Bell Curve

382 The National Context Social Behatior and the Prevaknce of Low Cognitive Ability 383Fifty-six percent of all children from bottom decile in home environmentwere born to mothers in the bottom 20 percent of intelligenceSixty-three percent of children who lived in poverty throughout thefirst three years had mothers in the bottom 20 percent of intelligenceChildren in the worst home environments Cumulative(bars)(line)Children living in poverty for 1st 3 yrs.(bars)Cumulative(line)Children in PovertyIQ DecileThe proportion of children living in poverty is one of the most frequentlycited statistics in public policy debates and one of the most powerfulappeals to action. In considering what actions might be taken, andwhat will and won't work, keep the following figure in mind. It showsthe distribution of maternal cognitive ability among children who spenttheir first three years below the poverty line. Mothers whose childrenlived in poverty throughout their first three years averaged an IQ of 84.Forty-one percent had mothers in the very bottom decile in cognitiveability. In all, 93 percent were born to women in the bottom half of theIQ distribution. Of all the social problems examined in this chapter,poverty among children is preeminently a problem associated with lowIQ-in this case, low IQ among the mothers.Developmental Problems Among ChildrenThe prevalence of developmental problems among children is skewedtoward the lower half of the IQ distribution. Rather than present graphsfor each of them, the table below summarizes a consistent situation. See. .1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10thIQ DecilePrevalence of Low IQ Among Mothers ofChildren with Developmental ProblemsPercentage ofThese Children Mean IQChildren in the with Mothers in ofWorst Decile on: Bottom: Mothers20% 50%of IQ of 1QFriendliness index,12-23 mos. 49 82 88Difficulty index,12-23 mos. 40 7 1 91Motor and social developmentindex, hirth-47 mos. 38 67 93Behavioral problems index,children ages 4-1 1 yrs. 42 78 90