Fernald and her colleagues found that children’s speed in the looking-while-listening task could be predicted by their socioeconomic status, or SES. Though nearly all mothers in the East Palo Alto sample had less than a high school education, there was enough of a range within the sample to show that maternal education level was correlated with faster response times. Researchers often make claims about the skills children possess at certain ages, but this study highlights that individual children can vary widely and that these claims may not generalize to all children in the same way. If researchers studying so-called general skills in campus labs “were to do the same experiment two miles away, they would very likely find different results or later emergence of that ability,” Fernald says.
Fernald and her team had a hard time figuring out how much of these differences were due to SES, or whether ethnicity, culture, or native language may have also contributed. To tease apart those factors, the lab needed to compare participants who differed in only one of those characteristics rather than all four. “Our answer to that—a conscious, difficult, and expensive answer—was that we need to open another community lab in a low-SES, English-speaking community,” said Fernald.
The San Francisco Bay Area is notorious for its high cost of living, so Fernald and her researchers needed to get away. They outfitted a 31-foot RV with a lab space and traveled to Mendocino, Lake, and Shasta counties in Northern California, where they tested children from low-income English-speaking families living at the poverty line. (The median per-capita income was $23,900, comparable to the East Palo Alto sample.)
Children participated in the looking-while-listening task at two ages: once at 18 months old, and again at 24 months old. Both the low-SES Northern California children and children from a high-SES group tested at Stanford improved between sessions, but at both ages, high-SES children were quicker to match a word with a picture. In fact, the high-SES kids’ speed at 18 months was roughly the same as the low-SES kids’ speed at 24 months. In other words, it appears that low-SES kids are roughly six months behind their high-SES counterparts.
Other researchers are also taking a systematic look at the effects of SES on children. Kimberly Noble, a developmental cognitive neuroscientist at Columbia University, has found that SES predicts differences in brain structure and function, which are related to language learning, memory, and self-control. For example, Noble has found that low-SES children tend to have a smaller hippocampus, a part of the brain used in the formation of memories, and show different levels of neural activity in language areas of the brain while reading. “From a scientific perspective, we really need to be taking [children’s] background into account,” she says. “SES is ignored in a lot of cognitive and developmental studies, and that’s probably inappropriate.”
Although a lot of these results sound gloomy, they are the first step in addressing the SES gap: acknowledging that SES does make a difference. Not every kid is raised by Ivy League grads that can afford to drive a BMW SUV to a developmental psychology lab, and it’s important to recognize that a family’s wealth and experience play a huge role in a child’s early life.
The next step is to break down the problem. The categorization of SES has many components: education level, employment, income, relative social standing. SES is unlikely to be the direct cause of differences we see in kids; rather, it indicates a host of other factors that vary between families, such as nutrition, stress levels, or the amount of time parents can invest in their children. For instance, in a low-SES family, both parents may need to work long hours, leaving less time to spend playing or talking with their kids. Less language input is correlated with slower language and reading skills at later ages.
A final step is to determine how these issues can be addressed. The good news is that some of the negative outcomes associated with low SES can be reduced by engaging children in active conversation or play. One simple suggestion for parents and educators is to talk with kids more; Fernald found that low-SES children whose parents talk to them more at home do better on language tasks. Of course, this is easier than it sounds—try working a 12-hour day and finding the energy to coo to your child about your day while making dinner. But this kind of research can provide basic tools for educators and policymakers to design programs and interventions that help families raise their children as successfully as possible.
Meanwhile, it’s important for researchers to continue probing the effects of SES. To do this, we need support. Developmental psych, in my experience, anyway, isn’t regarded as a sexy field, and many research groups are underfunded. Without grants to purchase equipment and hire people to develop outreach programs, it’s hard for researchers to explore populations beyond the “convenience sample” of privileged children in the lab. Fernald and Noble are not the only ones seeking out less advantaged children as test subjects, but they are still in the minority.
It’s not yet part of our field’s culture to consider children’s background as a factor, but it should be. “If I reported results about kids in Senegal, people would nail me—they would say, ‘You need to say that’s about children in Senegal,’ ” Fernald said. A similar qualifier should be added to the typical developmental psychology research sample: These are not generic kids; they are kids who have grown up with rich, well-educated parents who have given them a taste for edamame.