1. Psychological Science ©2013 W. W. Norton & Company, Inc.
Gazzaniga • Heatherton • Halpern
Psychological Science
FOURTH EDITION
Chapter 8
Thinking and Intelligence
©2013 W. W. Norton & Company, Inc.

2. “Mind Reading”
As pollsters often demonstrate during elections, reading minds, whether of voters or the person next to you, is close to impossible. However, as this ScienCentral News video explains, scientists are one step closer to reading our thoughts.

3. Thinking and Intelligence
GerdGigerenzer has written about fears that he calls dread risks
Dread risks can result when events with dire consequences receive a lot of publicity, even when the publicized events have a low probability of recurring
The resulting fears can profoundly affect reasoning and decision making
9/11 caused many more people to fear flying even though the number of people who die in car accidents every year far exceeds the number who die in airline disasters or hijackings

4. 8.1 What Is Thought?
Distinguish between analogical and symbolic representations.
Describe the defining attribute, prototype, and exemplar models of concepts.
Discuss the positive and negative consequences of using schemas and scripts. 4

5. Thinking Is the Manipulation of Mental Representations
The field of cognitive psychology is the study of thought. It was originally based on two ideas:
The brain represents information
Thinking is the mental manipulation of these representations
Our thoughts consist of mental representations of the objects and information that we encounter in our environments
Cognition includes thinking and the understandings that result from thinking 5

6. Thinking Involves Two Types of Representations
Analogical representations: mental representations that have some of the physical characteristics of objects, e.g. maps
When we think of an object, we often bring to mind a visual image, or analogical representation, of the object
Pause and think about a lemon: What form did your “lemon” thought take?
Symbolic representations: abstract mental representations that do not correspond to the physical features of objects or ideas, e.g. words or ideas
Neural activity occurs when we look at objects, and it can be reactivated when we recall the objects

7. FIGURE 8.3 Analogical Representations and Symbolic Representations
(a) Analogical representations, such as this picture of a violin, have some characteristics of the objects they represent. (b) Symbolic representations, such as the word violin, are abstract and do not have relationships to the objects.

8. Mental Maps Combine Representation
Mental maps can include both analogical and symbolic representations
Symbolic representations can lead to errors, because we can represent only a limited range of knowledge analogically and thus use memory shortcuts unconsciously
Which is farther east, San Diego, California, or Reno, Nevada?
Which is farther north, Seattle, Washington, or Montreal, Canada?

9. FIGURE 8.4 Try for Yourself: Conceptual Mental Maps

10. FIGURE 8.4 Try for Yourself: Conceptual Mental Maps

11. Concepts Are Symbolic Representations
Grouping things based on shared properties, categorization, reduces the amount of knowledge we must hold in memory and is therefore an efficient way of thinking
Much of our knowledge of the world is based on concepts, or categories of items organized around common themes
concept: a mental representation that groups or categorizes objects, events, or relations around common themes

12. FIGURE 8.5 Categorization
We group objects into categories according to the objects’ shared properties.

13. Defining Attribute Model
Defining attribute model: In this way of thinking about concepts, a category is characterized by a list of features that determine if an object is a member
For example, a “bachelor” is characterized by being unmarried and male
The model suggests:
membership within a category is on an all-or-none basis;
all of a given category’s attributes are equally important in defining that category;
all members of a category are equal in category membership
We often make exceptions in our categorizations, and some attributes are more important for defining membership
The boundaries between categories are much fuzzier than the defining attribute model suggests
Is every unmarried male a “bachelor”?

14. FIGURE 8.6 The Defining Attribute Model
In the defining attribute model, concepts are organized hierarchically. That is, they can be subordinate or superordinate to each other. For example, horns and stringed instruments are subordinate categories of the superordinate category of musical instruments.

15. Prototype Model
Prototype model: Within each category, there is a best example—a prototype—for that category
One positive feature of the prototype model is that it allows for flexibility in the representation of concepts
One drawback related to such flexibility is that a particular prototype can be chosen for different reasons: Life experiences, culture, or location can influence the prototype for a category

16. FIGURE 8.7 The Prototype Model
According to the prototype model, some items within a group or class are more representative (or prototypical) of that category than are other items within that group or class.

