Distribution:

    • Approximately 68\% of people score between 85 and 115 (within one standard deviation of the mean).

    • Approximately 95\% of people score between 70 and 130 (within two standard deviations of the mean).

    • The remaining 5\% are outliers at the extremes.

  • Theories of Intelligence:

    • Charles Spearman (Two-Factor Theory):

    • First person to describe intelligence as a g factor (general intelligence), a basic overall intellectual ability.

    • Did not significantly advance the idea beyond this general concept.

    • Howard Gardner (Theory of Multiple Intelligences):

    • Believed there are multiple, distinct intelligences, not just a single g factor.

    • Proposed at least eight intelligences for a comprehensive understanding of IQ, including:

      • Bodily-kinesthetic intelligence (e.g., athletes).

      • Musical intelligence.

      • Art (e.g., artistic ability).

    • Argued that any area where one shows strong aptitude should be considered an intelligence.

    • Received some support but also criticism due to the difficulty in objectively measuring many of these intelligences.

    • Robert Sternberg (Triarchic Theory of Intelligence):

    • Proposed three interdependent areas of intelligence:

      • Analytic Intelligence: Problem-solving, general learning, extracting information, creating plans (e.g., traditional IQ test questions).

      • Creative Intelligence: Dealing with novel situations, thinking outside the box, applying existing knowledge in new ways to solve new problems.

      • Practical Intelligence: "Street smarts," navigating real-world situations, common sense, adapting to practical demands (e.g., navigating a new city safely).

    • Integrating Theories: Some researchers aim to combine these ideas to better link how intelligence is understood with how it is applied and measured in the real world, though this is still a work in progress.

  • Extremes of Intelligence:

    • Intellectual Disability: Diagnosed when an IQ score is 70 or below (two standard deviations below average).

    • Individuals typically require some level of support to navigate the world independently.

    • High Intelligence: Charles Terman's study (1921)

    • Followed 1,500 children with IQs above 140 throughout their lives.

    • Found that as adults, their income tended to be higher than average.

    • However, not all were successful; success was more strongly predicted by personality traits such as perseverance, self-confidence, and a positive response to failure, rather than IQ alone.

  • Nature vs. Nurture in IQ:

    • Genetics: Plays a role in determining a general range of IQ, not a specific score.

    • Children of intelligent parents are likely to have higher IQs due to genetic predisposition.

    • Environment (Epigenetics): Significantly influences the expression of genetic potential.

    • Positive Environmental Factors: Exposure to books and language early in life, educational opportunities (camps, gifted programs) can lead to higher IQ expression.

    • Negative Environmental Factors: Lack of intellectual stimulation (e.g., limited conversation, no books, discouragement of education) can result in lower IQ expression.

    • Twin Studies (Correlational): Provide insight into genetic and environmental influences.

    • Identical twins raised in the same environment: Share identical DNA and environment, showing the most similar IQ scores (correlation of about 0.86).

    • Identical twins raised separately: Still show a high correlation (about 0.76), indicating a strong genetic component to IQ, even when environments differ.

    • It is crucial to remember these are correlational studies, not causation; IQ differences have both genetic and environmental components.

  • Diversity and Bias in Test Creation:

    • Historically, IQ tests were often created by a narrow demographic (e.g., white, middle-aged men).

    • This lack of diversity leads to cultural bias (reiterating the immigrant testing example and introducing new ones).

    • Example: "Scissors" vs. "Shears": A test might count "shears" as incorrect for a picture of scissors, unaware that "shears" is a common Southern term, thereby unfairly lowering scores for individuals from that region.

    • To accurately assess everyone, test creators need a variety of backgrounds and perspectives (diverse ages, cultures, regions) to anticipate and account for different valid responses and cultural understandings.

  • Stereotype Threat:

    • The phenomenon where individuals, aware of a negative stereotype about their group, perform poorly on tests that highlight that stereotype.

    • Example: Women and Math Tests (1990s research):

    • Women scored lower on math tests when tested in a room full of men, especially when aware of the stereotype that women are not good at math.

    • The same women scored significantly higher when tested with other women and informed that the test was designed for "how women learn math." This removed the stereotype threat.

    • Mechanism: Stereotype threat causes physiological arousal (e.g., accelerated heart rate), diverting cognitive resources away from the task and leading to poorer performance.

  • Cultural IQ Differences (Extended Example):

    • Burakumi of Japan: A group within Japan that is not racially or genetically different from other Japanese citizens, yet has faced significant societal discrimination and prejudice.

    • Despite similar genetics, Burakumi individuals score 10 to 15 points lower on IQ tests compared to other Japanese citizens.

    • This demonstrates that societal discrimination and prejudice, rather than genetic factors, can significantly impact measured IQ scores.

  • The Flynn Effect:

    • Observation that IQ scores in developed nations have increased over the last four generations.

    • Each successive generation scores slightly higher than previous ones.

    • Hypothesized Reasons: Increased educational access, better nutrition, more stimulating environments, and generational building upon previous knowledge.

    • Future Outlook: Developmentalists suggest a potential shift or regression in the Flynn effect due to factors like increased screen time and reliance on technology, which could impact learning styles and cognitive abilities. This remains a subject of ongoing research and prediction.