1. Is Intelligence Neurologically Measurable?
Brain size correlation to intelligence: +.33
What does this mean?
Portion sizes vary as well
Einstein had abnormally large parietal lobes
Environmental experiences impact
Rat neural connections example
Highly educated people die with 17% more synapses than counterparts

2. Other Environmental Influences
Infants who suffer from extreme malnutrition during infancy average 20 I.Q. points lower than other children (Stock and Smythe, 1963)
Toxins in the environment such as lead found in some paints are associated with reduced I.Q. (Needleman, 1990)
Intelligence declines with family size; the fewer children there are the smarter you are likely to be (Zajonc, 1975)
Intelligence declines with birth order; first-borns tend to be brighter (Zajonc, 1975)
I.Q. is negatively correlated with family risk factors, such as social class or absence of father figure (1989)

3. Are There Multiple Intelligences?
Social Intelligence
the know-how involved in comprehending social situations and managing oneself successfully
Emotional Intelligence
ability to perceive, express, understand, and regulate emotions

5. Brain Function and Intelligence
Correlation between fast perceptual speed and general intelligence
People who can perceive the stimulus very quickly tend to score somewhat higher on intelligence tests
Stimulus
Mask
Question: Long side on left or right?
Neurological Speed
Correlation between intelligence and neurological processing

6. Assessing Intelligence
Aptitude Test
a test designed to predict a person’s future performance
aptitude is the capacity to learn
Achievement Test
a test designed to assess what a person has learned (ex: unit exams, driver’s test)

7. Assessing Intelligence
Wechsler Adult Intelligence Scale (WAIS)
most widely used intelligence test
subtests
verbal
performance (nonverbal)

8. Assessing Intelligence: Sample Items from the WAIS
From Thorndike and Hagen, 1977
VERBAL
General Information
Similarities
Arithmetic Reasoning
Vocabulary
Comprehension
Digit Span
PERFORMANCE
Picture Completion
Picture Arrangement
Block Design
Object Assembly
Digit-Symbol Substitution

10. Assessing Intelligence
Standardization
defining meaningful scores by comparison with the performance of a pretested “standardization group”
Normal Curve
the symmetrical bell-shaped curve that describes the distribution of many physical and psychological attributes
most scores fall near the average, and fewer and fewer scores lie near the extremes

11. The Normal Curve

12. Getting Smarter?
Flynn Effect: IQ scores going up about 3 points per decade

13. Assessing Intelligence
Reliability
the extent to which a test yields consistent results
assessed by consistency of scores on:
two halves of the test
alternate forms of the test
retesting
Validity
the extent to which a test measures or predicts what it is supposed to

14. Assessing Intelligence
Content Validity
the extent to which a test samples the behavior that is of interest
driving test that samples driving tasks
Criterion
behavior (such as college grades) that a test (such as the SAT) is designed to predict
the measure used in defining whether the test has predictive validity

15. Assessing Intelligence
Predictive Validity
success with which a test predicts the behavior it is designed to predict
assessed by computing the correlation between test scores and the criterion behavior
also called criterion-related validity

16. Assessing Intelligence
Greater correlation
over broad range
of body weights 10 9 8 7 6 5 4 3 2 1
Little corre-
lation within
restricted
range
Football linemen’s
success
Body weight in pounds
As the range of data under consideration narrows, its predictive power diminishes

17. The Dynamics of Intelligence
Is intelligence stable across the lifespan or does it change?
Intelligence test scores don’t stabilize until about age 7; after that about a +.66 correlation over time

18. The Dynamics of Intelligence
Extremes of Intelligence
Mental Retardation
a condition of limited mental ability
indicated by an intelligence score below 70
produces difficulty in adapting to the demands of life
varies from mild to profound
Down Syndrome
retardation and associated physical disorders caused by an extra chromosome in one’s genetic makeup

20. The Dynamics of Intelligence

21. Tracking
From early age students are often tracked into “gifted” programs and “remedial” programs… what’s a potential problem with this?
Self-Fulfilling Prophecy

23. Genetic Influences
The most genetically similar people have the most similar scores

24. Genetic Influences

25. Environmental Influences
The Schooling Effect
Intelligence scores drop over the summer when students are not in school

26. Group Differences Average IQ scores by racial groups
Whites: Roughly 100
Blacks: Roughly 85
Hispanics: Roughly 92/93
Differences are diminishing over time
What explains these differences?

27. Group Differences Gender Differences Girls score higher on:
Spelling
Verbal Ability
Nonverbal Memory
Sensation (more sensitive)
Detecting Emotion
Boys outnumber girls in special education, talk later, stutter more often
Girls now match or surpass boys at math

28. The Question of Bias Stereotype Threat
Are intelligence tests biased?
Depends on definition of “biased,” but…
Yes, often due to CULTURAL BIAS
Chitling Test, Australian Aboriginie Test examples
Stereotype Threat
A self-confirming concern that one will be evaluated based on a negative stereotype
Example: Women score higher on math tests when no male test-takers are in the room

29. Group Differences Stereotype Threat
A self-confirming concern that one will be evaluated based on a negative stereotype