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Post by Admin on Aug 24, 2013 6:34:07 GMT
Murray (2005) notes that standardizations of the Kaufman-ABC in 1983 and 2004 show black IQs of 93 and 92.1. The K-ABC subtests were selected to minimize the black/white gap (Jensen, 1984) and diminish g in favour of short-term memory (Naglieri and Jensen, 1987). Jensen argues that the 1983 sample contained too great a range of ability, thus yielding an inflated SD and a diminished black/white gap (measured in SD units). Standardization samples of the Woodcock-Johnson (WJ) are excellent but the race data does not come from them. A research sample is taken from the full sample and a sub-sample of that (those who took all subtests used to compute IQ) used to calculate g scores. This sub-sub-sample comprised 90% of the 1987 research sample and just over 50% of the 1999 sample. Racial comparisons are based on blacks and whites in the subsub-sample with blacks more likely to be absent in both years. Wicherts (2005) gave us data for ages 1 to 65: black IQ was steady at 88 between 1987 and 1999; for those under 25, it stood at 90 in 1987 and 88.70 in 1999. Our analysis of standardization samples showed black IQ (age 12) rising from 85 in 1972 to 90.5 in 2002. For young blacks, the K-ABC gives 93 in 1983, Raven's 93 in 1985, the WJ 90 in 1987, and the Wonderlic 87 in 1992. Averaging these puts black IQ at 91 circa 1987. The three tests with results both near and after that date show no gains thereafter. The imperfect data support the contention that black school children attained.an IQ of 90.5 by 2002, but has them reaching that value 15 years earlier than our results from standardisation samples. Lynn (1996, p. 272) uses results by age to infer trends. Age patterns do not chart trends over time but rather, reflect an altering black/white gap as cohorts age. His 85.83 (our convention) for blacks aged 6 to 17 (1986) is close to our 84 for the WISC-III (1989).Richard Lynn's studies on racial IQ differences in the 1970s, which concluded that African Americans had an average IQ of 85, are not relevant now as his research was done in the 1970s, reflecting dismal social conditions at the time. The recent study (Dickens 2006) found that blacks gained 4 to 7 IQ points between 1972 and 2002 and black school children had an IQ of 90.5 in 2002. Black Americans Reduce the Racial IQ Gap: Evidence from Standardization Samples
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Post by Admin on Aug 25, 2013 2:11:10 GMT
Numerous studies have estimated the rate of European admixture in African Americans; these studies have documented average admixture rates in the range of 10% to 20%, with some regional variation, but also with substantial variation among individuals [1]. For example, the largest study of African Americans to date, based on autosomal short tandem repeat (STR) markers, found an average of 14% European ancestry with a standard deviation of approximately 10%, and a range of near 0 to 65% [1], whereas another study based on ancestry informative markers (AIMs) found an average of 17.7% European ancestry with a standard deviation of 15.0% [2]. By using nine AIMs, Parra and colleagues [3] found substantial variation of European ancestry proportions in African-American populations across the United States, ranging from just over 10% in a Philadelphia group to more than 20% in a New Orleans population. Similar levels (11% to 15%) of European ancestry also were reported by Tishkoff and co-workers [4], based on more than 1,000 nuclear microsatellite and insertion/deletion markers. These results were confirmed in the estimation of IA by using the program frappe (also in Figure 1). The amount of European ancestry shows considerable variation, with an average (± SD) of 21.9% ± 12.2%, and a range of 0 to 72% (Table 1). Characterizing the admixed African ancestry of African Americans (Zakharia et al. 2009).
