An Historical Framework for Cohort Differences in Intelligence

In the paper

“In fact, number ability exhibits a negative trend, which, as we show, is much more pronounced when examined across a broader range of cohorts.”

In the paper

“Indeed, the cohort differences (1889–1952) for verbal ability are of equivalent magnitude to that for inductive reasoning until the 1959 cohort, which is when the gradient began to decline for verbal meaning.”

In the paper

“In contrast to the conclusions that would be drawn from data cited for the Flynn effect, these data indicate that there are systematic and substantial positive advances in cohort level for both crystallized ability (verbal meaning) and fluid abilities (spatial orientation and inductive reasoning).”

In the paper

“For example, over the Baby Boomer cohorts (1945–1966), there has been a positive linear trend for inductive reasoning, a negative trend for number, and a plateau for verbal ability.”

In the paper

“Word fluency, by contrast, shows a concave pattern. A negative cohort trend prevails until the 1938 cohort, but improvement occurs for subsequent cohorts.”

In the paper

“A similar trend is shown in the SLS data in Figure 3.”

In the paper

“Far more substantial differences in level are found in old age between Cohorts 2 and 6, but now there is also a substantial difference in slope, particularly for verbal meaning, favoring the later born cohort.”

In the paper

“For this ability, then, earlier cohorts have a slight advantage over the later born ones; but beginning with the cohort born in 1945, there are also successive positive cohort differences for this ability.”

In the paper

“The trajectories for the three sample cohorts, first of all, reflect the overall cohort differences in level, but they also demonstrate that the trajectories differ by ability as well as by life stage.”

In the paper

“The 1924 cohort exceed both earlier and later born cohorts; the youngest cohorts are, therefore, currently at a disadvantage when compared with the older cohorts.”

In the paper

“Thus, in midlife, there is little difference between Cohorts 6 and 10 on verbal meaning but a modest systematic gain for Cohort 10 on inductive reasoning.”

In the paper

“And, indeed, our own studies show marked increase in educational attainment for subsequent cohorts, resulting in an average increase of 5½ years over the period studied, with a greater increase of 1 year for men (see Figure 3).”

In the paper

“Number ability shows positive cohort differences up to about the 1910 cohort. But then there is a plateau followed by a negative shift that indicates a successive lowering of performance level.”

In the paper

“There is strong suggestive evidence that current cohorts may be peaking at later ages or maintaining their peak level of functioning until a later chronological age (Schaie, 2005).”

What the sources say

• ?Not checked — no full text of the sourcecites Schaie, 2005 source

In the paper

“Perhaps the largest difference between our Cohorts 2 and 6 is the dramatic increase in educational attainment, which is accompanied by marked cohort differences at comparable ages for both verbal ability and inductive reasoning skills.”

In the paper

“We also noted dramatic changes in the level of occupational pursuits, associated with structural changes in the labor market, but also requiring acquisition of educational skills commonly associated with upward socioeconomic mobility.”

In the paper

“We pointed out, however, that cohort differences in intelligence were even more dramatic for cohorts born prior to those studied by Flynn, but they have diminished in subsequent cohorts.”

In the paper

“Another major change for the latter cohort is the increase of women in the workforce, accompanied by an increase in their educational levels (now similar to their male peers).”

In the paper

“Also, these transitions are usually defined by a circumscribed relatively brief time period during which they occur.”

In the paper

“Two types of transitions have been distinguished in the psychological and sociological literatures (Baltes, 1979; Riley et al., 1972): normative (school entry, puberty, work entry, marriage, child bearing, and retirement) and nonnormative (death or severe illness, divorce, and winning the lottery).”

What the sources say

• ?Not checked — no full text of the sourcecites Baltes, 1979
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Riley et al., 1972

In the paper

“The cohort effects estimated in this manner will, of course, be confounded with period effects, but if a series of cohort differences are computed across the same time period, each estimate will be equally affected.”

In the paper

“The data reported by Flynn and others are insufficient to address this question given the limited range of cohorts examined.”

What the sources say

• ?Not checked — no full text of the sourcecites Flynn, 1987 source

In the paper

“On the other hand, sampling with replacement may be problematic if the population frame changes over time.”