17. FIGURE 8.8 Try for Yourself: The Prototype Model of Concepts

18. Exemplar Model
Exemplar model: All members of a category are examples (exemplars); together they form the concept and determine category membership
It assumes that, through experience, people form a fuzzy representation of a concept because there is no single representation of any concept
It accounts for the observation that some category members are more prototypical than others: The prototypes are simply members we have encountered more often
How would you explain the difference between a dog and a cat to someone who has never seen either? Most dogs bark, but a dog is still a dog if it does not bark

19. FIGURE 8.9 The Exemplar Model
The exemplar model holds that all members of a category are exemplars. For example, even this strange-looking feline is an exemplar of the category cats. (This cat happens to be a brown tortie white and tabby sphinx.)

20. Schemas Organize Useful Information about Environments
Schemas are cognitive structures that help us perceive, organize, and process information
Scripts are schemas that dictate appropriate behavior.
What we view as appropriate is shaped by culture
Schemas and scripts are adaptive in that they enable us to make quick judgments with little effort
What sequence of events does the script going to the movies include? How would you feel if a stranger sat next to you in the theater, or started talking?

21. FIGURE 8.12a Script Theory of Schemas
According to this theory, we tend to follow general scripts of how to behave in particular settings. (a) At the movies, we expect to buy a ticket or print one if we bought it online. The cost of the ticket might depend on the moviegoer’s age and the time of day.

22. FIGURE 8.12b Script Theory of Schemas
According to this theory, we tend to follow general scripts of how to behave in particular settings. (b) Next, we might buy a snack before selecting a seat. Popcorn is a traditional snack at movie theaters. Caviar is not.

23. FIGURE 8.12c Script Theory of Schemas
According to this theory, we tend to follow general scripts of how to behave in particular settings. (c) If we are part of a couple or group, we expect to sit with the other person in that couple or the people in the group. Although quiet talking might be appropriate before the movie, most of us expect talking to cease once the feature begins.

24. Schemas Organize Useful Information about Environments
Schemas and scripts may lead us to think and act in stereotypical ways
stereotypes: cognitive schemas that allow for easy, fast processing of information about people based on their membership in certain groups
Gender roles are the prescribed behaviors for females and males and represent a type of schema that operates at the unconscious level
The schemas and scripts that children learn are likely to affect their behavior when they are older

25. FIGURE 8.13 Scientific Method: Study of Preschoolers’ Use of Cigarettes and Alcohol while Role-Playing as Adults

26. Psychology: Knowledge You Can Use— How Can Dating Scripts Help Me Navigate in My Romantic Life?
According to Amiraian and Sobal (2009), “Dating scripts are shared cognitive representations of likely sequences of dating events and sets of appropriate dating behaviors based on social norms and previous experiences that direct decisions and behavior on dates.”
Knowing how a date is likely to unfold removes some of the ambiguity of an event
Following a generally accepted script and behaving consistently with a set of culturally accepted rules helps manage the impressions that other people form about you
Let your values and beliefs guide your behavior; collaborate on a date that feels right to you

28. 8.2 How Do We Make Decisions and Solve Problems?
Distinguish between deductive and inductive reasoning.
Distinguish between normative and descriptive models of decision making.
Explain how heuristics, framing, and affective forecasting influence decision making.
Review strategies that facilitate insight and problem solving.

29. 8.2 How Do We Make Decisions and Solve Problems?
Thinking enables us to do the following:
reasoning: using information to determine if a conclusion is valid or reasonable
decision making: attempting to select the best alternative among several options
problem solving: finding a way around an obstacle to reach a goal 29

30. People Use Deductive and Inductive Reasoning
When drawing conclusions, we engage in deductive and inductive reasoning
Errors, such as making biased choices in what evidence to consider, can lead to false conclusions in both deductive and inductive reasoning tasks

31. FIGURE 8.14 Deductive Reasoning, Inductive Reasoning, Decision Making, and Problem Solving

32. Deductive Reasoning
In deductive reasoning, you use logic to draw specific conclusions under certain assumptions (premises)
deductive reasoning: using general rules to draw conclusions about specific instances
In research, a deductive reasoning task is often expressed as a syllogism, e.g. If A is true, then B is true
We can come up with a valid but incorrect conclusion, however, if the premises use terms inconsistently or ambiguously
Consider the following:
Nothing is better than a piece of warm apple pie
A few crumbs of bread are better than nothing
Therefore, a few crumbs of bread are better than warm apple pie
How might prior beliefs or schemas interfere with deductive reasoning?

