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What Happens to Fluid and Crystallized Intelligence as People Age and How Each Relates to Overall IQ Scores?

According to research by the Illinois State Board of Education, fluid intelligence peaks in early adulthood before a gradual decline, while crystallized intelligence continues to increase well into middle age. Understanding what happens to fluid and crystallized intelligence as people age and how each relates to overall IQ scores is key to appreciating the complex nature of human cognitive development throughout the lifespan.