19 minute read

Individual Differences

Affective And Conative Processes, Ethnicity, Gender Equity And SchoolingABILITIES AND APTITUDES

Patrick C. Kyllonen

Drew H. Gitomer

Lyn Corno

Hsiu-Zu Ho

Jason Duque Raley
Angela D. Whipple

Hsiu-Zu Ho

Heather A. Tomlinson
Angela D. Whipple


Abilities are cognitive or mental characteristics that affect one's potential to learn or to perform. Aptitudes are sometimes treated as interchangeable with abilities, particularly when they focus on prediction of performance in other settings or on other occasions. Cognitive abilities have been conceived very broadly (e.g., intelligence) and also in terms of specialized abilities such as verbal, spatial, memory, reasoning, problem solving, and psychomotor ability. Some authors have defined aptitudes more broadly than abilities, to include any number of individual-differences factors—affective, cognitive, and personality characteristics—that influence one's readiness or likelihood of learning or performing successfully.

During the twentieth century, there have been significant changes in conceptions of ability, moving from atheoretical models that have their basis in measurement and psychophysics to ones that are based largely on cognitive theories of human performance. Social issues continue to influence conceptions of ability and practices of ability testing. The scientific measurement of abilities has been viewed as either enabling or stifling social progress, and such controversy continues in the twenty-first century.


Ability testing in education began in 1905 in Paris when Alfred Binet along with his assistant Théodore Simon developed the Binet-Simon scale to solve the practical problem of reliably differentiating between educable, educable with special help, and uneducable children. Prior to the development of the scale, such classifications were made subjectively and inconsistently; thus the scale was considered a significant practical achievement. The scale consisted of thirty tests, such as "naming objects in pictures," "defining common words by function," and "retaining a memory of a picture." In historical treatments, Binet and Simon's approach is sometimes referred to as a task-sampling approach, in that the tests are essentially samples of typical educational events.

The task-sampling approach may be contrasted with another tradition in ability testing, a basic elements approach. This tradition began with Francis Galton's development of a battery of basic sensory-motor, reaction time, and memory tests. Galton believed that a general mental ability with biological underpinnings underlay performance on these tests, but to his disappointment, he found no relationship with educational or occupational levels. Charles Spearman developed a statistical method known as factor analysis, which demonstrated that Galton's hypothesis of a general ability was supported after all. Later, researchers such as Louis Thurstone and J.P. Guilford refined Spearman's notion, by adding various kinds of tests to the more basic batteries, and identifying "group factors" such as spatial and verbal ability in addition to general ability (Spearman's "g") to account for patterns of performance.

Developing conceptions of ability and aptitude have proceeded in tandem with practical applications, particularly in military, educational, and employment settings. In the military, the development of the "Army Alpha and Beta" intelligence tests during World War I, which helped efficiently sort 1.7 million World War I conscripts into job classifications (training, frontline, officer, and so forth) has been cited by Frederick McGuire as one of psychology's most influential contributions to American society. The Army Alpha, used essentially as a measure of general cognitive ability, consisted of eight subtests (oral directions, arithmetic problems, practical judgment, antonyms, disarranged sentences, number series, analogies, and information), most of which are still being used in test batteries today. During World War II and through the 1950s the number of abilities measured was expanded to include such constructs as verbal and quantitative ability, technical knowledge, and psychomotor abilities, the latter being particularly important for pilot and navigator selection. In the early twenty-first century the U.S. military services use a multidimensional test battery, the Armed Services Vocational Aptitude Battery (ASVAB), for both selecting applicants and assigning them to training and occupational specialties.

Following the success of the Army Alpha, there was general optimism about the role ability assessment could play in "social engineering," such as providing opportunities for higher education to students based on merit rather than on birthright. An example was the Scholastic Aptitude Test (now known as the SAT) during the period between World War I and World War II. The SAT was designed, in the words of the American educator James Bryant Conant, to "reorder the 'haves and have-nots' in every generation to give flux to our social order." The composition of the SAT has fluctuated minimally over the years, consistently yielding "verbal" and "mathematical" scores, relying on tasks that are arguably work samples of academic tasks (e.g., reading comprehension) to those that are more abstract from such tasks (e.g., verbal analogies).