In the paper

“Hauser and Featherman (1976) noted that intergenerational differences in schooling peaked among men born shortly after World War I and that a deceleration has occurred across more recent cohorts.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser and Featherman (1976) source

In the paper

“The negative cohort effects on verbal ability reported by Alwin (1991) may be due to confusing cohort effects with aging, treating the relationship between age and verbal ability as linear rather than curvilinear (Wilson & Gove, 1999).”

What the sources say

• ?Not checked — no full text of the sourcecites Alwin (1991) source
• ?Not checked — no full text of the sourcecites Wilson & Gove, 1999 source

In the paper

“The impact of such historical or sociocultural life-course events on individual development has been an important focus of the work of social psychologists such as Elder (1974), Stewart (2003), and, to some extent, Helson and Moane (1987).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Elder (1974)
• ?Not checked — no full text of the sourcecites Stewart (2003) source
• ?Not checked — no full text of the sourcecites Helson and Moane (1987) source

In the paper

“Hence, performance on psychometric markers of fluid ability can be improved through educational procedures, although their basic information-processing components might not be affected.”

In the paper

“there is a large body of literature indicating that fluid abilities (as measured by psychometric tests) as well as crystallized abilities are significantly impacted by environmental influences.”

In the paper

“The issue of the lack of comparable chronological ages across cohorts is, in particular, a critical one in evaluating cohort differences and a criterion that has been seriously abused in prior studies.”

In the paper

“That is, the same test items may not mark the construct equally well in all cohorts; content becomes obsolete.”

In the paper

“As Kahn and Antonucci’s (1980) model of convoys of social support suggest, the significant others in the individual’s life would be expected to change across the life course, progressing from parents to spouses and extended family, friends, and colleagues.”

What the sources say

• ?Not checked — no full text of the sourcecites Kahn and Antonucci’s (1980)

In the paper

“As research in the SLS and other cohort-sequential studies have shown, each of these criteria is problematic.”

In the paper

“That is, the direct comparison of different cohorts at one point in time confounds cohort with age effects, whereas comparison of cohorts at the same age but different points in time confound cohort and period effects (cf. Ryder, 1965; Schaie, 1965; Wilson & Gove, 1999).”

What the sources say

• ?Not checked — no full text of the sourcecites Ryder, 1965 source
• ?Not checked — no full text of the sourcecites Schaie, 1965 source
• ?Not checked — no full text of the sourcecites Wilson & Gove, 1999 source

In the paper

“These transitions are usually specific to a particular life domain (e.g., marriage or work) although there may be spillover to other domains.”

In the paper

“We then use Seattle Longitudinal Study (SLS) data to illustrate how the recent debate has been too narrow due to the limited range of birth cohorts examined and because cohort differences are often studied nondevelopmentally by considering only a single chronological age.”

In the paper

“Also, the difficulty level of specific test items may shift markedly across cohorts and time.”

In the paper

“The appropriate data to be used for comparison of the trajectories of different cohort come from successive independent random samples of each of the three cohorts. These data are thus unbiased with respect to attrition and/or retest effects.”

In the paper

“Given the seven waves of the SLS, this means that cohort differences for those cohorts entering the study at an early stage can be compared at as many as six different ages, whereas the most recently entered cohort can be compared only at the one age at which it was measured.”

In the paper

“The average length of the school year for Cohort 2 was 140 days compared with 170 days and 180 days for Cohorts 6 and 10, respectively.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites U.S. Department of Education, National Center for Education Statistics, 2002

In the paper

“State legislation on the length of the school year and compulsory school attendance passed during the same period impacted not only the proportion of children in school but the intensity of the educational experience.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites U.S. Department of Education, National Center for Education Statistics, 2002

In the paper

“The declining influence of social background reflects changes both in the variance of the social background characteristics and in their effects on schooling.”

In the paper

“Both father’s education and occupation status have increased across cohorts, whereas the number of siblings has decreased.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“A final caution: As Riley (1972) taught us, changes in the characteristics of populations will, in turn, change the social structures that have produced these changes; hence, we experience an interactive process that requires continuous monitoring and study.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Riley (1972)

In the paper

“Sampson and Laub (1996) reported that GI Bill training as well as in-service schooling enhanced subsequent occupational status, job stability, and economic well being, independent of childhood differences and socioeconomic background.”

