Poverty and IQ

Among the section of the right that regards IQ as the only explanatory variable in society aside from money, the relationship between poverty and IQ is used to defend the huge inequities in ours society as an outcome of a functioning meritocracy. It does not require much deep inspection of how modern capitalist societies work to see that they are neither functioning well not are they meritocracies.

The opposite view is that difference in performance on IQ is more caused by poverty than vice-versa. There are multiple reasons for believing this from access to education, motivation and attitudes towards the role of test taking in a person’s life (e.g. how much effort do you put into something that you expect to do poorly in?) However, specific causes are hard to demonstrate empirically. Hard to demonstrate, perhaps, but maybe a clever experimental design can shed more light on that.

I was just reading a 2013 paper that looked at the impact of poverty on cognition in an interesting way: Poverty Impedes Cognitive Function Anandi Mani, Sendhil Mullainathan, Eldar Shafir, Jiaying Zhao (Abstract http://science.sciencemag.org/content/341/6149/976 )

“The poor often behave in less capable ways, which can further perpetuate poverty. We hypothesize that poverty directly impedes cognitive function and present two studies that test this hypothesis. First, we experimentally induced thoughts about finances and found that this reduces cognitive performance among poor but not in well-off participants. Second, we examined the cognitive function of farmers over the planting cycle. We found that the same farmer shows diminished cognitive performance before harvest, when poor, as compared with after harvest, when rich. This cannot be explained by differences in time available, nutrition, or work effort. Nor can it be explained with stress: Although farmers do show more stress before harvest, that does not account for diminished cognitive performance. Instead, it appears that poverty itself reduces cognitive capacity. We suggest that this is because poverty-related concerns consume mental resources, leaving less for other tasks. These data provide a previously unexamined perspective and help explain a spectrum of behaviors among the poor. We discuss some implications for poverty policy.”

Poverty Impedes Cognitive Function Anandi Mani et al. Science 341, 976 (2013); DOI: 10.1126/science.1238041

First some caveats. It’s two fairly narrow experiments both of which have some contrived circumstances (for good reasons). I don’t know if these results have been reproduced.

Having said that it is interesting to look at the two experiments and what the results were.

The basic hypothesis was this:

“We propose a different kind of explanation, which focuses on the mental processes required by poverty. The poor must manage sporadic in- come, juggle expenses, and make difficult trade- offs. Even when not actually making a financial decision, these preoccupations can be present and distracting. The human cognitive system has lim- ited capacity (12–15). Preoccupations with pressing budgetary concerns leave fewer cognitive resources available to guide choice and action.

Poverty Impedes Cognitive Function Anandi Mani et al. Science 341, 976 (2013); DOI: 10.1126/science.1238041

To test this they compared individual performance on cognitive test both with and without some degree of financial stress. The first was a ‘laboratory study’ that demonstrates the impact as a kind of proof of concept. The financial stress here is artificial but if anything that makes the results more interesting.

In the first study the researchers went to a New Jersey shopping mall and recruited shoppers (who got paid) to take part in four related experiments. The basic principle of each experiment was two tasks. One task asked people to consider a realistic but hypothetical financial problem. For example, they might be asked about their car having to get some urgent repairs. Participants randomly were given a ‘hard’ situation were the costs would be high or an ‘easy’ situation were the costs were low but both easy & hard situations were cognitively similar. The second task was a more classic IQ style test (Raven’s Progressive Matrices) and a spatial compatibility task.

The four versions were designed to control for cognitive impacts of the first activity. The first two versions changed the amount of maths needed in the financial scenario. The third version added incentives to correct answers. The fourth version separated the two activities so that the first was completely finished before the person sat the IQ style test.

The group being studied also provided information on their income and the the data was analysed by looking at the participants as either rich or poor. The point being to see not if the ‘rich’ participants performed better on the IQ test but rather how much impact did the first activity (i.e. having to engage with a potentially financial stressful situation) have on the cognitive scores

Accuracy on the Raven’s matrices and the cognitive control tasks in the hard and easy conditions, for the poor and the rich participants in experiment 1

The graph is for experiment 1 but the results were similar for all four. The impact of ‘hard’ versus ‘easy’ of the first activity on the second activity was much bigger for people with less money. For the wealthier participants, the ‘hard’ scenario had less impact, almost certainly because they were faced with a situation that would have less of an impact on their own finances. In short having to worry about money and how you will pay for things that you need has a genuine and measurable impact on your ability to perform some cognitive tasks… At least within this experimental scenario but that a PRETEND bit of financial stress had a measurable impact is itself notable.

The second study was quite different and looked at some real financial stress.

“Our second study examined 464 sugarcane farmers living in 54 villages in the sugarcane- growing areas around the districts of Villupuram and Tiruvannamalai in Tamil Nadu, India. These were a random sample of small farmers (with land plots of between 1.5 and 3 acres) who earned at least 60% of their income from sugarcane and were interviewed twice—before and after harvest—over a 4-month period in 2010. There were occasional nonresponses, but all of our pre- post comparisons include only farmers we surveyed twice. “

Poverty Impedes Cognitive Function Anandi Mani et al. Science 341, 976 (2013); DOI: 10.1126/science.1238041

The work of the sugarcane farmers created a set of natural controls. An individual farmer has only one harvest a year and hence essentially only one pay-day a year. However, the timing of harvests are staggered over several months. So at a particular time of year it maybe post-harvest for one farmer but pre-harvest for another. The farmers naturally face greater financial pressure the longer it has been since their last harvest.

The results showed a similar but slightly smaller impact than the laboratory study. Farmers performed better on an IQ style test (Raven’s Progressive Matrices) after* they had been paid than before and the difference was large.