A third major application of abilities and aptitudes is in employment testing. The General Aptitude Test Battery (GATB) was developed around the time of World War II, by a commission of industrial psychologists and measurement experts for the U.S. Department of Labor. The test measures general ability, verbal aptitude, numerical aptitude, psychomotor ability (motor coordination, finger dexterity, and manual dexterity), and general perceptual ability (spatial aptitude, form perception, and clerical perception). The GATB was designed to predict job performance. More than seven hundred validity studies have demonstrated that it does so, and consequently the test is widely used as an employment screen. A meta-analysis of these studies conducted by John Hunter and Ronda Hunter has shown that general cognitive ability is the primary determinant of job success, but that psychomotor ability is important for relatively low complexity jobs.

Modern Views

The major aptitude batteries–the ASVAB, GATB, and SAT, in the military, industrial, and educational sectors, respectively–were developed in the post—World War I period, and although still in use in the early twenty-first century, have not fundamentally changed over the years in what they measure or how they measure it. But advances in the knowledge of how people think, learn, and solve problems, since the 1970s, has triggered a reevaluation of what abilities are and how they ought to be measured.

Information processing. The information-processing view likens the individual to an information-processing system, suggesting that the parameters governing the performance of an information-processing system, such as speed and memory capacity, might be the abilities that govern human learning and performance. Since the 1960s, numerous studies have examined the relationship between mental speed and learning and performance. The conclusion has been that increased sophistication in the procedures for measurement are responsible for a slightly more favorable view than Galton had of the importance of mental speed in everyday life. Still, the work has primarily been of theoretical interest, and there have been few suggestions that mental speed is an important ability to begin routinely including it in large-scale aptitude batteries. In fact, to the contrary, the military services are in the process of removing their "speed" composite from the ASVAB because it has proven not to be a valid predictor of training success or job performance. Similarly, ETS routinely considers speed to be an irrelevant factor for most of its measures.

There has been considerable support, though, for the notion that another aspect of information processing, working-memory capacity, is central to human performance. Several studies have shown that working-memory capacity (as measured by tasks such as mental arithmetic) is indistinguishable from Spearman's "g" and therefore is the primary ability governing learning and performance. Ian Deary has suggested that Spearman's "g" is simply being relabeled to have a more contemporary-sounding title. But information-processing explanations of abilities have several advantages. One is that they allow for the construction of ability measures based not simply on previous measures, but on the understanding of how people learn, think, and solve problems. A second is that an information-processing scheme has potential use in task analysis. For example, as Susan Embretson has demonstrated, the requirements of a task can be characterized in information-processing terms, enabling the a priori prediction of item difficulty. A third advantage is that information-processing based concepts connect with wider areas of inquiry such as cognitive and brain sciences, and therefore allow for the uniting of what Lee Cronbach referred to as the two disciplines of scientific psychology, the correlational and the experimental.

Knowledge and expertise. A second perspective based on new conceptions in cognitive science might be called the knowledge and expertise view. In this view, characteristics such as working-memory capacity and information-processing speed are not viewed as fixed characteristics of an individual, but as dependent upon knowledge and skill that is developed over long periods of time. So, for example, expert chess players have the ability to recall actual chess positions with impressive accuracy and to a much greater extent than novice players. However, when chess pieces are arranged in random fashion, the two groups have equal recall. Similarly, many studies have demonstrated that processing speed is a direct function of repeated practice. These studies have demonstrated that efficient information processes are, in large part, the residue of well-organized knowledge structures that are developed over years of active engagement and practice within a domain. Further, well-developed knowledge structures in a domain make one a much more effective learner of other concepts in that domain, since there is an established knowledge organization within which to embed and connect new information.

