THEORIES OF INTELLIGENCE
To read up on the theories of intelligence, refer to pages 265–284 of Eysenck’s A2
Level Psychology.
Ask yourself
 What is intelligence, i.e. what factors are indicators of this?
 What do you think are the causal factors in intelligence?
 What are multiple intelligences?
What you need to know
PSYCHOMETRIC
APPROACH
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Factor
analysis
Spearman
vs.
Thurstone
The
hierarchical
approach
Evidence
and
evaluation
INFORMATIONPROCESSING
APPROACH
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Reaction
time and
inspection
time
Short-term
memory and
working
memory
Research
evidence for
and against
Evaluation
LEARNING
APPROACH
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Deliberate
practice
Research for
and against
Evaluation
GARDNER’S
THEORY OF
MULTIPLE
INTELLIGENCES
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Research
evidence
Evaluation
Psychometric Approach
Intelligence tests have been developed to try to provide an accurate way of
measuring intelligence. Well-known tests include the Stanford–Binet test, the
Wechsler Intelligence Scale for Children, and the British Ability Scales. These tests
are designed to measure several aspects of intelligence and so include mathematical
items, vocabulary tests, problems based on analogies, and items relating to spatial
ability.
The standardised intelligence quotient (IQ) tests were introduced so that scores
could be compared to those of others. These were tested on large representative
samples to establish the reliability and validity of the measures. The intelligence test
is devised so that the scores form a normal distribution (see A2 Level Psychology
page 266), which means that the majority of the scores cluster around the mean.
The distance from the mean is measured in standard deviations, 68% of the scores
fall within one standard deviation of the mean, 95% fall within two standard
deviations, and 99.73% are within three standard deviations. Intelligence tests are
designed to produce a mean IQ of 100 and a standard deviation of about 16.
Structure of Intelligence: Factor Analysis
Factor analysis is a statistical technique used to assess how well factors correlate to
help separate out different aspects of intelligence. If two items correlate highly with
each other, those who perform well on one item tend to perform well on the other
one. The key assumption is that two items correlating highly with each other assess
the same factor of intelligence. Spearman (1923) suggested that there is a general
factor of intelligence, which he called “g” because most of the items within an
intelligence test correlate positively with each other. However, most of these
positive correlations are fairly weak and so Spearman argued there are specific
factors associated with each test.
Thurstone (1938, see A2 Level Psychology page 268) also believed that intelligence
was more specific than general. He identified seven factors of intelligence, which he
termed primary mental abilities: inductive reasoning (forming generalisations from
examples), verbal meaning, numerical ability, spatial ability, perceptual speed,
memory, and verbal fluency.
Research evidence for the psychometric approach
 The validity of intelligence tests can be checked by seeing if students with
high IQs have a higher level of academic performance than those with low
IQs. There is a positive correlation of about +.5 or +.6 between intelligence
test score and academic performance (Mackintosh, 1998 see A2 Level
Psychology page 269), indicating there is a moderately strong relationship
between these two variables.
 Hunter (1986, see A2 Level Psychology page 269) found that IQ as assessed by
intelligence tests correlated +.58 with work performance among individuals
with high-complexity jobs (e.g. biologist; city circulation manager). The
finding that IQ predicted job performance moderately well suggests that
intelligence tests are at least reasonably valid.
EVALUATION OF THE PSYCHOMETRIC APPROACH
 The specific factors correlate. Thurstone’s specific approach to intelligence
is challenged by the fact that all seven primary mental abilities correlate
positively with each other and so can’t be regarded as completely
independent factors. Factor analysis of Thurstone’s seven factors produces
the general factor that he claimed wasn’t important!
 The hierarchical approach. According to this approach (e.g. Carroll, 1986,
see A2 Level Psychology page 268; Vernon, 1971), a combination of
Spearman’s and Thurstone’s approaches best accounts for the structure of
human intelligence. This results in a three-level hierarchical approach. At the
highest level is the general factor of intelligence originally identified by
Spearman. At the intermediate level of the hierarchy are six or seven group
factors as originally suggested by Thurstone, each more specific than the
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general factor. At the lowest level of the hierarchy, there are numerous
specific factors (e.g. spelling ability).
