Aptitude, Ability, and Achievement

October 25, 2007

What’s in a name? That which we call a rose by any other name would smell as sweet.
Wm. Shakespeare

Juliet’s famous lament to Romeo was intended to make the obvious but important point that the names we give objects, ideas or indeed ourselves are quite arbitrary, and that these names do not alter the essence of the things themselves. Measurement specialists and test developers have sometimes forgotten this self-evident truth in their laudable zeal to assess human attributes.

Some 30 years ago, the late educational measurement specialist Robert Ebel observed that psychologists do not call a series of word problems, verbal analogies, vocabulary items and quantitative reasoning problems an “Academic Problems Test.” They call it a test of “Mental Ability” or “General Intelligence.” Similarly, a test that asks a series of commonly encountered social and practical problems is not labeled as such, but is called a test of “Practical Judgment.” This type of test is used to support rather tenuous theories of social interaction, since as many have noted, it is a significant leap to conclude that someone who does not answer enough items with the keyed responses is “lacking in practical judgment.”

The reason for the broad labeling of tests is not difficult to discern. The science of psychology, like any other science, requires constructs if it is to progress. In fact, a science progresses precisely in proportion as its constructs are unambiguously defined and measured and their interrelationships clearly specified.

As many have noted, constructs in the social sciences are decidedly more problematic and more difficult to measure than constructs in the physical sciences. The physical constructs of speed, momentum, mass and volume, for example, are unambiguous and, given an agreed upon unit of measure, can be clearly specified. Not so in education and psychology. Nowhere is this more evident than in the development of instruments intended to measure the three related constructs aptitude, ability and achievement. The distinctions among these three concepts are a favorite and long-standing source of disagreement in measurement circles. William Cooley and Paul Lohnes, two educational researchers and policy analysts, argued years ago that the distinction among the three terms is a purely functional one. If a test is used as an indication of past instruction and experience, it is an achievement test. If it is used as a measure of current competence, it is an ability test. If it is used to predict future performance, it is an aptitude test. Yesterday’s achievement is today’s ability and tomorrow’s aptitude. These authors co-mingle items from the Otis-Lennon Mental Ability Test and the Stanford Achievement Test and challenge the reader to distinguish which items are from which test. Their point is well taken. It is virtually impossible to do so.

It is important to note here that Cooley and Lohnes’ perceptive insight regarding the purely functional distinctions among the terms aptitude, ability and achievement was not intended to deny that these are in fact different concepts. Rather, their insight pointed to our inability to construct tests that highlight the differences. In a less enlightened era, we thought that the distinctions among the three concepts were straightforward and that we could devise exercises that would zero in on the difference. That wish was not and is not entirely fanciful. In fact, I would argue that the functional distinction of Cooley and Lohnes is true as far as it goes, but it does not go far enough. There is more to it than that. To ignore or deny the existence of aptitude, for example, would require us to deny the reality of Mozart in music and innumerable prodigies in chess and mathematics.

To take but one example, the verbal reasoning abilities measured by the SAT can and should be distinguished from an achievement test in, say, geography or the French language. In like manner, the quantitative reasoning abilities measured by the SAT-Math are distinguishable from a test that simply assesses one’s declarative knowledge of algebraic rules. The distinction lies in what cognitive scientists call procedural knowledge or, more precisely, the procedural use of declarative knowledge. It is the principal reason that word problems continue to strike fear in the hearts of novice mathematics students.

Unlike many purely academic debates, the distinctions among the concepts of aptitude, ability and achievement have real implications for teaching and learning and for how teachers approach their craft. If a teacher believes that a student’s failure to understand is the result of basic aptitude, then this implies for many a certain withdrawal of additional effort since the problem resides in the student’s basic ability. If, on the other hand, the teacher believes that all children can learn the vast majority of things we want to teach them in school, then a student’s failure to understand a particular concept or principle implies a failure of readiness or motivation on the part of the student, or a failure of pedagogical ingenuity and imagination on the part of the teacher, which in turn implies renewed instructional effort.

Shakespeare was of course right. The names we give objects do not alter the objects themselves, but they may well alter our behavior.