In a study of twins reared apart in the 1980s and 1990s, a sample of identical twins who were raised in separated environments produced scores on three measures of intelligence that were as similar to each other as a sample of twins who were raised together. Though the sample sizes were relatively small, this research has been repeated with approximately the same findings. We can have some confidence that these findings are valid because of the critical thinking principle of

Mr. Tully, the principal at an all-boys boarding school, has instituted a number of policies in order to try to curb violence and aggression among his students. Based on the research in social psychology, which of these policies will probably be ineffective?

a. encouraging aggressive sports, so that students can release their aggression b. restricting students' consumption of fried foods and sugary foods c. banning violent television programs d. banning violent video games

Which term refers to the combination of a strong sense of social cohesion with a high level of informal social control?

a. Self-efficacy b. Social attachment c. Leadership d. Collective efficacy