Here’s an excerpt from chapter 2 of the current draft of The Case Against Education.

Making You Smarter

While educators often promise to teach students how to think, they rarely vow to raise students’ intelligence.  Trying to “make your pupils smarter” smacks of hubris.  However, when you look at the data on IQ – psychologists’ standard measure of intelligence – education matters.  Summer vacation, intermittent attendance,delayed school entry, and dropping out all measurably depress IQ.[1]  Some experimental early childhood programs have increased IQ by over 30 points – moving kids’ performance from roughly the 2nd percentile to the 50th percentile of their age group.[2]  Studies that carefully measure students’ time show that IQ rises more on school days than non-school days.[3]  Isn’t this conclusive evidence that education makes us smarter?

Not really.  While the facts are secure, the interpretation is shaky. The first major worry: People can sharply improve on virtually any test by practicing – and a little practice goes along way.  A major review article pulled together fifty relevant studies of practice on cognitive tests.  On average, “a candidate who scored at the 50th percentile on the first test could be expected to score at the 60th percentile on the second test and at the 71st percentile on the third test.”[4]  Explicit coaching – “teaching to the test” – works even better.[5]  When students repeatedly take identical versions of the same test, their scores skyrocket.[6]

A cock-eyed optimist might rejoice that mankind is only a few hours worth of practice away from massive intelligence gains.  This optimism, however, leads to absurdity: Can you transform average students into geniuses by handing them the answer key before their IQ test?  Most researchers draw the sobering conclusion that test preparation yields only “hollow gains.”[7]  Preparation inflates measured intelligence without raising genuine intelligence.[8]

The fact that test preparation yields large but hollow gains hardly shows that all large gains are hollow.  Still, the power of preparation should make us suspicious.  Maybe education raises IQ because education is a dilute form of IQ test preparation.   As psychologist Steven Ceci explains:

It is through direct forms of instruction… that children learn the answers to many of the questions that appear on a popular IQ (and other aptitude) tests.  For example, within a given grade level there is a correlation between the total number of hours of schooling a child receives and scores on verbal and mathematical aptitude tests. Similarly, there are negative correlations between the total number of teacher or student absences and scores on such tests. Also, quantitative and language-related scores are strongly correlated with the length of the school day and with the actual amount of time on task, beginning in first grade. So it makes intuitive sense that much of the knowledge that aptitude tests, including IQ, tap is accumulated through direct encounters with the educational system. Answers to questions on the WISC-R, such as “In what continent is Egypt?”; “Who wrote Hamlet?”; “What is the boiling point of water?”; and “How many miles is New York from L.A.?” are probably learned through direct teaching methods. Teachers may not be aware that they are teaching answers to questions on IQ tests, but this is precisely what they are doing in their history, reading, literature, geography, and math classes…[9]

Ceci also notes that schools teach students to offer the kinds of answers IQ tests favor.  How are an apple and an orange alike?  IQ tests award only partial credit for such factually correct answers as, “They’re both round,” “They’re both edible,” or “They both have seeds.”  For full credit, you have to say, “They’re both fruits.”  School also makes students sit still and pay attention.[10]  These habits aren’t just crucial for test-taking; they’re useful life skills.  Yet sitting still and paying attention aren’t “intelligence” in any normal sense of the word.

If education truly raised intelligence, education would enhance performance on all sorts of cognitive challenges – in and out of the classroom.  In reality, though, IQ gains yield spotty payoffs even on narrowly academic subjects.  Probably the best study of the effect of education on IQ looks at the scores of over one million 18-year-old Swedish men.[11]  The researchers know each student’s exact age and test date, so they possess an unusually precise measure of how many days they spent in and out of school.  Their major finding: school days noticeably raise scores on synonym and technical comprehension subtests without raising scores on spatial and logic subtests.  The authors infer that education raises “crystallized intelligence” but not “fluid intelligence.”  A better interpretation, though, is that education improves some specific skills without increasing intelligence at all.  Considering how little students usually learn, the measured effect of Swedish education on the synonym and technical comprehension subtests is impressive.  Still, to equate subject-specific gains with higher intelligence smacks of double-counting.