What the sources say

• ?Not checked — no full text of the sourcecites Sampson and Laub (1996) source

In the paper

“Almost 50% of all veterans of World War II and the Korean War used the benefits for education and training, and 82% of those veterans who had attended college before the war made use of GI benefits to continue their education.”

In the paper

“There have been a number of studies examining key social background variables associated with final educational attainment (cf. Alwin & Thornton, 1984).”

What the sources say

• ?Not checked — no full text of the sourcecites Alwin & Thornton, 1984 source

In the paper

“The SLS’s Cohort 6 would have been particularly affected by the GI Bill associated with World War II.”

In the paper

“However, despite this restriction, the data, because of their extensive comparative and longitudinal findings within one study, have far-reaching implications for interpretations of the so-called Flynn effect.”

In the paper

“On average a farm background cost men 1 full year of schooling, and Southern birth cost .4 to .8 years of schooling.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“The variables of being raised on a farm and being born in the South also had a substantial effect.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“Approximately 33% of veterans whose college work was interrupted by military service finished college or went on to graduate or professional school.”

In the paper

“Among the social background variables studied were father’s education, father’s occupation, number of siblings, broken family, farm background, and Southern birth—many of these variables clearly pertain to the environment of the father as well as the subject of interest.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“Almost 50% of all veterans of World War II and the Korean War used the benefits for education and training, and 82% of those veterans who had attended college before the war made use of GI benefits to continue their education.”

In the paper

“Thus, Cohort 6 could represent the children of Cohort 2; likewise, Cohort 10 could represent children of Cohort 6.”

In the paper

“A marked shift in educational philosophy between Cohort 2 and Cohort 6 was the Progressive movement in education, which peaked in the 1920s and whose most noted proponent was John Dewey (Emirbayer, 1992).”

What the sources say

• ?Not checked — no full text of the sourcecites Emirbayer, 1992 source

In the paper

“First, given the existing psychometric ability measures, it is unlikely that fluid abilities would provide stronger tests of cohort effects than those provided by crystallized measures.”

In the paper

“The benefits of the GI Bill were larger for younger veterans and for those who had some evidence of delinquency in military service records.”

In the paper

“On the one hand, due to the increased number of pupils resulting from child labor laws and compulsory school attendance, the educational practices of standardized testing and tracking of students was introduced.”

In the paper

“Of relevance for this article is the fact that a number of these social background variables pertain to the parent’s characteristics and thus would be considered in our framework in ExoSystem models.”

In the paper

“In the child literature, the parents’ work environment has been shown to impact child-rearing practices (Kohn & Schooler, 1983), occupational aspirations of adolescents (Mortimer & Kumka, 1982), and curricular activities (Morgan, Alwin, & Griffin, 1979).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Kohn & Schooler, 1983

In the paper

“A major provision of the law involving a $15 million grant was the provision of funds to identify talented students and encourage them to pursue higher education.”

In the paper

“Advances in cognitive science would suggest, in any event, that a test of cohort differences in fluid abilities should be conducted using measures of more basic levels of information processing.”

In the paper

“Its focus is specific to historical contexts affecting the United States.”

In the paper

“The analysis of cohort effects in the SLS, although rich in within-nation longitudinal and cohort-comparative sampling, is, of course, restricted in the scope of cross-national comparisons.”

In the paper

“In the 1957–1958 term alone, congress proposed over 80 laws to establish programs that would seek out bright students and provide them with financial support for schooling.”

In the paper

“Yet, changes in rates of aging in intellectual performance have serious societal consequences for the nature of the workforce, the stability of pension systems, and the nature of the health care system required to serve a growing elderly population that differs markedly from earlier cohorts.”

In the paper

“The national panic generated by this event resulted in Congress passing a federal-aid-to-education bill, known as The National Defense Education Act of 1958.”

In the paper

“Our analysis of the historical influences on education suggests that cohort differences in intellectual abilities are shaped largely by changes in educational attainment and educational process and by changes in the labor market that are shaped by sociopolitical developments.”

In the paper

“One of the most prominent examples are the postwar rehabilitation programs for veterans, known as the GI Bills (Nam, 1964; Sampson & Laub, 1996).”

