Home » IQ » The “Fade-Out Effect”

The “Fade-Out Effect”

Enter your email address to follow this blog and receive notifications of new posts by email.

Join 218 other followers

Follow me on Twitter

Charles Darwin

Denis Noble

JP Rushton

Richard Lynn

L:inda Gottfredson



2050 words

The “fade-out effect” occurs when interventions are given to children to increase their IQs, such as Head Start (HS) or other similar programs. In such instances when IQ gains are clear, hereditarians argue that the effect of the interventions “washes” away or “fades out.” Thus, when discussing such studies, hereditarians think they are standing in victory. That the effects from the intervention fade away is taken to be evidence for the hereditarian position and is taken to refute a developmental, interactionist position. However, that couldn’t be further from the truth.

Think about where the majority of HS individuals come from—poorer environments and which are more likely to have disadvantaged people in them. Since IQ tests—along with other tests of ability—are experience-dependent, then it logically follows that one who is not exposed to the test items or structure of the test, among other things, will be differentially prepared to take the test compared to, say, middle-class children who are exposed to such items daily.

When it comes to HS, for instance, whites who attend HS are “significantly more likely to complete high school, attend college, and possibly have higher earnings in their early twenties. African-Americans who participated in Head Start are less likely to have been booked or charged with a crime” (Garces, Thomas, and Currie, 2002). Deming (2009) shows many positive health outcomes in those who attend HS. This is beside the case, though (even if we accept the hereditarian hypothesis here, there are still many, many good reasons for programs such as HS).

Just as Protzko (2016) argues that IQ score gains “fade away” after adolescence, so, too, Chetty et al (2011) who write:

Students who were randomly assigned to higher quality classrooms in grades K–3—as measured by classmates’ end-of-class test scores—have higher earnings, college attendance rates, and other outcomes. Finally, the effects of class quality fade out on test scores in later grades, but gains in noncognitive measures persist.

So such gains “faded out”, therefore hereditarianism is a more favorable position, right? Wrong.

Think about test items, and testing as a whole. Then think about differing environments that social classes are in. Now, thinking about test items, think about how exposure to such items and similar questions would have an effect on the test-taking ability of the individual in question. Thus, since tests of ability are experience-dependent, then the logical position to hold is that if they are exposed to the knowledge and experience needed for successful test-taking then they will score higher. And this is what we see when such individuals are enrolled in the program, but when the program ends and the scores decrease, the hereditarian triumphs that it is another piece of the puzzle, another piece of evidence in favor of their position. Howe (1997: 53) explains this perfectly:

It is an almost universal characteristic of acquired competences that when their is a prolonged absence of opportunities to use, practise, and profit from them, they do indeed decline. It would therefore be highly surprising if acquired gains in intelligence did not fade or diminish. Indeed, had the research findings shown that IQs never fade or decline, that evidence would have provided some support for the view that measured intelligence possesses the inherent — rather than acquired — status that intelligence theorists and other writers within the psychometric position have believed it to have.

A similar claim is made by Sauce and Matzel (2018):

In simpler terms, the analysis of Protzko should not lead us to conclude that early intervention programs such as Head Start can have no long-term benefits. Rather, these results highlight the need to provide participants with continuing opportunities that would allow them to capitalize on what might otherwise be transient gains in cognitive abilities.

Now, if we think in the context of the HS and similar interventions, we can see why such stark differences in scores appear, and why some studies show a fade out effect. Such new knowledge and skills (what IQ tests are tests of; Richardson, 2002) are largely useless in those environments since they have little to no opportunity to hone their newly-acquired skills.

Take success in an action video game, weight-lifting, bodybuilding (muscle-gaining), or pole-vaulting. One who does well in any one of these three events will of course have countless of hours of training learning new techniques and skills. They continue this for a while. Then they abruptly stop. They are no longer honing (and practicing) their acquired skills so they begin to lose them. The “fade-out effect” has affected their performance and the reason is due to their environmental stimulation—the same holds for IQ test scores.

I’ll use the issue of muscle-building to illustrate the comparison. Imagine you’re 20 years old and just start going to the gym on a good program. The first few months you get what are termed “newbie gains”, as your body and central nervous system begins to adapt to the new stressor you’re placing on your body. Then after the initial beginning period, at about 2 to 3 months, these gains eventually stop and then you’ll have to be consistent with your training and diet or you won’t progress in weight lifted or body composition. But you are consistent with training and diet and you then have a satisfactory body composition and strength gains.

But then things change you stop going to the gym as often as you did before and you get lazy with your nutrition. Your body composition you worked so hard for along with your strength gains start to dissipate since you’re not placing your body under the stressor it was previously under. But there is something called “muscle memory” which occurs due to motor learning in the central nervous system.

The comparison here is clear: strength is IQ and lifting weights is doing tests/tasks to prepare for the tests (exposure to middle-class knowledge and skills). So when one leaves their “enriching environments” (in this case, the gym and a good nutritional environment), they then lose the gains they worked for. The parallel then becomes clear: leave the enriched environments and return to the baseline. This example I have just illustrated shows exactly how and why these gains “fade out” (though they don’t in all of these types of studies).

One objection to my comparison I can imagine an IQ-ist making is that training for strength (which is analogous to types of interventions in programs like HS), one can only get so strong as, for example, their frame allows, or that there is a limit to which one only get to a certain level of musculature. They may say that one can only get to a certain number of IQ and there, their “genetic potential” maxes out, as it would in the muscle-building and strength-gaining example. But the objection fails. Tests of ability (IQ tests) are cultural in nature. Since they are cultural in nature, then exposure to what’s on the test (middle-class knowledge and skills) will have one score better. That is, IQ tests are experience-dependent, as is body composition and strength, but such tests aren’t (1) construct valid and (2) such tests are biased due to the items selected to be on them. When looking at weights, we have an objective, valid measure. Sure, weight-lifting measures a whole slew of variables including, what it is intended to, strength. But it also measures a whole slew of other variables associated with weight training, dependent on numerous other variables.