Worries about “hollow IQ gains” are admittedly a tad philosophical.  The other major worry about the effect of education on IQ, however, is completely pragmatic.  Suppose for the sake of argument that IQ were a perfect measure of genuine intelligence. When IQ goes up, genuine intelligence automatically rises in sync.  Even in this scenario, a large effect of education on IQ would only be impressive if it were durable.  In the short story “Flowers for Algernon,” a mentally retarded man named Charlie Gordon receives an experimental treatment to cure his disability.[12]  Charlie’s intelligence eventually rises to the level of genius.  Tragically, though, the transformation is short-lived.  By the end of the story, all of Charlie’s intellectual progress evaporates.  In one sense, the experiment worked.  In a deeper sense, the experiment failed.

“Flowers for Algernon” is science fiction, but life mirrors art.  Making IQ higher is easy.  Keeping IQ higher is hard.  Researchers call this “fade-out.”  We see fade-out in early childhood education programs.  After six years in the famous Milwaukee Project, experimental subjects’ IQs were 32 points higher than controls’.  By age fourteen, this advantage had declined to 10 points.[13]  In the Perry Preschool program, experimental subjects gained 13 points of IQ, but all of this vanished by age 8.[14]  Head Start raises pre-schoolers’ IQs by a few points, but the gains disappear by the end of kindergarten.[15]

You could object that pre-schoolers are unusually likely to forget what they learn.  The pattern, however, extends all the way through high school.  Extensive research on “summer learning loss” compares students’ scores at the end of one school year to their scores at the beginning of the next school year.  The average student intellectually regresses roughly one full month during a three-month summer vacation.[16]  The older the students, the steeper their decline.  For reading, to take the clearest case, first- and second-graders actually slightly improve over the summer.  By the time students are in middle school, however, one summer vacation wipes out over three months of reading proficiency.[17]

Educators tend to see summer learning loss as an argument for year-round school.  If summer makes students stupid, let’s abolish summer.  The key flaw in this argument: You can’t keep kids in school forever.  Everyone graduates eventually.  Once you graduate, you’re no longer in school – and learning loss kicks in.  To quote “Tiger Mother” Amy Chua, “Every day you don’t practice is a day that you’re getting worse.”[18]

Does education have any effect on genuine intelligence?  Despite decades of research, we really don’t know.  What we do know is that education has far less effect than meets the eye.  The effect of education on intelligence may not be entirely hollow, but it is largely hollow.  The effect of education on intelligence may not be entirely temporary, but it is largely temporary.  School might permanently make you slightly smarter. As we shall see next chapter, though, this can’t explain more than a sliver of the effect of education on income.

[1] See especially Ceci, “How Much Does Schooling Influence General Intelligence and Its Cognitive Components?,” pp.705-8.

[2] Arthur Jensen, The g Factor, pp.333-44.

[3] Carlsson, Dahl, and Rooth, “The Effect of Schooling on Cognitive Skills”; Steltz et al, “The Effect of Schooling on the Development of Fluid and Crystallized Intelligence”

[4] Hausknecht et al, “Retesting in Selection,” p.381.

[5] Hausknecht et al, “Retesting in Selection,”p.380-1.  Commercial claims about the effectiveness of SAT preparation classes are however grossly overstated: see e.g. Powers and Rock, “Effects of Coaching on SAT I.”

[6] more cites

[7] See e.g. Arthur Jensen, The g Factor, pp.333-44; Nijenjuis, Voskuiji, and Schijve, “Practice and Coaching on IQ Tests: Quite a Lot of g” + others

[8] Freund and Holling, “How to Get Really Smart”

[9]  Ceci, “How Much Does Schooling Influence General Intelligence and Its Cognitive Components?,” p.717 (referenced omitted).

[10] Ceci, p.718.

[11] Carlsson, Dahl, and Rooth, “The Effect of Schooling on Cognitive Skills”

[12] cite

[13] Jensen p.341; check w/Garber

[14] Barnett, “The Effectiveness of Early Childhood Intervention,” p.975.

[15] Barnett, p.976.

[16] Cooper et al, “The Effects of Summer Vacation on Achievement Test Scores.”  Most of this research focuses on “achievement tests” rather than “IQ tests,” but the content closely overlaps.  Math and reading questions are staples on both kinds of tests.  [Also get Heyns stuff on IQ specifically?]

[17] Cooper et al, p.259.

[18] Battle Hymn of the Tiger Mother, p.86.  Chua is approvingly quoting her daughter’s violin teacher.