33. Inductive Reasoning
Inductive reasoning involves reasoning from the specific to the general
inductive reasoning: using specific instances to draw conclusions about general rules
For example, if your Italian friend is fashionable, you may induce that Italians in general are fashionable
How might inductive reasoning lead to erroneous conclusions?

34. Inductive and Deductive Reasoning Combined
You always bump into your roommate at the coffee shop
Through inductive reasoning, you believe she really likes coffee
Therefore you decide through deductive reasoning to get her a Starbucks gift card for her birthday

35. Reasoning and the Scientific Method
The use of the scientific method to discover general principles is one example of inductive reasoning
The scientific method dictates that scientists meet certain standards when inducing general principles from several specific instances
These standards are designed to guard against biases in inductive reasoning
In day-to-day life, however, we may be more likely to reach inappropriate conclusions when reasoning about general principles from everyday circumstances
People are strongly influenced by anecdotal reports

36. Decision Making Often Involves Heuristics
In their research on decision making, psychologists have studied normative models and descriptive models:
Normative models of decision making view people as optimal decision makers
Descriptive models account for actual behavior
Expected utility theory is one normative model of how we should make decisions by considering the possible alternatives and choosing the most desirable one
Research has demonstrated, however, that we are not always rational in making decisions

37. Decision Making Often Involves Heuristics
Tversky and Kahneman identified several common heuristics
heuristics: shortcuts (rules of thumb or informal guidelines) used to reduce the amount of thinking that is needed to make decisions
Heuristic thinking often occurs unconsciously and allows us to free up some cognitive resources
Heuristic thinking can be adaptive in that it allows us to decide quickly rather than weighing all the evidence each time we have to decide
Heuristics can also result in biases, which may lead to errors or faulty decisions
An algorithm is a procedure that, if followed correctly, will always yield the correct answer

38. Framing Effects
How information is presented can alter how people perceive it
framing: the effect of presentation on how information is perceived

40. Framing Effects
To account for framing’s effects, Kahneman and Tversky came up with prospect theory, a major theory in decision making
Prospect theory has two main components:
a person’s wealth affects his or her choices
loss aversion: Because losses feel much worse than gains feel good, a person will try to avoid situations that involve losses

41. FIGURE 8.17 Loss Aversion
How happy would you feel if someone walked over to you right now and handed you $1,000? How bad would you feel if someone took $1,000 from your checking account? Potential losses affect decision making more than potential gains do. In your opinion, why do people dislike losses so much?

42. Critical Thinking Skills: Understanding How Heuristics Can Affect Your Thinking
Prototypes are readily available in memory. We tend to rely on prototypes in making decisions
availability heuristic: making a decision based on the answer that most easily comes to mind
We base decisions on the extent to which each option reflects what we already believe about a situation
representativeness heuristic: placing a person or object in a category if that person or object is similar to one’s prototype for that category
Heuristics can lead to faulty reasoning if you fail to take other information into account, such as the base rate (how frequently an event occurs)
Once we know that such shortcuts can lead us to make faulty judgments, we can use heuristics carefully as we seek to make rational decisions

43. FIGURE 8.16 The Availability Heuristic at Work
If you are like most people, you thought of words with r as the first letter (such as right and read). Then you thought of words with r as the third letter (such as care and sir). Because words with r at the beginning came most easily to mind, you concluded that r is more often the first letter of a word. R is much more likely, however, to be the third letter in a word.