Culture bias. It has often been argued that most intelligence tests are biased
in favour of white individuals. Williams (1972, see A2 Level Psychology page
270) compared white and black children who were given the Black
Intelligence Test of Cultural Homogeneity (BITCH), which was designed for
black Americans. White American children did no better than black American
children on this test, and sometimes performed worse. This reveals the
difficulty of testing IQ as the questions are biased to the dominant group, so
intelligence tests are only directly applicable to the majority group of the
culture in which they were devised. Therefore they may tell us relatively
little about intelligence in other cultures or sub-cultures.
Strong research support. The factorial approach has produced reasonable
agreement that intelligence has a hierarchical structure. There is also strong
evidence for a general factor of intelligence.
Descriptive rather than explanatory. The psychometric approach is
descriptive rather than explanatory because it describes intelligence but
does not explain how or why it has developed. It does not explain the
influence of genetic and environmental factors in determining individual
differences in intelligence and so offers no insight into the causes of
intelligence.
Reductionist. In seeking only to measure intelligence, the psychometric
approach is very limited and so reductionist because it tells us little about the
cognitive processes and mechanisms underlying intelligent behaviour. This
limitation has been addressed by researchers adopting the informationprocessing approach.
Emotional intelligence. Another way in which the psychometric approach is
reductionist is that it only considers one type of intelligence. Social or
emotional intelligence seems important, and yet is typically excluded from
the hierarchical model
Information-processing approach
The information-processing approach tries to move beyond the descriptive account
of intelligence provided by the psychometric approach. This approach has tried to
explain intelligence by looking at differences in information-processing speeds and
abilities.
Reaction time and inspection time
Research evidence for the information-processing approach
 A key assumption of information-processing theorists is that processing
speed of very simple tasks depends to a large extent on IQ.
 Deary, Der, and Ford (2001, see A2 Level Psychology pages 271–272) provide
evidence for a relationships between IQ and reaction time by testing
participants on two tasks, one simple and the other a four-choice reaction
time task. On the simple task, participants rested the second finger of their
preferred hand on the central “0” key and responded as rapidly as possible
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when a zero appeared in the display. On the four-choice task, participants
rested the second and third finger of each hand on the keys labelled 1, 2, 3,
and 4, and pressed the appropriate key when one of the digits 1 to 4
appeared in the display. The correlation between IQ and simple reaction time
was -.31, a clear but modest relationship; the correlation between IQ and the
four-choice reaction time was -.49, a moderately strong relationship. IQ
correlated -.15 with the difference between the four-choice and simple
reaction time. This means more intelligent people showed a smaller increase
in reaction time when moving from the simple to the more complex task.
The inspection-time task involves two parallel vertical lines differing in
length and joined at the top by a horizontal line and participants must decide
which is longer. Kranzler and Jensen (1989, see A2 Level Psychology page
271) reviewed the findings from 31 studies. The correlation between IQ and
inspection time was -.50, which is moderately high. It means that more
intelligent people achieve a high level of accuracy and do so in a shorter time
period than less intelligent participants.
Research evidence against the information-processing approach
 The findings from numerous early studies on processing speed were
disappointing (reviewed by Deary, Der, & Ford, 2001, see A2 Level Psychology
page 271) because there was a very small relationship between intelligence
and reaction time.
 Deary (1995, see A2 Level Psychology page 273) provides evidence of the
direction of effect, which suggests that it is speed of processing that causally
affects IQ. In a 2-year study on children, he found that inspection-time
differences at the start of the study causally affected differences in IQ
assessed at the end of the study. There was no evidence that IQ causally
affected inspection time.
EVALUATION OF THE INFORMATION-PROCESSING APPROACH
 Sample bias. The early research on intelligence and reaction time lacks
generalisability because it was conducted on mostly young, intelligent
students. This is a real problem, because the research may have failed to
discern an effect because the sample had such a restricted range of IQ; to see
any effect the sample would need to include the full IQ range.
