Hockenbury Discovering Psychology 5th txtbk

The Nature of Intelligence307Culture and Educational AchievementThese little girls attend kindergarten inTokyo, Japan. Children in Japan attendschool six days a week. Along with spendingmore time in school each year thanAmerican children, Japanese children growup in a culture that places a strong emphasison academic success as the key tooccupational success.Why the increasing gap once children enter school? Japanese and Chinese studentsspend more time in school, spend more time doing homework, and experiencemore pressure and support from their parents to achieve academically. Inaddition, the Japanese and Chinese cultures place a high value on academic achievement(Gardner, 1995; Li, 2005). Clearly, the difference between American andAsian students is due not to genetics but to the educational system.Differences Within Groups Versus Differences BetweenGroupsSome group differences in average IQ scores do exist (Ceci & Williams, 2009). Inmany societies, the average IQ scores of minority groups are lower than the averageIQ scores of the dominant or majority groups. The question is how to explain suchdifferences. But heritability cannot be used to explain group differences. Althoughit is possible to estimate the degree of difference within a specific group that is dueto genetics, it makes no sense to apply this estimate to the differences betweengroups (Rose, 2009). Why? A classic analogy provided by geneticist RichardLewontin (1970) may help you understand this important point (see Ceci &Williams, 2009).Suppose you have a 50-pound bag of corn seeds and two pots. A handful of seedsis scooped out and planted in pot A, which has rich, well-fertilized soil. A secondhandful is scooped out and planted in pot B, which has poor soil with few nutrients(see Figure 7.9 on the next page).Because the seeds are not genetically identical, the plants within group A will varyin height. So will the plants within group B. Given that the environment (the soil)is the same for all the plants in one particular pot, this variation within each groupof seeds is completely due to heredity—nothing differs but the plants’ genes.However, when we compare the average height of the corn plants in the twopots, pot A’s plants have a higher average height than pot B’s. Can the differencein these average heights be explained in terms of overall genetic differences betweenthe seeds in each pot? No. The overall differences can be attributed to the two differentenvironments, the good soil and the poor soil. In fact, because the environmentsare so different, it is impossible to estimate what the overall genetic differencesare between the two groups of seeds.Note also that even though, on the average, the plants in pot A are taller thanthe plants in pot B, some of the plants in pot B are taller than some of the plants in