In the Classic Study by McGraw (1935) on the Twins

Multiple Choice

In the classic study by McGraw (1935) on the twins Johnny and Jimmy, it was found that Johnny skated at less than 1 year of age; Jimmy, who was not introduced to skating until almost a year later, however, never succeeded in this task. McGraw believed that Johnny's ability in skating was a function of which of the following?

A) Greater readiness
B) Greater recklessness
C) Lower center of gravity
D) Practice