After taking a personality test that differentiates introverts from extraverts, two groups are formed. Tested individually, introverted participants are given a series of problems to solve in a small (36 square feet) room, while extroverts are given the same problems in a larger room (81 square feet). Which of the following is true?
a. the independent variable is shyness.
b. introversion/extraversion is a manipulated independent variable.
c. room size is the dependent variable.
d. personality (introvert/extravert) is confounded with room size.
