At its most basic level, self-control is the ability to not do something you want to do in pursuance of a more long term goal. Our need for self-control arises from the fact that, generally speaking, we prefer current rewards to future rewards. For instance, if given the choice, most people would prefer to be given $1,000 today rather than a year from now. This is true of basically everyone: if the immediate and future reward are the same, our tendency is to choose the immediate reward. It’s when the future reward is greater than the immediate reward that self-control comes into play. Everyone would prefer to have $1,000 now instead of next year, but there is some amount of money that we would prefer to get in a year over getting $1,000 today. That amount might be $1,100 for some people, and $10,000 for others. The exact amount will depend on how strong your preference for immediate rewards is. This preference will be stronger in some people than others, and this will lead to important differences in how their lives turn out.

Measuring self-control

Before looking at how people vary in self-control, let’s take a moment to consider how self-control is measured. The most famous measure of self-control is the so called Marshmallow experiment. The premise is simple: sit a kid in a room with a marshmallow and tell them that if they wait in the room for X amount of time without eating the marshmallow they will get 2 marshmallows instead of one. The longer the kid can wait the better they are at delaying gratification and so the more self-control they have. This sometimes sounds silly to adults, but, as can be seen in the video below, for small children this is no easy task:

Of course, not all kids like marshmallows and so researchers use lots of different treats, but you get the idea: self-control is experimentally measured by allowing people to choose between a small benefit now and a larger one later. The same principle can be applied to adults. However, adults are usually offered some amount of money now and a larger amount later rather than marshmallows.

Self-control can also be measured with surveys that ask people about how often they engage in the kind of behavior we would expect from people with high or low self-control. Obviously, people can lie on self-report measures, but in general this has not proven to be a significant problem with measuring self-control. As will be seen, both experimental and survey based measures of self-control predict life outcomes.

Self-Control, IQ, and SES, as predictors of Life Outcomes

Looking at how well self-control predicts life outcomes is complicated by the fact that self-control correlates with IQ and parental socio-economic status (SES), both of which are known to predict life outcomes themselves. Some people like to overstate the relationship between IQ and self-control. Shamosh and Gray (2008) meta-analyzed 24 studies and found that IQ correlates with self-control at .23, which would typically be considered a weak effect size. Nonetheless, in this section I will only rely on studies which measure both self-control and IQ and, with one exception, parental SES.

The best study in this literature is Moffitt et al. (2010) which looked at how well self-control, measured in childhood (under the age of 10) based on self and peer reported behavior, predicted life outcomes at age 32 compared to childhood IQ and parental socio-economic status. Moffitt et al.’s work is especially useful because it compared the predictive power of each of these metrics while the other two variables were held constant. Higher childhood self-control was found to predict better health, more wealth, less criminality, and a lower chance of being a single parent, in adulthood even while IQ and parental SES were controlled for. Particularly interesting is the fact that IQ was not predictive of criminality or drug abuse after controlling for parental SES and self-control. Moreover, of the three variables only self-control continued to predict single parenthood while the other two were held constant. Consistent with past literature, Moffitt et al. found IQ to be the best predictor of wealth and adult SES

Another important study in this area is Duckworth and Seligman (2005). This paper reported on two studies with a combined sample of 308 eight graders. Duckworth and Seligman found that self-control was better than IQ at predicting GPA. Also of interest, they found that self-control and intelligence had opposite relationships with time spend on homework: kids with high self-control spent more time than average on homework while kids with high IQs spent less.

Finally, Daly et al. (2015) looked at how childhood self-control, IQ, and class, predicted adult unemployment in a sample of 16,780 Brits. Daly et al. found that, when holding the other two variables constant, IQ and self-control both had a negative relationship with unemployment. Class, however, failed to predict unemployment after IQ and self-control were controlled for.

The Behavioral Genetics of Self Control

We’ve seen that individual differences in self-control are important. People who have higher self-control, even as children, grow up to have better lives across a wide range of domains even after controlling for differences in intelligence and socio-economic status. Now, let’s look at the causes of individual differences in self-control.

Twin studies on self-control have consistently shown that about half of individual variation is due to genes (Beaver et al., 2008; Anokhin et al., 2011; Anokhin et al., 2015; Isen et al., 2014). More surprisingly, these twin studies have also shown that absolutely no variation in self-control is due to the shared environment. In other words, genetics is the only reason why people within the same family tend to be more alike than average in terms of self-control. The environmental variables that do impact self-control are uniformly not part of the “home environment”.

These environmental stimuli also lose some of their power with age. As is the case for many traits, the heritability of self-control rises with age.

A few specific gene variants have been found which influence self-control (Watts and McNullty 2016). However, most of the genetic variation in self-control remains unexplained. This is because self-control is controlled by many genes of very small effect which can only be detected with huge sample sizes of genomic data. Such studies are becoming cheaper by the year, and we can expect to know more on this front in the not too distant future.

Finally, it is worth mentioning that there is a genetic correlation between IQ and self-control (Polderman et al. 2009). This means that many of the alleles (gene variants) which cause individual variation in IQ also cause variation in self-control. This factor explains part of why intelligent individuals also tend to have higher than average self-control.

