May 28, 2009

A Clue to the Puzzle of Persistent Poverty

by Tim Ogden

The inter-generational cycle of poverty has resisted several centuries worth of philanthropic efforts. Basically, the best predictor of adult poverty is childhood poverty. Children who grow up poor under-perform in school, get lower-paying jobs, have their own children earlier, and often remained mired in poverty. To fight this cycle, a huge proportion of anti-poverty philanthropy is devoted to improving school performance among poor children. Unfortunately there are few replicable success stories from these efforts.

Two studies published this month offer some hope of understanding why the cycle of poverty is so hard to break and what philanthropists can do about it.

First, research by Gary Evans and Michelle Schamberg from Cornell University has persuasively shown that poverty raises the allostatic load of a child, and a higher allostatic load has dramatic depressive effects on working memory. (The full paper is here.) In layman’s terms, allostatic load is a measure of the physiological effects of stress; working memory is the ability to hold and manipulate “bits” of information. Working memory is critical for math, reading comprehension and analytical thinking. While we’ve essentially always known that poor children perform below average in school, this research conclusive demonstrates one of the major factors in that poor performance. (Keep in mind that working memory isn’t a measure of intelligence but does have an impact on the type of learning most easily measured on standardized tests.)

The second study is a working paper by Roland Fryer of Harvard University that shows the first methodologically sound evidence of closing the achievement gap among a population of poor children. This success was achieved at an intensive middle school program run by Harlem Children’s Zone. This is big news since, much to the surprise of much of the public, to date there has been no evidence that any program can systematically and consistently improve school performance. Evans and Schamberg’s research perhaps sheds some light on why the intensive method used by HCZ (and, to be fair, by many other programs like KIPP) appears to be working: children with impaired working memory would benefit from longer periods of focused repetition and practice of key concepts and skills.

So there is a lot of good news: clear evidence of one source of poor children’s lowered school performance and evidence that something can be done to overcome some of the limitations.

Philanthropy’s drive to deal with “root causes” will undoubtedly send many looking for ways to reduce stress among poor children. That would lead us back into very questionable territory, however. Evans and Schamberg’s research doesn’t explain what the exact source of the stress experienced by poor children is, nor why the stress experienced by poor children is so different than that experienced by many non-poor children. For example the children of parents in the armed forces obviously experience heightened levels of stress, between frequent moves and having a parent deployed to a war zone—but there is no reason to believe that military children systematically underperform compared to their peers. Another large, unanswered, question is the role of nutrition. Allostatic load measures physiological changes that are also tied to poor diet and a lack of exercise (blood pressure, creatinine levels, BMI). Is there an interaction between stress and the poor diets of many children? We simply don’t know.  There’s also the fact that interventions that take poor children out of the typically stressful environment (by relocating them to middle-class housing for example) have been shown not to have much effect.

The lack of certainty about root causes should encourage us to focus philanthropy on interventions that help children with impaired working memories—and to fund research that can help understand the exact interrelation between allostatic load and poverty.