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Session Overview

Photo of a person filling in answers on a computer-graded test answer sheet.

How much is intelligence determined by our childhood environment vs. our genetics? Are there things we can do later in life to become more intelligent? What exactly is intelligence, anyway? This session explores the strengths and weaknesses of IQ testing, various models of intelligence, some underlying neural mechanisms, the influences of nature and nurture on intelligence, and perspectives on influences of race, effort, and practice.

Keywords: IQ, testing, education, Flynn effect, nature vs. nurture, acheivement gap, stereotype threat, Head Start

How well do standardized tests measure intelligence? (Photo courtesy of biologycorner on Flickr. License CC BY-NC.)

Session Activities


Read the following before watching the lecture video.

  • One of the following textbook selections:
    • [K&R] Finish Chapter 6, "Language, Thinking, and Intelligence: What Humans Do Best"
    • [Stangor] Sections in Chapter 9, "Intelligence and Language"
      • Introduction
      • 9.1: Defining and Measuring Intelligence
      • 9.2: The Social, Cultural, and Political Aspects of Intelligence

Lecture Videos

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Video Resources

Discussion: Thinking & Intelligence

This discussion section covers thinking and intelligence. We'll discuss two topics: whether we think in words or pictures, and some approaches to creative problem solving… Read more »

Check Yourself

Short Answer Questions

1) What is intelligence? What is IQ? How are they related?

Sample Answer

Intelligence, as it is understood in psychological science, is "the ability to reason and solve problems well and to understand and learn complex material" (Kosslyn & Rosenberg, 2011).

IQ (intelligence quotient) is a score on an intelligence test, based on population and age norms.

In many cases, IQ is used as a measure (index) of intelligence, although intelligence is a complex and multifaceted construct, whereas IQ is a single number over many factors.


2) What are some examples of how IQ scores relate to real-world performance outcomes? Does IQ tell the whole story? What other factors have been shown to play a role in real-world performance?

Sample Answer

IQ has been shown to correlate with career success, financial success, marriage stability, and avoiding jail. Other factors bear on real-world success too, such as personality traits, motivation and ambition, and culture.


3) Many researchers have proposed different constructs that they claim capture different factors in intelligence. Describe Spearman's g and how it relates to the idea of intelligence. Compare and contrast fluid intelligence and crystalized intelligence – what does each describe and how are they related?

Sample Answer

Spearman's g is a 'general factor' which is thought to underlie performance on a variety of different intelligence tasks. For example, performance on many subtests of intelligence are positively correlated (meaning that people with high scores on one tend to have high scores on the others); the overall degree of relatedness across tests is captured by g.

Fluid intelligence is the ability to reason about novel problems without relying on specific past experiences; whereas crystallized intelligence relies on applying specific past experiences and knowledge to problem solving. For example, fluid intelligence supports the ability to find a solution when familiar tools are unavailable, and crystallized intelligence supports the ability to recall facts or procedures that are related to a problem at hand. These intelligences work together. Fluid intelligence can draw on extensive crystallized intelligence by abstracting general principles that will work in new, previously unencountered situations.


Further Study

These optional resources are provided for students that wish to explore this topic more fully.

Supplemental video jayrandall22011. "Talking Twin Babies – Part 2." Feb. 14, 2011. YouTube. Accessed Jan. 9, 2012. Mentioned at about minute 36 in lecture – "two twins babbling, demonstrative…"
Supplemental video StanfordSCOPE. "Claude Steele on Stereotype Threat." Nov. 23, 2011. YouTube. Accessed March 9, 2012. Brief interview with Prof. Steele, whose research first identified the stereotype threat effect on acheivement gaps.
Textbook supplement Study materials for Ch. 9 "Types of Intelligence: What Does It Mean To Be Smart?" In Kosslyn & Rosenberg, Psychology in Context, 3/e (Pearson, 2007) Practice test questions, flashcards, and media for a related textbook


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