Two major interpretations of intelligence exist -- the concept of 'general intelligence,' which is often pitted against the concept of 'multiple intelligences.' For many years, it was though that only one kind of intelligence existed, known as the 'g-factor,' or general intelligence. "In recent decades, psychologists have devoted much effort to isolating that general factor, which is abbreviated g, from the other aspects of cognitive ability gauged in mental tests" (Gottfredson 2010). However, some researchers such as Howard Gardner have attempted to reframe the g-factor and advocate that intelligence is a multi-faceted concept.
Intelligence tests are often contrasted against personality tests, in which different characteristics are viewed to exist as unrelated to one another. For example, in a standard Myers-Briggs personality test, a person can be 'extroverted' and a 'judging' type or 'introverted' and a 'judging' type. Different personality characteristics do not necessarily link together. However, most theorists today believe, intelligence does possess a general component. This component can be extrapolated from the different tests used to assess individual intelligence -- "This is true regardless of what specific ability a test is meant to assess, regardless of the test's manifest content (whether words, numbers or figures) and regardless of the way the test is administered (in written or oral form, to an individual or to a group). Tests of specific mental abilities do measure those abilities, but they all reflect g to varying degrees as well. Hence, the g factor can be extracted from scores on any diverse battery of tests" (Gottfredson 2010). In other words, although some people might perform better on tests of verbal intelligence, others upon mathematical intelligence, people with high 'g' quotients tend to excel overall on all types of intelligence tests, regardless of the test's specific emphasis.
Even Howard Gardner does not deny the presence of a g-factor measured across intelligence tests such as the Stanford-Binet and the Wechsler. Instead, his contention is that all current IQ tests overemphasize the academic components of intelligence, like verbal and mathematical abilities, and thus present only an incomplete picture of the test-taker's potential. Gardner stresses socially-constructed nature of intelligence: "Intelligence is a bio-psychological potential to process information that can be activated in a cultural setting to solve problems or create products that are of value in a culture" (Gilman 2001).
Creators of intelligence tests have not been insensible to criticisms that the tests are insufficiently comprehensive in their measurements of all forms of intelligence and have begun to include components which strive to assess general intelligence. For example, the most recent edition of the Stanford-Binet has introduced "several completely new subtests, such as Matrices and Equation Building…Besides the new and expanded tests, the Fourth Edition provided several factors (Verbal Reasoning, Abstract/Visual Reasoning, Quantitative Reasoning, and Short-Term Memory) in addition to IQ" (Becker 2003). The test has also always had certain non-verbal components that draw upon elementary logic, such as identifying what is 'wrong' in a particular picture.
Another intelligence test, the Wechsler, also reflects recent criticisms that IQ tests give insufficient attention to a variety of factors that contribute to intelligence in their construction. For example, the Wechsler for children "age 4-61/2 years….is divided into six verbal and five performance subtests. The eleven subtests are presented in the following order: information, animal house and animal house retest, vocabulary, picture completion, arithmetic, mazes, geometric design, similarities, block design, comprehension, and sentences" (Ford-Martin 1999:1). Children are tested verbally, mathematically, spatially, and also upon questions that relate to general intelligence. "An example of questions on the subtest of similarities might be: 'Describe how the following pair of words is alike or the same -- hamburger and pizza.' A correct response would be 'Both are things to eat'" (Ford-Martin 1999).
However, recent revisions to the Stanford-Binet and Wechsler reveal the extent to which emphasizing certain sections and deemphasizing others can produce very different results, in terms of abilities. Children traditionally identified as gifted "show greater variability and lower overall performance on processing speed items such as those included on the WISC-IV (Wechsler, 1991) and on working memory items which are included in both tests (Roid, 2003), use of full-scale scores that place an increasing emphasis on these factors will likely exclude some children who would have been identified as gifted on earlier tests. The inclusion of items that are more dependent upon visual-spatial and nonverbal skills will increase scores upwards for children with these strengths while lowering scores of children who have strengths in the verbal-abstract-reasoning area more traditionally emphasized by those who provide programs for the gifted" (Minton 2006:1).
These changes in the definition of 'intelligence' show the cultural variability of the concept, despite the fact that these standard intelligence tests produce consistent (reliable) results. The implications of defining intelligence as a culture can have a tremendous influence upon children's lives -- a child's IQ score has an undeniable influence in the shape of his or her academic career, particularly as standardized testing grows more important, and the influence of testing is more acute than ever before in people's lives. Given the questionable nature of arriving at a universally-agreed upon definition of testing, Gardner questions the validity of such tests and stresses that an "assessment of intelligence should encompass multiple measures. Relying on a single IQ score from a WISC-III (Wechsler Intelligence Scale for Children) without substantiating the findings through other data sources does the individual examinee a disservice and produces insufficient information for those who provide interventions" (Gilman 2001).
Another common objection to IQ tests is their potential for cultural bias. One critic of IQ tests even created a false IQ test that used common knowledge particular to children from African-American and low-income backgrounds, to illustrate the cultural biases and assumptions of common knowledge inherent in all IQ tests. The implication is that all intelligence tests are, in fact, achievement tests like the Iowa Tests of Basic Skills and the current version of the SAT (which was once called an 'aptitude' test, although the current Mental Measurements yearbook lists it as an achievement test). Achievement tests, unlike intelligence tests, measure content knowledge rather than the potential to learn. According to its publisher, the Iowa Test screens for vocabulary, reading comprehension, understanding of fractions and a 'skills-based' demonstration of learning. They are norm-referenced, meaning that children are measured in terms of how they perform in relation to other test-takers, rather than if they perform according to a certain criteria or not. Likewise, the norm-referenced SAT likewise has reading comprehension questions demanding the test-taker fill in a particular word of phrase in a sentence and mathematical questions that test learned concepts, such as geometry, or how to write an analytical essay.
The SAT (the College Board Scholastic Aptitude Test) has been criticized for favoring males, non-whites, and particularly students of more affluent backgrounds who are more apt to be familiar with the skills needed for the test. However, it should be noted that achievement tests merely aspire measure the child's current state of knowledge. The SAT has been found to be a good predictor of college performance in the first year, and unsurprisingly students from more affluent backgrounds tend to have an easier transition into their first year of schooling (What does the SAT really measure, 2010, PBS).
Although the Iowa and the SATs do not aspire to be as comprehensive as the Stanford-Binet and Wechsler in terms of their measures of student ability, their repercussions can still be great: schools with under-performing students on achievement tests can be penalized in terms of the disbursement of federal funding, and the SAT still has a great influence in college acceptance rates. "The SAT has been found to correlate with first-year college grades. But...the test has been found to measure only about 18% of the things that…