This emphasis on domain specific expertise has profound implications for considering ability testing and ability development. The implication of the expertise approach is to assess and then facilitate the development of knowledge structures and processing skills that will support performance and learning within a domain, without significant attention paid to broad, domain-independent skills. Clearly, the debate over how much of ability is specific to or independent of particular domains continues, and has profound implications for the selection, education, and training of individuals.

Hierarchical model. A third new development might be called the hierarchical model of ability differences. This work continues the factor analytic tradition began by Spearman, and further refined by Thurstone and Guilford. The key idea behind the hierarchical model is that what had been thought to be rival hypotheses concerning the number and organization of human abilities can be now seen as compatible. Even into the 1980s one had to take a position on whether the evidence was more favorable towards the Spearman view of one general ability (along with number test-specific abilities); with Thurstone's view of eight to eleven primary mental abilities; or Guilford's 120 or 160 ability models. The hierarchical model, as developed by Jan-Eric Gustafsson and John Carroll, shows the fruitfulness of considering abilities as varying in their generality from fairly specific abilities (e.g., memory span, associative memory, and free recall memory), to broader ones (e.g., general memory and learning), to the most broad (general intelligence). In fact, this example is taken from Carroll's "Three-stratum structure of cognitive abilities," which posits sixty-seven or so "Stratum I" abilities, eight "Stratum II" abilities, and one "Stratum III" ability. Gustafsson's scheme is similar in spirit, but he did not consider nearly as many datasets as Carroll did, and so consequently his proposal may be seen as a subset of Carroll's.

Multiple intelligences. A final new development might be called the "multiple intelligences" view. There are actually two quite distinct notions that might be considered in this category, the "triarchic theory" of Robert Sternberg and the "multiple intelligences" theory of Howard Gardner. Sternberg's idea is that the field, the testing industry, and the application sectors themselves (education, industry, and the military) are preoccupied with one notion of abilities, which he playfully refers to as the "gocentric view." He also calls this analytic intelligence, and suggests that while important, success in school and in life is perhaps equally if not more importantly determined by other intelligences, namely creativity and practical intelligence. Although this work has not yet resulted in any widescale applications, preliminary work, particularly in the area of practical intelligence appears promising.

Gardner has proposed a different scheme, called "multiple intelligence theory," which identifies eight abilities–linguistic, logical-mathematical, musical, spatial, bodily-kinesthetic, interpersonal, intrapersonal, and naturalist intelligences. This scheme is quite popular in educational circles, perhaps attributable to its elevation of abilities other than the usual linguistic and logical-mathematical abilities, encouraging the recognition of some students for talents normally overlooked. However, the scheme is often dismissed in scientific circles because by eschewing measurement, it fails to allow for its validity to be tested. As Nathan Brody has pointed out, multiple-intelligence theory is at odds with the rest of the field in its rejection of a general cognitive ability, and with its choice of the particular eight abilities–neither empirical nor theoretical justifications for these features of the theory have been produced.


Discussions and investigations of aptitudes, abilities, and individual differences have been fraught with controversy throughout their history. Certainly one of the most contentious issues is that of the heritability of abilities. Comparisons of monozygotic and dizygotic twins, twins reared apart versus together, adoption studies, and various other behavioral genetics studies, suggest that abilities are somewhat heritable, although the issue of by what amount remains unsettled. There is ample evidence for notably high consistency in test scores over time. A study reported by Ian Deary showed that Scottish eleven-year-olds performed remarkably similarly on an identical test of mental ability administered sixty-six years later, when they were seventy-seven years old.

Some of the reason for the intense interest in heritability seems to be inappropriately due to a misconception that to the degree that abilities are inherited, there is not much one can do to improve one's abilities. Heritability, however, is not synonymous with immutability, as can be proven with a simple thought experiment. Height is highly heritable, but has steadily increased over the twentieth century due to improvements in environmental factors such as nutrition. Similarly, as documented by James Flynn, intelligence scores have been shown to have risen quite dramatically in the second half of the twentieth century in numerous parts of the world. Early childhood intervention programs, such as Head Start, have met with mixed success, but others, such as the Carolina Abecedarian project, have shown strong and persistent gains in cognitive skills, academic test scores, and language use in follow-up studies through the age of fifteen.