44. Affective Forecasting
Gilbert and Wilson have found that people are not good at affective forecasting, or predicting how they will feel about a future event
People tend to overestimate the extent to which negative events will affect them in the future
We engage in adaptive strategies — such as rationalizing why an event happened and minimizing the event’s importance — to cope with negative events.
People seem unaware that they can find positive outcomes from tragic events, and typically when considering a hypothetical aversive event, they overestimate the misery and underestimate how well they will cope with the event
Affective forecasting can also influence our perceptions of positive events:
How would you feel if you won an Olympic medal?
Now, compare winning the silver medal vs. the gold.

45. “Drinking vs. Talking”
You “walk the line” during a sobriety test because you shouldn’t drive if you’ve drunk so much you can’t walk in a straight line. But as this ScienCentral News video explains, research suggests that talking while driving may be just as dangerous.

46. FIGURE 8.19 Affective Forecasting
Mardy Fish (left) was disappointed when he won the silver medal for tennis at the 2004 Olympics. At any point in your life, have you been disappointed by an outcome that someone else might have viewed as success? How did the circumstances contribute to your disappointment?

47. The Paradox of Choice
Psychological reactance occurs when we are told what to do and what not to do; we react by wanting to do exactly what is forbidden to us even if we had no strong preferences before our choices were restricted
Iyengar and Lepper’s study indicates that having many possibilities can make it difficult to choose one item
According to psychologist Barry Schwartz, the consequence of nearly unlimited choice makes some people miserable and may help explain the increase in clinical depression. He divides the world into satisficersand maximizers.
Satisficerslook around until they find something that most closely matches what they want and buy it, without worrying about whether better or cheaper products are available
Maximizers always seek to make the best possible choices. They hesitate in making decisions, and they feel paralyzed by indecision when they have to select between equally attractive choices. As a result, they generally are more disappointed with their decisions and more likely to experience regret

48. FIGURE 8.21 Way Too Much Choice?
Spam—a canned, precooked meat product—tends to divide people into lovers and haters. Haters of Spam would most likely not have a problem passing this display quickly. Suppose you were a lover of Spam. How would Barry Schwartz recommend that you deal with the many varieties of Spam (and related products) offered here?

49. Problem Solving Achieves Goals
A person has a problem when he or she has no simple and direct means of attaining a particular goal
To solve the problem, the person must use knowledge to determine how to move from the current state to the goal state
Often, the person must devise strategies to overcome obstacles
How the person thinks about the problem can help or hinder that person’s ability to find solutions

50. Organization of Subgoals
One approach to the study of problem solving is to identify people’s steps in solving particular problems
Breaking down a problem into subgoals is an important component of problem solving
When you are facing a complex problem, identifying the appropriate steps or subgoals and their order can be challenging

51. FIGURE 8.22 The Tower of Hanoi Problem

52. Sudden Insight
Unconscious processes sometimes lead to objectively better solutions than conscious processes do
Insight: the sudden realization of a solution to a problem
Köhler demonstrated that chimpanzees, as well as humans, have insightful moments
Maier’s study with the string and pliers provides an example of how insight can be achieved when a problem initially seems unsolvable
How we view or represent a problem can significantly affect how easily we solve it
A saying like think outside the box embodies ideas about insight; however, it may not be very useful without hints for how to get started

53. Changing Representation to Overcome Obstacles
In problem solving we often need to revise a mental representation to overcome an obstacle
restructuring: a new way of thinking about a problem that aids its solution; representing the problem in a novel way
The new view reveals a solution that was not visible under the old problem structure
Attempt to solve Sheerer’s Nine Dot Problem:
How can you “think outside the box” to connect all nine dots using at most four straight lines, without lifting the pencil off the page (see next slide)?

54. FIGURE 8.23 Scheerer’s Nine-Dot Problem

55. Changing Representation to Overcome Obstacles
In trying to solve a problem, we commonly think back to how we have solved similar problems
mental sets: problem-solving strategies that have worked in the past
Functional fixedness (mental representations about the typical functions of particular objects) can also create difficulties in problem solving
To overcome this kind of obstacle, the problem solver needs to reinterpret the object’s potential function, e.g. Duncker’s candle challenge

