Since the beginning of the twentieth century, IQ scores around the world have been increasing at a rate of around three points per decade, leaving intelligence researchers puzzling over whether historical gains in IQ—known as the “Flynn effect”—reflect an increase in general intelligence or something else, be it better education, better nutrition or even bigger brains. A new paper published in the journal Learning and Individual Differences (2014) may have the answer: We’re getting better at taking tests.
People today are not only staying in school longer, the authors point out, but are more than ever taught to the test: Students are trained in test-taking strategies and heuristics that, according to the paper, can be applied to IQ-type problems. “People are exposed to the formats of tests all the time—they are able to detect certain regularities, and they are able to exploit those regularities,” said Michael Woodley, one of the paper’s co-authors, in an interview over Skype. “You were probably taught in school, for instance, to guess on multiple choice tests.” Even outside the classroom, increasing exposure—often online—to cognitive games like Sudoku, Bridge and Go mean that people are more familiar with IQ-type problems when they sit down to an IQ test. “We live in a more cognitively intense environment than ever,” said Woodley.
IQ tests are updated periodically. For example, the Wechsler Intelligence Scale for Children (WISC), originally developed in 1949, was updated in 1974, in 1991, and again in 2003. The revised versions are standardized based on the performance of test-takers in standardization samples. A standard score of IQ 100 is defined as the median performance of the standardization sample. Thus one way to see changes in norms over time is to conduct a study in which the same test-takers take both an old and new version of the same test. Doing so confirms IQ gains over time.