Francis Galton (1884) Darwin’s cousin Interested in measuring “natural ability” in hopes of identifying people with greater natural ability to reproduce Gave his test to 10,000 volunteers There was no reliability or validity
Alfred Binet (1904) French Mental age- the level of performance typically associated with chronological age Believed that identifying students mental age range could help inform interventional strategies Feared that intelligence testing would be used to label children and limit their opportunities
Lewis Terman (1911) Developed the Stanford-Binet Test Believed that intelligence tests measured the intelligence with which the person was born IQ = (MA/CA)100 MA = CA average intelligence MA > CA above average intelligence MA < CA below average intelligence
Modern Tests of Mental Abilities The Stanford-Binet Does approximate a normal distribution Can be used as a portion of an assessment Achievement Tests- measure what you have learned Examples? Aptitude Test- predicts your future ability- capacity to learn Examples?
Modern Tests of Mental Abilities (cont.) Wechsler Adult Intelligence Scale (WAIS) Measures intelligence with 15 subtests including similarities, vocabulary, block design, and letter-numbering sequences Can give an overall intelligence score as well as subsets for Verbal comprehension Perceptual organization Working memory Processing speed Can identify cognitive strengths and weaknesses Less culturally biased
Intelligence Testing Design Validity- does it measure what it is intended to measure Reliability- does it yield consistent, reproducible results Standardization Does it have uniform procedure for administering and scoring Does it have norms- performance standards for comparison Must be periodically restandardized due to changes in populations
The Normal Curve What to know… The percentages that fall under each potion The percentage that falls within 1 standard deviation of the mean (68%) The percentage that falls within 2 standard deviations of the mean (95%) The cut off for intellectually disabled and gifted
Gifted Individuals Above average intelligence 130-132 or higher on an IQ test Terman (same guy that developed the Stanford-Binet) studied 1500 students in CA starting in 1921 (“Termites”) Studied over 7 decades, most had attained high levels of education, becoming doctors, lawyers, professors, scientists, and writers
Individuals with Intellectual Disabilities Low IQ (below 70) AND difficulty adapting to everyday life Severity is determined by adaptive function rather than IQ Adaptive behavior includes: Conceptual skills- literacy, numbers, money and time Social skills- interpersonal skills, responsibility, self-esteem, ability to follow rules Practical skills- personal care, occupational skills, health care, travel, telephone skills
Causes of Intellectual Disability Genetics Early childhood environment
Nature vs. Nurture Heritability- the proportion of observable differences in a group that can be explained by genes The highest measure of heritability would be 100% Intelligence is rated 75% in adolescents and about 80% in adults
Heritability cannot be applied to a single individual because it is based on percentages of a population Environment can effect the expression of genetic components Nutrition Epigenetics For most people, changes in the environment can have a substantial impact on intelligence.
The discussion depends on what we assess and how we assess it Crystalized Intelligence Accumulated knowledge as reflected in vocabulary any analogies testing Increases up to old age Fluid Intelligence Our ability to reason speedily and abstractly Decreases beginning in your 20s and 30s Social reasoning and emotional intelligence also increase as we age
Cultural Bias in Testing Wording can be culturally biased based on Living location (rural, urban, country, region) Socioeconomic status Race Example:
Culture-Fair Tests Intelligence tests that are intended to be culturally unbiased May contain questions familiar to people from all socioeconomic and ethnic backgrounds or may contain no words at all
Challenges of Developing Culture-Fair Tests Tests often reflect what is important in a dominate culture Attitudes, values, and motivation can affect test performance