56. FIGURE 8.24 Luchins’s Mental Set
In 1942, the Gestalt psychologist Abraham Luchins demonstrated a classic example of a mental set.
He asked participants to measure out specified amounts of water, such as 100 cups, using three jars of different sizes.
Say that jar A held 21cups, jar B held 127 cups, and jar C held 3 cups.
The solution to this problem was to fill jar B, use jar A to remove 21 cups from jar B’s 127 cups, then use jarC to remove 3 cups of water twice, leaving 100 cups in jar B.
The structure to the solution is B – A – 2(C). Participants were given many of these problems. In each problem, the jar sizes and goal measurements differed, but the same formula applied.
Then participants were given another problem: They were given jar A, which held 23 cups; jar B, which held 49 cups; and jar C, which held 3 cups.
They were asked to measure out 20 cups.
Even though the simplest solution was to fill jar A and use jar C to remove 3 cups from jar A’s 23, participants usually came up with a much more complicated solution that involved all three jars.
Having developed a mental set of using three jars in combination to solve this type of problem, they had trouble settling on the simpler solution of using only two jars.
Surprisingly, when given a problem with a simple solution for which the original formula did not work, many participants failed to solve the problem most efficiently.

57. FIGURE 8.25 Overcoming Functional Fixedness

58. Conscious Strategies Two examples of conscious strategies:
working backward: When the appropriate steps for solving a problem are not clear, proceeding from the goal state to the initial state can help yield a solution
finding an appropriate analogy: Using a strategy that works in one context can help to solve a problem that is structurally similar with analogous constraints
Analogous solutions work only if we recognize the similarities between the problem we face and those we have solved

59. “Writer’s Block”
Anyone who has tried to write and ended up staring at a blank page knows the pain of writer’s block. But for some, this barrier is devastating. As this ScienCentral News video reports, researchers have found some nontraditional ways to unlock extreme writer’s block.

60. 8.3 How Do We Understand Intelligence?
Identify common measures of intelligence.
Discuss the validity of measures of intelligence.
Review theory and research related to general intelligence, fluid intelligence, crystallized intelligence, multiple intelligences, and emotional intelligence.
Discuss the relationship between intelligence and cognitive performance.
Summarize research examining genetic and environmental influences on intelligence.
Discuss sex and race differences in intelligence.
Define stereotype threat.

61. 8.3 How Do We Understand Intelligence?
Individuals differ in terms of intelligence just as they differ physically and in terms of their personalities.
intelligence: the ability to use knowledge to reason, make decisions, make sense of events, solve problems, understand complex ideas, learn quickly, and adapt to environmental challenges
Psychologists consider two aspects when measuring intelligence: They study the ways that knowledge and its applications in everyday life translate into intelligence, and they examine the degree to which intelligence is determined by genes and by environment. 61

62. “Brainy Brains”
The size of your brain doesn’t necessarily determine how smart you are; your IQ, brain researchers say, is more influenced by how your brain thickens and thins when you’re a kid. This ScienCentral News video has more.

63. Intelligence Is Assessed with Psychometric Tests
The psychometric approach to measuring intelligence focuses on how people perform on standardized tests
Some psychometric tests focus on achievement;other psychometric tests focus on aptitude
Binet proposed that intelligence is best understood as a collection of high-level mental processes
Psychometric tests of general intelligence include the Stanford-Binet test, which measures intelligence using the intelligence quotient, or IQ score
The Wechsler Adult Intelligence Scale has two parts: verbal and performance

64. Intelligence Quotient
Binet introduced the important concept of mental age:
mental age: an assessment of a child’s intellectual standing compared with that of same-age peers; determined by comparing the child’s test score with the average score for children of each chronological age
The intelligence quotient (IQ) was developed by the psychologist Wilhelm Stern:
intelligence quotient (IQ): an index of intelligence computed by dividing a child’s estimated mental age by the child’s chronological age, then multiplying this number by 100
IQ in the adult range is measured in comparison with the average adult and not with adults at different ages
Across large groups of people, the distribution of IQ scores forms a bell curve, or normal distribution;most people are close to the average

65. FIGURE 8.27 The Distribution of IQ Scores
IQ is a score on a normed test of intelligence. That is, one person’s score is relative to the scores of the large number of people who already took the test. And as discussed in Chapter 2, the statistical concept of standard deviation indicates how far people are from an average. The standard deviation for most IQ tests is 15. The average, or mean, is 100. As shown in this bell curve, approximately 68 percent of people fall within 1 standard deviation of the mean (they score from 85 to 115). Just over 95 percent of people fall within 2 standard deviations (they score from 70 to 130).

