Journal Issue: School Readiness: Closing Racial and Ethnic Gaps Volume 15 Number 1 Spring 2005
Implications and Conclusions
The indirect evidence on the role of genes in explaining the black-white gap does not tell us how much of the gap genes explain and may be of no value at all in deciding whether genes do play a role. Because the direct evidence on ancestry, adoption, and cross-fostering is most consistent with little or no role for genes, it is unlikely that the black-white gap has a large genetic component.
But what if it does? What would be the implications for the school readiness of children? Much of the variance in human behavior, including cognitive ability and achievement test scores, can be traced to differences in individuals' genetic endowments. But as indisputable as is the role of genes in shaping differences in outcomes within races, so is the role of environment. Studies of young children show that environmental differences explain more variation than do genetic differences. And even studies showing an important role for genes in no way rule out the possibility of improving the school performance of disadvantaged children through interventions aimed at enhancing their school readiness. Interventions should stand or fall on their own costs and benefits and not be prejudged on the basis of genetic pessimism.
In fact, studies of the role of genes and environment in determining school readiness offer some useful lessons in designing and evaluating interventions. These studies show that normally occurring differences in preschool resources or parenting practices in working- and middle-class families have only limited effects on school readiness once the correlation due to parents' and children's genes is taken out of play.34 Thus small interventions that make only modest changes in the allocation of resources or the nature of parenting practices will have limited to modest effects at best. Effects will likely be somewhat larger if interventions target very disadvantaged families, probably because the room for improvement is greater.35
Achieving permanent effects on cognitive ability is harder than achieving large effects. Most environmental effects on cognitive ability seem to be like the effect of exercise on physical conditioning: profound but short-lived. But even short-lived improvements in cognitive ability can be valuable if they mediate longer-term changes in achievement—for example, if improved cognitive ability for some period of time allows students to learn to read more quickly, putting them on a permanently higher achievement path. And evidence suggests that programs aimed at improving cognitive ability do have long-term effects on achievement even if they have no significant long-term effects on cognitive ability. However, if interventions make even small permanent changes in behavior that support improved cognitive ability, they can set off multiplier processes, with improved ability leading to better environments and still further improvements in ability. If we knew what aspects of preschool programs help elevate cognitive ability, and if we could get children to continue to seek out such stimulation after they leave preschool programs, their increased ability could lead them to associate with more able peers, to have the confidence to take on more demanding academic challenges, and to get the further advantage of yet more positive stimulation from these activities. This, in turn, could further develop their cognitive ability. Long-lived effects are more likely to be large effects.
Effects are particularly likely to be large if an intervention saturates a social group and allows the individual multiplier effects to be reinforced by social multipliers or feedback effects. If students find themselves among others with greater ability, individual interactions and group activities are more likely to give rise to further improvements in cognitive ability. In this same vein, evaluations that do not take into account the social effects of the intervention on children who did not directly take part may be missing an important aspect of the effects of an intervention.
Although much of normal environmentally induced variance in cognitive ability seems to be transient, if interventions could induce even small long-lasting changes in behavior, they might produce very large effects through the multiplier process. Taking advantage of such processes may make it possible to overcome the black-white gap and put black and white children on an even footing.