Racial Differences in Self-Control

Now that we’ve reviewed the evidence on individual differences in self-control, let’s turn to race. The empirical evidence suggests that Whites have higher self-control than Blacks. Unfortunately, there is not enough good data on Asians to make a determination. Anyway, here are all the studies I could find which compared Blacks and Whites on an experimental measure of self-control:

Michel (1958) conducted the first ever marshmallow type experiment on a sample of 53 children aged 7-9 living in Trinidad. He found Black children had less self-control than Asian children.

Herzberger and Dweck (1978) looked at a sample of 100 4rth grade American school children and found that Blacks had lower self-control than Whites even after controlling for socio-economic status.

Warner and Pleeter (2001) took advantage of a semi-natural experiment which came about due to the military. In the mid 1990’s the U.S Government offered sufficiently experienced military personnel two options when they retired: they could take a large lump sum of money now or agree to get a yearly payment from the military for the rest of their lives which, over time, would add up to far more than the lump sum. Warner and Pleeter were able to find data on the choices of 66,000 individuals and found that Blacks were 15% more likely than non-Blacks to take the lump-sum while White were .4% less likely than non-Whites to take the lump-sum. The differences between 15% and .4% implies that, in this sample, Asians probably had higher self control than Whites.

Wany, Rieger, and Hens (2011) utilized a sample of 5,291 university students from 45 countries and gave participants a chance to choose an immediate monetary reward or a larger long term reward. The chart below shows the proportion of people from different regions that chose the larger and less immediate reward:

Castillo, Ferraro, Jordan, and Petrie (2011) had a sample consisting of 82% of the student population of 4 middle schools in a poor Georgia school district. As they write “In our experiment, subjects are asked, orally and in writing, to make twenty decisions in total. For each decision, subjects are asked if they would prefer $49 one month from now or $49+$X seven months from now. The amount of money, $X, is strictly positive and increases over the twenty decisions.” Using this design, they were able to measure at what point people began to prefer the later reward and, thus, the strength of their preference for immediate gratification. Blacks were found to have significantly less self-control than Whites.

Borgo (2013) looked at data on 25,820 American households and found that Black homes had lower savings rates than White homes even after controlling for differences in income, age, family size, education, region of residence, and marriage. Normally, using savings rates as a measure of self-control would be problematic because it is obviously easier to save money if you have a large income, but this study utilized an impressive set of controls and so can be taken as a valid measure of self-control.

Finally, Andrade and Petry (2014) looked at a sample of 317 individuals with gambling problems and found that White gambling addicts had more self-control than Black gambling addicts even after controlling for education, drug problems, and income.

Thus, samples from many nations, and many decades, and of many ages, have consistently confirmed that Blacks have lower self-control than non-Blacks and that this difference remains after controlling for racial differences in socio-economic status.

Why Should We Care?

These Racial differences in self-control likely play a role in many other racial disparities which are often blamed on White people. Blacks make less money, are less healthy, have more kids out of wedlock, and are more criminal than Whites. As we’ve seen, self-control correlates with all these variables. Thus, we would expect Blacks to preform poorly in these areas based on their lower levels of self-control.

Blacks are also more likely than Whites to be obese, and to engage in risky behavior such as smoking, not wearing a seat belt, and not engaging in proper dental hygiene (Hersch 1996; CDC). These differences may too be caused by the Black population’s lower mean level of self-control.

Of course, self-control is not the only cause of these and other racial differences. But it probably plays a role, as do other psychological/sociological traits such as IQ and individualism. Knowing this is important, because without this knowledge people have a tendency to blame Whites for the life outcomes of Blacks and to take political action based on these views.

With this in mind, let’s turn to explaining why some groups have more self-control that others.

Why do Blacks Lack Self Control?

There are some good reasons to think that Blacks have lower self-control than Whites partly for genetic reasons. As we have already seen, these racial gaps appear early in life, have been found all over the world, and persist after controlling for socio-economic status.

Moreover, as we saw when reviewing Polderman et al. (2009), some of the same alleles that explain IQ variation also explain self-control variation and, as gone over elsewhere on this site, Blacks have lower IQ than Whites for genetic reasons.

These two facts are more important than they might at first appear: if the races differ in IQ for genetic reasons then the only way they could not differ in self-control as well is if the portion of their genome which impacts self-control but not IQ differed racially in a way that “made up” for the self-control gap that would be caused by IQ related genes. This is possible but would only happen in the face of some very powerful evolutionary pressures for which there is no evidence.

On top of this, as was discussed previously, self-control is significantly heritable and living in the same home doesn’t seem to make individuals any more similar than average in terms of self-control. The inert influence of the home environment makes it unlikely that racial differences could be caused by shared environmental factors. The significant heritability of self-control, and its polygenic nature, also makes it less likely that the environment alone explains the Black/White self-control gap.

Finally, the molecular genetic evidence which currently exists on self-control supports the hereditarian viewpoint. As I said before, we don’t know the identities of most genes involved in self-control. However, a handful of gene variants have been shown to associate with impulsive behavior and they are all more common in Blacks than in Whites (Minkov and Bond, 2015; Alt-Hypothesis).

Conclusion

In conclusion, Blacks have lower self-control than Whites and this is probably, in part, due to genetics. This difference in turn likely leads to many of the social and economic disparities we see between the races which are normally blamed on Whites. Hopefully, you will consider this and other group psychological differences next time you feel tempted to blame something on White people.