 Reaction time task was too easy. Another limitation of the early research
was that the reaction time task was so simple that even individuals of low IQ
could probably perform it fairly rapidly, and so no difference would be found
between those of high and low IQ.
 Direction of effect. It is possible that the ability to take in information very
rapidly helps to produce a high level of intelligence. Alternatively, being
highly intelligent may allow individuals to take in information speedily. Thus,
it is difficult to establish the direction of effect, although research that has
attempted to do this (see Deary, 1995, above), suggests that it is speed of
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processing that affects IQ. However, we cannot be sure of the direction of
effect and it is possible that the causation goes both ways.
Usefulness of the findings. Reaction time studies have produced important
findings as they show that highly intelligent individuals have a key advantage
over less intelligent ones in that their basic processing speed is greater, and
so reaction time and inspection time correlate with intelligence.
Expands on the psychometric approach. The information-processing
approach improves on the psychometric approach because it has begun to
identify the basic mechanisms that underpin intelligence and so has more
explanatory power. A further improvement is that reaction time and
inspection time are free from culture bias and so have much wider
generalisability as measures of intelligence than the culture-biased IQ tests
used by the psychometric approach.
Intelligence correlates with performance on nearly all cognitive tasks.
This means it is hard to know whether findings from reaction-time and
inspection-time studies are of particular significance in terms of intelligence.
Limited explanatory power. The information-processing approach lacks
explanatory power because it only focuses on very simple processes, it does
not explain the role of the seven factors of intelligence, nor the influence of
genetic and environmental factors.
Short-term memory and working memory
The processing capacity of short-term memory has been shown in tests of memory
span in which a series of random digits or letters is presented, after which the
participant repeats back the items in the correct order. This leads to the prediction
that perhaps more intelligent individuals have a greater short-term memory
capacity than other people. Alternatively, perhaps intelligence is related to the
ability to store information in short-term memory while at the same time processing
other information. This is working memory, and so those who are intelligent may
have higher working memory capacity than those who are less intelligent.
Research evidence into short-term and working memory
 Conway, Kane, and Engel (2003, see A2 Level Psychology page 274) reviewed
some of the evidence, and concluded there is only a very small correlation
between intelligence and memory span.
 Probably the most used method for testing working memory was devised by
Daneman and Carpenter (1980, see A2 Level Psychology page 274). People
read several sentences for comprehension (processing task) and then recall
the final word of each sentence (storage task). The largest number of
sentences from which an individual can recall the final words more than 50%
of the time is his/her reading span, and this is taken as a measure of working
memory capacity. Those who are more intelligent will use less of their total
capacity in the processing task and so they will have more capacity available
for retaining the last words of the sentences.
 Conway et al. (2003), in a review of the research, found the typical
correlation between working memory capacity and general intelligence was
about +.6. This indicates that more intelligent individuals typically have
greater working memory capacity than less intelligent ones.
EVALUATION OF THE RESEARCH EVIDENCE ON SHORT-TERM AND WORKING MEMORY
 Usefulness of the findings. The research expands on the research into
processing speed as it shows that capacity differences also play a part in
intelligence. The correlation with intelligence is actually greater for memory
capacity than it is for processing and so this shows its importance.
 Lack of explanatory power. The tasks used to assess working memory
capacity are complex so it is not really clear which processes underpin
intelligence, and so there is a lack of explanatory power.
 Direction of effect. The direction of effect is unclear and so we do not know
whether having a high working memory capacity causes a high level of
intelligence or whether a high level of intelligence produces high working
memory capacity.
Learning approach
Learning from experience is assumed to play a crucial role in intelligence. Even if
one is naturally gifted, in for example music, practice would be needed to perfect
this ability. Howe (1998, see A2 Level Psychology page 275) identified two rather
different kinds of learning: knowledge, which is often based on language; and skills,
which take the form of actions and are typically not based on language.
