The term that explains the rise of IQ scores across decades is:

• A. Flynn Effect
• B. The Hawthorne effect
• C. Jensen effect
• D. Spearman effect

Answer: (A)

The rise in IQ scores across decades is described by the Flynn Effect. This term captures the observed, consistent increases in average IQ test performance over time across many populations and different tests. It is believed to stem from environmental and cultural changes that enhance cognitive test-taking performance—factors like longer or better education, more exposure to abstract problem solving in everyday life, improvements in nutrition and health, smaller family sizes, and greater familiarity with standardized testing. Because of this secular trend, tests are periodically re-normed so the average remains around 100, highlighting that the change reflects external influences rather than a universal gain in innate ability. The other options describe different phenomena not responsible for this long-term population trend: the Hawthorne effect involves behavior changes due to being observed, while the remaining terms are not used to explain decade-spanning increases in IQ scores.