66. Validity of Testing
The overall evidence indicates that IQ is a fairly good predictor of life outcomes, e.g. doing well at school
Data suggests modest correlations between IQ and work performance, IQ and income, IQ and jobs requiring complex skills
IQ scores typically predict only about 25 percent of the variation in performance at either school or work
IQ may be important, but it is only one of the factors that contributes to success in the classroom, the workplace, and life generally; additional factors include background, self- control, motivation, and willingness to work

67. Cultural Bias
One important criticism of intelligence tests is that they may penalize people for belonging to particular cultures or particular groups
A person’s exposure to mainstream language and culture affects which meaning of a word comes most quickly to mind, if the person knows the meaning at all:
What does it mean when someone says something is “rad”?
Most measures of IQ reflect values of what is considered important in modern Western culture
What is adaptive in one society is not necessarily adaptive in others
One approach to dealing with cultural bias is to use items that do not depend on language, e.g. performance measures on the Wechsler Adult Intelligence Scale (WAIS)

68. FIGURE 8.28 Removing Bias from Tests
According to the creators of this test, the task is not culturally biased. Do you agree? Why or why not?

69. Critical Thinking Skill: Recognizing and Avoiding Reification
Reification is the tendency to think about complex traits as though they have a single cause and an objective reality, e.g. the complex concept of intelligence
Intelligence is a multifaceted concept defined within a context, not just by a score in isolation
For example, if English is your native language but you speak enough Spanish to take an intelligence test in Spanish, you probably would not expect the resulting IQ to reflect your intelligence accurately
Critical thinkers avoid treating an abstract concept as though it has a tangible reality. They recognize the complexity in complex concepts

70. General Intelligence Involves Multiple Components
An early line of research examined the correlations among intelligence test items using factor analysis
In this statistical technique, items similar to one another are clustered, and the clusters are referred to as factors
Charles Spearman found that most intelligence test items tended to cluster as one factor
Spearman viewed general intelligence, or g, as a factor that contributes to performance on any intellectual task
general intelligence (g): the idea that one general factor underlies intelligence

71. FIGURE 8.29 General Intelligence as a Factor
As depicted in this cluster of overlapping circles and ovals, Spearman viewed g as a general factor in intelligence. This underlying factor influences an individual’s specific abilities related to intelligence.

72. The Importance of g
Research has shown that g influences important life outcomes, such as by predicting performance in school and at work
Low g is related to early death from causes including heart disease, diabetes, stroke, Alzheimer’s disease, traffic accidents, and drownings
However, researchers from the United Kingdom and Finland found that lower socioeconomic status may be the most important predictor of early mortality
A number of theorists have proposed that g’s main value is in allowing people to adapt quickly to environmental challenges
Although most psychologists agree that some form of g exists, they also recognize that intelligence comes in various forms

73. Fluid Versus Crystallized Intelligence
Raymond Cattell (1971) proposed that g consists of two types of intelligence:
fluid intelligence: intelligence that reflects the ability to process information, particularly in novel or complex circumstances, e.g. reasoning
crystallized intelligence: intelligence that reflects both the knowledge one acquires through experience and the ability to use that knowledge
Distinguishing between fluid intelligence and crystallized intelligence is somewhat analogous to distinguishing between working memory (more like fluid intelligence) and long-term memory (more like crystallized intelligence)
Crystallized intelligence grows steadily throughout the adult years, while fluid intelligence declines steadily

74. Multiple Intelligences
Howard Gardner proposed a theory of multiple intelligences:
multiple intelligences: the idea that there are different types of intelligence that are independent of one another
Proposed intelligences include: musical, bodily-kinesthetic, linguistic, mathematical/logical, spatial, intrapersonal, and interpersonal (social understanding) intelligence
There are still no standardized ways to assess many of Gardner’s intelligences and some psychologists argue these are special talents
Sternberg theorized that there are three types of intelligence:
Analytical intelligence is similar to that measured by psychometric tests— being good at problem solving and other academic challenges;
Creative intelligence involves the ability to gain insight and solve novel problems—to think in new and interesting ways;
Practical intelligence refers to dealing with everyday tasks, such as knowing whether a parking space is large enough for your vehicle
Evidence for the existence of such multiple intelligences is presented in the cases of many phenomenally successful public figures who did not excel academically, e.g. Bill Gates dropped out of college

