In two seminal articles, David Wechsler emphasized the importance of non- ability determinants of adult intelligence, and called for a more inclusive consideration of traits beyond that which is assessed by traditional intelligence quotient (IQ)– type measures. Wechsler’s main point was that in order to predict an individual’s ability to “understand the world about him and his resourcefulness to cope with its challenges” (Wechsler, 1950 , 1975 , p. 139), one needs to have a much broader understanding of the individual beyond a single IQ score. A second issue with modern intelligence assessment is that at various times, an IQ score has been seen to reflect an individual’s ‘capacity’ for intellectual competence, rather than a snapshot of the individual’s performance from which inferences can be made, such as the likelihood that a child will succeed academically (Anastasi, 1983 ). In the current chapter, an effort will be made to explicitly distinguish between the concept of intelligence as a ‘potentiality’ from intelligence as an ‘actuality,’ and inclusion of non- ability constructs, especially with respect to the abilities of older adolescents and adults.

Fundamental Issues about Intelligence

Ever since Binet and Simon published the first modern scales to measure child intelligence, the fundamental purpose of intelligence assessment has been for prediction – whether it be performance in the classroom, laboratory, workplace, or in success at other life tasks. Although there have been many basic research efforts that purport to focus on finding basic properties of intelligence, the majority of research and application efforts during the past century has focused on the utilitarian value of predicting the rankordering of individuals on some criterion performance measure. Once one understands this fundamental issue in the study of intelligence, several key concepts must be considered, as follows:

First, intelligence is, more or less, contextually (and culturally) bounded. That is, because performance criteria (such as success in school or work) differ to some degree from one cultural environment to another, the underlying components of intelligence that are relevant to predicting success may differ from one environment to another. For example, ‘intelligence’ for writing a novel is not exactly the same as ‘intelligence’ for solving calculus problems. That is not to say that these two intelligences are unrelated to one another. Indeed, there are many intelligences that are highly related to each other, which ultimately gives rise to the notion of ‘general intelligence’ (or g ). Second, intelligence is a ‘relative’ or normative construct. One of Binet’s seminal contributions to the assessment of intelligence was to introduce the idea that we can best index intelligence, especially during childhood when rapid cognitive development occurs, as the individual’s performance in comparison to a reference group (e.g., all six-year-old children). It is almost universally accepted that one can only quantify an individual’s intelligence by referring to the reference or norming group. The principal advantage to this approach is that an individual’s intelligence is indexed in a way that it has the same meaning, even though norming groups may change from one decade to the next (e.g., in terms of the core knowledge and skills that are within the capabilities of the larger reference group). The principal disadvantage to this approach is that it renders comparisons across norming groups somewhat problematic. For example, it is arguably nonsensical to say that a large sample of today’s 18-year-olds is more or less ‘intelligent’ than a large sample of 18-year-olds in 1930. The average 18-year-old today has very different knowledge and skills from the 18-year-old in 1930, in areas of math, science, arts and literature, and so on (see, e.g., Learned & Wood, 1938). An intelligence test designed for 18-year-olds in 1930 would be expected to yield very different performance norms if administered today, yet an IQ score for 18-year-olds in 1930 on a then-current test has the same normative meaning as an IQ score for an 18-year-old today on a current test. The IQ score only tells us the individual’s standing with respect to other members of the norming sample. Th ird, intelligence is dynamic. That is, although one’s IQ score may be relatively constant (e.g., see Thorndike, 1940 ), the underlying capabilities of the individual (and the reference group) change with age. Over the course of the life span, intellectual development is quite rapid in early childhood, slows in adolescence and early adulthood, and then, for many components of intellectual ability, shows declines in middle- to- late adulthood (e.g., see Schaie, 1996 ). Fourth, because prediction is the key determinant of the utility of intelligence assessments, one can make a critical distinction between intelligence potentiality and intelligence actuality. Th ese terms are derived from Aristotle’s Metaphysics (see Gill, 2005 ), but they are especially appropriate for understanding the construct of intelligence, the practicalities of intelligence assessment, and the insights that can be derived from individual intelligence scores. Moreover, as will be introduced later, this particular consideration illustrates the importance of non- ability constructs in the development and expression of intelligence. Potentiality, in Aristotle’s view, can be imagined in terms of a block of bronze (metal). It has the ‘potential’ to become a statue of a person or many other objects. Yet, in order to realize the goal of a statue, ‘work’ must be done to transform the block of bronze, by carving or hammering and so on. A completed bronze statue represents an actuality – which is the result of the work done to it by the artist. In terms of intelligence, performance scores on an IQ test are an actuality, but they are not generally of interest, in and of themselves, for many of the reasons provided previously. Consistent with Wechsler’s (1975) suggestions, the goal for an intelligence assessment is an index of the individual’s potential for intellectually demanding learning and task performance. Yet, there are three problems that prevent one from reasonably equating an IQ score with an individual’s potential: (a) the test score only represents the individual’s actual performance, and as such, potential can only be indirectly inferred (see Anastasi, 1983); (b) although one may be able to make effective predictions of later academic and occupational achievement from a current IQ score, it is impossible to know what future scientific and/or medical developments might be made that would fundamentally change the capability of individuals of different IQ levels to acquire new intellectual skills and knowledge (e.g., so-called brain drugs or new educational instructional techniques); and (c) like Aristotle’s example, the translation from the block of bronze to a statue requires the substantial investment of work time and effort on the part of the artist. For an individual to acquire new intellectually demanding knowledge and skills, he/she must invest time and effort, which in turn, implicates non-ability constructs, such as personality and motivation.