8. Correlation studies are often used to help determine whether certain characteristics are controlled more by genetic influences or by environmental influences.

These studies often examine adopted children and compare their behaviors with the behaviors of their birth parents and their adoptive parents. One study examined how much time individuals spend watching TV (Plomin, Corley, DeFries, & Fulker, 1990). The following data are similar to the results obtained in the study.

Amount of Time Spent Watching TV Adopted Birth Adoptive Children Parents Parents 201 334 642 110 310 023 532 213 533

a. Compute the correlation between the children and their birth parents.

b. Compute the correlation between the children and their adoptive parents.

c. Based on the two correlations, does TV watching appear to be inherited from the birth parents or is it learned from the adoptive parents?