What Evidence Did Spearman Cite to Support His Concept of a "G

Multiple Choice

What evidence did Spearman cite to support his concept of a "g" factor in intelligence?

A) Mean performance on IQ tests rises until age 14-20, and then begins to decline.
B) Changes in the instructions can alter the mean performance of various groups.
C) Mean performance on IQ tests has been rising from one generation to the next.
D) Most people who do well on one intellectual task do well on others tasks also.