Deliberate Practice
Ericsson, Krampe, and Tesch-Römer (1993, see A2 Level Psychology page 275) and
Ericsson and Lehmann (1996, see A2 Level Psychology page 275) propose that
abilities and forms of expertise are developed through deliberate practice.
Deliberate practice has four aspects:
1. The task is at an appropriate level of difficulty (not too easy or hard).
2. The learner is given informative feedback about his/her performance.
3. The learner has adequate chances to repeat the task.
4. The learner has the opportunity to correct his/her errors.
Ericsson et al. (1993, see A2 Level Psychology page 276) controversially claim that
deliberate practice is all that is needed to develop expert performance. Thus, innate
talent or ability has practically no influence on expert performance.
Research evidence for the learning approach
 Ericsson and Chase (1982, see A2 Level Psychology page 276) studied a
university student, SF, who was paid to practise a digit-span task (memorise
and recall digits in serial order) for 1 hour a day for 2 years. Initially, SF’s
digit span was about seven digits but within the 2-year period he achieved a
digit span of 80 digits. SF used his extensive knowledge of running times to
achieve this digit span and so this shows the role of long-term memory in
intelligence.
 Ericsson et al. (1993, see A2 Level Psychology page 277) reported a study on
violinists in a German music academy. The most expert violinists had spent
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on average nearly 7500 hours engaged in deliberate practice compared to
the 5300 hours clocked up by the good violinists. This shows the importance
of practice and so learning on expertise.
Savants have mental retardation and low IQs but possess some special
expertise so they show that such expertise is not necessarily an expression of
intelligence. This suggests that learning accounts better for specific expertise
than does innate intelligence.
Ceci and Liker (1986, see A2 Level Psychology page 278) studied individuals
who had spent thousands of hours acquiring knowledge of harness racing, in
which horses pull a sulky (a light two-wheeled cart). These individuals could
work out betting odds very accurately and this involved taking account of up
to seven variables (e.g. track size, each horse’s lifetime speed). Bearing in
mind some of these experts had IQs in the low 80s, this shows the role of
learning rather than innate intelligence in developing specific abilities.
Grabner, Stern, and Neubauer (2007, see A2 Level Psychology page 278)
studied adult tournament chess players. They obtained a correlation of +.35
between general intelligence and ELO ranking (a measure of playing ability),
indicating that intelligence was moderately predictive of chess-playing level.
In addition, numerical intelligence correlated +.46 with ELO ranking.
However, as predicted by the learning approach, players’ chess experience
(e.g. amount of practice) was an even better predictor of ELO ranking.
Research evidence against the learning approach
 Sloboda et al. (1996, see A2 Level Psychology page 277) compared highly
successful young musicians with less successful ones. The two groups didn’t
differ in the amount of practice required to achieve a given level of
performance. This suggests that the advantage possessed by the very
successful musicians is due to their greater level of natural musical ability,
rather than the amount of deliberate practice (learning).
 The mean IQ of those in very complex occupations (e.g. accountants; lawyers;
doctors) is between 120 and 130, much higher than the population mean of
100 (Mackintosh, 1998, see A2 Level Psychology page 278). This suggests that
innate ability determines professional status rather than just learning.
EVALUATION OF THE LEARNING APPROACH
 Applications. Deliberate practice is more effective than non-deliberate
practice for the development of high levels of ability or expertise: this has
real-world applications since anybody wishing to develop expertise should
use deliberate practice.
 Cause and effect. Research on deliberate practice, such as on the violinists
and the chess players, does not establish cause and effect because the
amount of hours of deliberate practice has not been manipulated. In such
research the individuals decide how much time to devote to deliberate
practice, so the amount of deliberate practice is not under experimental
control. This means that only an association can be identified, which in turn
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means that we cannot conclude that the deliberate practice causes greater
expertise, only that the two are associated.
Sample bias may minimise the effect of intelligence. Much of the research
has found that intelligence fails to predict level of expertise. However, this
may be because the experts in the sample are mostly highly intelligent, thus
making it difficult for individual differences in intelligence to predict
performance. Given that they are all of approximately the same intelligence,
this exaggerates the role of practice in explaining differences in expertise. If
the sample was of a more varied range of intelligence then the influence of
practice and the influence of intelligence may be reversed.
