Chapter 11

 EXPERIMENTAL DILEMMA

A researcher studying developmental changes in intelligence conducted the following cross-sectional study. The Wechsler Adult Intelligence Scale (a reliable and valid test) was given to 20 people at each of the following ages: 20, 30, 40, 50, 60, and 70. These are the results:

               AGE                 IQ

                   20               120

                   30               110

                   40               100

                   50                 95

                   60                 93

                   70                 89

From these results the researcher concluded that intelligence peaks in the early years and declines steadily thereafter. Do you agree with the researcher's conclusion? Why or why not?