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Post by Admin on Sept 1, 2013 2:47:38 GMT
For people struggling to live paycheck-to-paycheck, daily life can sometimes seem like a gauntlet of impossible-to-answer questions – Can I afford to put food on the table? Will I make rent this month? What will happen if I lose my job? or my car breaks down? For many, those questions become so persistent it's hard to concentrate on anything else. And that's exactly the problem, says Harvard economist Sendhil Mullainathan. The accumulation of those money woes and day-to-day worries leaves many low-income individuals not only struggling financially, but cognitively, Mullainathan said. In a study published August 29 in Science, he showed that the "cognitive deficit" caused by poverty translates into as many as 10 IQ points. To understand the cognitive load that comes with financial constraints, Mullainathan and colleagues conducted studies of two dramatically different groups – shoppers at a mall in New Jersey and sugar cane farmers in rural India. In the mall study, researchers gathered dozens of low- and middle-income shoppers and subjected them to a battery of tests to measure IQ and impulse control. Half of those who took part in the study, however, were first prompted with a "teaser" question – what would they do if their car broke down, and the repair cost $1,500 – designed to get participants thinking about their own financial worries. "For the poor, because these monetary concerns are just below the surface, the question brings them to the top," Mullainathan said. "The result was, for that group, the gap between the rich and the poor goes up, in both IQ and impulse control. There was no gap in the other group, but ask them anything that makes them think about money and you see this result." "The effect here is about two-thirds of the size of the effect found in the mall study – it's at least nine or 10 IQ points, just between these months," Mullainathan added. "Between these two studies, you both see the mechanism at work, and you see that, in the real world, these effects are enormous. phys.org/news/2013-08-poverty-cognitive-ten-iq.html
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Post by Admin on Sept 1, 2013 16:50:02 GMT
The existence of substantial class differences in average IQ have been widely accepted in the scientific literature and children of professional and managerial parents recorded average IQ scores of 113, compared with an average of around 96 for the children of unskilled manual workers. The socioeconomic differences associated with social class have much larger effect on IQ than biological factors and good home environments could add 12–18 points to the IQ of adopted children who are either white or black. Dickens and Flynn (2006) found that blacks gained 5.5 IQ points on whites between 1972 and 2002, which is closely associated with growing economic prosperity among African Americans in the past few decades, and black children from middle-class backgrounds usually perform better than average white children. Research suggests that part of the Black–White IQ gap may be attributable to the fact that Blacks, on average, tend to live in more stressful environments than do Whites. This is particularly the case in urban environments, where Black children are exposed to multiple stressors. Sharkey (2010), for example, has recently found that Black children living in Chicago (ages 5–17) scored between 0.5 and 0.66 SD worse on tests (both the WISC-Revised and the Wide Range Achievement Test-3) in the aftermath of a homicide in their neighborhood. Sharkey’s data show that debilitating effects were evident among children regardless of whether they were witnesses to the homicide or had simply heard about it. www.apa.org/pubs/journals/releases/amp-67-2-130.pdfRacial differences in brain size and intelligence start early in life. The National Collaborative Perinatal Project, to which we will return later, followed more than 35,000 American children from birth to age seven (Broman, Nichols, Shaugnessy & Kennedy, 1987). Analyses shown in Fig. 1 revealed that Asian Americans had larger average cranial capacities than Whites, and Whites had larger cranial capacities than Blacks at birth, 4 months, 1 year,and 7 years. The same differences were present among adults (Rushton, 1992). At 7 years of age, head circumference and IQ correlated r = 0.20 in all three races and Asian American children averaged an IQ of 110, White children an IQ of 102, and Black children an IQ of 90. Moreover, Asian Americans, who averaged the largest craniums, were the shortest in stature and the lightest in weight, whereas Blacks, who averaged the smallest craniums, were the tallest in stature and the heaviest in weight (see Fig. 2). psychology.uwo.ca/faculty/rushtonpdfs/sizematters.pdf
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Post by Admin on Sept 3, 2013 16:33:15 GMT
It's known that adoption into upper-middle class families has a positive influence on the IQ and school performance of adopted children and the unpublished thesis on transnationally adopted Koreans by Linda Gildea (1992) showed that the average IQ of 43 adopted Korean children raised by white American families was approximately 10 points higher than the Korean national average (106). It's obvious that the socioeconomic status of the American parents positively affected Korean children's intelligence as 74% of the fathers and 68% of the mothers were college graduates and 81% of the fathers and 55% of the mothers were professionals. In this kind of environment, adopted children of any ethnic background are likely to have higher IQs than they normally do and Elsie Moore (1986) found that black children adopted by white parents had IQ scores 13.5 points higher than usual. Drawing on Wilson (1987), this article assesses two hypotheses concerning the relationship between neighborhood disadvantage and crime: (1) extremely disadvantaged neighborhoods have unusually high rates of crime; and (2) local structural disadvantage is equally important in influencing crime in black and white neighborhoods. Hence, racial differences in structural disadvantage account for black-white differences in crime across communities. To test these hypotheses, we examine 1990 census and crime data for load areas in the city of Columbus, Ohio. The analysis lends substantial support for both arguments, particularly for the influence of structural disadvantage on violent crime. The researchers examined crime rates for 1989 to 1991 in 177 census tracts in Columbus. They separated the census tracts -- which are the units researchers use to approximate neighborhoods -- into those with low poverty rates (less than 20 percent), high rates (20 to 40 percent) and extreme rates (more than 40 percent). They also separated the census tracts into those that were predominantly white or Black (at least 70 percent of one race). Along with poverty rates, the researchers also compared neighborhoods on other measures of disadvantage: levels of male joblessness, female-headed families, and professionals living in the community. They then calculated a disadvantage index that combined all of these measures. Violent crime rates were lowest in those neighborhoods with low disadvantage, regardless of whether they were predominantly Black or white. Extremely disadvantaged neighborhoods had violent crime rates that were 16.3 per 1000 higher than rates in low disadvantage neighborhoods. Violent crime rates in extremely disadvantaged white neighborhoods were very similar to rates in comparable Black neighborhoods and the violent crime rate in highly disadvantaged Black areas was 22 per 1,000 residents, not much different from the 20 per 1,000 rate in similar white communities. researchnews.osu.edu/archive/badcomm.htm
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