Reductionism. Learning in the form of deliberate practice is not the only
important factor in the development of broad, complex abilities. For example,
intelligence predicts level of expertise. The learning approach also ignores
the motivational factors that are involved in the development of expertise.
Consequently, the explanation is too simplistic because it tries to reduce
everything to just learning when intelligence and motivation, and other
factors, need to be considered.
Multi-perspective. Hunter (1983, see A2 Level Psychology page 278)
reported the findings from 14 studies on civilian and military groups, which
support the importance of general intelligence. There was a high correlation
between intelligence and job knowledge and there was a direct influence of
intelligence on job performance not dependent on job knowledge. Learning
(i.e. job knowledge) was also strongly associated with job performance.
These findings show the importance of intelligence (more intelligent
individuals learn more rapidly) and learning (deliberate practice does
develop expertise) to the development of expertise, and so a multiperspective best accounts for the development of expertise.
Gardner’s theory of multiple intelligences
Gardner (1983, see A2 Level Psychology page 279) proposed that we possess several
intelligences that are relatively separate or independent of each other. He criticised
previous attempts to explain intelligence as too simplistic.
Any potential intelligence had to meet various criteria to become one of the multiple
intelligences:
1. It should depend on identifiable brain structures.
2. Studies of brain-damaged patients should indicate that it could be impaired
without disrupting other intelligences.
3. It should involve the use of distinct cognitive processes.
4. There should be exceptional individuals showing a remarkable ability (or
deficit) with respect to the intelligence in question.
5. In evolutionary terms the development of the intelligence should have
improved humans’ adaptation to the environment.
6. There should be evidence for its existence from psychometric findings.
Based on the above criteria Gardner proposed seven intelligences:
1. Logical-mathematical intelligence: the ability to handle abstract problems of a
logical or mathematical nature.
2. Spatial intelligence: ability to navigate and manipulate objects spatially, e.g.
how to arrange suitcases in the boot of a car, and so on.
3. Musical intelligence: used both for active musical processes (e.g. playing an
instrument, singing) and more passive processes (e.g. appreciating music).
4. Bodily/kinaesthetic intelligence: the ability to have fine control of bodily
movements in activities such as sport and dancing.
5. Linguistic intelligence: involved in language activities (e.g. reading, writing,
speaking).
6. Intrapersonal intelligence: the ability to understand one’s own feelings.
7. Interpersonal intelligence: the ability to understand others’ feelings, beliefs,
and intentions.
Research evidence
 Gardner (1993, see A2 Level Psychology page 281) used geniuses in different
areas as evidence for his multiple intelligences. Albert Einstein was seen as
representative of logical-mathematical intelligence; Pablo Picasso (spatial
intelligence), Igor Stravinsky (musical intelligence), Martha Graham (bodilykinaesthetic intelligence), T. S. Eliot (linguistic intelligence), Sigmund Freud
(intrapersonal intelligence), and Mahatma Gandhi (interpersonal
intelligence).
 Lisle (2007, see A2 Level Psychology page 282) studied adult participants
with intellectual difficulties. Among these adults, 34% expressed a
preference for learning through visual presentation of material, 34% through
auditory presentation, 23% through kinaesthetic presentation, and 9%
through multi-modal presentation. This links to the educational applications.
 Case studies of savants with brain damage and people with exceptional
abilities provide some support for the intelligences.
EVALUATION OF THE THEORY OF MULTIPLE INTELLIGENCES
 Offer a broader approach to intelligence. The multiple intelligences
greatly expand upon the very narrow approach usually taken in terms of
intelligence when just academic intelligence is considered.
 Educational applications. The idea that children can exhibit high levels of
intelligence in areas other than the traditional ones such as language or
mathematics has applications in terms of encouraging students’ self
confidence and in the ways that students are taught, which has improved
educational programmes in terms of the range of learning styles being
accommodated.