How large are these effects? Sleep researchers have examined the cognitive impact (on Raven’s) of losing a full night of sleep through experi- mental manipulations (38). In standard deviation terms, the laboratory study findings are of the same size, and the field findings are three quarters that size. Put simply, evoking financial concerns has a cognitive impact comparable with losing a full night of sleep. In addition, similar effect sizes have been observed in the performance on Raven’s matrices of chronic alcoholics versus normal adults (39) and of 60- versus 45-year-olds (40). By way of calibration, according to a common approximation used by intelligence researchers, with a mean of 100 and a standard deviation of 15 the effects we observed correspond to ~13 IQ points. These sizable magnitudes suggest the cognitive impact of poverty could have large real consequences.

Poverty Impedes Cognitive Function Anandi Mani et al. Science 341, 976 (2013); DOI: 10.1126/science.1238041

Put another way: we don’t think in isolation (even if you aren’t neurotypical). Background concerns and worries all have an impact on how you think and your capacity to problem solve. They definitely have an impact on your thinking in the artificial conditions of an IQ test.

*[There were also controls on the order they did the tests. Some of the participants took the test first after they had been paid and then were tested later in the year when their money had run low.]

12 thoughts on “Poverty and IQ

  1. I have a feeling I have seen another similar study referenced somewhere (this one based in the US not India), but I am sick and I may be misremembering.

    I have a tendency to valorise the ‘impoverished student’ stereotype, having spent some time as a very impoverished student. It’s easy to romanticise some aspects, and forget how wearing it was after a couple of years living that way. I should remember this study when I am inclined to grumble at how easy my kids have things.

    Liked by 1 person

    1. angharad: It’s easy to… forget how wearing it was after a couple of years living that way. I should remember this study when I am inclined to grumble at how easy my kids have things.

      Every once in a while, something will remind me of how I worked part-time jobs all through university, and ate ramen noodles (5 pkg for $1) — or, for the occasional treat! 99c Kraft boxed Macaroni & Cheese mixes — on Sunday nights when the dorm food service was not open. It’s a long time ago and a world away, and doesn’t seem so painful now, but at the time it was a real grind. And it wasn’t until at least 10 years after graduation that I finally paid off my student loans and no longer felt as though I was constantly scraping to survive from one paycheck to the next. It’s like John Scalzi said, the first time you can actually fill up your car’s gas tank without being concerned about the total amount, instead of just putting in the $5 or $10 that you can afford, is a real revelation.

      Liked by 2 people

  2. The mental gymnastics that must be done to try to prove your point instead of going where the evidence leads is astounding. The evidence shows that IQ is highly predictive and the causal factor. Can poverty contribute to the cycle once you are there> Sure, but twin and adoption studies show that SES does not improve outcome for those who are lower IQ. The question is what do you do in a meritocracy (the best available system) when people have low IQ’s and cannot be productive members of society (many can, but many cannot). That is a hard problem, and where we should be focusing our attention.


    1. I’m sure that you’ll be happy to post citations supporting those assertions you’re throwing around. I look forward to reading them. 😀


    2. As far as I can see “mental gymnastics” is a synonym for thinking. However, you flatter me unnecessarily. The evidence that poverty and financial stress impacts IQ and other cognitive tests is demonstrated in the research which is both described and adequately referenced in the post above. As you can see, it’s not a small effect either.

      Moving on to your broader question. Let us imagine for a moment a world in which poverty did not impact IQ and it lower IQ was purely genetic and any correlation between poverty and IQ was caused by low IQ rather than vice-versa. In such a “meritocracy” a section of society would through no fault of their own and with the odds stacked against them be condemned to poverty with little chance of bettering themselves. A just society would not condone such a circumstance for physical disability and I can see no justice (or liberty) in a society that would condone that outcome through some kind of genetic predestination by virtue of IQ. Ensuring that all people could live purposeful lives with a living wage would be the only sane and moral choice. The core moral justification for free-market capitalist meritocracy is social mobility – the genetic predestination scenario would essentially gut capitalist meritocracy of its core defence. The only decent response would be a more social-democratic society with improved economic equality and a substantial safety net for people with lower incomes and less cognitively demanding jobs.

      Now, let’s consider the more realistic scenario – poverty does impact cognitive performance to some degree (and we know that it does and that is not contradicted by other factors). Whence then is this meritocracy? Poverty becomes self-reinforcing – which is an observation that people have made independently. Social mobility is no longer impossible in principle but is actually denied in practice. Again, the only decent response would be a more social-democratic society with improved economic equality and a substantial safety net for people with lower incomes and less cognitively demanding jobs.

      Capitalist meritocracy is undermined by either scenario. To sustain “meritocracy” as myth of capitalism would require IQ to be something that had no impact on life success.

      {does a twirl a double back-flip and lands on my feet with my hands in the air}


    3. The question is what do you do in a meritocracy (the best available system)

      Are you effing kidding me? Assumes facts not in evidence, to say the least.

      Even if the rest of your ridiculous screed is true (it isn’t), a meritocracy is unethical and immoral. Full stop. It’s also selfish and privileged. An IQ, either high or low, does not make anyone more or less human, and for you to suggest this is simply terrible. This idea is the starting point for a horrible slope, and last century, if you remember, we fought an entire war over it.


      1. Meritocracy is just fine when it comes to rewarding my superiority to the common herd, but it’s intolerable when it elevates, above me, people who are just a bunch of genetic freaks (and living proof that IQ doesn’t make you smart)! Who wants to defer to those ivory-tower bozos? There’s clearly such a thing as going too far, and the fact that I stand right smack at the defining line makes me wonder if maybe there isn’t a God after all.


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