Intelligence (trait)

Intelligence is usually said to involve mental capabilities such as the ability to reason, plan, solve problems, think abstractly, comprehend ideas and language, and learn. Although laymen generally regard the concept of intelligence as having much broader scope, in psychology, the study of intelligence generally regards this personality trait as distinct from creativity, personality, character, or wisdom.

Definitions of intelligence

At least two major "consensus" definitions of intelligence have been proposed. First, from "Intelligence: Knowns and Unknowns" a report of a task force convened by the American Psychological Association:

Individuals differ from one another in their ability to understand complex ideas, to adapt effectively to the environment, to learn from experience, to engage in various forms of reasoning, to overcome obstacles by taking thought. Although these individual differences can be substantial, they are never entirely consistent: a given person’s intellectual performance will vary on different occasions, in different domains, as judged by different criteria. Concepts of "intelligence" are attempts to clarify and organize this complex set of phenomena.
A second definition of intelligence comes from "Mainstream Science on Intelligence", which was signed by 52 intelligence researchers in 1994:

Psychometric intelligence

Main articles: IQ, General intelligence factor

Despite the variety of concepts of intelligence, the most influential approach to understanding intelligence (i.e., the one that has generated the most systematic research) is based on psychometric testing.

Intelligence, narrowly defined, can be measured by intelligence tests, also called IQ tests. Such tests are among the most accurate (reliable and valid) psychological tests. Such intelligence tests take many forms, but g theory proponents argue that the common tests (Stanford-Binet, Raven's Progressive Matrices, Wechsler Adult Intelligence Scale, Wechsler-Bellevue I, and others) all measure the same dominant form of intelligence, g or "general intelligence". The abstraction of g stems from the observation that scores on all forms of cognitive tests correlate positively with one another. g can be derived as the principle factor from cognitive test scores using the method of principal components analysis or factor analysis.

In the psychometric view, the concept of intelligence is most closely identified with g, or Gf ("fluid g"). However, psychometricians can measure a wide range of abilities, which are distinct yet intercorrelated. One common view is that these abilties as hierarchically arranged with g at the vertex (or bottom, underlying all other abilities).

One or several types of intelligence?

Some experts accept the concept of a single dominant factor of intelligence, general mental ability or g, while others argue that intelligence consists of a set of relatively independent abilities (American Psychological Association task force report, Gottfredson 1998). A single factor is not guaranteed. Other psychological tests which do not measure cognitive ability, such as personality tests, generate multiple factors.

Proponents of multiple-intelligence theories often claim that g is, at best, a measure of academic ability. Other types of intelligence, they claim, might be just as important outside of a school setting. One theory even suggests the existence of two types of g (see Fluid and crystallized intelligence).

Yale psychologist Robert J. Sternberg has proposed a Triarchic Theory of Intelligence. Harvard psychologist Howard Gardner's theory of multiple intelligences breaks intelligence down into at least eight different components: logical, linguistic, spatial, musical, kinesthetic, naturalist, intra-personal and inter-personal intelligences. Daniel Goleman and several other researchers have developed the concept of emotional intelligence and claim it is at least as important as more traditional sorts of intelligence.

In response, g theorists have pointed out that g's predictive validity has been repeatedly demonstrated, for example in predicting important non-academic outcomes such as job performance (see IQ), while no multiple-intelligences theory has shown comparable validity. Meanwhile, they argue, the relevance, and even the existence, of multiple intelligences have not been borne out when actually tested (Hunt 2001).

The fundamental indicator of a general factor is that test scores on a wide range of seemingly unrelated cognitive ability tests (such as sentence completion, arithmetic, and memorization) are positively correlated. People who score highly on one test tend to score highly on all of them. This suggests that the tests are not unrelated, but that they all tap a common factor. The common factor, g, can be extracted using mathematical techniques such as factor analysis or principal components analysis. IQ tests measure g better than any other test. According to Jeff Hawkins, the brain's cortex implements a memory prediction system to form the basis of intelligence.

Controversies

Researchers in the field of human intelligence have encountered a considerable amount of public concern and criticism - much more than many scientists would be accustomed to or comfortable with (for examples, see Gottfredson, 2005). Some of the controversial topics include:

1. the relevance of psychometric intelligence to the common-sense understanding of the topic.
2. the importance of intelligence in everyday life (see IQ).
3. the genetic and environmental contributions to individual variation in intelligence (see Nature versus nurture).
4. differences in average measured intelligence between different groups and the source and meaning of these differences (see Race and intelligence and Sex and intelligence).

Collective and non-human intelligence

Some thinkers have explored the idea of collective intelligence, arising from the coordination of many people. A battleship, for instance, cannot be operated by a single person's knowledge, actions and intelligence, it takes a coordinated and interacting crew. Similarly, the interesting behaviors of a bee colony are not exhibited in the intelligence and actions of any single bee, but rather manifested in the behavior of the hive. These ideas are explored as a basis for human thought, with applications for artificial intelligence (AI), by MIT AI pioneers Norbert Wiener and Marvin Minsky. Artificial intelligence (AI) has emerged from Computer science as a specialty which seeks to make computers act in increasingly intelligent ways, and provides insights into human thought processes.

When considering animal intelligence, a more general definition of intelligence might be applied: the "ability to adapt effectively to the environment, either by making a change in oneself or by changing the environment or finding a new one" (Encyclopædia Britannica). Many people have also speculated about the possibility of extraterrestrial intelligence.