 Support from further research. Goleman (1995, see A2 Level Psychology
page 282) has lent further support to intrapersonal intelligence and
interpersonal intelligence, as identified by Gardner, because he has
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advocated the importance of emotional intelligence, which is basically a
combination of Gardner’s two intelligences.
Lack of evidence. There is little direct evidence to support Gardner’s theory
of multiple intelligences. There has been no thorough experimental test of its
validity. Thus, it must be regarded as somewhat speculative, it is theoretical
rather than research based.
The genius-based approach to identifying intelligences is flawed. Jensen
(see A2 Level Psychology page 281) criticised Gardner’s use of geniuses as
evidence by pointing out that, based on this logic, we could claim that, “Al
Capone displayed the highest level of ‘criminal intelligence’, or that Casanova
was ‘blessed’ with exceptional ‘sexual intelligence’.” Thus, just because
somebody has exceptional ability, this does not distinguish the ability as a
multiple intelligence.
The criteria for multiple intelligences lack scientific validity. As can be
seen above, exceptional ability does not necessarily distinguish multiple
intelligences. A key problem of the criteria for multiple intelligences is that
they are subjective because they involve a judgement. These judgements are
open to bias and so the criteria are not objective and scientific.
Savants as evidence can also be criticised. Gardner used the very specific
abilities of savants as evidence of different types of intelligence. However, it
is doubtful whether the very specific abilities of savants should be regarded
as intelligent.
The multiple intelligences are not completely separate. The seven
intelligences correlate positively with each other, whereas Gardner assumed
they were independent. This means that Gardner was wrong to disregard the
general factor of intelligence.
Descriptive not explanatory. The theory is mostly descriptive. For example,
it fails to explain how each intelligence works or why some individuals are
more intelligent than others.
Mixed evidence for the psychometric criteria of multiple intelligences.
There is psychometric support for some of the intelligences, for example,
Gardner’s spatial intelligence matches Thurstone’s spatial ability; Gardner’s
logical-mathematical intelligence matches Thurstone’s numerical ability; and
Gardner’s linguistic intelligence matches Thurstone’s verbal meaning and
verbal fluency factors. However, the psychometric evidence provides less
support for the other intelligences proposed by Gardner.
SO WHAT DOES THIS MEAN?
The theories of intelligence offer very different approaches to intelligence. The
psychometric approach focuses on the measurement of intelligence. This is useful in
that it provides a reasonably scientific way to assess intelligence and it describes
what it is. However, it does not explain why intelligence develops and so it is
descriptive rather than explanatory.
The information-processing theory offers more of an explanation because it
examines the cognitive processes that underpin intelligence such as reaction-time
and inspection-time. However, intelligence correlates with performance on nearly
all cognitive tasks. This means it is hard to know whether findings from reactiontime, inspection-time, or working memory studies are of particular significance in
terms of intelligence. Furthermore, it is not clear whether being able to process
information quickly causes intelligence or if being highly intelligent allows
individuals to take in information quickly. Neither approach so far considers the
influence of genetics versus learning.
The learning approach does consider the influence of genetics versus learning, and
Ericsson et al. (1993) reject genetics through the suggestion that innate talent or
ability has practically no influence on expert performance. However, the evidence
used by the learning approach that intelligence doesn’t predict expertise is biased
by the fact that the samples all tend to have high intelligence.
Thus, a multi-perspective combining both innate potential and learning offers a
more comprehensive account for the development of expertise. Gardner’s multiple
intelligences expand on the narrow focus of academic intelligence. However, the key
issue is the lack of any real scientific support for Gardner’s theory, which means it is
speculation. Thus, whilst there have been positive applications in terms of
education, it is of concern that this theory has been implemented in spite of the lack
of evidence.
OVER TO YOU
1(a). Describe one theory of intelligence. (9 marks)
1(b). Evaluate the theory described in part (a). (16 marks)
2. Discuss Gardener’s theory of multiple intelligences. (25 marks)