“The Creativity Crisis: The Decrease in Creative Thinking Scores on the Torrance Tests of Creative Thinking”, 2011-11-09 (; similar):
The Torrance Tests of Creative Thinking (TTCT) was developed in 1966 and renormed 5×: in 1974, 1984, 1990, 1998, and 2008. The total sample for all 6 normative samples included 272,599 kindergarten through 12th grade students and adults.
Analysis of the normative data showed that creative thinking scores:
remained static or decreased, starting at 6th grade. Results also indicated that since 1990, even as IQ scores have risen, creative thinking scores have statistically-significantly decreased. The decrease for kindergartners through third graders was the most statistically-significant.