What the sources say

• ?Not checked — no full text of the sourcecites Nam, 1964 source
• ?Not checked — no full text of the sourcecites Sampson & Laub, 1996 source

In the paper

“The Progressive movement also involved the introduction of the kindergarten, manual and vocational education, and evening classes for adults.”

In the paper

“In addition, primarily as a consequence of the secular rise in educational attainment, successive cohorts of young persons have distributions of social background variables that are gradually becoming more favorable to high levels of schools, as evidenced by increases in parent’s educational and their occupational levels.”

In the paper

“These background variables account for 30% to 37% of the variance in educational attainment of males of various cohorts.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“First, we note that the three illustrative SLS cohorts (Cohorts 2, 6, and 10) discussed herein represent three successive generations, separated by approximately 30 years.”

In the paper

“Similarly, in 1956 25% of all male college students were veterans of the Korean War (Nam, 1964).”

What the sources say

• ?Not checked — no full text of the sourcecites Nam, 1964 source

In the paper

“In the child literature, the parents’ work environment has been shown to impact child-rearing practices (Kohn & Schooler, 1983), occupational aspirations of adolescents (Mortimer & Kumka, 1982), and curricular activities (Morgan, Alwin, & Griffin, 1979).”

What the sources say

• ?Not checked — no full text of the sourcecites Mortimer & Kumka, 1982 source

In the paper

“Further educational training was provided through GI Bills for veterans of World War II, the Korean War, and the Vietnam War.”

In the paper

“For veterans who had just completed high school or had barely started college, 20% went on to get a college degree and a larger proportion took at least some college courses.”

In the paper

“The mean level of fathers’ education had increased from about 7 years to almost 11 years.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“Each of the following variables accounted for about 25% of a year gain in level of educational attainment: 1 year of father’s schooling, 10 points of father’s occupation status, and additional sibling.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“In 1957 the Soviet Union launched Sputnik.”

In the paper

“Standardized testing was viewed as a more scientific way to determine children’s likely occupational attainment and to allocate them into different educational channels (Ackerman, 1995).”

What the sources say

• ?Not checked — no full text of the sourcecites Ackerman, 1995 source

In the paper

“Hauser and Featherman (1976) utilized data from the OCG surveys (Blau & Duncan, 1967) to examine key social background variables associated with educational attainment of male birth cohorts from 1897 to 1951.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Blau & Duncan, 1967

In the paper

“For example, the discussion of the effect of the GI Bill on educational attainment of Cohort 6 could be construed as an ExoSystem environment for Cohort 10.”

In the paper

“Second, the notion that one should measure cohort differences in mature persons implies that ages of peak performance remain constant across cohorts (not true) or, when samples ranging widely in age are utilized, assumes that there are no adult age changes.”

In the paper

“In the child literature, the parents’ work environment has been shown to impact child-rearing practices (Kohn & Schooler, 1983), occupational aspirations of adolescents (Mortimer & Kumka, 1982), and curricular activities (Morgan, Alwin, & Griffin, 1979).”

What the sources say

• ?Not checked — no full text of the sourcecites Morgan, Alwin, & Griffin, 1979 source

In the paper

“The goal of the movement was development of a demographic character equipped for responsible citizenship.”

In the paper

“Thus, the ChronoSystem environments that we have discussed for a given cohort could be considered as the ExoSystem environment for a preceding cohort.”

In the paper

“Daily attendance was approximately 65% for Cohort 2 compared with 85% and 90% for Cohorts 6 and 10, respectively (U.S. Department of Education, National Center for Education Statistics, 2002).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites U.S. Department of Education, National Center for Education Statistics, 2002

In the paper

“On the other hand, the Progressive movement also advocated movement away from teacher-directed lecture and rote recitation to increased student–teacher interaction, group exercises, and critical reflection.”

In the paper

“For example, the father’s educational or occupational status experienced as a young adult and occurring in a particular historical period have been studied as influences on subsequent intellectual functioning of the offspring (Hauser & Featherman, 1976).”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“Father’s education was relatively more important than any other background variable in all groups examined.”

What the sources say

• ?Not checked — no full text of the sourcecites Hauser & Featherman, 1976 source

In the paper

“The Progressive movement advocated what today seem to be contradictory initiatives (Emirbayer, 1992).”

What the sources say

• ?Not checked — no full text of the sourcecites Emirbayer, 1992 source