75. Emotional Intelligence
Emotional intelligence (EI) was conceived by the psychologists Peter Salovey and John Mayer and popularized by the science writer Daniel Goleman
emotional intelligence (EI): a form of social intelligence that emphasizes the abilities to manage, recognize, and understand emotions and use emotions to guide appropriate thought and action
Regulating our moods, resisting impulses and temptations, and controlling our behaviors are all important components of EI
Emotional intelligence is correlated with the quality of social relationships
Some critics have questioned whether EI really is a type of intelligence or whether it stretches the definition of intelligence too far

76. Intelligence Is Associated with Cognitive Performance
Galton believed that intelligence was related to the speed of neural responses and the sensitivity of the sensory/perceptual systems, and he speculated that intelligent people have larger, more efficient brains
Other psychologists believe intelligence is supported by low-level cognitive processes, such as mental processing, working memory, and attention

77. Speed of Mental Processing
People who score higher on intelligence tests respond more quickly and consistently on reaction time tests
A test of simple reaction time might require a person to press a computer key as quickly as possible whenever a stimulus appears on the screen
Further support for the relation between general intelligence and speed of mental processing comes from inspection time tests:
If a stimulus is presented and then covered up, how much viewing time does a particular person need to answer a question about the stimulus?
By measuring the electrical activity of brains in response to the presentation of stimuli, researchers have found that highly intelligent people’s brains work faster than less intelligent people’s brains
The relation between general intelligence and mental speed appears to be correlated with the greater longevity of people with high IQs
The relationship between reaction time and longevity was somewhat stronger than the relationship between scores on standardized intelligence tests and longevity

78. FIGURE 8.32 Inspection Time Tasks

79. Working Memory
General intelligence scores are closely related to working memory but are not identical
Studies differentiate between simple tests of memory span and memory tests that require some form of secondary processing
Memory tests that have dual components, however, show a strong relation between working memory and general intelligence
The link between working memory and general intelligence may be attention, or the ability to pay attention

80. FIGURE 8.33 Memory Span Tasks

81. Brain Structure and Function
Many studies have documented a relationship between head circumference, which researchers use to estimate brain size, and scores on intelligence tests
Studies using magnetic resonance imaging have found a small but significant correlation between the size of selected brain structures and scores on intelligence tests
These findings are correlations, however, so we cannot infer that brain size necessarily causes differences in intelligence
Different kinds of intelligence seem to be related to the sizes of certain brain regions. These regions include areas associated with working memory, planning, reasoning, and problem solving
General intelligence appears to be associated mainly with increased cortex size
These findings are consistent with evidence that injury to the frontal lobes causes impairments in fluid intelligence but not in crystallized intelligence

82. FIGURE 8.34 Extraordinary Brain
Sandra Witelson with Einstein’s brain in her lab at McMaster University. Does the size of Einstein’s parietal lobe indicate that larger brains are smarter? Why or why not?

83. Savants
Savants have minimal intellectual capacities in most domains, but at a very early age each savant shows an exceptional ability in some “intelligent” process
A savant’s exceptional ability may be related to math, music, or art
The combination of prodigious memory and the inability to learn seemingly basic tasks is a great mystery; this rare combination adds a dimension to our understanding of intelligence

84. FIGURE 8.35 Stephen Wiltshire
Despite his autism, Stephen Wiltshire had published a book of his remarkably accurate, expressive, memory-based drawings by the time he was a young teenager. Here, in October 2010, he holds his drawing of an architectural site in London, England. Wiltshire observed the site briefly, then completed the picture largely from memory.

