What is the g factor in intelligence research? I keep seeing this term but I’m not sure what it means. Is it the same thing as IQ, or something different? Why do psychologists talk about g as if it’s the most important thing?
The g factor, or general intelligence, is the common element that underlies performance across different cognitive tasks. People who do well on one type of mental task tend to do well on others.
The g factor is general intelligence, a concept developed by Charles Spearman in 1904. He noticed that people’s scores on different cognitive tests tend to correlate positively, meaning someone good at verbal reasoning is likely also decent at spatial tasks, math, memory, etc. G represents this common variance, the shared cognitive ability underlying all mental tasks. It’s not the same as IQ, but IQ tests attempt to measure g. Think of it hierarchically: g is at the top as general ability, then you have specific abilities like verbal, spatial, and quantitative underneath. G is considered important because it’s the single best predictor of academic achievement, job performance, and learning capacity across domains. It’s one of psychology’s most replicated findings and has strong biological correlates in brain structure and function.