Level I/Level II: Factors or Categories? Arthur R. Jensen Institute of Human Learning, University of California, Berkeley An explanation is sought for the striking apparent failure of the interactions of intelligence and memory factors with socioeconomic status predicted by Jensen's Level I/Level II theory, in a study by Stankov, Horn, and Roy (1980). It is suggested that Level I ability may not be a higher-order factor, like Spear- man's g or Level II but rather a category of narrower abilities involving rote learning and primary memory, with little transformation between input and output. Orthogonal! zed hierarchical factor analysis of the abilities domain is recommended as potentially the most fruitful method for discovering the na- ture of Ability X SES (or Race) interactions. The recent article in this journal "On the the phenomena that it has helped to reveal. Relationship Between Gf/Gc Theory and When the theoretical scaffolding is torn Jensen's Level I/Level II Theory" by Stan- down, are the established empirical findings kov, Horn, and Roy (1980) merits a critical that are left standing of interest, scientifi- comment. These authors (henceforth sig- cally or practically, and worthy of attempts nified as SHR) investigated Level I/Il in a at better theoretical formulation? If so, the factor analytic framework that seems to theory has served its legitimate purpose. highlight certain aspects of the Level I/II I believe this is the case with the Level I/II theory thai have been neglected in previous theory. A large number of studies, of which studies. This is indeed valuable. But what my own studies of Level I/II are only a minor I see as the main contribution of their study fraction, have now established certain phe- is apt to be lost in the article's clutter of side nomena that must be understood by differ- issues, including some confusions about the ential psychologists. A recent comprehen- Level I/II theory and all the previous em- sive review of this research literature con- pirical research on it. cludes: Level I/II is more a set of empirical gen- eralizations than it is a theory, although the The majority of studies . provide support for the attempt to explain these generalizations, major hypotheses of Jensen's [Level I/II] theory. Dif- which so far has not been uppermost, can ferent socioeconomic status (SES) and racial groups fend to obtain equal average scores on Level I, whereas loosely be termed a theory. I regard theories middle SES and white groups obtain higher scores on merely as tools and scaffolding for the dis- tests of Level 11, on average, than groups of low SKS and covery of previously unnoticed phenomena. black individuals. Among the mentally retarded, low A theory is useful so long as it serves this SES children consistently outperform middle SES purpose, and it is defensible on this ground children on measures of Level 1. (Vernon, 1981) alone. As the phenomena that a theory re- Also, the results of other large-scale studies veals increase in extent and complexity, the of Level I/II (Hall & Kaye, 1980; Scarr, 1981) theory must undergo revision or be discarded too recent for inclusion in Vernon's review and replaced by some other theory, if our are consistent with the major hypotheses aim is to go on probing reality. The danger derived from Level I/II theory—for example, of a theory is not that the theory is wrong or much smaller race and SES differences on inadequate in light of further discovery, for Level I (memory) than on Level II (intelli- that is inevitable and necessary. The danger gence). is that proving the theory to be deficient may That the SHR study apparently did not be misconstrued as justification for ignoring yield results consistent with expectations from Level I/II, as so many other much Requests for reprints should he sent to Arthur R. larger studies have done, is itself in need of Jensen, Institute of Human Learning, University of explanation. SHR's findings do not "dis- California, Berkeley, California 94720. prove," or even bring into question, the main 868 LEVEL I/LEVEL II 869 empirical generalizations of Level I/II that as Level I, and in fact one of the tests (free are well supported by a host of other studies. recall of categorized lists) was used as a Level But a more careful examination of how and II test in one study (Jensen & Frederiksen, why the SHR results differ from those of 1973), and it behaved as a Level II measure other studies might well throw important should behave in relation to other variables, new light on the Level I/II formulation. in terms of the theory—this, despite the fact that the Mm primary is as substantially The SHR Study loaded on the second-order SAR factor as are the other two primaries, Ms and Ma, that Essentially, what SHR did was as follows: also define the SAR factor. SHR thus wisely They began with 12 primary (first order) dropped the free recall tests in their subse- factors that had already been established in quent analyses because of their ambiguity as earlier studies. Each of these primary fac- a SAR factor. tors is measured by a small group of tests. Factor scores were then obtained on the Three of the primaries involving memory oblique second-order factors Gf, Gc, and tests were identified as characteristic of SAR. These factor scores were then used to Level I ability: Memory Span (Ms), mea- compare the means of three SES groups sured by auditory and visual number and after the total sample of 201 high school letter span; Associative Memory (Ma), students was divided into high (n = 45), measured by low association word paired- medium (n = 75), and low (n = 81) SES associates, word-number pairs, and free re- groups on the basis of father's occupation. call of uncategorized lists; and Meaningful The main prediction from Level I/II Memory (Mm), measured by high associa- theory, which many other studies have borne tion word pairs, emphasized word recall, and out (Vernon, 1981), is that the SES groups free recall of categorized lists. The 12 pri- should differ very much less on Level I mary factors (including Ms, Ma, and Mm) ability (as here measured by SAR factor were factor analyzed, and three second-order scores) than on Level II ability (as measured factors with eigenvalues larger than 1 by Gf and Gc factor scores). The results of emerged. These three second-order factors, the SHR study, however, did not bear out obliquely rotated to approximate simple this prediction. The SES groups differ structure, were identified as Fluid Intelli- consistently and significantly on all of the gence (Gf), Crystalized intelligence (Gc), factor scores, and the SES differences are of and Short- Term Acquisition and Retention about the same magnitude on Gf, Gc, and (SAR). The Gf and Gc factors are both es- SAR. This striking result is virtually sentially Level II ability, which I have always unique, so consistently has this particular considered to be much the same ability as prediction from Level I/II theory been sub- Spearman's g factor. Gf and Gc are differ- stantiated in previous studies comparing ent (although usually highly correlated) SES and racial (white/black) groups on phenotypic expressions of the same ge- measures of Level I and Level II. Unfortu- notypic Spearman's g. The SAR factor, nately, SHR's explanation for this surprising being defined by tests of short-term memory, finding is inadequate and inaccurate. It is presumably a factor analogue of Level I requires a closer, more careful look than they ability. That is to say, the SAR factor rep- gave to it. It is even possible that they have resents mainly the common variance among found something more interesting than they three primary factors derived from nine had apparently realized. various tests of short-term memory. At least two of the primary factors—Ms and False Explanations Ma—would surely appear to qualify as Level I; their defining tests, or something very SHR suggest that their results are a result equivalent, have all been used as Level I of their better, less biased sampling. They measures in previous studies. In terms of state that Level I/II theory, however, the Mm (Mean- ingful Memory) primary is not as clearly when sampling does not produce a contrast between defined by tests that would be characterized only one extreme group and a midgroup with respect to 870 ARTHUR R. JENSEN the abilities of interest, the differences between SES ferences (see next section) from I/II groups are significant for LI (i.e., SAR) as well as for IJI theory tested in this study, the sample sizes (i.e., Gf or Gc), and the differences between the differ- ences are neither noteworthy nor significant." (p. cannot be held responsible for the failure of 807) the main hypothesis, that is, the absence of a significant and appreciable Level I/II X And they then go on to explain the statistical SES interaction. However, it is noteworthy effects and possible artifacts that could re- that the SES classification into high, medi- sult from selecting extreme groups, con- um, and low SES groups in this Australian cluding that sample does not result in as large mean SES differences on the Level II factor scorers (Gf the present analyses and results differ from those of Jensen in one notable respect: Groups are selected at and Gc) as are typically found in American both extremes and in the middle with respect to each samples that are stratified in much the same of the three major factors.