85. Genes and Environment Influence Intelligence
Even if intelligence has a genetic component, the way intelligence becomes expressed is affected by various situational circumstances
For example, the capacity for having a large vocabulary is considerably heritable, but every word in a person’s vocabulary is learned in an environment
Instead of seeking to demonstrate whether nature or nurture is the more important factor, psychologists try to identify how each of these crucial factors contributes to intelligence

86. Behavioral Genetics
Numerous behavioral genetics studies have made clear that genes help determine intelligence—but the extent to which genes do so is difficult to determine
Behavioral geneticists study the genetic basis of behaviors and traits such as intelligence; they use twin and adoption studies to estimate the extent to which particular traits are heritable
Even when raised apart, twins who have inherited an advantage might receive some social multiplier, an environmental factor or an entire environment, that increases what might have started as a small advantage
Suppose twins have inherited a higher than average verbal ability? Adults who notice this ability might read to them more often and give them more books

87. FIGURE 8.36 Genes and Intelligence
This graph represents average IQ correlations from family, adoption, and twin study designs. As shown by the red and blue bars on the left, siblings raised together show more similarity than siblings raised apart. As indicated by the relations between parent and offspring (P-O) in the red and blue bars, a parent and child are more similar when the parent raises the child than when the child is raised by someone else. As shown by the red and blue bars on the right, the highest correlations are found among monozygotic twins, whether they are raised in the same household or not. Overall, the greater the degree of genetic relation, the greater the correlation in intelligence.

88. Environmental Factors
Prenatal and postnatal factors, such as poor nutrition, can affect brain development and result in lower intelligence
Research from numerous laboratories has shown that enriched environments enhance learning and memory
The implication is that environment influences how genes involved in brain development are expressed
Schooling encourages the development of children’s brains and cognitive capacities and therefore fosters intelligence
The dramatic rise of IQ scores during the last century has been called the Flynn effect after James R. Flynn, the researcher who first described it
Since genes cannot have changed much during this period, the increase must be due to environmental factors

89. “Go Play Outside”
Feel like you’re suffering from brain drain and can’t concentrate? Psychologists have found that taking some time to interact with nature, even in cold weather; can make you a bit smarter.

90. FIGURE 8.37 Environmental Impacts
Within each of these planters, differences in the plants are likely due to genes. But note how different the plants are as a whole between one planter and the other. Those differences likely result from the environmental differences between the planters. (a) This planter has provided an impoverished environment. The poor conditions have negatively affected growth and development. (b) This planter has provided an enriched environment. The proper resources have contributed to robust growth and development.

91. FIGURE 8.38 Birth Weight and Intelligence
Among children of normal birth weight, mean IQ scores increase with weight.

92. Group Differences in Intelligence Have Multiple Determinants
Which is the smarter sex?
Using IQ scores to determine which is the smarter sex does not work because most of the commonly used intelligence tests were written in ways that would avoid creating an overall sex difference in IQ
Using only tests that had not deliberately eliminated sex differences, Jensen found no evidence for sex differences in the mean level of g or in the variability of g. Males, on average, excel on some factors; females on others

93. Group Differences in Intelligence Have Multiple Determinants
Are there intelligence differences based on race?
The most controversial aspect of intelligence testing over the last century has been the idea that genetics can explain overall differences in intelligence scores between racial groups
In a 1969 paper, Jensen created a firestorm of controversy by asserting that African Americans are, on average, less intelligent than European Americans
Given the importance of intelligence to educational and career attainment, claims that some groups are superior to others require close scrutiny, and it is important to discuss controversial and sensitive topics with an eye to being as fair to all sides as possible

94. Group Differences in Intelligence Have Multiple Determinants
Whether the effects of race are real or not, it is not scientifically appropriate to conclude that genes cause differences between groups if there are any environmental differences between those groups
Research has demonstrated that stereotype threat may be reduced by informing people of the negative consequences of stereotype threat, having people focus on positive aspects of their lives, and bolstering people’s peer relations and social connections.
stereotype threat: apprehension about confirming negative stereotypes related to one’s own group

95. FIGURE 8.40 Stereotype Threat
Stereotype threat may lead black students to perform poorly on some standardized tests.

96. FIGURE 8.41 Stereotype Threat Counteracted
Stereotype threat can be counteracted when people are warned about it.