Another area of some controversy in the abilities and aptitudes literature concerns the role of other factors such as metacognition, attitudes, motivation, and concepts such as emotional intelligence, in performance in school and the workplace. Concepts such as test anxiety have for a long time been cited as a threat to the validity of an estimate of a student's ability. Claude Steele has suggested that additional attitudinal factors, "disidentification" and "stereotype threat," may impair the performance of minority students in certain contexts. Motivation has long been considered an important factor in governing learning and performance success and related concepts such as goal setting, self-efficacy, and optimism are being investigated for their role in learning. Emotional intelligence refers to a wide variety of factors that may mediate the relationship between abilities and performance, or may serve as abilities and aptitudes in their own right.

A third controversy centers on the extent to which ability can even be considered as an individual phenomenon. In the situated cognition view, abilities can only be considered as they are manifest and develop within social situations. The interaction of the person with the social environment is what defines ability–it is not a construct that can be defined independent of such interaction. Much of the support for this work comes from examining very sophisticated cognitive strategies that develop without the benefit of any formal academic training or ability to demonstrate the strategies in traditional academic ways.

Further Directions

The predominant use of individual differences in abilities and aptitudes in education has been in assigning students to special remedial programs, selecting them for admission into schools (e.g., colleges), or identifying them for receiving awards such as scholarships or fellowships. Although this use will undoubtedly continue, it is likely that an increasing emphasis will be put on new uses, opening the door to additional opportunities, in the form of diagnosis, tailored educational programs, and self-assessments to facilitate more efficacious career choices. It is likely that the noncognitive ability and aptitude variables, including interests, personality, motivation, and the like, will prove particularly important for the new uses role.

Another trend in ability and aptitude testing in education is an increased emphasis on the assessment of achievements rather than the more basic abilities. Some of this is due to what some have characterized as the pernicious effects of test coaching, and is certainly consistent with cognitive conceptions of expertise. The idea is that as long as there are high-stakes ability tests, there will be a coaching industry designed to help students improve their chances of succeeding on those tests. To the extent that the tests directly reflect the achievements that are supposed to be learned in school, coaching then becomes a positive force, a productive adjunct to the school curriculum, reinforcing lessons learned in school. Another reason for this trend is that test users and the public in general have increasingly demanded tests that look more like the learning or performance activities that the tests are designed to predict. There seems to be less patience with arguments based exclusively on predictive validity statistics. One sees this in military and industry testing as well as educational testing.

A third trend in abilities and aptitude assessment is what is sometimes called "embedded assessment" or the insertion of abilities tests within the context of instruction itself. This trend fits with the general trend toward the increased use of achievement testing, but for the specific purpose of tailoring instruction to a particular individual, based on that individual's changing knowledge and understanding of a particular topic area. Richard Snow and Valerie Shute have suggested both "macroadaptive" and "microadaptive" responding on the part of a computerized ("intelligent") tutoring system. Microadaptive instruction refers to the specific reactions a tutor makes in response to its continually updated understanding of what a student knows and is learning; macroadaptive instruction refers to more global approaches to delivering coaching and feedback the tutor makes based on more general assessments of a student's abilities.

Finally, a possible future trend is increasing attention paid to what might be called "mediators" for their role in affecting abilities and aptitudes. These include factors such as nutrition, psychopharmacology, fatigue, and circadian rhythms. Nutritional explanations have begun to appear more frequently in discussions of changes in abilities, and the role of nutrition, vitamins, and glucose has been investigated but as of yet, little is known. Similarly, there have been some investigations of "smart drugs," such as caffeine, ginseng, and ginko biloba, as well as other psychopharmacological agents, particularly cholinergic enhancers. Finally, much has been learned over the past decade about the role of circadian rhythms in affecting hormonal production and concommittant behavioral effects such as fatigue and alertness over the course of the day. There has been some work suggesting that "morningness" and "eveningness" may be characteristic dispositions that mediate both cognitive abilities and personality factors.


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