Intelligence and Measurement - Essay Example

A number of theories have been postulated in an attempt to better understand the nature of human intelligence. Significant among these are those given by Spearman, Thurstone, Gardner, and Sternberg. Spearman (1904) believed that intelligence is a generic fluid ability that affects all our behaviors. This ‘g’ factor was manifested in different ways in particular or ‘specific’ behaviors. While this theory did explain the tendency for a more intelligent person’s higher overall competency as compared to a less intelligent person; it did not explain how some individuals demonstrated genius or high ability in some areas while being barely average in others.

Thurstone (1938) tried to explain these incidences by postulating his theory of Primary mental Abilities which states that people have a number of primary intelligences; and each is relatively independent of each other. These primary intelligences are associated with different mental processes. Gardner believed that while Thurstone was right in saying that there are a number of intelligences; a simple numerical scale was not adequate to measure them. He proposed a theory of multiple intelligences that covered elements that are valued in different cultures.

He proposed eight such intelligences, some of which deviate distinctly from the traditional concept of intelligence. Sternberg (1985) critiqued these theories on the basis that some of the specific intelligences postulated are more likely to be talents and not a type of intelligence. He in turn proposed a triarchic theory that speaks of three types of intelligence that govern different types of functions. The exact nature of intelligence is still under question. But a number of instruments that measure intelligence and achievement have been developed on the basis of the existing theories.

Each instrument is based on a particular perspective; and attempts to capture as accurate an evaluation of the persons’ abilities as possible on the basis of the operational definition of intelligence. One measure of achievement is the Basic Achievement Skills Inventory developed by Bardos (2004). This instrument measures reading, language use and mathematical achievement in children and adults. The instrument is based on the Thurstone model of intelligence; which distinguishes between specific abilities by isolating the scores for three abilities.

The BASI has a comprehensive version having six subtests as well as a survey version with two subtests; and can be used for group or individual testing. The scales were tested for internal, test – retest and alternate form Reliability. Most coefficients were quite high – above 0.65 (many being above 0.90); with the composite scores for any area showing higher reliability than the subtests themselves. Validity studies were not as promising. The BASI was compared to the Iowa Test of Basic Skills, Iowa Tests of Educational Development and the Tests of Adult Basic Education.

While the coefficients were stronger when measured against the Iowa Tests of Educational Development in comparison to the other two; in general, the coefficients were not very high, and were found to be below 0.60 in most cases. In rare instances, the subtests that measured the same construct were strongly related. A comparison showed that the comprehensive version and the survey version were not very similar; with validity coefficients ranging from 0.30 to 0.65. This does raise concern that the two versions do not measure the same