Therefore, my example with weights illustrates that if one removes themselves from their enriching environments that allows X, then they will necessarily decline. But due to, in this example, muscle memory, they can quickly return to where they were. Such gains will “fade out” if, and only if, they discontinue their training and meal prep, among other things. The same is true for IQ in these intervention studies.

Howe (1997: 54-55) (this editorial here has the discussion, pulled directly from the book) discusses the study carried out by Zigler and Seitz. They measured the effects of a four year intervention program which emphasized math skills. They were inner-city children who were enrolled in the orgrwm at kindergarten. The program was successful, in that those who participated in the program were two years ahead of a control group, but a few heads after in a follow-up, they were only a year ahead. Howe (1997:54-55) explains why:

For instance, to score well at the achievement tests used with older children it is essential to have some knowledge of algebra and geometry, but Seitz found that while the majority of middle-class children were being taught these subjects, the disadvantaged pupils were not getting the necessary teaching. For that reason they could hardly be expected to do well. As Seitz perceived, the true picture was not one of fading ability but of diminishing use of it.

So in this case, the knowledge gained from the intervention was not lost. Do note, though, how middle-class knowledge continues to appear in these discussions. That’s because tests of ability are cultural in nature since culture-fair impossible (Cole, 2004). Cole imagines a West African Binet who constructs a test of Kpelle culture. Cole (2004) ends up concluding that:

tests of ability are inevitably cultural devices. This conclusion must seem dreary and disappointing to people who have been working to construct valid, culture-free tests. But from the perspective of history and logic, it simply confirms the fact, stated so clearly by Franz Boas half a century ago, that “mind, independent of experience, is inconceivable.”

So, in this case, the test would be testing Kpelle knowledge, and not middle-class cultural skills and knowledge, which proves that IQ tests are bound by culture and that culture-fair (“free”) tests are impossible. This, then, also shows why such gains in test scores decrease: they are not in the types of environments that are conducive to that type of culture-specific knowledge (see some examples of questions on IQ tests here).

The fact is the matter is this: that the individuals in such studies return to their “old” environments is why their IQ gains disappear. People just focus on the scores, say “They decreased”—hardly without thinking why. Why should test scores reflect the efficacy of the HS and similar programs and not the fact that outcomes for children in this program are substantially better than those who did not participate? For example:

HS compared to non-HS children faired better on cognitive and socio-emotive measures having fewer negative behaviors and (Zhai et al, 2011). Adults who were in the HS program are more likely to graduate high school, go to college and receive a seconday degree (Bauer and Schanzenbach, 2016). A pre-school program raised standardized test scores through grade 5. Those who attended HS were less likely to become incarcerated, become teen parents, and are more likely to finish high-school and enroll in college (Barr and Gibs, 2017).

The cause of the fading out of scores is simple: if you don’t use it you lose it, as can be seen with the examples given above. IQ scores can and do increase is evidenced by the Flynn effect, so that is not touched by the fade-out effect. But this “fading-out” (in most studies, see Howe for more information) of scores, in my opinion, is ancillary to the main point: those who attend HS and similar programs do have better outcomes in life than those who did not attend. The literature on the matter is vast. Therefore, the “fading-out” of test scores doesn’t matter, as outcomes for those who attended are better than outcomes for those who do not.

HS and similar programs show that IQ is, indeed, malleable and not “set” or “stable” as hereditarians claim. That IQ tests are experience-dependent implies that those who receive such interventions get a boost, but when they leave their abilities decrease, which is due to not learning any new ones along with returning to their previous, less-stimulating environments. The cause of the “fading-out” is therefore simple: During the intervention they are engrossed in an enriching environment, learning about, by proxy, middle-class knowledge and skills which helps with test performance. But after they’re done they return to their previous environments and so they do not put their skills to use and they therefore regress. Like with my muscle-building example: if you don’t use it, you lose it.



  1. dealwithit says:

    thanks for repeating everything i’ve ever said at peepee’s blog but with citations.

    BUT…one’s environment is partially within one’s control. so theoretically seeking and finding a more stimulating environment will raise one’s scores, and some will do this while others won’t.


    • dealwithit says:

      an example of that is how arnold once broke into a locked gym so he could lift.

      and it’s even more than motivation. it’s endurance. two people might be equally motivated for gains, but one can lift longer or harder.

      are there steroids for the brain?


  2. Some Guy says:

    “Are Headstart gains on the g factor? A meta-analysis

    We report a meta-analysis of the correlation between Headstart gains on the subtests of IQ batteries and the g loadings of these same subtests (K = 8 studies, total N = 602). A meta-analytic sample-weighed correlation of − .51 was found, which became − .80 after corrections for measurement error. We conclude that the pattern in Headstart gains on subtests of an IQ battery is highly similar to the pattern in test–retest gains and is hollow with respect to g. So, Headstart leads to gains in IQ scores, but not to gains in g. ”


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Please keep comments on topic.

Jean Baptiste Lamarck

Eva Jablonka

Charles Murray

Arthur Jensen

Blog Stats

  • 586,385 hits
Follow NotPoliticallyCorrect on

suggestions, praises, criticisms

If you have any suggestions for future posts, criticisms or praises for me, email me at
%d bloggers like this: