When Researchers Use a ____________ Design, They Typically Find That

Multiple Choice

When researchers use a ____________ design, they typically find that both fluid and crystallized intelligence decline relatively early in life, but when they use a(n) ___________ design, they often find that both of these abilities remain stable until much later in life.

A) correlational; experimental
B) cross-sectional; longitudinal
C) naturalistic observation; self-report
D) placebo; double-blind